Thomas Robert Malthus

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Thomas Robert Malthus FRS
Portrait by John Linnell
Born	13/14 February 1766 Westcott, Surrey, England
Died	23 December 1834 (aged 68) Bath, Somerset, England
Spouse(s)	Harriet Eckersall ​ (m. 1804)​
Children	3
Field	Demography macroeconomics
School or tradition	Classical economics
Alma mater	Jesus College, Cambridge
Influences	David Ricardo Jean Charles Léonard de Sismondi
Contributions	Malthusian growth model

Thomas Robert Malthus FRS (/ˈmælθəs/; 13/14 February 1766 – 23 December 1834) was an English cleric, scholar and influential economist in the fields of political economy and demography.

In his 1798 book An Essay on the Principle of Population, Malthus observed that an increase in a nation's food production improved the well-being of the population, but the improvement was temporary because it led to population growth, which in turn restored the original per capita production level. In other words, humans had a propensity to utilize abundance for population growth rather than for maintaining a high standard of living, a view that has become known as the "Malthusian trap" or the "Malthusian spectre". Populations had a tendency to grow until the lower class suffered hardship, want and greater susceptibility to famine and disease, a view that is sometimes referred to as a Malthusian catastrophe. Malthus wrote in opposition to the popular view in 18th-century Europe that saw society as improving and in principle as perfectible.

Malthus saw population growth as being inevitable whenever conditions improved, thereby precluding real progress towards a utopian society: "The power of population is indefinitely greater than the power in the earth to produce subsistence for man". As an Anglican cleric, he saw this situation as divinely imposed to teach virtuous behaviour. Malthus wrote that "the increase of population is necessarily limited by the means of subsistence"; "population does invariably increase when the means of subsistence increase"; and "the superior power of population is repressed by moral restraint, vice and misery".

Malthus criticized the Poor Laws for leading to inflation rather than improving the well-being of the poor. He supported taxes on grain imports (the Corn Laws). His views became influential and controversial across economic, political, social and scientific thought. Pioneers of evolutionary biology read him, notably Charles Darwin and Alfred Russel Wallace. Malthus' failure to predict the industrial revolution was a frequent criticism of his theories.

Malthus laid the "...theoretical foundation of the conventional wisdom that has dominated the debate, both scientifically and ideologically, on global hunger and famines for almost two centuries." He remains a much-debated writer.

Early life and education

The sixth child of Henrietta Catherine Graham and Daniel Malthus, Robert Malthus grew up in The Rookery, a country house in Westcott, near Dorking in Surrey. William Petersen describes Daniel Malthus as "a gentleman of good family and independent means [...] [and] a friend of David Hume and Jean-Jacques Rousseau". The young Malthus received his education at home in Bramcote, Nottinghamshire, and then at the Warrington Academy from 1782. Warrington was a dissenting academy, which closed in 1783. Malthus continued for a period to be tutored by Gilbert Wakefield, who had taught him there.

Malthus entered Jesus College, Cambridge, in 1784. While there, he took prizes in English declamation, Latin and Greek, and graduated with honours, Ninth Wrangler in mathematics. His tutor was William Frend. He took the MA degree in 1791, and was elected a Fellow of Jesus College two years later. In 1789, he took orders in the Church of England, and became a curate at Oakwood Chapel (also Okewood) in the parish of Wotton, Surrey.

Population growth

Essay on the principle of population, 1826

Malthus was a demographer before he was ever considered an economist. He first came to prominence for his 1798 publication, An Essay on the Principle of Population. In it, he raised the question of how population growth related to the economy. He affirmed that there were many events, good and bad, that affected the economy in ways no one had ever deliberated upon before. The main point of his essay was that population multiplies geometrically and food arithmetically, therefore whenever the food supply increases, population will rapidly grow to eliminate the abundance. Eventually in the future, there would not be enough food for the whole of humanity to consume and people would starve. Until that point, the more food made available, the more the population would increase. He also stated that there was a fight for survival amongst humans and that only the strong who could attain food and other needs would survive, unlike the impoverished population he saw during his time period.

Malthus wrote the original text in reaction to the optimism of his father and his father's associates (notably Jean-Jaques Rousseau) regarding the future improvement of society. He also constructed his case as a specific response to writings of William Godwin (1756–1836) and of the Marquis de Condorcet (1743–1794). His assertions evoked questions and criticism, and between 1798 and 1826 he published six more versions of An Essay on the Principle of Population, updating each edition to incorporate new material, to address criticism, and to convey changes in his own perspectives on the subject. Even so, the propositions made in An Essay were shocking to the public and largely disregarded during the 19th century. The negativity surrounding his essay created a space filled with opinions on population growth, connected with either praise or criticism of ideas about contraception and the future of agriculture.

The Malthusian controversy to which the Essay gave rise in the decades following its publication tended to focus attention on the birth rate and marriage rates. The neo-Malthusian controversy, comprising related debates of many years later, has seen a similar central role assigned to the numbers of children born. On the whole it may be said that Malthus's revolutionary ideas in the sphere of population growth remain relevant to economic thought even today and continue to make economists ponder about the future.

Travel and further career

In 1799, Malthus made a European tour with William Otter, a close college friend, travelling part of the way with Edward Daniel Clarke and John Marten Cripps, visiting Germany, Scandinavia and Russia. Malthus used the trip to gather population data. Otter later wrote a Memoir of Malthus for the second (1836) edition of his Principles of Political Economy. During the Peace of Amiens of 1802 he travelled to France and Switzerland, in a party that included his relation and future wife Harriet.

In 1803, he became rector of Walesby, Lincolnshire.

In 1805, Malthus became Professor of History and Political Economy at the East India Company College in Hertfordshire. His students affectionately referred to him as "Pop", "Population", or "web-toe" Malthus.

Near the end of 1817, the proposed appointment of Graves Champney Haughton to the college was made a pretext by Randle Jackson and Joseph Hume to launch an attempt to close it down. Malthus wrote a pamphlet defending the college, which was reprieved by the East India Company within the same year, 1817.

In 1818, Malthus became a Fellow of the Royal Society.

Malthus–Ricardo debate on political economy

During the 1820s, there took place a setpiece intellectual discussion among the exponents of political economy, often called the Malthus–Ricardo debate after its leading figures, Malthus and theorist of free trade David Ricardo, both of whom had written books with the title Principles of Political Economy. Under examination were the nature and methods of political economy itself, while it was simultaneously under attack from others. The roots of the debate were in the previous decade. In The Nature of Rent (1815), Malthus had dealt with economic rent, a major concept in classical economics. Ricardo defined a theory of rent in his Principles of Political Economy and Taxation (1817): he regarded rent as value in excess of real production—something caused by ownership rather than by free trade. Rent therefore represented a kind of negative money that landlords could pull out of the production of the land, by means of its scarcity. Contrary to this concept, Malthus proposed rent to be a kind of economic surplus.

The debate developed over the economic concept of a general glut, and the possibility of failure of Say's Law. Malthus laid importance on economic development and the persistence of disequilibrium. The context was the post-war depression; Malthus had a supporter in William Blake, in denying that capital accumulation (saving) was always good in such circumstances, and John Stuart Mill attacked Blake on the fringes of the debate.

Ricardo corresponded with Malthus from 1817 about his Principles. He was drawn into considering political economy in a less restricted sense, which might be adapted to legislation and its multiple objectives, by the thought of Malthus. In Principles of Political Economy (1820) and elsewhere, Malthus addressed the tension, amounting to conflict he saw between a narrow view of political economy and the broader moral and political plane. Leslie Stephen wrote:

If Malthus and Ricardo differed, it was a difference of men who accepted the same first principles. They both professed to interpret Adam Smith as the true prophet, and represented different shades of opinion rather than diverging sects.

It is now considered that the different purposes seen by Malthus and Ricardo for political economy affected their technical discussion, and contributed to the lack of compatible definitions. For example, Jean-Baptiste Say used a definition of production based on goods and services and so queried the restriction of Malthus to "goods" alone.

In terms of public policy, Malthus was a supporter of the protectionist Corn Laws from the end of the Napoleonic Wars. He emerged as the only economist of note to support duties on imported grain. By encouraging domestic production, Malthus argued, the Corn Laws would guarantee British self-sufficiency in food.

Later life

Malthus was a founding member in 1821 of the Political Economy Club, where John Cazenove tended to be his ally against Ricardo and Mill. He was elected in the beginning of 1824 as one of the ten royal associates of the Royal Society of Literature. He was also one of the first fellows of the Statistical Society, founded in March 1834. In 1827 he gave evidence to a committee of the House of Commons on emigration.

In 1827, he published Definitions in Political Economy The first chapter put forth "Rules for the Definition and Application of Terms in Political Economy". In chapter 10, the penultimate chapter, he presented 60 numbered paragraphs putting forth terms and their definitions that he proposed should be used in discussing political economy following those rules. This collection of terms and definitions is remarkable for two reasons: first, Malthus was the first economist to explicitly organize, define, and publish his terms as a coherent glossary of defined terms; and second, his definitions were for the most part well-formed definitional statements. Between these chapters, he criticized several contemporary economists—Jean-Baptiste Say, David Ricardo, James Mill, John Ramsay McCulloch, and Samuel Bailey—for sloppiness in choosing, attaching meaning to, and using their technical terms.

