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Sunday, September 19, 2021

Electroconvulsive therapy

From Wikipedia, the free encyclopedia

Electroconvulsive therapy
MECTA spECTrum ECT.jpg
MECTA spECTrum 5000Q with electroencephalography (EEG) in a modern ECT suite
Other namesElectroshock therapy
ICD-10-PCSGZB
ICD-9-CM94.27
MeSHD004565
OPS-301 code8-630
MedlinePlus007474

Electroconvulsive therapy (ECT) is a psychiatric treatment where a generalized seizure (without muscular convulsions) is electrically induced to manage refractory mental disorders. Typically, 70 to 120 volts are applied externally to the patient's head resulting in approximately 800 milliamperes of direct current passed through the brain, for 100 milliseconds to 6 seconds duration, either from temple to temple (bilateral ECT) or from front to back of one side of the head (unilateral ECT).

The ECT procedure was first conducted in 1938 by Italian psychiatrist Ugo Cerletti and rapidly replaced less safe and effective forms of biological treatments in use at the time. ECT is often used with informed consent as a safe and effective intervention for major depressive disorder, mania, and catatonia. ECT machines were originally placed in the Class III category by the United States Food and Drug Administration (FDA) in 1976. They were re-classified as Class II devices, for treatment of catatonia, major depressive disorder, and bipolar disorder, in 2018.

Aside from effects on the brain, the general physical risks of ECT are similar to those of brief general anesthesia. Immediately following treatment, the most common adverse effects are confusion and transient memory loss. Among treatments for severely depressed pregnant women, ECT is one of the least harmful to the fetus.

A usual course of ECT involves multiple administrations, typically given two or three times per week until the patient is no longer suffering symptoms. ECT is administered under anesthesia with a muscle relaxant. ECT can differ in its application in three ways: electrode placement, treatment frequency, and the electrical waveform of the stimulus. These treatment parameters can pose significant differences in both adverse side effects and symptom remission in the treated patient.

Placement can be bilateral, where the electric current is passed from one side of the brain to the other, or unilateral, in which the current is solely passed across one hemisphere of the brain. High-dose unilateral ECT has some cognitive advantages compared to moderate-dose bilateral ECT while showing no difference in antidepressant efficacy.

ECT appears to work in the short term via an anticonvulsant effect primarily in the frontal lobes and longer term via neurotrophic effects primarily in the medial temporal lobe.

Medical use

ECT is used with informed consent in treatment-resistant major depressive disorder, treatment-resistant catatonia, prolonged or severe mania, and in conditions where "there is a need for rapid, definitive response because of the severity of a psychiatric or medical condition (e.g., when illness is characterized by stupor, marked psychomotor retardation, depressive delusions or hallucinations, or life-threatening physical exhaustion associated with mania)." It has also been used to treat autism in adults with an intellectual disability, yet findings from a systematic review found this an unestablished intervention.

Major depressive disorder

For major depressive disorder, despite a Canadian guideline and some experts arguing for using ECT as a first line treatment, ECT is generally used only when one or other treatments have failed, or in emergencies, such as imminent suicide. ECT has also been used in selected cases of depression occurring in the setting of multiple sclerosis, Parkinson's disease, Huntington's chorea, developmental delay, brain arteriovenous malformations, and hydrocephalus.

Efficacy

A meta-analysis on the effectiveness of ECT in unipolar and bipolar depression was conducted in 2012. Results indicated that although patients with unipolar depression and bipolar depression responded to other medical treatments very differently, both groups responded equally well to ECT. Overall remission rate for patients given a round of ECT treatment was 50.9% for those with unipolar depression and 53.2% for those with bipolar depression. The severity of each patient's depression was assessed at the same baseline in each group. Most of severely depressed patients respond to ECT. 

In 2004, a meta-analytic review paper found in terms of efficacy, "a significant superiority of ECT in all comparisons: ECT versus simulated ECT, ECT versus placebo, ECT versus antidepressants in general, ECT versus tricyclics and ECT versus monoamine oxidase inhibitors."

In 2003, The UK ECT Review Group published a systematic review and meta-analysis comparing ECT to placebo and antidepressant drugs. This meta-analysis demonstrated a large effect size (high efficacy relative to the mean in terms of the standard deviation) for ECT versus placebo, and versus antidepressant drugs.

Compared with repetitive transcranial magnetic stimulation (rTMS) for people with treatment-resistant major depressive disorder, ECT relieves depression as shown by reducing the score on the Hamilton Rating Scale for Depression by about 15 points, while rTMS reduced it by 9 points.

The response rate is from 50 to 60% in treatment-resistant patients. Efficacity does not depend on depression subtype.

Follow-up

There is little agreement on the most appropriate follow-up to ECT for people with major depressive disorder. When ECT is followed by treatment with antidepressants, about 50% of people relapsed by 12 months following successful initial treatment with ECT, with about 37% relapsing within the first 6 months. About twice as many relapsed with no antidepressants. Most of the evidence for continuation therapy is with tricyclic antidepressants; evidence for relapse prevention with newer antidepressants is lacking.

Lithium has also been found to reduce the risk of relapse; especially in younger patients.

Catatonia

ECT is generally a second-line treatment for people with catatonia who do not respond to other treatments, but is a first-line treatment for severe or life-threatening catatonia. There is a plethora of evidence for its efficacy, notwithstanding a lack of randomised controlled trials, such that "the excellent efficacy of ECT in catatonia is generally acknowledged". For people with autism spectrum disorders who have catatonia, there is little published evidence about the efficacy of ECT; as of 2014 there were twelve case reports.

Mania

ECT is used to treat people who have severe or prolonged mania; NICE recommends it only in life-threatening situations or when other treatments have failed and as a second-line treatment for bipolar mania.

Schizophrenia

ECT is widely used worldwide in the treatment of schizophrenia, but in North America and Western Europe it is invariably used only in treatment resistant schizophrenia when symptoms show little response to antipsychotics; there is comprehensive research evidence for such practice. It is useful in the case of severe exacerbations of catatonic schizophrenia, whether excited or stuporous. There are also case reports of ECT improving persistent psychotic symptoms associated with Stimulant-induced psychosis.

Effects

Aside from effects in the brain, the general physical risks of ECT are similar to those of brief general anesthesia; the U.S. Surgeon General's report says that there are "no absolute health contraindications" to its use. Immediately following treatment, the most common adverse effects are confusion and memory loss. Some patients experience muscle soreness after ECT. The death rate during ECT is around 4 per 100,000 procedures. There is evidence and rationale to support giving low doses of benzodiazepines or otherwise low doses of general anesthetics, which induce sedation but not anesthesia, to patients to reduce adverse effects of ECT.

While there are no absolute contraindications for ECT, there is increased risk for patients who have unstable or severe cardiovascular conditions or aneurysms; who have recently had a stroke; who have increased intracranial pressure (for instance, due to a solid brain tumor), or who have severe pulmonary conditions, or who are generally at high risk for receiving anesthesia.

In adolescents, ECT is highly efficient for several psychiatric disorders, with few and relatively benign adverse effects.

Cognitive impairment

Cognitive impairment is sometimes noticed after ECT. It has been claimed by some non-medical authors that retrograde amnesia occurs to some extent in almost all patients receiving ECT. However, most experts consider this adverse effect relatively uncommon. The American Psychiatric Association (APA) report in 2001 acknowledges: “In some patients the recovery from retrograde amnesia will be incomplete, and evidence has shown that ECT can result in persistent or permanent memory loss”. After treatment, drug therapy is usually continued and some patients will continue to receive maintenance ECT treatments. It is the purported effects of ECT on long-term memory that give rise to much of the concern surrounding its use. However, the methods used to measure memory loss are generally poor, and their application to people with depression, who have cognitive deficits including problems with memory, have been problematic.

The acute effects of ECT can include amnesia, both retrograde (for events occurring before the treatment) and anterograde (for events occurring after the treatment). Memory loss and confusion are more pronounced with bilateral electrode placement rather than unilateral, and with outdated sine-wave rather than brief-pulse currents. The use of either constant or pulsing electrical impulses also varied the memory loss results in patients. Patients who received pulsing electrical impulses, as opposed to a steady flow, seemed to incur less memory loss. The vast majority of modern treatment uses brief pulse currents.

Retrograde amnesia is most marked for events occurring in the weeks or months before treatment, with one study showing that although some people lose memories from years prior to treatment, recovery of such memories was "virtually complete" by seven months post-treatment, with the only enduring loss being memories in the weeks and months prior to the treatment. Anterograde memory loss is usually limited to the time of treatment itself or shortly afterwards. In the weeks and months following ECT these memory problems gradually improve, but some people have persistent losses, especially with bilateral ECT. One published review summarizing the results of questionnaires about subjective memory loss found that between 29% and 55% of respondents believed they experienced long-lasting or permanent memory changes. In 2000, American psychiatrist Sarah Lisanby and colleagues found that bilateral ECT left patients with more persistently impaired memory of public events as compared to right unilateral ECT.

Effects on brain structure

Considerable controversy exists over the effects of ECT on brain tissue, although a number of mental health associations—including the APA—have concluded that there is no evidence that ECT causes structural brain damage. A 1999 report by the U.S. Surgeon General states: "The fears that ECT causes gross structural brain pathology have not been supported by decades of methodologically sound research in both humans and animals."

Many expert proponents of ECT maintain that the procedure is safe and does not cause brain damage. Dr. Charles Kellner, a prominent ECT researcher and former chief editor of the Journal of ECT, stated in a 2007 interview that, "There are a number of well-designed studies that show ECT does not cause brain damage and numerous reports of patients who have received a large number of treatments over their lifetime and have suffered no significant problems due to ECT." Dr. Kellner cites a study purporting to show an absence of cognitive impairment in eight subjects after more than 100 lifetime ECT treatments. Dr. Kellner stated "Rather than cause brain damage, there is evidence that ECT may reverse some of the damaging effects of serious psychiatric illness."

Effects in pregnancy

If steps are taken to decrease potential risks, ECT is generally accepted to be relatively safe during all trimesters of pregnancy, particularly when compared to pharmacological treatments. Suggested preparation for ECT during pregnancy includes a pelvic examination, discontinuation of nonessential anticholinergic medication, uterine tocodynamometry, intravenous hydration, and administration of a nonparticulate antacid. During ECT, elevation of the pregnant woman's right hip, external fetal cardiac monitoring, intubation, and avoidance of excessive hyperventilation are recommended. In many instances of active mood disorder during pregnancy, the risks of untreated symptoms may outweigh the risks of ECT. Potential complications of ECT during pregnancy can be minimized by modifications in technique. The use of ECT during pregnancy requires thorough evaluation of the patient's capacity for informed consent.

Effects on the heart

ECT can cause a lack of blood flow and oxygen to the heart, heart arrhythmia, and "persistent asystole". Deaths, however, are very rare after ECT: 6 per 100,000 treatments. If they do occur, cardiovascular complications are considered as causal in about 30%.

Procedure

Electroconvulsive therapy machine on display at Glenside Museum in Bristol, England
 
ECT device produced by Siemens and used for example at the Asyl psychiatric hospital in Kristiansand, Norway from the 1960s to the 1980s.

The placement of electrodes, as well as the dose and duration of the stimulation is determined on a per-patient basis.

In unilateral ECT, both electrodes are placed on the same side of the patient's head. Unilateral ECT may be used first to minimize side effects such as memory loss.

In bilateral ECT, the two electrodes are placed on opposite sides of the head. Usually bitemporal placement is used, whereby the electrodes are placed on the temples. Uncommonly bifrontal placement is used; this involves positioning the electrodes on the patient's forehead, roughly above each eye.

Unilateral ECT is thought to cause fewer cognitive effects than bilateral treatment, but is less effective unless administered at higher doses. Most patients in the US and almost all in the UK receive bilateral ECT.

The electrodes deliver an electrical stimulus. The stimulus levels recommended for ECT are in excess of an individual's seizure threshold: about one and a half times seizure threshold for bilateral ECT and up to 12 times for unilateral ECT. Below these levels treatment may not be effective in spite of a seizure, while doses massively above threshold level, especially with bilateral ECT, expose patients to the risk of more severe cognitive impairment without additional therapeutic gains. Seizure threshold is determined by trial and error ("dose titration"). Some psychiatrists use dose titration, some still use "fixed dose" (that is, all patients are given the same dose) and others compromise by roughly estimating a patient's threshold according to age and sex. Older men tend to have higher thresholds than younger women, but it is not a hard and fast rule, and other factors, for example drugs, affect seizure threshold.

Immediately prior to treatment, a patient is given a short-acting anesthetic such as methohexital, etomidate, or thiopental, a muscle relaxant such as suxamethonium (succinylcholine), and occasionally atropine to inhibit salivation. In a minority of countries such as Japan, India, and Nigeria, ECT may be used without anesthesia. The Union Health Ministry of India recommended a ban on ECT without anesthesia in India's Mental Health Care Bill of 2010 and the Mental Health Care Bill of 2013. The practice was abolished in Turkey's largest psychiatric hospital in 2008.

The patient's EEG, ECG, and blood oxygen levels are monitored during treatment.

ECT is usually administered three times a week, on alternate days, over a course of two to four weeks.

An illustration depicting electroconvulsive therapy.

Neuroimaging prior to ECT

Neuroimaging prior to ECT may be useful for detecting intracranial pressure or mass given that patients respond less when one of these conditions exist. Nonetheless it is not indicated due to high cost and low prevalence of these conditions in patients needing ECT.

Concurrent pharmacotherapy

Whether psychiatric medications are terminated prior to treatment or maintained, varies. However, drugs that are known to cause toxicity in combination with ECT, such as lithium, are discontinued, and benzodiazepines, which increase the seizure threshold, are either discontinued, a benzodiazepine antagonist is administered at each ECT session, or the ECT treatment is adjusted accordingly.

A 2009 RCT provides some evidence indicating that concurrent use of some antidepressant improves ECT efficacy.

Course

ECT is usually done from 6 to 12 times in 2 to 4 weeks but can sometimes exceed 12 rounds. It is also recommended to not do ECT more than 3 times per week.

The team

In the US, the medical team performing the procedure typically consists of a psychiatrist, an anesthetist, an ECT treatment nurse or qualified assistant, and one or more recovery nurses. Medical trainees may assist, but only under the direct supervision of credentialed attending physicians and staff.

Devices

ECT machine from before 1960.

Most modern ECT devices deliver a brief-pulse current, which is thought to cause fewer cognitive effects than the sine-wave currents which were originally used in ECT. A small minority of psychiatrists in the US still use sine-wave stimuli. Sine-wave is no longer used in the UK or Ireland. Typically, the electrical stimulus used in ECT is about 800 milliamps and has up to several hundred watts, and the current flows for between one and six seconds.

In the US, ECT devices are manufactured by two companies, Somatics, which is owned by psychiatrists Richard Abrams and Conrad Swartz, and Mecta. In the UK, the market for ECT devices was long monopolized by Ectron Ltd, which was set up by psychiatrist Robert Russell.

Mechanism of action

Despite decades of research, the exact mechanism of action of ECT remains elusive. Neuroimaging studies in people who have had ECT, investigating differences between responders and nonresponders, and people who relapse, find that responders have anticonvulsant effects mostly in the frontal lobes, which corresponds to immediate responses, and neurotrophic effects primarily in the medial temporal lobe. The anticonvulsant effects are decreased blood flow and decreased metabolism, while the neurotrophic effects are opposite - increased perfusion and metabolism, as well as increased volume of the hippocampus.