McCulloch was the editor of The Scotsman of Edinburgh and replied cuttingly in a review printed on the front page of his newspaper in March 1827. He implied that Malthus wanted to dictate terms and theories to other economists. McCulloch clearly felt his ox gored, and his review of Definitions is largely a bitter defence of his own Principles of Political Economy, and his counter-attack "does little credit to his reputation", being largely "personal derogation" of Malthus. The purpose of Malthus's Definitions was terminological clarity, and Malthus discussed appropriate terms, their definitions, and their use by himself and his contemporaries. This motivation of Malthus's work was disregarded by McCulloch, who responded that there was nothing to be gained "by carping at definitions, and quibbling about the meaning to be attached to" words. Given that statement, it is not surprising that McCulloch's review failed to address the rules of chapter 1 and did not discuss the definitions of chapter 10; he also barely mentioned Malthus's critiques of other writers.

In spite of this and in the wake of McCulloch's scathing review, the reputation of Malthus as economist dropped away for the rest of his life. On the other hand, Malthus did have supporters, including Thomas Chalmers, some of the Oriel Noetics, Richard Jones and William Whewell from Cambridge.

Malthus died suddenly of heart disease on 23 December 1834 at his father-in-law's house. He was buried in Bath Abbey. His portrait, and descriptions by contemporaries, present him as tall and good-looking, but with a cleft lip and palate. The cleft palate affected his speech: such birth defects had occurred before amongst his relatives.

Family

On 13 March 1804, Malthus married Harriet, daughter of John Eckersall of Claverton House, near Bath. They had a son and two daughters. His first born Henry became vicar of Effingham, Surrey in 1835 and of Donnington, Sussex in 1837; he married Sofia Otter (1807–1889), daughter of Bishop William Otter and died in August 1882, aged 76. His middle child Emily died in 1885, outliving her parents and siblings. The youngest Lucille died unmarried and childless in 1825, months before her 18th birthday.

An Essay on the Principle of Population

Malthus argued in his Essay (1798) that population growth generally expanded in times and in regions of plenty until the size of the population relative to the primary resources caused distress:

Yet in all societies, even those that are most vicious, the tendency to a virtuous attachment [i.e., marriage] is so strong that there is a constant effort towards an increase of population. This constant effort as constantly tends to subject the lower classes of the society to distress and to prevent any great permanent amelioration of their condition.

— Malthus, T. R. 1798. An Essay on the Principle of Population. Chapter II, p. 18 in Oxford World's Classics reprint.

Malthus argued that two types of checks hold population within resource limits: positive checks, which raise the death rate; and preventive ones, which lower the birth rate. The positive checks include hunger, disease and war; the preventive checks: birth control, postponement of marriage and celibacy.

The rapid increase in the global population of the past century exemplifies Malthus's predicted population patterns; it also appears to describe socio-demographic dynamics of complex pre-industrial societies. These findings are the basis for neo-malthusian modern mathematical models of long-term historical dynamics.

Malthus wrote that in a period of resource abundance, a population could double in 25 years. However, the margin of abundance could not be sustained as population grew, leading to checks on population growth:

If the subsistence for man that the earth affords was to be increased every twenty-five years by a quantity equal to what the whole world at present produces, this would allow the power of production in the earth to be absolutely unlimited, and its ratio of increase much greater than we can conceive that any possible exertions of mankind could make it ... yet still the power of population being a power of a superior order, the increase of the human species can only be kept commensurate to the increase of the means of subsistence by the constant operation of the strong law of necessity acting as a check upon the greater power.

— Malthus T. R. 1798. An Essay on the Principle of Population. Chapter 2, p. 8

In later editions of his essay, Malthus clarified his view that if society relied on human misery to limit population growth, then sources of misery (e.g., hunger, disease, and war) would inevitably afflict society, as would volatile economic cycles. On the other hand, "preventive checks" to population that limited birthrates, such as later marriages, could ensure a higher standard of living for all, while also increasing economic stability. Regarding possibilities for freeing man from these limits, Malthus argued against a variety of imaginable solutions, such as the notion that agricultural improvements could expand without limit.

Of the relationship between population and economics, Malthus wrote that when the population of laborers grows faster than the production of food, real wages fall because the growing population causes the cost of living (i.e., the cost of food) to go up. Difficulties of raising a family eventually reduce the rate of population growth, until the falling population again leads to higher real wages.

In the second and subsequent editions Malthus put more emphasis on moral restraint as the best means of easing the poverty of the lower classes."

Editions and versions

• 1798: An Essay on the Principle of Population, as it affects the future improvement of society with remarks on the speculations of Mr. Godwin, M. Condorcet, and other writers.. Anonymously published.
• 1803: Second and much enlarged edition: An Essay on the Principle of Population; or, a view of its past and present effects on human happiness; with an enquiry into our prospects respecting the future removal or mitigation of the evils which it occasions. Authorship acknowledged.
• 1806, 1807, 1816 and 1826: editions 3–6, with relatively minor changes from the second edition.
• 1823: Malthus contributed the article on Population to the supplement of the Encyclopædia Britannica.
• 1830: Malthus had a long extract from the 1823 article reprinted as A summary view of the Principle of Population.

Other works

1800: The present high price of provisions

In this work, his first published pamphlet, Malthus argues against the notion prevailing in his locale that the greed of intermediaries caused the high price of provisions. Instead, Malthus says that the high price stems from the Poor Laws, which "increase the parish allowances in proportion to the price of corn." Thus, given a limited supply, the Poor Laws force up the price of daily necessities. However, he concludes by saying that in time of scarcity such Poor Laws, by raising the price of corn more evenly, actually produce a beneficial effect.

1814: Observations on the effects of the Corn Laws

Although government in Britain had regulated the prices of grain, the Corn Laws originated in 1815. At the end of the Napoleonic Wars that year, Parliament passed legislation banning the importation of foreign corn into Britain until domestic corn cost 80 shillings per quarter. The high price caused the cost of food to increase and caused distress among the working classes in the towns. It led to serious rioting in London and to the Peterloo Massacre in Manchester in 1819.

In this pamphlet, printed during the parliamentary discussion, Malthus tentatively supported the free-traders. He argued that given the increasing cost of growing British corn, advantages accrued from supplementing it from cheaper foreign sources.

1820: Principles of political economy

In 1820 Malthus published Principles of Political Economy. (A second edition was posthumously published in 1836.) Malthus intended this work to rival Ricardo's Principles (1817). It, and his 1827 Definitions in political economy, defended Sismondi's views on "general glut" rather than Say's Law, which in effect states "there can be no general glut".

Other publications

• 1807. A letter to Samuel Whitbread, Esq. M.P. on his proposed Bill for the Amendment of the Poor Laws. Johnson and Hatchard, London.
• 1808. Spence on Commerce. Edinburgh Review 11, January, 429–448.
• 1808. Newneham and others on the state of Ireland. Edinburgh Review 12, July, 336–355.
• 1809. Newneham on the state of Ireland, Edinburgh Review 14 April, 151–170.
• 1811. Depreciation of paper currency. Edinburgh Review 17, February, 340–372.
• 1812. Pamphlets on the bullion question. Edinburgh Review 18, August, 448–470.
• 1813. A letter to the Rt. Hon. Lord Grenville. Johnson, London.
• 1817. Statement respecting the East-India College. Murray, London.
• 1821. Godwin on Malthus. Edinburgh Review 35, July, 362–377.
• 1823. The Measure of Value, stated and illustrated
• 1823. Tooke – On high and low prices. Quarterly Review, 29 (57), April, 214–239.
• 1824. Political economy. Quarterly Review 30 (60), January, 297–334.
• 1829. On the measure of the conditions necessary to the supply of commodities. Transactions of the Royal Society of Literature of the United Kingdom. 1, 171–180. John Murray, London.
• 1829. On the meaning which is most usually and most correctly attached to the term Value of a Commodity. Transactions of the Royal Society of Literature of the United Kingdom. 2, 74–81. John Murray.

Reception and influence

Malthus developed the theory of demand-supply mismatches that he called gluts. Discounted at the time, this theory foreshadowed later work by an admirer, John Maynard Keynes.

The vast bulk of continuing commentary on Malthus, however, extends and expands on the "Malthusian controversy" of the early 19th century.

In popular culture

• Ebenezer Scrooge from A Christmas Carol by Charles Dickens represents the perceived ideas of Malthus, famously illustrated by his explanation as to why he refuses to donate to the poor and destitute: "If they would rather die they had better do it, and decrease the surplus population". In general, Dickens had some Malthusian concerns (evident in Oliver Twist, Hard Times and other novels), and he concentrated his attacks on Utilitarianism and many of its proponents, like Jeremy Bentham, whom he thought of, along with Malthus, as unjust and inhumane.
• In Brave New World by Aldous Huxley, a dystopian novel set in a World State which controls reproduction, women wear the "Malthusian belt," containing "the regulation supply of contraceptives."
• In the musical Urinetown, written by Greg Kotis and Mark Hollmann, the characters live in a society in which a fee must be paid in order to urinate, for a drought has made water incredibly scarce. A revolution starts with a "pee for free" agenda. At the end of the show, the revolution wins but the characters end up dying because water was not being conserved, unlike when the 'pee fee' was in place. The penultimate line is "Hail Malthus!"
• In the film Avengers: Infinity War, the main villain called Thanos appears to be motivated by Malthusian views about population growth, and commits universal mass genocide known as The Blip.