A recently proposed mechanism of action is that the seizures induced by ECT cause a profound change in sleep architecture; it is this change in the state of the organism that drives the therapeutic effects of ECT and not any simple change in the release of neurotransmitters, neurotrophic factors and/or hormones.

Use

As of 2001, it was estimated that about one million people received ECT annually.

There is wide variation in ECT use between different countries, different hospitals, and different psychiatrists. International practice varies considerably from widespread use of the therapy in many Western countries to a small minority of countries that do not use ECT at all, such as Slovenia.

About 70 percent of ECT patients are women. This may be due to the fact that women are more likely to be diagnosed with depression. Older and more affluent patients are also more likely to receive ECT. The use of ECT is not as common in ethnic minorities.

Sarah Hall reports, "ECT has been dogged by conflict between psychiatrists who swear by it, and some patients and families of patients who say that their lives have been ruined by it. It is controversial in some European countries such as the Netherlands and Italy, where its use is severely restricted".

United States

ECT became popular in the US in the 1940s. At the time, psychiatric hospitals were overrun with patients whom doctors were desperate to treat and cure. Whereas lobotomies would reduce a patient to a more manageable submissive state, ECT helped to improve mood in those with severe depression. A survey of psychiatric practice in the late 1980s found that an estimated 100,000 people received ECT annually, with wide variation between metropolitan statistical areas. Accurate statistics about the frequency, context and circumstances of ECT in the US are difficult to obtain because only a few states have reporting laws that require the treating facility to supply state authorities with this information. In 13 of the 50 states, the practice of ECT is regulated by law. In the mid-1990s in Texas, ECT was used in about one third of psychiatric facilities and given to about 1,650 people annually. Usage of ECT has since declined slightly; in 2000–01 ECT was given to about 1500 people aged from 16 to 97 (in Texas it is illegal to give ECT to anyone under sixteen). ECT is more commonly used in private psychiatric hospitals than in public hospitals, and minority patients are underrepresented in the ECT statistics. In the United States, ECT is usually given three times a week; in the United Kingdom, it is usually given twice a week. Occasionally it is given on a daily basis. A course usually consists of 6–12 treatments, but may be more or fewer. Following a course of ECT some patients may be given continuation or maintenance ECT with further treatments at weekly, fortnightly or monthly intervals. A few psychiatrists in the US use multiple-monitored ECT (MMECT), where patients receive more than one treatment per anesthetic. Electroconvulsive therapy is not a required subject in US medical schools and not a required skill in psychiatric residency training. Privileging for ECT practice at institutions is a local option: no national certification standards are established, and no ECT-specific continuing training experiences are required of ECT practitioners.

United Kingdom

In the UK in 1980, an estimated 50,000 people received ECT annually, with use declining steadily since then to about 12,000 per annum in 2002. It is still used in nearly all psychiatric hospitals, with a survey of ECT use from 2002 finding that 71 percent of patients were women and 46 percent were over 65 years of age. Eighty-one percent had a diagnosis of mood disorder; schizophrenia was the next most common diagnosis. Sixteen percent were treated without their consent. In 2003, the National Institute for Health and Care Excellence, a government body which was set up to standardize treatment throughout the National Health Service in England and Wales, issued guidance on the use of ECT. Its use was recommended "only to achieve rapid and short-term improvement of severe symptoms after an adequate trial of treatment options has proven ineffective and/or when the condition is considered to be potentially life-threatening in individuals with severe depressive illness, catatonia or a prolonged manic episode".

The guidance received a mixed reception. It was welcomed by an editorial in the British Medical Journal but the Royal College of Psychiatrists launched an unsuccessful appeal. The NICE guidance, as the British Medical Journal editorial points out, is only a policy statement and psychiatrists may deviate from it if they see fit. Adherence to standards has not been universal in the past. A survey of ECT use in 1980 found that more than half of ECT clinics failed to meet minimum standards set by the Royal College of Psychiatrists, with a later survey in 1998 finding that minimum standards were largely adhered to, but that two-thirds of clinics still fell short of current guidelines, particularly in the training and supervision of junior doctors involved in the procedure. A voluntary accreditation scheme, ECTAS, was set up in 2004 by the Royal College, and as of 2017 the vast majority of ECT clinics in England, Wales, Northern Ireland and the Republic of Ireland have signed up.

The Mental Health Act 2007 allows people to be treated against their will. This law has extra protections regarding ECT. A patient capable of making the decision can decline the treatment, and in that case treatment cannot be given unless it will save that patient's life or is immediately necessary to prevent deterioration of the patient's condition. A patient may not be capable of making the decision (they "lack capacity"), and in that situation ECT can be given if it is appropriate and also if there are no advance directives that prevent the use of ECT.

China

ECT was introduced in China in the early 1950s and while it was originally practiced without anesthesia, as of 2012 almost all procedures were conducted with it. As of 2012, there are approximately 400 ECT machines in China, and 150,000 ECT treatments are performed each year. Chinese national practice guidelines recommend ECT for the treatment of schizophrenia, depressive disorders, and bipolar disorder and in the Chinese literature, ECT is an effective treatment for schizophrenia and mood disorders.

Although the Chinese government stopped classifying homosexuality as an illness in 2001, electroconvulsive therapy is still used by some establishments as a form of "conversion therapy". Alleged Internet addiction (or general unruliness) in adolescents is also known to have been treated with ECT, sometimes without anestheia, most notably by Yang Yongxin. The practice was banned in 2009 after news on Yang broke out.

History

A Bergonic chair, a device "for giving general electric treatment for psychological effect, in psycho-neurotic cases", according to original photo description. World War I era.
 

As early as the 16th century, agents to induce seizures were used to treat psychiatric conditions. In 1785, the therapeutic use of seizure induction was documented in the London Medical and Surgical Journal. As to its earliest antecedents one doctor claims 1744 as the dawn of electricity's therapeutic use, as documented in the first issue of Electricity and Medicine. Treatment and cure of hysterical blindness was documented eleven years later. Benjamin Franklin wrote that an electrostatic machine cured "a woman of hysterical fits." By 1801, James Lind as well as Giovanni Aldini had used galvanism to treat patients suffering from various mental disorders. G.B.C. Duchenne, the mid-19th century "Father of Electrotherapy", said its use was integral to a neurological practice.

In the second half of the 19th century, such efforts were frequent enough in British asylums as to make it notable.

Convulsive therapy was introduced in 1934 by Hungarian neuropsychiatrist Ladislas J. Meduna who, believing mistakenly that schizophrenia and epilepsy were antagonistic disorders, induced seizures first with camphor and then metrazol (cardiazol). Meduna is thought to be the father of convulsive therapy. In 1937, the first international meeting on schizophrenia and convulsive therapy was held in Switzerland by the Swiss psychiatrist Max Müller. The proceedings were published in the American Journal of Psychiatry and, within three years, cardiazol convulsive therapy was being used worldwide. Italian Professor of neuropsychiatry Ugo Cerletti, who had been using electric shocks to produce seizures in animal experiments, and his assistant Lucio Bini at Sapienza University of Rome developed the idea of using electricity as a substitute for metrazol in convulsive therapy and, in 1938, experimented for the first time on a person affected by delusions. It was believed early on that inducing convulsions aided in helping those with severe schizophrenia but later found to be most useful with affective disorders such as depression. Cerletti had noted a shock to the head produced convulsions in dogs. The idea to use electroshock on humans came to Cerletti when he saw how pigs were given an electric shock before being butchered to put them in an anesthetized state. Cerletti and Bini practiced until they felt they had the right parameters needed to have a successful human trial. Once they started trials on patients, they found that after 10-20 treatments the results were significant. Patients had much improved. A positive side effect to the treatment was retrograde amnesia. It was because of this side effect that patients could not remember the treatments and had no ill feelings toward it. ECT soon replaced metrazol therapy all over the world because it was cheaper, less frightening and more convenient. Cerletti and Bini were nominated for a Nobel Prize but did not receive one. By 1940, the procedure was introduced to both England and the US. In Germany and Austria, it was promoted by Friedrich Meggendorfer. Through the 1940s and 1950s, the use of ECT became widespread. At the time the ECT device was patented and commercialized abroad, the two Italian inventors had competitive tensions that damaged their relationship. In the 1960s, despite a climate of condemnation, the original Cerletti-Bini ECT apparatus prototype was hotly contended by scientific museums between Italy and the USA The ECT apparatus prototype is now owned and displayed by the Sapienza Museum of the History of Medicine in Rome.

In the early 1940s, in an attempt to reduce the memory disturbance and confusion associated with treatment, two modifications were introduced: the use of unilateral electrode placement and the replacement of sinusoidal current with brief pulse. It took many years for brief-pulse equipment to be widely adopted. In the 1940s and early 1950s ECT, was usually given in "unmodified" form, without muscle relaxants, and the seizure resulted in a full-scale convulsion. A rare but serious complication of unmodified ECT was fracture or dislocation of the long bones. In the 1940s, psychiatrists began to experiment with curare, the muscle-paralysing South American poison, in order to modify the convulsions. The introduction of suxamethonium (succinylcholine), a safer synthetic alternative to curare, in 1951 led to the more widespread use of "modified" ECT. A short-acting anesthetic was usually given in addition to the muscle relaxant in order to spare patients the terrifying feeling of suffocation that can be experienced with muscle relaxants.

The steady growth of antidepressant use along with negative depictions of ECT in the mass media led to a marked decline in the use of ECT during the 1950s to the 1970s. The Surgeon General stated there were problems with electroshock therapy in the initial years before anesthesia was routinely given, and that "these now-antiquated practices contributed to the negative portrayal of ECT in the popular media." The New York Times described the public's negative perception of ECT as being caused mainly by one movie: "For Big Nurse in One Flew Over the Cuckoo's Nest, it was a tool of terror, and, in the public mind, shock therapy has retained the tarnished image given it by Ken Kesey's novel: dangerous, inhumane and overused".

In 1976, Dr. Blatchley demonstrated the effectiveness of his constant current, brief pulse device ECT. This device eventually largely replaced earlier devices because of the reduction in cognitive side effects, although as of 2012 some ECT clinics still were using sine-wave devices. The 1970s saw the publication of the first American Psychiatric Association (APA) task force report on electroconvulsive therapy (to be followed by further reports in 1990 and 2001). The report endorsed the use of ECT in the treatment of depression. The decade also saw criticism of ECT. Specifically, critics pointed to shortcomings such as noted side effects, the procedure being used as a form of abuse, and uneven application of ECT. The use of ECT declined until the 1980s, "when use began to increase amid growing awareness of its benefits and cost-effectiveness for treating severe depression". In 1985, the National Institute of Mental Health and National Institutes of Health convened a consensus development conference on ECT and concluded that, while ECT was the most controversial treatment in psychiatry and had significant side-effects, it had been shown to be effective for a narrow range of severe psychiatric disorders.

Because of the backlash noted previously, national institutions reviewed past practices and set new standards. In 1978, the American Psychiatric Association released its first task force report in which new standards for consent were introduced and the use of unilateral electrode placement was recommended. The 1985 NIMH Consensus Conference confirmed the therapeutic role of ECT in certain circumstances. The American Psychiatric Association released its second task force report in 1990 where specific details on the delivery, education, and training of ECT were documented. Finally, in 2001 the American Psychiatric Association released its latest task force report. This report emphasizes the importance of informed consent, and the expanded role that the procedure has in modern medicine. By 2017, ECT was routinely covered by insurance companies for providing the "biggest bang for the buck" for otherwise intractable cases of severe mental illness, was receiving favorable media coverage, and was being provided in regional medical centers.

Though ECT use declined with the advent of modern antidepressants, there has been a resurgence of ECT with new modern technologies and techniques. Modern shock voltage is given for a shorter duration of 0.5 milliseconds where conventional brief pulse is 1.5 milliseconds.

Society and culture

Controversy

Surveys of public opinion, the testimony of former patients, legal restrictions on the use of ECT and disputes as to the efficacy, ethics and adverse effects of ECT within the psychiatric and wider medical community indicate that the use of ECT remains controversial. This is reflected in the January 2011 vote by the FDA's Neurological Devices Advisory Panel to recommend that FDA maintain ECT devices in the Class III device category for high risk devices, except for patients suffering from catatonia, major depressive disorder, and bipolar disorder. This may result in the manufacturers of such devices having to do controlled trials on their safety and efficacy for the first time. In justifying their position, panelists referred to the memory loss associated with ECT and the lack of long-term data.

Legal status

Informed consent

The World Health Organization (2005) advises that ECT should be used only with the informed consent of the patient (or their guardian if their incapacity to consent has been established).

In the US, this doctrine places a legal obligation on a doctor to make a patient aware of the reason for treatment, the risks and benefits of a proposed treatment, the risks and benefits of alternative treatment, and the risks and benefits of receiving no treatment. The patient is then given the opportunity to accept or reject the treatment. The form states how many treatments are recommended and also makes the patient aware that consent may be revoked and treatment discontinued at any time during a course of ECT. The US Surgeon General's Report on Mental Health states that patients should be warned that the benefits of ECT are short-lived without active continuation treatment in the form of drugs or further ECT, and that there may be some risk of permanent, severe memory loss after ECT. The report advises psychiatrists to involve patients in discussion, possibly with the aid of leaflets or videos, both before and during a course of ECT.

To demonstrate what he believes should be required to fully satisfy the legal obligation for informed consent, one psychiatrist, working for an anti-psychiatry organisation, has formulated his own consent form using the consent form developed and enacted by the Texas Legislature as a model.

According to the US Surgeon General, involuntary treatment is uncommon in the US and is typically used only in cases of great extremity, and only when all other treatment options have been exhausted. The use of ECT is believed to be a potentially life-saving treatment.

In one of the few jurisdictions where recent statistics on ECT usage are available, a national audit of ECT by the Scottish ECT Accreditation Network indicated that 77% of patients who received the treatment in 2008 were capable of giving informed consent.

In the UK, in order for consent to be valid it requires an explanation in "broad terms" of the nature of the procedure and its likely effects. One review from 2005 found that only about half of patients felt they were given sufficient information about ECT and its adverse effects and another survey found that about fifty percent of psychiatrists and nurses agreed with them.

A 2005 study published in the British Journal of Psychiatry described patients' perspectives on the adequacy of informed consent before ECT. The study found that "About half (45–55%) of patients reported they were given an adequate explanation of ECT, implying a similar percentage felt they were not." The authors also stated:

Approximately a third did not feel they had freely consented to ECT even when they had signed a consent form. The proportion who feel they did not freely choose the treatment has actually increased over time. The same themes arise whether the patient had received treatment a year ago or 30 years ago. Neither current nor proposed safeguards for patients are sufficient to ensure informed consent with respect to ECT, at least in England and Wales.

Involuntary ECT

Procedures for involuntary ECT vary from country to country depending on local mental health laws.

United States

In most states in the US, a judicial order following a formal hearing is needed before a patient can be forced to undergo involuntary ECT. However, ECT can also be involuntarily administered in situations with less immediate danger. Suicidal intent is a common justification for its involuntary use, especially when other treatments are ineffective.