Epitaph

The epitaph of Malthus just inside the entrance to Bath Abbey

The epitaph of Malthus in Bath Abbey reads [with commas inserted for clarity]:

Sacred to the memory of the Rev THOMAS ROBERT MALTHUS, long known to the lettered world by his admirable writings on the social branches of political economy, particularly by his essay on population.

One of the best men and truest philosophers of any age or country, raised by native dignity of mind above the misrepresentation of the ignorant and the neglect of the great, he lived a serene and happy life devoted to the pursuit and communication of truth, supported by a calm but firm conviction of the usefulness of his labours, content with the approbation of the wise and good.

His writings will be a lasting monument of the extent and correctness of his understanding.

The spotless integrity of his principles, the equity and candour of his nature, his sweetness of temper, urbanity of manners and tenderness of heart, his benevolence and his piety are still dearer recollections of his family and friends.

Born 14 February 1766 – Died 29 December 1834.

 

The dismal science

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"The dismal science" is a derogatory alternative name for economics coined by the Victorian historian Thomas Carlyle in the 19th century (originally in the context of his argument to reintroduce slavery in the West Indies). The term drew a contrast with the then-familiar use of the phrase "gay science" to refer to song and verse writing. The latter phrase later appeared as the title of a book by Friedrich Nietzsche, The Gay Science.

Some modern synonyms include the term "the miserable science".

Origin

The phrase "the dismal science" first occurs in Thomas Carlyle's 1849 tract called "Occasional Discourse on the Negro Question", in which he argued in favor of reintroducing slavery in order to restore productivity to the West Indies:

Not a "gay science", I should say, like some we have heard of; no, a dreary, desolate and, indeed, quite abject and distressing one; what we might call, by way of eminence, the dismal science.

It was "dismal" in "find[ing] the secret of this Universe in 'supply and demand', and reducing the duty of human governors to that of letting men alone". Instead, the "idle Black man in the West Indies" should be "compelled to work as he was fit, and to do the Maker's will who had constructed him".

Carlyle's view was attacked by John Stuart Mill as making a virtue of toil itself, stunting the development of the weak, and committing the "vulgar error of imputing every difference which he finds among human beings to an original difference of nature".

Carlyle did not originally coin the phrase "dismal science" as a response to the economically-influential theories of Thomas Malthus, who predicted that starvation would inevitably result as projected population growth exceeded the rate of increase in the food supply. However, Carlyle used the word "dismal" in relation to Malthus' theory in Chartism (1839):

The controversies on Malthus and the 'Population Principle', 'Preventive Check' and so forth, with which the public ear has been deafened for a long while, are indeed sufficiently mournful. Dreary, stolid, dismal, without hope for this world or the next, is all that of the preventive check and the denial of the preventive check.

Beyond Carlyle

Many at the time and afterward have understood the phrase in relation to the grim predictions drawn from the principles of 19th century political economy. According to Humphry House:

Carlyle's phrase, "the dismal science", has been so often quoted, that there is a risk of thinking that the opinion behind it was confined to him and his followers; but the opinion was widespread, and thought to be a justifiable inference from the works of the economists: "No one," said J. E. Cairnes, "can have studied political economy in the works of its earlier cultivators without being struck with the dreariness of the outlook which, in the main, it discloses for the human race. It seems to have been Ricardo's deliberate opinion that a substantial improvement in the condition of the mass of mankind was impossible." It is not merely that the Malthusian principle of population and the doctrine that wages must normally and necessarily fall to the minimum point were gladly accepted by wicked exploiters as the justification of their profits; but thousands whose immediate interests were not touched by these beliefs found it difficult to avoid them. ... Malthus hung over England like a cloud. It is difficult now to realize what it meant to thousands of good and sensible men that they believed his principle of population to be exactly true—believed that as poverty was relieved and the standard of life raised, so surely there would be bred a new race hovering on the misery-line, on the edge of starvation. However they might wish it false, they feared it true...

(Ricardo, however, did not believe that wages must always fall to the minimum. He believed that they were a function of the margin of production.)

In modern terms, the phrase is sometimes referenced by synonymous terms like "the miserable science", as shown in this quote by E. W. Dijkstra:

As economics is known as "The Miserable Science", software engineering should be known as "The Doomed Discipline"

 

Dementia

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Dementia

Dementia
Other names	Senility, senile dementia
Image of a man diagnosed with dementia in the 1800s
Specialty	Neurology, psychiatry
Symptoms	Decreased ability to think and remember, emotional problems, problems with language, decreased motivation
Usual onset	Gradual
Duration	Long term
Causes	Alzheimer's disease, vascular disease, Lewy body disease and frontotemporal lobar degeneration.
Diagnostic method	Cognitive testing (Mini-Mental State Examination)
Differential diagnosis	Delirium Hypothyroidism
Prevention	Early education, prevent high blood pressure, prevent obesity, no smoking, social engagement
Treatment	Supportive care
Medication	Acetylcholinesterase inhibitors (small benefit)
Frequency	50 million (2020)
Deaths	2.4 million (2016)

Dementia occurs as a set of related symptoms when the brain is damaged by injury or disease. The symptoms involve progressive impairments to memory, thinking, and behavior, that affect the ability to look after oneself as a measure of carrying out everyday activities. Other common symptoms include emotional problems, difficulties with language, and decreased motivation. The symptoms may be described as occurring in a continuum over several stages. Dementia is not a disorder of consciousness, and consciousness is not usually affected. A diagnosis of dementia requires a change from a person's usual mental functioning, and a greater cognitive decline than that due to normal aging. Several diseases, and injuries to the brain such as a stroke, can give rise to dementia. However, the most common cause is Alzheimer's disease a neurodegenerative disorder. Dementia has a significant effect on the individual, relationships and caregivers. In DSM-5, dementia has been reclassified as a major neurocognitive disorder, with varying degrees of severity, and many causative subtypes.

Causative subtypes of dementia may be based on a known potential cause such as Parkinson's disease, for Parkinson's disease dementia; Huntington's disease for Huntingtons disease dementia; vascular disease for vascular dementia; brain injury including stroke often results in vascular dementia; or many other medical conditions including HIV infection for HIV dementia; and prion diseases. Subtypes may be based on various symptoms as may be due to a neurodegenerative disorder such as Alzheimer's disease; frontotemporal lobar degeneration for frontotemporal dementia; or Lewy body disease for dementia with Lewy bodies. More than one type of dementia, known as mixed dementia, may exist together. Diagnosis is usually based on history of the illness and cognitive testing with imaging. Blood tests may be taken to rule out other possible causes that may be reversible such as an underactive thyroid, and to determine the subtype. The Mini-Mental State Examination is one commonly used cognitive test. The greatest risk factor for developing dementia is aging, however dementia is not a normal part of aging. Several risk factors for dementia are described with some such as smoking, and obesity being preventable by lifestyle changes. Screening the general population for the disorder is not recommended.

There is no known cure for dementia. Acetylcholinesterase inhibitors such as donepezil are often used and may be beneficial in mild to moderate disorder. The overall benefit, however, may be minor. There are many measures that can improve the quality of life of people with dementia and their caregivers. Cognitive and behavioral interventions may be appropriate. Educating and providing emotional support to the caregiver is important. Exercise programs may be beneficial with respect to activities of daily living and may potentially improve outcomes. Treatment of behavioral problems with antipsychotics is common but not usually recommended, due to the limited benefit and the side effects, including an increased risk of death.

It was estimated in 2020 that dementia affected about 50 million people worldwide. This is an increase on the 2016 estimate of 43.8 million, and more than double the estimated 20.2 million in 1990. The number of cases is increasing by around 10 million every year. About 10% of people develop the disorder at some point in their lives, commonly as a result of aging. About 3% of people between the ages of 65–74 have dementia, 19% between 75 and 84, and nearly half of those over 85 years of age. In 2016 dementia resulted in about 2.4 million deaths, up from 0.8 million in 1990. In 2020 it was reported that dementia was listed as one of the top ten causes of death worldwide. Another report stated that in 2016 it was the fifth leading cause of death. As more people are living longer, dementia is becoming more common. For people of a specific age, however, it may be becoming less frequent in the developed world, due to a decrease in modifiable risk factors made possible by greater financial and educational resources. It is one of the most common causes of disability among the old. Worldwide the cost of dementia in 2015 was put at US$818 billion. People with dementia are often physically or chemically restrained to a greater degree than necessary, raising issues of human rights. Social stigma against those affected is common.

Signs and symptoms

A drawing of a woman diagnosed with dementia

 

A drawing of an old man diagnosed with senile dementia

The signs and symptoms of dementia, are termed as the neuropsychiatric symptoms of dementia, also known as the behavioral and psychological symptoms of dementia. Behavioral symptoms can include agitation, restlessness, inappropriate behavior, sexual disinhibition, and aggression which can be verbal or physical. These symptoms may result from impairments in cognitive inhibition. Psychological symptoms can include depression, psychotic hallucinations and delusions, apathy, and anxiety. The most commonly affected areas include memory, visuospatial function affecting perception and orientation, language, attention and problem solving. The rate of symptoms progression may be described as occurring in a continuum over several stages, and varies across the dementia subtypes. Most types of dementia are slowly progressive with some deterioration of the brain well established before signs of the disorder become apparent. Often there are other conditions present such as high blood pressure, or diabetes, and there can sometimes be as many as four of these comorbidities.