United Kingdom

Until 2007 in England and Wales, the Mental Health Act 1983 allowed the use of ECT on detained patients whether or not they had capacity to consent to it. However, following amendments which took effect in 2007, ECT may not generally be given to a patient who has capacity and refuses it, irrespective of his or her detention under the Act. In fact, even if a patient is deemed to lack capacity, if they made a valid advance decision refusing ECT then they should not be given it; and even if they do not have an advance decision, the psychiatrist must obtain an independent second opinion (which is also the case if the patient is under age of consent). However, there is an exception regardless of consent and capacity; under Section 62 of the Act, if the treating psychiatrist says the need for treatment is urgent they may start a course of ECT without authorization. From 2003 to 2005, about 2,000 people a year in England and Wales were treated without their consent under the Mental Health Act. Concerns have been raised by the official regulator that psychiatrists are too readily assuming that patients have the capacity to consent to their treatments, and that there is a worrying lack of independent advocacy. In Scotland, the Mental Health (Care and Treatment) (Scotland) Act 2003 also gives patients with capacity the right to refuse ECT.

Regulation

In the US, ECT devices came into existence prior to medical devices being regulated by the Food and Drug Administration. In 1976, the Medical Device Regulation Act required the FDA to retrospectively review already existing devices, classify them, and determine whether clinical trials were needed to prove efficacy and safety. The FDA initially classified the devices used to administer ECT as Class III medical devices. In 2014, the American Psychiatric Association petitioned the FDA to reclassify ECT devices from Class III (high-risk) to Class II (medium-risk), which would significantly improve access to an effective and potentially lifesaving treatment. A similar reclassification proposal in 2010 met significant resistance from anti-psychiatry groups and did not pass. In 2018, the FDA re-classified ECT devices as Class II devices when used to treat catatonia or a severe major depressive episode associated with major depressive disorder or bipolar disorder.

Public perception

A questionnaire survey of 379 members of the general public in Australia indicated that more than 60% of respondents had some knowledge about the main aspects of ECT. Participants were generally opposed to the use of ECT on depressed individuals with psychosocial issues, on children, and on involuntary patients. Public perceptions of ECT were found to be mainly negative. A sample of the general public, medical students, and psychiatry trainees in the United Kingdom found that the psychiatry trainees were more knowledgeable and had more favorable opinions of ECT than did the other groups. More members of the general public believed that ECT was used for control or punishment purposes than medical students or psychiatry trainees.

Famous cases

Ernest Hemingway, an American author, died by suicide shortly after ECT at the Mayo Clinic in 1961. He is reported to have said to his biographer, "Well, what is the sense of ruining my head and erasing my memory, which is my capital, and putting me out of business? It was a brilliant cure but we lost the patient."

Robert Pirsig suffered a nervous breakdown and spent time in and out of psychiatric hospitals between 1961 and 1963. He was diagnosed with paranoid schizophrenia and clinical depression as a result of an evaluation conducted by psychoanalysts, and was treated with electroconvulsive therapy on numerous occasions, a treatment he discusses in his novel, Zen and the Art of Motorcycle Maintenance.

Thomas Eagleton, United States Senator from Missouri, was dropped from the Democratic ticket in the 1972 United States Presidential Election as the party's Vice Presidential candidate after it was revealed that he had received electroshock treatment in the past for depression. Presidential nominee George McGovern replaced him with Sargent Shriver, and later went on to lose by a landslide to Richard Nixon.

American surgeon and award-winning author Sherwin B. Nuland is another notable person who has undergone ECT. In his 40s, this successful surgeon's depression became so severe that he had to be institutionalized. After exhausting all treatment options, a young resident assigned to his case suggested ECT, which ended up being successful. Author David Foster Wallace also received ECT for many years, beginning as a teenager, before his suicide at age 46.

New Zealand author Janet Frame experienced both insulin coma therapy and ECT (but without the use of anesthesia or muscle relaxants). She wrote about this in her autobiography, An Angel at My Table (1984), which was later adapted into a film (1990).

American actor Carrie Fisher wrote about her experience with memory loss after ECT treatments in her memoir Wishful Drinking.

Fictional examples

Electroconvulsive therapy has been depicted in fiction, including fictional works partly based on true experiences. These include Sylvia Plath's autobiographical novel, The Bell Jar, Ken Loach's film Family Life, and Ken Kesey's novel One Flew Over the Cuckoo's Nest; Kesey's novel is a direct product of his time working the graveyard shift as an orderly at a mental health facility in Menlo Park, California.

In the 2000 film Requiem for a Dream, Sarah Goldfarb receives "unmodified" electroconvulsive therapy after experiencing severe amphetamine psychosis following prolonged stimulant abuse. Unlike typical ECT treatment, she is given no anesthetic or medication before.

In the 2014 TV series Constantine, the protagonist John Constantine is institutionalized and specifically requests electroconvulsive therapy as an attempt to alleviate or resolve his mental problems.

In the final episode of Season 1 of the US television series Homeland, Carrie Mathison receives electroconvulsive therapy in an attempt to alleviate her bipolar disorder.

The musical Next to Normal revolves around the family of a woman who undergoes the procedure.

In the HBO series Six Feet Under season 5, George undergoes an ECT treatment to deal with his increasing paranoia. The depiction is shown realistically, with an actual ECT machine.

In the WB/CW TV series Smallville, Lionel Luthor condemns his son Lex Luthor to electroshock therapy to remove Lex's short-term memory of a murder he discovered Lionel committed.

In the Netflix series Stranger Things, Eleven's mother is given electroshock therapy to silence her.

Electroshock therapy is used on various characters throughout season 2 of American Horror Story.

Special populations

Sex difference

Throughout the history of ECT, women have received it two to three times as often as men. Currently, about 70 percent of ECT patients are women. This may be due to the fact that women are more likely to be diagnosed with depression. A 1974 study of ECT in Massachusetts reported that women made up 69 percent of those given ECT. The Ministry of Health in Canada reported that from 1999 until 2000 in the province of Ontario, women were 71 percent of those given ECT in provincial psychiatric institutions, and 75 percent of the total ECT given was given to women.

Evolutionary biology

From Wikipedia, the free encyclopedia

Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics, and paleontology.

The investigational range of current research widened to encompass the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution, such as sexual selection, genetic drift, and biogeography. Moreover, the newer field of evolutionary developmental biology ("evo-devo") investigates how embryogenesis, the development of the embryo, is controlled, thus yielding a wider synthesis that integrates developmental biology with the fields of study covered by the earlier evolutionary synthesis.

Subfields

Evolution is the central unifying concept in biology. Biology can be divided in various ways. One way is by the level of biological organization, from molecular to cell, organism to population. An earlier way is by perceived taxonomic group, with fields such as zoology, botany, and microbiology, reflecting what were once seen as the major divisions of life. A third way is by approach, such as field biology, theoretical biology, experimental evolution, and paleontology. These alternative ways of dividing up the subject can be combined with evolutionary biology to create subfields like evolutionary ecology and evolutionary developmental biology.

More recently, the merge between the biological science and applied sciences gave birth to new fields that are extensions of evolutionary biology, including evolutionary robotics, engineering, algorithms, economics, and architecture. The basic mechanisms of evolution are applied directly or indirectly to come up with novel designs or solve problems that are difficult to solve otherwise. The research generated in these applied fields in turn, contribute to progress, especially thanks to work on evolution in computer science and engineering fields such as mechanical engineering.

Evolutionary developmental biology

In evolutionary developmental biology the different processes of development can play a role in how a specific organism reaches its current body plan. The genetic regulation of ontogeny and phylogenetic process is what allows for this kind of understanding of biology to be possible. Looking at different processes during development, and going through the evolutionary tree, one can determine at which point a specific structure came about. For example, the three germ layers can be observed to not be present in cnidarians and ctenophores, which instead present in worms, being more or less developed depending on the kind of worm itself. Other structures like the development of Hox genes and sensory organs such as eyes can also be traced with this practice.

History

The idea of evolution by natural selection was proposed by Charles Darwin in 1859, but evolutionary biology, as an academic discipline in its own right, emerged during the period of the modern synthesis in the 1930s and 1940s. It was not until the 1980s that many universities had departments of evolutionary biology. In the United States, many universities have created departments of molecular and cell biology or ecology and evolutionary biology, in place of the older departments of botany and zoology. Palaeontology is often grouped with earth science.

Microbiology too is becoming an evolutionary discipline, now that microbial physiology and genomics are better understood. The quick generation time of bacteria and viruses such as bacteriophages makes it possible to explore evolutionary questions.

Many biologists have contributed to shaping the modern discipline of evolutionary biology. Theodosius Dobzhansky and E. B. Ford established an empirical research programme. Ronald Fisher, Sewall Wright and J. S. Haldane created a sound theoretical framework. Ernst Mayr in systematics, George Gaylord Simpson in paleontology and G. Ledyard Stebbins in botany helped to form the modern synthesis. James Crow, Richard Lewontin, Dan Hartl, Marcus Feldman, and Brian Charlesworth trained a generation of evolutionary biologists.

Current research topics

Current research in evolutionary biology covers diverse topics and incorporates ideas from diverse areas, such as molecular genetics and computer science.

First, some fields of evolutionary research try to explain phenomena that were poorly accounted for in the modern evolutionary synthesis. These include speciation, the evolution of sexual reproduction, the evolution of cooperation, the evolution of ageing, and evolvability.

Second, biologists ask the most straightforward evolutionary question: "what happened and when?". This includes fields such as paleobiology, as well as systematics and phylogenetics.

Third, the modern evolutionary synthesis was devised at a time when nobody understood the molecular basis of genes. Today, evolutionary biologists try to determine the genetic architecture of interesting evolutionary phenomena such as adaptation and speciation. They seek answers to questions such as how many genes are involved, how large are the effects of each gene, how interdependent are the effects of different genes, what do the genes do, and what changes happen to them (e.g., point mutations vs. gene duplication or even genome duplication). They try to reconcile the high heritability seen in twin studies with the difficulty in finding which genes are responsible for this heritability using genome-wide association studies.

One challenge in studying genetic architecture is that the classical population genetics that catalysed the modern evolutionary synthesis must be updated to take into account modern molecular knowledge. This requires a great deal of mathematical development to relate DNA sequence data to evolutionary theory as part of a theory of molecular evolution. For example, biologists try to infer which genes have been under strong selection by detecting selective sweeps.

Fourth, the modern evolutionary synthesis involved agreement about which forces contribute to evolution, but not about their relative importance. Current research seeks to determine this. Evolutionary forces include natural selection, sexual selection, genetic drift, genetic draft, developmental constraints, mutation bias and biogeography.

An evolutionary approach is key to much current research in organismal biology and ecology, such as in life history theory. Annotation of genes and their function relies heavily on comparative approaches. The field of evolutionary developmental biology ("evo-devo") investigates how developmental processes work, and compares them in different organisms to determine how they evolved.

Many physicians do not have enough background in evolutionary biology, making it difficult to use it in modern medicine. 

Drug resistance today

Evolution plays a role in resistance of drugs. For example, how HIV becomes resistant to medications and the body's immune system. The mutation of resistance of HIV is due to the natural selection of the survivors and their offspring. The one HIV that survived the immune system reproduced and had offspring that were also resistant to the immune system.  Drug resistance also causes many problems for patients such as a worsening sickness or the sickness can mutate into something that can no longer be cured with medication. Without the proper medicine a sickness can be the death of a patient. If their body has resistance to a certain number of drugs, then the right medicine will be harder and harder to find. Not finishing an antibiotic is also an example of resistance that will cause the bacteria or virus to evolve and continue to spread in the body. When the full dosage of the medication does not enter the body and perform its proper job, the virus and bacteria that survive the initial dosage will continue to reproduce. This makes for another sickness later on that will be even harder to cure because this disease will be resistant to the first medication used. Finishing medicine that is prescribed is a vital step in avoiding antibiotic resistance. Also, those with chronic illnesses, illnesses that last throughout the lifetime, are at a greater risk to antibiotic resistance than others. This is because overuse of a drug or too high of a dosage can cause a patient's immune system to weaken and the illness will evolve and grow stronger. For example, cancer patients will need a stronger and stronger dosage of medication because of their low functioning immune system.

Journals

Some scientific journals specialise exclusively in evolutionary biology as a whole, including the journals Evolution, Journal of Evolutionary Biology, and BMC Evolutionary Biology. Some journals cover sub-specialties within evolutionary biology, such as the journals Systematic Biology, Molecular Biology and Evolution and its sister journal Genome Biology and Evolution, and Cladistics.

Other journals combine aspects of evolutionary biology with other related fields. For example, Molecular Ecology, Proceedings of the Royal Society of London Series B, The American Naturalist and Theoretical Population Biology have overlap with ecology and other aspects of organismal biology. Overlap with ecology is also prominent in the review journals Trends in Ecology and Evolution and Annual Review of Ecology, Evolution, and Systematics. The journals Genetics and PLoS Genetics overlap with molecular genetics questions that are not obviously evolutionary in nature.

Evolutionary mismatch

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

Evolutionary mismatch, also known as mismatch theory or evolutionary trap, is a concept in evolutionary biology that refers to evolved traits that were once advantageous but became maladaptive due to changes in the environment. This can take place in humans and animals and is often attributed to rapid environmental change.

Timeline showing a period of mismatch following an environmental change.

Mismatch theory represents the idea that traits that evolved in an organism in one environment can be disadvantageous in a different environment. This environmental change leading to evolutionary mismatch can be broken down into two major categories: temporal (change of the existing environment over time, e.g. a climate change) or spatial (placing organisms into a new environment, e.g. a population migrating). Since environmental change occurs naturally and constantly, there will certainly be examples of evolutionary mismatch over time. However, because large-scale natural environmental change – like a natural disaster – is often rare, it is less often observed. Another more prevalent kind of environmental change is anthropogenic (human-caused). In recent times, humans have had a large, rapid, and trackable impact on our environment, thus creating scenarios where it is easier to observe evolutionary mismatch.

Because of the mechanism of evolution by natural selection, the environment ("nature") determines ("selects") which traits will persist in a population. Therefore, there will be a gradual weeding out of disadvantageous traits over several generations as the population becomes more adapted to its environment. Any significant change in a population's traits that cannot be attributed to other factors (such as genetic drift and mutation) will be responsive to a change in that population's environment; in other words, natural selection is inherently reactive. Shortly following an environmental change, traits that evolved in the previous environment, whether they were advantageous or neutral, are persistent for several generations in the new environment. Because evolution is gradual and environmental changes often occur very quickly on a geological scale, there is always a period of "catching-up" as the population evolves to become adapted to the environment. It is this temporary period of "disequilibrium" that is referred to as mismatch. Mismatched traits are ultimately addressed in one of several possible ways: the organism may evolve such that the maladaptive trait is no longer expressed, the organism may decline and/or become extinct as a result of the disadvantageous trait, or the environment may change such that the trait is no longer selected against.

History

As evolutionary thought became more prevalent, scientists studied and attempted to explain the existence of disadvantageous traits, known as maladaptations, that are the basis of evolutionary mismatch.

The theory of evolutionary mismatch began under the term evolutionary trap as early as the 1940s. In his 1942 book, evolutionary biologist Ernst Mayr described evolutionary traps as the phenomenon that occurs when a genetically uniform population suited for a single set of environmental conditions is susceptible to extinction from sudden environment changes. Since then, key scientists such as Warren J. Gross and Edward O. Wilson have studied and identified numerous examples of evolutionary traps.

The first occurrence of the term "evolutionary mismatch" may have been in a paper by Jack E. Riggs published in the Journal of Clinical Epidemiology in 1993. In the years to follow, the term evolutionary mismatch has become widely used to describe biological maladaptations in a wide range of disciplines. A coalition of modern scientists and community organizers assembled to found the Evolution Institute in 2008, and in 2011 published a more recent culmination of information on evolutionary mismatch theory in an article by Elisabeth Lloyd, David Sloan Wilson, and Elliott Sober. In 2018 a popular science book appeared by evolutionary psychologists on evolutionary mismatch and the implications for humans.