Stages

The course of dementia is often described in four stages that show a pattern of progressive cognitive and functional impairment. However, the use of numeric scales allow for more detailed descriptions. These scales include: the Global Deterioration Scale for Assessment of Primary Degenerative Dementia (GDS or Reisberg Scale), the Functional Assessment Staging Test (FAST), and the Clinical Dementia Rating (CDR). Using the GDS which more accurately identifies each stage of the disease progression, a more detailed course is described in seven stages – two of which are broken down further into five and six degrees. Stage 7(f) is the final stage.

Pre-dementia states

Pre-dementia states include pre-clinical and prodromal stages.

Pre-clinical

Sensory dysfunction is claimed for this stage which may precede the first clinical signs of dementia by up to ten years. Most notably the sense of smell is lost. The loss of the sense of smell is associated with depression and loss of appetite leading to poor nutrition. It is suggested that this dysfunction may come about because the olfactory epithelium is exposed to the environment. The lack of blood-brain-barrier protection here means that toxic elements can enter and cause damage to the chemosensory networks.

Prodromal

Pre-dementia states considered as prodromal are mild cognitive impairment (MCI), and mild behavioral impairment (MBI).

Kynurenine is a metabolite of tryptophan that regulates microbiome signalling, immune cell response, and neuronal excitation. A disruption in the kynurenine pathway may be associated with the neuropsychiatric symptoms and cognitive prognosis in mild dementia.

In this stage signs and symptoms may be subtle. Often, the early signs become apparent when looking back. 70% of those diagnosed with MCI later progress to dementia. In MCI, changes in the person's brain have been happening for a long time, but symptoms are just beginning to appear. These problems, however, are not severe enough to affect daily function. If and when they do, the diagnosis becomes dementia. They may have some memory trouble and trouble finding words, but they solve everyday problems and competently handle their life affairs.

Mild cognitive impairment has been relisted in both DSM-5, and ICD-11, as mild neurocognitive disorders, – milder forms of the major neurocognitive disorder (dementia) subtypes.

Early stages

In the early stage of dementia, symptoms become noticeable to other people. In addition, the symptoms begin to interfere with daily activities, and will register a score on a Mini–Mental State Examination (MMSE). MMSE scores are set at 24 to 30 for a normal coginitive rating and lower scores reflect severity of symptoms. The symptoms are dependent on the type of dementia. More complicated chores and tasks around the house or at work become more difficult. The person can usually still take care of themselves but may forget things like taking pills or doing laundry and may need prompting or reminders.

The symptoms of early dementia usually include memory difficulty, but can also include some word-finding problems, and problems with executive functions of planning and organization. Managing finances may prove difficult. Other signs might be getting lost in new places, repeating things, and personality changes.

In some types of dementia, such as dementia with Lewy bodies and frontotemporal dementia, personality changes and difficulty with organization and planning may be the first signs.

Middle stages

As dementia progresses, initial symptoms generally worsen. The rate of decline is different for each person. MMSE scores between 6–17 signal moderate dementia. For example, people with moderate Alzheimer's dementia lose almost all new information. People with dementia may be severely impaired in solving problems, and their social judgment is usually also impaired. They cannot usually function outside their own home, and generally should not be left alone. They may be able to do simple chores around the house but not much else, and begin to require assistance for personal care and hygiene beyond simple reminders. A lack of insight into having the condition will become evident.

Late stages

People with late-stage dementia typically turn increasingly inward and need assistance with most or all of their personal care. Persons with dementia in the late stages usually need 24-hour supervision to ensure their personal safety, and meeting of basic needs. If left unsupervised, they may wander or fall; may not recognize common dangers such as a hot stove; or may not realize that they need to use the bathroom and become incontinent. They may not want to get out of bed, or may need assistance doing so. Commonly, the person no longer recognizes familiar faces. They may have significant changes in sleeping habits or have trouble sleeping at all.

Changes in eating frequently occur. Cognitive awareness is needed for eating and swallowing and progressive cognitive decline results in eating and swallowing difficulties. This can cause food to be refused, or choked on, and help with feeding will often be required. For ease of feeding, food may be liquidized into a thick purée.

Subtypes

Many of the subtypes of dementia are neurodegenerative, and protein toxicity is a cardinal feature of these.

Alzheimer's disease

Brain atrophy in severe Alzheimer's

Alzheimer's disease accounts for 60–70% of cases of dementia worldwide. The most common symptoms of Alzheimer's disease are short-term memory loss and word-finding difficulties. Trouble with visuospatial functioning (getting lost often), reasoning, judgment and insight fail. Insight refers to whether or not the person realizes they have memory problems.

Common early symptoms of Alzheimer's include repetition, getting lost, difficulties tracking bills, problems with cooking especially new or complicated meals, forgetting to take medication and word-finding problems.

The part of the brain most affected by Alzheimer's is the hippocampus. Other parts that show atrophy (shrinking) include the temporal and parietal lobes. Although this pattern of brain shrinkage suggests Alzheimer's, it is variable and a brain scan is insufficient for a diagnosis. The relationship between anesthesia and AD is unclear.

Vascular dementia

Vascular dementia accounts for at least 20% of dementia cases, making it the second most common type. It is caused by disease or injury affecting the blood supply to the brain, typically involving a series of mini-strokes. The symptoms of this dementia depend on where in the brain the strokes occurred and whether the blood vessels affected were large or small. Multiple injuries can cause progressive dementia over time, while a single injury located in an area critical for cognition such as the hippocampus, or thalamus, can lead to sudden cognitive decline. Elements of vascular dementia may be present in all other forms of dementia.

Brain scans may show evidence of multiple strokes of different sizes in various locations. People with vascular dementia tend to have risk factors for disease of the blood vessels, such as tobacco use, high blood pressure, atrial fibrillation, high cholesterol, diabetes, or other signs of vascular disease such as a previous heart attack or angina.

Lewy body dementias

Lewy body dementias are dementia with Lewy bodies (DLB), and Parkinson's disease dementia (PDD). They are classified in DSM5 as mild or major neurocognitive disorders due to Lewy bodies.

Dementia with Lewy bodies

The prodromal symptoms of dementia with Lewy bodies (DLB) include mild cognitive impairment, and delirium onset. The symptoms of DLB are more frequent, more severe, and earlier presenting than in the other dementia subtypes. Dementia with Lewy bodies has the primary symptoms of fluctuating cognition, alertness or attention; REM sleep behavior disorder (RBD); one or more of the main features of parkinsonism, not due to medication or stroke; and repeated visual hallucinations. The visual hallucinations in DLB are generally vivid hallucinations of people or animals and they often occur when someone is about to fall asleep or wake up. Other prominent symptoms include problems with planning (executive function) and difficulty with visual-spatial function, and disruption in autonomic bodily functions. Abnormal sleep behaviors may begin before cognitive decline is observed and are a core feature of DLB. RBD is diagnosed either by sleep study recording or, when sleep studies cannot be performed, by medical history and validated questionnaires.

Parkinson's disease dementia

Parkinson's disease is a Lewy body disease that often progresses to Parkinson's disease dementia following a period of dementia-free Parkinson's disease.

Frontotemporal dementia

Frontotemporal dementias (FTDs) are characterized by drastic personality changes and language difficulties. In all FTDs, the person has a relatively early social withdrawal and early lack of insight. Memory problems are not a main feature. There are six main types of FTD. The first has major symptoms in personality and behavior. This is called behavioral variant FTD (bv-FTD) and is the most common. The hallmark feature of bv-FTD is impulsive behaviour, and this can be detected in pre-dementia states. In bv-FTD, the person shows a change in personal hygiene, becomes rigid in their thinking, and rarely acknowledges problems; they are socially withdrawn, and often have a drastic increase in appetite. They may become socially inappropriate. For example, they may make inappropriate sexual comments, or may begin using pornography openly. One of the most common signs is apathy, or not caring about anything. Apathy, however, is a common symptom in many dementias.

Two types of FTD feature aphasia (language problems) as the main symptom. One type is called semantic variant primary progressive aphasia (SV-PPA). The main feature of this is the loss of the meaning of words. It may begin with difficulty naming things. The person eventually may lose the meaning of objects as well. For example, a drawing of a bird, dog, and an airplane in someone with FTD may all appear almost the same. In a classic test for this, a patient is shown a picture of a pyramid and below it a picture of both a palm tree and a pine tree. The person is asked to say which one goes best with the pyramid. In SV-PPA the person cannot answer that question. The other type is called non-fluent agrammatic variant primary progressive aphasia (NFA-PPA). This is mainly a problem with producing speech. They have trouble finding the right words, but mostly they have a difficulty coordinating the muscles they need to speak. Eventually, someone with NFA-PPA only uses one-syllable words or may become totally mute.