Many members of the scientific community continue to explore the effects of evolutionary mismatch in our quickly changing world.

Mismatch in human evolution

The Neolithic Revolution: transitional context

The Neolithic Revolution brought about significant evolutionary changes in humans; namely the transition from a hunter-gatherer lifestyle, in which humans foraged for food, to an agricultural lifestyle. This change occurred approximately 10,000–12,000 years ago. Humans began to domesticate both plants and animals, allowing for the maintenance of constant food resources. This transition quickly and dramatically changed the way that humans interact with the environment, with societies taking up practices of farming and animal husbandry. However, human bodies had evolved to be adapted to their previous foraging lifestyle. The slow pace of evolution in comparison with the very fast pace of human advancement allowed for the persistence of these adaptations in an environment where they are no longer necessary. In human societies that now function in a vastly different way from the hunter-gatherer lifestyle, these outdated adaptations now lead to the presence of maladaptive, or mismatched, traits.

Some modern human populations engage in hunter-gatherer practices.

Human disease

Obesity and diabetes

Human bodies are predisposed to maintain homeostasis, especially when storing energy as fat. This trait serves as the main basis for the "thrifty gene hypothesis", the idea that "feast-or-famine conditions during human evolutionary development naturally selected for people whose bodies were efficient in their use of food calories". Hunter-gatherers, who used to live under environmental stress, benefit from this trait; there was an uncertainty of when the next meal would be, and they would spend most of their time performing high levels of physical activity. Therefore, those that consumed many calories would store the extra energy as fat, which they could draw upon in times of hunger.

However, modern humans have evolved to a world of more sedentary lifestyles and convenience foods. People are sitting more throughout their days, whether it be in their cars during rush hour or in their cubicles during their full-time jobs. Less physical activity in general means fewer calories burned throughout the day. Human diets have changed considerably over the 10,000 years since the advent of agriculture, with more processed foods in their diets that lack nutritional value and lead them to consume more sodium, sugar, and fat. These high calorie, nutrient-deficient foods cause people to consume more calories than they burn. Fast food combined with decreased physical activity means that the "thrifty gene" that once benefit human predecessors now works against them, causing their bodies to store more fat and leading to higher levels of obesity in the population.

Obesity is one consequence of mismatched genes. Known as "metabolic syndrome", this condition is also associated with other health concerns, including insulin resistance, where the body no longer responds to insulin secretion, so blood glucose levels are unable to be lowered, which can lead to type 2 diabetes.

Osteoporosis

Another human disorder that can be explained by mismatch theory is the rise in osteoporosis in modern humans. In advanced societies, many people, especially women, are remarkably susceptible to osteoporosis during aging. Fossil evidence has suggested that this was not always the case, with bones from elderly hunter-gatherer women often showing no evidence of osteoporosis. Evolutionary biologists have posited that the increase in osteoporosis in modern Western populations is likely due to our considerably sedentary lifestyles. Women in hunter-gatherer societies were physically active both from a young age and well into their late-adult lives. This constant physical activity likely lead to peak bone mass being considerably higher in hunter-gatherer humans than in modern-day humans. While the pattern of bone mass degradation during aging is purportedly the same for both hunter-gatherers and modern humans, the higher peak bone mass associated with more physical activity may have led hunter-gatherers to be able to develop a propensity to avoid osteoporosis during aging.

Hygiene hypothesis

The hygiene hypothesis, a concept initially theorized by immunologists and epidemiologists, has been proved to have a strong connection with evolutionary mismatch through recent year studies. Hygiene hypothesis states that the profound increase in allergies, autoimmune diseases, and some other chronic inflammatory diseases is related to the reduced exposure of the immune system to antigens. Such reduced exposure is more common in industrialized countries and especially urban areas, where the inflammatory chronic diseases are also more frequently seen. Recent analysis and studies have tied the hygiene hypothesis and evolutionary mismatch together. Some researchers suggest that the overly sterilized urban environment changes or depletes the microbiota composition and diversity. Such environmental conditions favor the development of the inflammatory chronic diseases because human bodies have been selected to adapt to a pathogen-rich environment in the history of evolution. For example, studies have shown that change in our symbiont community can lead to the disorder of immune homeostasis, which can be used to explain why antibiotic use in early childhood can result in higher asthma risk. Because the change or depletion of the microbiome is often associated with hygiene hypothesis, the hypothesis is sometimes also called "biome depletion theory".

Human behavior

Behavioral examples of evolutionary mismatch theory include the abuse of dopaminergic pathways and the reward system. An action or behavior that stimulates the release of dopamine, a neurotransmitter known for generating a sense of pleasure, will likely be repeated since the brain is programmed to continually seek such pleasure. In hunter-gatherer societies, this reward system was beneficial for survival and reproductive success. But now, when there are fewer challenges to survival and reproducing, certain activities in the present environment (gambling, drug use, eating) exploit this system, leading to addictive behaviors.

Work stress

Examples of evolutionary mismatch also occur in the modern workplace. Unlike our hunter-gatherer ancestors who lived in small egalitarian societies the modern work place is large, complex, and hierarchical. Humans spend significant amounts of time interacting with strangers in conditions that are very different from those of our ancestral past. Hunter-gatherers do not separate work from their private lives, they have no bosses to be accountable to, or no deadlines to adhere to. Our stress system reacts to immediate threats and opportunities. The modern workplace exploits evolved psychological mechanisms that are aimed at immediate survival or longer-term reproduction. These basic instincts misfire in the modern workplace, causing conflicts at work, burnout, job alienation and poor management practices.

Gambling

There are two aspects of gambling that make it an addictive activity: chance and risk. Chance gives gambling its novelty. Back when humans had to forage and hunt for food, novelty-seeking was advantageous for them, particularly for their diet. However, with the development of casinos, this trait of pursuing novelties has become disadvantageous. Risk assessment, the other behavioral trait applicable to gambling, was also beneficial to hunter-gatherers in the face of danger. However, the types of risks hunter-gatherers had to assess are significantly different and more life-threatening than the risks people now face. The attraction to gambling stems from the attraction to risk and reward related activity.

Drug addiction

Herbivores have created selective pressure for plants to possess specific molecules that deter plant consumption, such as nicotine, morphine, and cocaine. Plant-based drugs, however, have reinforcing and rewarding effects on the human neurological system, suggesting a "paradox of drug reward" in humans. Human behavioral evolutionary mismatch explains the contradiction between plant evolution and human drug use. In the last 10,000 years, humans found the dopaminergic system, or reward system, particularly useful in optimizing Darwinian fitness. While drug use has been a common characteristic of past human populations, drug use involving potent substances and diverse intake methods is a relatively contemporary feature of society. Human ancestors lived in an environment that lacked drug use of this nature, so the reward system was primarily used in maximizing survival and reproductive success. In contrast, present-day humans live in a world where the current nature of drugs render the reward system maladaptive. This class of drugs falsely triggers a fitness benefit in the reward system, leaving people susceptible to drug addiction. The modern-day dopaminergic system presents vulnerabilities to the difference in accessibility and social perception of drugs.

Eating

In the era of foraging for food, hunter-gatherers rarely knew where their next meal would come from. As a result, filling their stomachs up with lots of food was advantageous since food was scarce. Intense consumption of high-energy foods was selected for when the availability of food was low and it was more difficult to find. Now, food is readily available, and the neurological system that once helped people recognize the survival advantages of essential eating has now become disadvantageous as it promotes overeating. This has become especially dangerous after the rise of processed foods, as the popularity of foods that have unnaturally high levels of sugar and fat has significantly increased.

Non-human examples

Evolutionary mismatch can occur any time an organism is exposed to an environment that does not resemble the typical environment the organism adapted in. Due to human influences, such as global warming and habitat destruction, the environment is changing very rapidly for many organisms, leading to numerous cases of evolutionary mismatch.