A frontotemporal dementia associated with amyotrophic lateral sclerosis (ALS) known as (FTD-ALS) includes the symptoms of FTD (behavior, language and movement problems) co-occurring with amyotrophic lateral sclerosis (loss of motor neurons). Two FTD-related disorders are progressive supranuclear palsy (also classed as a Parkinson-plus syndrome), and corticobasal degeneration. These disorders are tau-associated.

Huntington's disease dementia

Huntington's disease is a degenerative disease caused by mutations in a single gene. Symptoms include cognitive impairment and this usually declines further into dementia.

HIV-associated dementia

HIV-associated dementia results as a late stage from HIV infection, and mostly affects younger people. The essential features of HIV-associated dementia are disabling cognitive impairment accompanied by motor dysfunction, speech problems and behavioral change. Cognitive impairment is characterised by mental slowness, trouble with memory and poor concentration. Motor symptoms include a loss of fine motor control leading to clumsiness, poor balance and tremors. Behavioral changes may include apathy, lethargy and diminished emotional responses and spontaneity. Histopathologically, it is identified by the infiltration of monocytes and macrophages into the central nervous system (CNS), gliosis, pallor of myelin sheaths, abnormalities of dendritic processes and neuronal loss.

Dementia due to prion disease

Creutzfeldt-Jakob disease is a rapidly progressive prion disease that typically causes dementia that worsens over weeks to months.

Alcohol-related dementia

Alcohol-related dementia also called alcohol-related brain damage occurs as a result of excessive use of alcohol particularly as a substance abuse disorder. Different factors can be involved in this development including thiamine deficiency and age vulnerability. A degree of brain damage is seen in more than 70% of those with alcohol use disorder. Brain regions affected are similar to those that are affected by aging, and also by Alzheimer's disease. Regions showing loss of volume include the frontal, temporal, and parietal lobes, the cerebellum, thalamus, and hippocampus. This loss can be more notable, with greater cognitive impairments seen in those aged 65 years and older.

Mixed dementia

More than one type of dementia, known as mixed dementia, may exist together in about 10% of dementia cases. The most common type of mixed dementia is Alzheimer's disease and vascular dementia. This particular type of mixed dementia's main onsets are a mixture of old age, high blood pressure, and damage to blood vessels in the brain.

Diagnosis of mixed dementia can be difficult, as often only one type will predominate. This makes the treatment of people with mixed dementia uncommon, with many people missing out on potentially helpful treatments. Mixed dementia can mean that symptoms onset earlier, and worsen more quickly since more parts of the brain will be affected.

Other conditions

Chronic inflammatory conditions that may affect the brain and cognition include Behçet's disease, multiple sclerosis, sarcoidosis, Sjögren's syndrome, lupus, celiac disease, and non-celiac gluten sensitivity. These types of dementias can rapidly progress, but usually have a good response to early treatment. This consists of immunomodulators or steroid administration, or in certain cases, the elimination of the causative agent. A 2019 review found no association between celiac disease and dementia overall but a potential association with vascular dementia. A 2018 review found a link between celiac disease or non-celiac gluten sensitivity and cognitive impairment and that celiac disease may be associated with Alzheimer's disease, vascular dementia, and frontotemporal dementia. A strict gluten-free diet started early may protect against dementia associated with gluten-related disorders.

Cases of easily reversible dementia include hypothyroidism, vitamin B12 deficiency, Lyme disease, and neurosyphilis. For Lyme disease and neurosyphilis, testing should be done if risk factors are present. Because risk factors are often difficult to determine, testing for neurosyphilis and Lyme disease, as well as other mentioned factors, may be undertaken as a matter of course where dementia is suspected.

Many other medical and neurological conditions include dementia only late in the illness. For example, a proportion of patients with Parkinson's disease develop dementia, though widely varying figures are quoted for this proportion. When dementia occurs in Parkinson's disease, the underlying cause may be dementia with Lewy bodies or Alzheimer's disease, or both. Cognitive impairment also occurs in the Parkinson-plus syndromes of progressive supranuclear palsy and corticobasal degeneration (and the same underlying pathology may cause the clinical syndromes of frontotemporal lobar degeneration). Although the acute porphyrias may cause episodes of confusion and psychiatric disturbance, dementia is a rare feature of these rare diseases. Limbic-predominant age-related TDP-43 encephalopathy (LATE) is a type of dementia that primarily affects people in their 80s or 90s and in which TDP-43 protein deposits in the limbic portion of the brain.

Hereditary disorders that can also cause dementia include: some metabolic disorders, lysosomal storage disorders, leukodystrophies, and spinocerebellar ataxias.

Diagnosis

Symptoms are similar across dementia types and it is difficult to diagnose by symptoms alone. Diagnosis may be aided by brain scanning techniques. In many cases, the diagnosis requires a brain biopsy to become final, but this is rarely recommended (though it can be performed at autopsy). In those who are getting older, general screening for cognitive impairment using cognitive testing or early diagnosis of dementia has not been shown to improve outcomes. However, screening exams are useful in 65+ persons with memory complaints.

Normally, symptoms must be present for at least six months to support a diagnosis. Cognitive dysfunction of shorter duration is called delirium. Delirium can be easily confused with dementia due to similar symptoms. Delirium is characterized by a sudden onset, fluctuating course, a short duration (often lasting from hours to weeks), and is primarily related to a somatic (or medical) disturbance. In comparison, dementia has typically a long, slow onset (except in the cases of a stroke or trauma), slow decline of mental functioning, as well as a longer trajectory (from months to years).

Some mental illnesses, including depression and psychosis, may produce symptoms that must be differentiated from both delirium and dementia. Therefore, any dementia evaluation should include a depression screening such as the Neuropsychiatric Inventory or the Geriatric Depression Scale. Physicians used to think that people with memory complaints had depression and not dementia (because they thought that those with dementia are generally unaware of their memory problems). This is called pseudodementia. However, in recent years researchers have realized that many older people with memory complaints in fact have MCI, the earliest stage of dementia. Depression should always remain high on the list of possibilities, however, for an elderly person with memory trouble.

Changes in thinking, hearing and vision are associated with normal ageing and can cause problems when diagnosing dementia due to the similarities.

Cognitive testing

Sensitivity and specificity of common tests for dementia

Test	Sensitivity	Specificity
MMSE	71%–92%	56%–96%
3MS	83%–93.5%	85%–90%
AMTS	73%–100%	71%–100%

Various brief tests (5–15 minutes) have reasonable reliability to screen for dementia. While many tests have been studied,^[88][89][90] presently the mini mental state examination (MMSE) is the best studied and most commonly used. The MMSE is a useful tool for helping to diagnose dementia if the results are interpreted along with an assessment of a person's personality, their ability to perform activities of daily living, and their behaviour. Other cognitive tests include the abbreviated mental test score (AMTS), the, Modified Mini-Mental State Examination (3MS), the Cognitive Abilities Screening Instrument (CASI), the Trail-making test, and the clock drawing test. The MoCA (Montreal Cognitive Assessment) is a reliable screening test and is available online for free in 35 different languages. The MoCA has also been shown somewhat better at detecting mild cognitive impairment than the MMSE. The AD-8 – a screening questionnaire used to assess changes in function related to cognitive decline – is potentially useful, but is not diagnostic, is variable, and has risk of bias. Brief cognitive tests may be affected by factors such as age, education and ethnicity.

Another approach to screening for dementia is to ask an informant (relative or other supporter) to fill out a questionnaire about the person's everyday cognitive functioning. Informant questionnaires provide complementary information to brief cognitive tests. Probably the best known questionnaire of this sort is the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Evidence is insufficient to determine how accurate the IQCODE is for diagnosing or predicting dementia. The Alzheimer's Disease Caregiver Questionnaire is another tool. It is about 90% accurate for Alzheimer's when by a caregiver. The General Practitioner Assessment Of Cognition combines both a patient assessment and an informant interview. It was specifically designed for use in the primary care setting.

Clinical neuropsychologists provide diagnostic consultation following administration of a full battery of cognitive testing, often lasting several hours, to determine functional patterns of decline associated with varying types of dementia. Tests of memory, executive function, processing speed, attention and language skills are relevant, as well as tests of emotional and psychological adjustment. These tests assist with ruling out other etiologies and determining relative cognitive decline over time or from estimates of prior cognitive abilities.

Laboratory tests

Routine blood tests are usually performed to rule out treatable causes. These include tests for vitamin B₁₂, folic acid, thyroid-stimulating hormone (TSH), C-reactive protein, full blood count, electrolytes, calcium, renal function, and liver enzymes. Abnormalities may suggest vitamin deficiency, infection, or other problems that commonly cause confusion or disorientation in the elderly.

Imaging

A CT scan or MRI scan is commonly performed, although these tests do not pick up diffuse metabolic changes associated with dementia in a person who shows no gross neurological problems (such as paralysis or weakness) on a neurological exam. CT or MRI may suggest normal pressure hydrocephalus, a potentially reversible cause of dementia, and can yield information relevant to other types of dementia, such as infarction (stroke) that would point at a vascular type of dementia.

The functional neuroimaging modalities of SPECT and PET are more useful in assessing long-standing cognitive dysfunction, since they have shown similar ability to diagnose dementia as a clinical exam and cognitive testing. The ability of SPECT to differentiate vascular dementia from Alzheimer's disease, appears superior to differentiation by clinical exam.

The value of PiB-PET imaging using Pittsburgh Compound B (PiB) as a radiotracer has been established in predictive diagnosis, particularly Alzheimer's disease.

Risk factors

The number of associated risk factors for dementia was increased from nine to twelve in 2020. The three added ones are over-indulgence in alcohol, traumatic brain injury, and air pollution. The other nine risk factors are: lower levels of education; high blood pressure; hearing loss; smoking; obesity; depression; inactivity; diabetes, and low social contact. Several of the group are known vascular risk factors that may be able to be reduced or eliminated. A reduction in a number of these risk factors can give a positive outcome. The decreased risk achieved by adopting a healthy lifestyle is seen even in those with a high genetic risk.

The two most modifiable risk factors for dementia are physical inactivity and lack of cognitive stimulation. Physical activity, in particular aerobic exercise is associated with a reduction in age-related brain tissue loss, and neurotoxic factors thereby preserving brain volume and neuronal integrity; cognitive activity strengthens neural plasticity and together they help to support cognitive reserve. The neglect of these risk factors diminishes this reserve.

Studies suggest that sensory impairments of vision and hearing are modifiable risk factors for dementia. These impairments may precede the cognitive symptoms of Alzheimer's disease for example, by many years. Hearing loss may lead to social isolation which negatively affects cognition. Social isolation is also identified as a modifiable risk factor. Age-related hearing loss in midlife is linked to cognitive impairment in late life, and is seen as a risk factor for the development of Alzheimer's disease and dementia. Such hearing loss may be caused by a central auditory processing disorder that makes the understanding of speech against background noise difficult. Age-related hearing loss is characterised by slowed central processing of auditory information. Worldwide, mid-life hearing loss may account for around 9% of dementia cases.

Evidence suggests that frailty may increase the risk of cognitive decline, and dementia, and that the inverse also holds of cognitive impairment increasing the risk of frailty. Prevention of frailty may help to prevent cognitive decline.

A 2018 review however concluded that no medications have good evidence of a preventive effect, including blood pressure medications. A 2020 review found a decrease in the risk of dementia or cognitive problems from 7.5% to 7.0% with blood pressure lowering medications.

Dental health

Limited evidence links poor oral health to cognitive decline. However, failure to perform tooth brushing and gingival inflammation can be used as dementia risk predictors.

Oral bacteria

The link between Alzheimer's and gum disease is oral bacteria. In the oral cavity, bacterial species include P. gingivalis, F. nucleatum, P. intermedia, and T. forsythia. Six oral treponema spirochetes have been examined in the brains of Alzheimer's patients. Spirochetes are neurotropic in nature, meaning they act to destroy nerve tissue and create inflammation. Inflammatory pathogens are an indicator of Alzheimer's disease and bacteria related to gum disease have been found in the brains of Alzheimer's disease sufferers. The bacteria invade nerve tissue in the brain, increasing the permeability of the blood-brain barrier and promoting the onset of Alzheimer's. Individuals with a plethora of tooth plaque risk cognitive decline. Poor oral hygiene can have an adverse effect on speech and nutrition, causing general and cognitive health decline.

Oral viruses

Herpes simplex virus (HSV) has been found in more than 70% of those aged over 50. HSV persists in the peripheral nervous system and can be triggered by stress, illness or fatigue. High proportions of viral-associated proteins in amyloid plaques or neurofibrillary tangles (NFTs) confirm the involvement of HSV-1 in Alzheimer's disease pathology. NFTs are known as the primary marker of Alzheimer's disease. HSV-1 produces the main components of NFTs.

Diet

Diet is seen to be a modifiable risk factor for the development of dementia. The Mediterranean diet, and the DASH diet are both associated with less cognitive decline. A different approach has been to incorporate elements of both of these diets into one known as the MIND diet.

These diets are generally low in saturated fats while providing a good source of carbohydrates, mainly those that help stabilize blood sugar and insulin levels. Raised blood sugar levels over a long time, can damage nerves and cause memory problems if they are not managed. Nutritional factors associated with the proposed diets for reducing dementia risk, include unsaturated fatty acids, antioxidants vitamin E vitamin C and flavonoids, vitamin B, and vitamin D.

The MIND diet may be more protective but further studies are needed. The Mediterranean diet seems to be more protective against Alzheimer's than DASH but there are no consistent findings against dementia in general. The role of olive oil needs further study as it may be one of the most important components in reducing the risk of cognitive decline and dementia.

In those with celiac disease or non-celiac gluten sensitivity, a strict gluten-free diet may relieve the symptoms given a mild cognitive impairment. Once dementia is advanced no evidence suggests that a gluten free diet is useful.

Omega-3 fatty acid supplements do not appear to benefit or harm people with mild to moderate symptoms. However, there is good evidence that omega-3 incorporation into the diet is of benefit in treating depression, a common symptom, and potentially modifiable risk factor for dementia.

Other interventions

Among otherwise healthy older people, computerized cognitive training may, for a time, improve memory. However it is not known whether it prevents dementia. Exercise has poor evidence of preventing dementia. In those with normal mental function evidence for medications is poor. The same applies to supplements.

Management

Except for the reversible types, no cure has been developed. acetylcholinesterase inhibitors are often used early in the disorder course; however, benefit is generally small. Treatments other than medication appear to be better for agitation and aggression. Cognitive and behavioral interventions may be appropriate. Some evidence suggests that education and support for the person with dementia, as well as caregivers and family members, improves outcomes. Exercise programs are beneficial with respect to activities of daily living, and potentially improve dementia.

The effect of therapies can be evaluated for example by assessing agitation using the Cohen-Mansfield Agitation Inventory (CMAI); by assessing mood and engagement with the Menorah Park Engagement Scale (MPES); and the Observed Emotion Rating Scale (OERS) or by assessing indicators for depression using the Cornell Scale for Depression in Dementia (CSDD) or a simplified version thereof.

Psychological and psychosocial therapies

Psychological therapies for dementia include some limited evidence for reminiscence therapy (namely, some positive effects in the areas of quality of life, cognition, communication and mood – the first three particularly in care home settings), some benefit for cognitive reframing for caretakers, unclear evidence for validation therapy and tentative evidence for mental exercises, such as cognitive stimulation programs for people with mild to moderate dementia. A 2020 Cochrane review found that offering personally tailored activities could help reduce challenging behavior and may improve quality of life. The reviewed studies (5 RCTs with 262 participants) were unable to draw any conclusions about impact on individual affect or on improvements for the quality of life for the caregiver.

Adult daycare centers as well as special care units in nursing homes often provide specialized care for dementia patients. Daycare centers offer supervision, recreation, meals, and limited health care to participants, as well as providing respite for caregivers. In addition, home care can provide one-to-one support and care in the home allowing for more individualized attention that is needed as the disorder progresses. Psychiatric nurses can make a distinctive contribution to people's mental health.

Since dementia impairs normal communication due to changes in receptive and expressive language, as well as the ability to plan and problem solve, agitated behaviour is often a form of communication for the person with dementia. Actively searching for a potential cause, such as pain, physical illness, or overstimulation can be helpful in reducing agitation. Additionally, using an "ABC analysis of behaviour" can be a useful tool for understanding behavior in people with dementia. It involves looking at the antecedents (A), behavior (B), and consequences (C) associated with an event to help define the problem and prevent further incidents that may arise if the person's needs are misunderstood. The strongest evidence for non-pharmacological therapies for the management of changed behaviours in dementia is for using such approaches. Low quality evidence suggests that regular (at least five sessions of) music therapy may help institutionalized residents. It may reduce depressive symptoms and improve overall behaviour. It may also supply a beneficial effect on emotional well-being and quality of life, as well as reduce anxiety. In 2003, The Alzheimer’s Society established 'Singing for the Brain' (SftB) a project based on pilot studies which suggested that the activity encouraged participation and facilitated the learning of new songs. The sessions combine aspects of reminiscence therapy and music. Musical and interpersonal connectedness can underscore the value of the person and improve quality of life.

Some London hospitals found that using color, designs, pictures and lights helped people with dementia adjust to being at the hospital. These adjustments to the layout of the dementia wings at these hospitals helped patients by preventing confusion.

Life story work as part of reminiscence therapy, and video biographies have been found to address the needs of clients and their caregivers in various ways, offering the client the opportunity to leave a legacy and enhance their personhood and also benefitting youth who participate in such work. Such interventions be more beneficial when undertaken at a relatively early stage of dementia. They may also be problematic in those who have difficulties in processing past experiences

Animal-assisted therapy has been found to be helpful. Drawbacks may be that pets are not always welcomed in a communal space in the care setting. An animal may pose a risk to residents, or may be perceived to be dangerous. Certain animals may also be regarded as “unclean” or “dangerous” by some cultural groups.

Medications

Donepezil

No medications have been shown to prevent or cure dementia. Medications may be used to treat the behavioural and cognitive symptoms, but have no effect on the underlying disease process.

Acetylcholinesterase inhibitors, such as donepezil, may be useful for Alzheimer 's disease, Parkinson's disease dementia, DLB, or vascular dementia. The quality of the evidence is poor and the benefit is small. No difference has been shown between the agents in this family. In a minority of people side effects include a slow heart rate and fainting. Rivastigmine is recommended for treating symptoms in Parkinson's disease dementia.