Examples with human influence

Sea turtles and light pollution

Female sea turtles create nests to lay their eggs by digging a pit on the beach, typically between the high tide line and dune, using their rear flippers. Consequently, within the first seven days of hatching, hatchling sea turtles must make the journey from the nest back into the ocean. This trip occurs predominantly at night in order to avoid predators and overheating.

Hatchling sea turtles must make their way back into the ocean.

In order to orient themselves towards the ocean, the hatchlings depend on their eyes to turn towards the brightest direction. This is because the open horizon of the ocean, illuminated by celestial light, tends to be much brighter in a natural undeveloped beach than the dunes and vegetation. Studies propose two mechanisms of the eye for this phenomenon. Referred to as the "raster system", the theory is that sea turtles' eyes contain numerous light sensors which take in the overall brightness information of a general area and make a "measurement" of where the light is most intense. If the light sensors detect the most intense light on a hatchling's left side, the sea turtle would turn left. A similar proposal called the complex phototropotaxis system theorizes that the eyes contain light intensity comparators that take in detailed information of the intensity of light from all directions. Sea turtles are able to "know" that they are facing the brightest direction when the light intensity is balanced between both eyes.

This method of finding the ocean is successful in natural beaches, but in developed beaches, the intense artificial lights from buildings, light houses, and even abandoned fires overwhelm the sea turtles and cause them to head towards the artificial light instead of the ocean. Scientists call this misorientation. Sea turtles can also become disoriented and circle around in the same place. Numerous cases show that misoriented hatchling sea turtles either die from dehydration, get consumed by a predator, or even burn to death in an abandoned fire. The direct impact of light pollution on the number of sea turtles has been too difficult to measure. However, this problem is exacerbated because all species of sea turtles are endangered. Other animals, including migratory birds and insects, are also victims to light pollution because they also depend on light intensity at night to properly orient themselves.

Dodo bird and hunting

Dodo birds became completely extinct due to hunting.

The Dodo bird lived on a remote Island, Mauritius, in the absence of predators. Here, the Dodo evolved to lose its instinct for fear and the ability to fly. This allowed them to be easily hunted by Dutch sailors who arrived on the island in the late 16th century. The Dutch sailors also brought foreign animals to the island such as monkeys and pigs that ate the Dodo bird's eggs, which was detrimental to the population growth of the slow breeding bird. Their fearlessness made them easy targets and their inability to fly gave them no opportunity to evade danger. Thus, they were easily driven to extinction within a century of their discovery.

The Dodo's inability to fly was once beneficial for the bird because it conserved energy. The Dodo conserved more energy relative to birds with the ability to fly, due to the Dodo's smaller pectoral muscles. Smaller muscle sizes are linked to lower rates of maintenance metabolism, which in turn conserves energy for the Dodo. Lacking an instinct for fear was another mechanism through which the Dodo conserved energy because it never had to expend any energy for a stress response. Both mechanisms of conservation of energy was once advantageous because it enabled the Dodo to execute activities with minimal energy expenditure. However, these proved disadvantageous when their island was invaded, rendering them defenseless to the new dangers that humans brought.

Peppered moths during the English Industrial Revolution

Before the English Industrial Revolution of the late 18th and early 19th centuries the most common phenotypic color of the peppered moth was white with black speckles. However, that changed when the Industrial Revolution produced high levels of pollution. Due to the Industrial Revolution the trees blackened in urban regions, causing the original phenotype to stand out significantly more to predators. Natural selection then began favoring the rare dark peppered carbonaria moth in order for the species to camouflage and prevent attacks. The dark moth's population expanded rapidly and by the 1950s vast amounts of England saw carbonaria frequencies rise above 90%. The once favorable white speckled phenotype quickly became mismatched in the new environment.

However, in the late 1900s, the English made efforts to reduce air pollution, causing the trees to turn back to their normal shade. The change in color led the dark skin phenotype to revert from beneficial to disadvantageous. Once again, the moth was not able to adapt fast enough to the changing environment and thus the carbonaria phenotype became mismatched. Since the trees' return to their natural color caused the original phenotype to become advantageous again since it allowed the peppered moth to hide from predators.

Giant jewel beetle and beer bottles

The Jewel Beetle has a shiny, brown exterior similar to that of a beer bottle

Evolutionary mismatch can also be seen among insects. One such example is in the case of the Giant Jewel Beetle (Julodimorpha bakewelli). The male jewel beetle has evolved to be attracted to certain features of the female jewel beetle that allow the male jewel beetle to identify a female as it flies across the desert. These features include size, color, and texture. However, these physical traits are seen manifested in beer bottles as well. As a result, male jewel beetles often consider beer bottles more attractive than female jewel beetles due to the beer bottle's large size and attractive coloring. Beer bottles are often discarded by humans in the Australian desert that the jewel beetle thrives in, creating an environment where male jewel beetles prefer to mate with beer bottles instead of female jewel beetles. This is a situation that is extremely disadvantageous as it reduces the reproductive output of the jewel beetle as fewer beetles are mating. This condition can be considered an evolutionary mismatch, as a habit that evolved to aid in reproduction has become disadvantageous due to the littering of beer bottles, an anthropogenic cause.

Examples without human influence

Information cascades between birds

A group of Nutmeg Mannikins at a bird feeder
A group of Nutmeg Mannikins at a bird feeder

Normally, gaining information from watching other organisms allows the observer to make good decisions without spending effort. More specifically, birds often observe the behavior of other organisms to gain valuable information, such as the presence of predators, good breeding sites, and optimal feeding spots. Although this allows the observer to spend less effort gathering information, it can also lead to bad decisions if the information gained from observing is unreliable. In the case of the nutmeg mannikins, the observer can minimize the time spent looking for an optimal feeder and maximize its feeding time by watching where other nutmeg mannikins feed. However, this relies on the assumption that the observed mannikins also had reliable information that indicated the feeding spot was an ideal one. This behavior can become maladaptive when prioritizing information gained from watching others leads to information cascades, where birds follow the rest of the crowd even though prior experience may have suggested that the decision of the crowd is a poor one. For instance, if a nutmeg mannikin sees enough mannikins feeding at a feeder, nutmeg mannikins have been shown to choose that feeder even if their personal experience indicates that the feeder is a poor one.

House finches and the introduction of the MG disease

Evolutionary mismatch occurs in house finches when they are exposed to infectious individuals. Male house finches tend to feed in close proximity to other finches that are sick or diseased, because sick individuals are less competitive than usual, in turn making the healthy male more likely to win an aggressive interaction if it happens. To make it less likely to lose a social confrontation, healthy finches are inclined to forage near individuals that are lethargic or listless due to disease. However, this disposition has created an evolutionary trap for the finches after the introduction of the MG disease in 1994. Since this disease is infectious, healthy finches will be in danger of contraction if they are in the vicinity of individuals that have previously developed the disease. The relatively short duration of the disease's introduction has caused an inability for the finches to adapt quickly enough to avoid nearing sick individuals, which ultimately results in the mismatch between their behavior and the changing environment.

Exploitation of earthworm's reaction to vibrations

Worm charming is a practice used by people to attract earthworms out of the ground by driving in a wooden stake to vibrate the soil. This activity is commonly performed to collect fishing bait and as a competitive sport. Worms that sense the vibrations rise to the surface. Research shows that humans are actually taking advantage of a trait that worms adapted to avoid hungry burrowing moles which prey on the worms. This type of evolutionary trap, where an originally beneficial trait is exploited in order to catch prey, was coined the "rare enemy effect" by Richard Dawkins, an English evolutionary biologist. This trait of worms has been exploited not only by humans, but by other animals. Herring gulls and wood turtles have been observed to also stamp on the ground to drive the worms up to the surface and consume them.

 

Inequality (mathematics)

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