Before prescribing antipsychotic medication in the elderly, an assessment for an underlying cause of the behavior is needed. Severe and life-threatening reactions occur in almost half of people with DLB, and can be fatal after a single dose. People with Lewy body dementias who take neuroleptics are at risk for neuroleptic malignant syndrome, a life-threatening illness. Extreme caution is required in the use of antipsychotic medication in people with DLB because of their sensitivity to these agents. Antipsychotic drugs are used to treat dementia only if non-drug therapies have not worked, and the person's actions threaten themselves or others. Aggressive behavior changes are sometimes the result of other solvable problems, that could make treatment with antipsychotics unnecessary. Because people with dementia can be aggressive, resistant to their treatment, and otherwise disruptive, sometimes antipsychotic drugs are considered as a therapy in response. These drugs have risky adverse effects, including increasing the person's chance of stroke and death. Given these adverse events and small benefit antipsychotics are avoided whenever possible. Generally, stopping antipsychotics for people with dementia does not cause problems, even in those who have been on them a long time.

N-methyl-D-aspartate (NMDA) receptor blockers such as memantine may be of benefit but the evidence is less conclusive than for AChEIs. Due to their differing mechanisms of action memantine and acetylcholinesterase inhibitors can be used in combination however the benefit is slight.

An extract of Ginkgo biloba known as EGb 761 has been widely used for treating mild to moderate dementia and other neuropsychiatric disorders. Its use is approved throughout Europe. The World Federation of Biological Psychiatry guidelines lists EGb 761 with the same weight of evidence (level B) given to acetylcholinesterase inhibitors, and mementine. EGb 761 is the only one that showed improvement of symptoms in both AD and vascular dementia. EGb 761 is seen as being able to play an important role either on its own or as an add-on particularly when other therapies prove ineffective. EGb 761 is seen to be neuroprotective; it is a free radical scavenger, improves mitochondrial function, and modulates serotonin and dopamine levels. Many studies of its use in mild to moderate dementia have shown it to significantly improve cognitive function, activities of daily living, neuropsychiatric symptoms, and quality of life. However, its use has not been shown to prevent the progression of dementia.

While depression is frequently associated with dementia, the use of antidepressants such as selective serotonin reuptake inhibitors (SSRIs) do not appear to affect outcomes. However, the SSRIs sertraline and citalopram have been demonstrated to reduce symptoms of agitation, compared to placebo.

The use of medications to alleviate sleep disturbances that people with dementia often experience has not been well researched, even for medications that are commonly prescribed. In 2012 the American Geriatrics Society recommended that benzodiazepines such as diazepam, and non-benzodiazepine hypnotics, be avoided for people with dementia due to the risks of increased cognitive impairment and falls. Benzodiazepines are also known to promote delirium. Additionally, little evidence supports the effectiveness of benzodiazepines in this population. No clear evidence shows that melatonin or ramelteon improves sleep for people with dementia due to Alzheimer's, but it is used to treat REM sleep behavior disorder in dementia with Lewy bodies. Limited evidence suggests that a low dose of trazodone may improve sleep, however more research is needed.

No solid evidence indicates that folate or vitamin B12 improves outcomes in those with cognitive problems. Statins have no benefit in dementia. Medications for other health conditions may need to be managed differently for a person who has a dementia diagnosis. It is unclear whether blood pressure medication and dementia are linked. People may experience an increase in cardiovascular-related events if these medications are withdrawn.

The Medication Appropriateness Tool for Comorbid Health Conditions in Dementia (MATCH-D) criteria can help identify ways that a diagnosis of dementia changes medication management for other health conditions. These criteria were developed because people with dementia live with an average of five other chronic diseases, which are often managed with medications.

Pain

As people age, they experience more health problems, and most health problems associated with aging carry a substantial burden of pain; therefore, between 25% and 50% of older adults experience persistent pain. Seniors with dementia experience the same prevalence of conditions likely to cause pain as seniors without dementia. Pain is often overlooked in older adults and, when screened for, is often poorly assessed, especially among those with dementia, since they become incapable of informing others of their pain. Beyond the issue of humane care, unrelieved pain has functional implications. Persistent pain can lead to decreased ambulation, depressed mood, sleep disturbances, impaired appetite, and exacerbation of cognitive impairment and pain-related interference with activity is a factor contributing to falls in the elderly.

Although persistent pain in people with dementia is difficult to communicate, diagnose, and treat, failure to address persistent pain has profound functional, psychosocial and quality of life implications for this vulnerable population. Health professionals often lack the skills and usually lack the time needed to recognize, accurately assess and adequately monitor pain in people with dementia. Family members and friends can make a valuable contribution to the care of a person with dementia by learning to recognize and assess their pain. Educational resources and observational assessment tools are available. Eating difficulties

Persons with dementia may have difficulty eating. Whenever it is available as an option, the recommended response to eating problems is having a caretaker assist them. A secondary option for people who cannot swallow effectively is to consider gastrostomy feeding tube placement as a way to give nutrition. However, in bringing comfort and maintaining functional status while lowering risk of aspiration pneumonia and death, assistance with oral feeding is at least as good as tube feeding. Tube-feeding is associated with agitation, increased use of physical and chemical restraints and worsening pressure ulcers. Tube feedings may cause fluid overload, diarrhea, abdominal pain, local complications, less human interaction and may increase the risk of aspiration.

Benefits in those with advanced dementia has not been shown. The risks of using tube feeding include agitation, rejection by the person (pulling out the tube, or otherwise physical or chemical immobilization to prevent them from doing this), or developing pressure ulcers. The procedure is directly related to a 1% fatality rate with a 3% major complication rate. The percentage of people at end of life with dementia using feeding tubes in the US has dropped from 12% in 2000 to 6% as of 2014.

Exercise

Exercise programs may improve the ability of people with dementia to perform daily activities, but the best type of exercise is still unclear. Getting more exercise can slow the development of cognitive problems such as dementia, proving to reduce the risk of Alzheimer's disease by about 50%. A balance of strength exercise to help muscles pump blood to the brain, and balance exercises are recommended for aging people, a suggested amount of about 2 and a half hours per week can reduce risks of cognitive decay as well as other health risks like falling.

Alternative medicine

Aromatherapy and massage have unclear evidence. Studies support the efficacy and safety of cannabinoids in relieving behavioral and psychological symptoms of dementia.

Palliative care

Given the progressive and terminal nature of dementia, palliative care can be helpful to patients and their caregivers by helping people with the disorder and their caregivers understand what to expect, deal with loss of physical and mental abilities, support the person's wishes and goals including surrogate decision making, and discuss wishes for or against CPR and life support. Because the decline can be rapid, and because most people prefer to allow the person with dementia to make their own decisions, palliative care involvement before the late stages of dementia is recommended. Further research is required to determine the appropriate palliative care interventions and how well they help people with advanced dementia.

Person-centered care helps maintain the dignity of people with dementia.

Epidemiology

Deaths per million persons in 2012 due to dementia

  0–4

  5–8

  9–10

  11–13

  14–17

  18–24

  25–45

  46–114

  115–375

  376–1266

Disability-adjusted life year for Alzheimer and other dementias per 100,000 inhabitants in 2004.

<100   100–120   120–140   140–160   160–180   180–200

200–220   220–240   240–260   260–280   280–300   >300

The most common type of dementia is Alzheimer's disease. Other common types include vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. Less common causes include normal pressure hydrocephalus, Parkinson's disease dementia, syphilis, HIV, and Creutzfeldt–Jakob disease. The number of cases of dementia worldwide in 2016 was estimated at 43.8 million. with 58% living in low and middle income countries. The prevalence of dementia differs in different world regions, ranging from 4.7% in Central Europe to 8.7% in North Africa/Middle East; the prevalence in other regions is estimated to be between 5.6 and 7.6%. The number of people living with dementia is estimated to double every 20 years. In 2016 dementia resulted in about 2.4 million deaths, up from 0.8 million in 1990. Around two-thirds of individuals with dementia live in low- and middle-income countries, where the sharpest increases in numbers were predicted in a 2009 study.

The annual incidence of dementia diagnosis is over 9.9 million worldwide. Almost half of new dementia cases occur in Asia, followed by Europe (25%), the Americas (18%) and Africa (8%). The incidence of dementia increases exponentially with age, doubling with every 6.3 year increase in age. Dementia affects 5% of the population older than 65 and 20–40% of those older than 85. Rates are slightly higher in women than men at ages 65 and greater.

Dementia impacts not only individuals with dementia, but also their carers and the wider society. Among people aged 60 years and over, dementia is ranked the 9th most burdensome condition according to the 2010 Global Burden of Disease (GBD) estimates. The global costs of dementia was around US$818 billion in 2015, a 35.4% increase from US$604 billion in 2010.

History

Until the end of the 19th century, dementia was a much broader clinical concept. It included mental illness and any type of psychosocial incapacity, including reversible conditions. Dementia at this time simply referred to anyone who had lost the ability to reason, and was applied equally to psychosis, "organic" diseases like syphilis that destroy the brain, and to the dementia associated with old age, which was attributed to "hardening of the arteries".

Dementia has been referred to in medical texts since antiquity. One of the earliest known allusions to dementia is attributed to the 7th-century BC Greek philosopher Pythagoras, who divided the human lifespan into six distinct phases: 0–6 (infancy), 7–21 (adolescence), 22–49 (young adulthood), 50–62 (middle age), 63–79 (old age), and 80–death (advanced age). The last two he described as the "senium", a period of mental and physical decay, and that the final phase was when "the scene of mortal existence closes after a great length of time that very fortunately, few of the human species arrive at, where the mind is reduced to the imbecility of the first epoch of infancy". In 550 BC, the Athenian statesman and poet Solon argued that the terms of a man's will might be invalidated if he exhibited loss of judgement due to advanced age. Chinese medical texts made allusions to the condition as well, and the characters for "dementia" translate literally to "foolish old person".

Athenians Aristotle and Plato spoke of the mental decay of advanced age, apparently viewing it as an inevitable process that affected all old men, and which nothing could prevent. Plato stated that the elderly were unsuited for any position of responsibility because, "There is not much acumen of the mind that once carried them in their youth, those characteristics one would call judgement, imagination, power of reasoning, and memory. They see them gradually blunted by deterioration and can hardly fulfill their function."

For comparison, the Roman statesman Cicero held a view much more in line with modern-day medical wisdom that loss of mental function was not inevitable in the elderly and "affected only those old men who were weak-willed". He spoke of how those who remained mentally active and eager to learn new things could stave off dementia. However, Cicero's views on aging, although progressive, were largely ignored in a world that would be dominated for centuries by Aristotle's medical writings. Physicians during the Roman Empire, such as Galen and Celsus, simply repeated the beliefs of Aristotle while adding few new contributions to medical knowledge.

Byzantine physicians sometimes wrote of dementia. It is recorded that at least seven emperors whose lifespans exceeded 70 years displayed signs of cognitive decline. In Constantinople, special hospitals housed those diagnosed with dementia or insanity, but these did not apply to the emperors, who were above the law and whose health conditions could not be publicly acknowledged.

Otherwise, little is recorded about dementia in Western medical texts for nearly 1700 years. One of the few references was the 13th-century friar Roger Bacon, who viewed old age as divine punishment for original sin. Although he repeated existing Aristotelian beliefs that dementia was inevitable, he did make the progressive assertion that the brain was the center of memory and thought rather than the heart.

Poets, playwrights, and other writers made frequent allusions to the loss of mental function in old age. William Shakespeare notably mentions it in plays such as Hamlet and King Lear.

During the 19th century, doctors generally came to believe that elderly dementia was the result of cerebral atherosclerosis, although opinions fluctuated between the idea that it was due to blockage of the major arteries supplying the brain or small strokes within the vessels of the cerebral cortex.

In 1907 Alzheimer's disease was described. This was associated with particular microscopic changes in the brain, but was seen as a rare disease of middle age because the first person diagnosed with it was a 50-year-old woman. By 1913–20, schizophrenia had been well-defined in a way similar to later times.

This viewpoint remained conventional medical wisdom through the first half of the 20th century, but by the 1960s it was increasingly challenged as the link between neurodegenerative diseases and age-related cognitive decline was established. By the 1970s, the medical community maintained that vascular dementia was rarer than previously thought and Alzheimer's disease caused the vast majority of old age mental impairments. More recently however, it is believed that dementia is often a mixture of conditions.

In 1976, neurologist Robert Katzmann suggested a link between senile dementia and Alzheimer's disease. Katzmann suggested that much of the senile dementia occurring (by definition) after the age of 65, was pathologically identical with Alzheimer's disease occurring in people under age 65 and therefore should not be treated differently. Katzmann thus suggested that Alzheimer's disease, if taken to occur over age 65, is actually common, not rare, and was the fourth- or 5th-leading cause of death, even though rarely reported on death certificates in 1976.

A helpful finding was that although the incidence of Alzheimer's disease increased with age (from 5–10% of 75-year-olds to as many as 40–50% of 90-year-olds), no threshold was found by which age all persons developed it. This is shown by documented supercentenarians (people living to 110 or more) who experienced no substantial cognitive impairment. Some evidence suggests that dementia is most likely to develop between ages 80 and 84 and individuals who pass that point without being affected have a lower chance of developing it. Women account for a larger percentage of dementia cases than men, although this can be attributed to their longer overall lifespan and greater odds of attaining an age where the condition is likely to occur.

Much like other diseases associated with aging, dementia was comparatively rare before the 20th century, because few people lived past 80. Conversely, syphilitic dementia was widespread in the developed world until it was largely eradicated by the use of penicillin after World War II. With significant increases in life expectancy thereafter, the number of people over 65 started rapidly climbing. While elderly persons constituted an average of 3–5% of the population prior to 1945, by 2010 many countries reached 10–14% and in Germany and Japan, this figure exceeded 20%. Public awareness of Alzheimer's Disease greatly increased in 1994 when former US president Ronald Reagan announced that he had been diagnosed with the condition.

In the 21st century, other types of dementia were differentiated from Alzheimer's disease and vascular dementias (the most common types). This differentiation is on the basis of pathological examination of brain tissues, by symptomatology, and by different patterns of brain metabolic activity in nuclear medical imaging tests such as SPECT and PETscans of the brain. The various forms have differing prognoses and differing epidemiologic risk factors. The causal etiology, meaning the cause or origin of the disease, of many of them, including Alzheimer's disease, remains unclear.

Terminology

Dementia in the elderly was once called senile dementia or senility, and viewed as a normal and somewhat inevitable aspect of aging.

By 1913–20 the term dementia praecox was introduced to suggest the development of senile-type dementia at a younger age. Eventually the two terms fused, so that until 1952 physicians used the terms dementia praecox (precocious dementia) and schizophrenia interchangeably. Since then, science has determined that dementia and schizophrenia are two different disorders, though they share some similarities. The term precocious dementia for a mental illness suggested that a type of mental illness like schizophrenia (including paranoia and decreased cognitive capacity) could be expected to arrive normally in all persons with greater age (see paraphrenia). After about 1920, the beginning use of dementia for what is now understood as schizophrenia and senile dementia helped limit the word's meaning to "permanent, irreversible mental deterioration". This began the change to the later use of the term. In recent studies, researchers have seen a connection between those diagnosed with schizophrenia and patients who are diagnosed with dementia, finding a positive correlation between the two diseases.

The view that dementia must always be the result of a particular disease process led for a time to the proposed diagnosis of "senile dementia of the Alzheimer's type" (SDAT) in persons over the age of 65, with "Alzheimer's disease" diagnosed in persons younger than 65 who had the same pathology. Eventually, however, it was agreed that the age limit was artificial, and that Alzheimer's disease was the appropriate term for persons with that particular brain pathology, regardless of age.

After 1952, mental illnesses including schizophrenia were removed from the category of organic brain syndromes, and thus (by definition) removed from possible causes of "dementing illnesses" (dementias). At the same, however, the traditional cause of senile dementia – "hardening of the arteries" – now returned as a set of dementias of vascular cause (small strokes). These were now termed multi-infarct dementias or vascular dementias.

Society and culture

Woman with dementia being cared for at home in Ethiopia

The societal cost of dementia is high, especially for family caregivers.

Many countries consider the care of people living with dementia a national priority and invest in resources and education to better inform health and social service workers, unpaid caregivers, relatives and members of the wider community. Several countries have authored national plans or strategies. These plans recognize that people can live reasonably with dementia for years, as long as the right support and timely access to a diagnosis are available. Former British Prime Minister David Cameron described dementia as a "national crisis", affecting 800,000 people in the United Kingdom.

There, as with all mental disorders, people with dementia could potentially be a danger to themselves or others, they can be detained under the Mental Health Act 1983 for assessment, care and treatment. This is a last resort, and is usually avoided by people with family or friends who can ensure care.

Some hospitals in Britain work to provide enriched and friendlier care. To make the hospital wards calmer and less overwhelming to residents, staff replaced the usual nurses' station with a collection of smaller desks, similar to a reception area. The incorporation of bright lighting helps increase positive mood and allow residents to see more easily.

Driving with dementia can lead to injury or death. Doctors should advise appropriate testing on when to quit driving. The United Kingdom DVLA (Driver & Vehicle Licensing Agency) states that people with dementia who specifically have poor short-term memory, disorientation, or lack of insight or judgment are not allowed to drive, and in these instances the DVLA must be informed so that the driving licence can be revoked. They acknowledge that in low-severity cases and those with an early diagnosis, drivers may be permitted to continue driving.

Many support networks are available to people with dementia and their families and caregivers. Charitable organisations aim to raise awareness and campaign for the rights of people living with dementia. Support and guidance are available on assessing testamentary capacity in people with dementia.

In 2015, Atlantic Philanthropies announced a $177 million gift aimed at understanding and reducing dementia. The recipient was Global Brain Health Institute, a program co-led by the University of California, San Francisco and Trinity College Dublin. This donation is the largest non-capital grant Atlantic has ever made, and the biggest philanthropic donation in Irish history.

On 2 November 2020, Scottish billionaire Sir Tom Hunter donated £1 million to dementia charities, after watching a former music teacher with dementia, Paul Harvey, playing piano using just four notes in a viral video. The donation was announced to be split between the Alzheimer's Society and Music for Dementia.