Neuropsychological assessment

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

Over the past three millennia, scholars have attempted to establish connections between localized brain damage and corresponding behavioral changes. A significant advancement in this area occurred between 1942 and 1948, when Soviet neuropsychologist Alexander Luria developed the first systematic neuropsychological assessment, comprising a battery of behavioral tasks designed to evaluate specific aspects of behavioral regulation. During and following the Second World War, Luria conducted extensive research with large cohorts of brain-injured Russian soldiers.

Among his most influential contributions was the identification of the critical role played by the frontal lobes of the cerebral cortex in neuroplasticity, behavioral initiation, planning, and organization. To assess these functions, Luria developed a range of tasks—such as the Go/no-go task, "count by 7," hands-clutching, clock-drawing task, repetitive pattern drawing, word associations, and category recall—which have since become standard elements in neuropsychological evaluations and mental status examinations.

Due to the breadth and originality of his methodological contributions, Luria is widely regarded as a foundational figure in the field of neuropsychological assessment. His neuropsychological test battery was later adapted in the United States as the Luria-Nebraska neuropsychological battery during the 1970s. Many of the tasks from this battery were subsequently incorporated into contemporary neuropsychological assessments, including the Mini–mental state examination (MMSE), which is commonly used for dementia screening.

History

Neuropsychological assessment has traditionally been employed to evaluate the degree of impairment in specific cognitive or functional abilities and to assist in identifying potential areas of brain damage resulting from brain injury or neurological illness. With the development of advanced neuroimaging techniques, the precise localization of space-occupying lesions can now be achieved with greater accuracy, thereby shifting the focus of neuropsychological assessment toward the evaluation of cognitive and behavioral functioning. This includes the systematic examination of the impact of brain injury or other neuropathological processes on an individual.

A central component of neuropsychological assessment involves the administration of standardized neuropsychological tests, which provide a structured means of evaluating cognitive abilities. However, neuropsychological assessment encompasses more than the mere administration and scoring of these tests and screening instruments. It is critical that such assessments also incorporate an evaluation of the individual's mental status, particularly in cases involving suspected Alzheimer's disease or other types of dementia.

Cognitive domains typically assessed include orientation, memory and new learning, general intellectual functioning, language abilities, visuoperceptual skills, and executive function. Nevertheless, comprehensive clinical neuropsychological assessment extends beyond cognitive evaluation to consider psychological factors, personality characteristics, interpersonal relationships, and the broader contextual and environmental circumstances relevant to the individual.

Assessment may be carried out for a variety of reasons, such as:

• Clinical evaluation, to understand the pattern of cognitive strengths as well as any difficulties a person may have, and to aid decision making for use in a medical or rehabilitation environment.
• Scientific investigation, to examine a hypothesis about the structure and function of cognition to be tested, or to provide information that allows experimental testing to be seen in context of a wider cognitive profile.
• Medico-legal assessment, to be used in a court of law as evidence in a legal claim or criminal investigation.

Miller outlined three broad goals of neuropsychological assessment. Firstly, diagnosis, to determine the nature of the underlying problem. Secondly, to understand the nature of any brain injury or resulting cognitive problem (see neurocognitive deficit) and its impact on the individual, as a means of devising a rehabilitation programme or offering advice as to an individual's ability to carry out certain tasks (for example, fitness to drive, or returning to work). And lastly, assessments may be undertaken to measure change in functioning over time, such as to determine the consequences of a surgical procedure or the impact of a rehabilitation programme over time.

Diagnosis of a neuropsychological disorder

Certain types of damage to the brain will cause behavioral and cognitive difficulties. Psychologists can start screening for these problems by using either one of the following techniques or all of these combined:

History taking

This includes gathering medical history of the patient and their family, presence or absence of developmental milestones, psychosocial history, and character, severity, and progress of any history of complaints. The psychologist can then gauge how to treat the patient and determine if there are any historical determinants for his or her behavior.

Interviewing

Psychologists use structured interviews in order to determine what kind of neurological problem the patient might be experiencing. There are a number of specific interviews, including the Short Portable Mental Status Questionnaire, Neuropsychological Impairment Scale, Patient's Assessment of Own Functioning, and Structured Interview for the Diagnosis of Dementia.

Test-taking

Scores on standardized tests of adequate predictive validity predictor well current and/or future problems. Standardized tests allow psychologists to compare a person's results with other people's because it has the same components and is given in the same way. It is therefore representative of the person's's behavior and cognition. The results of a standardized test are only part of the jigsaw. Further, multidisciplinary investigations (e.g. neuroimaging, neurological) are typically needed to officially diagnose a brain-injured patient.

Intelligence testing

Testing one's intelligence can also give a clue to whether there is a problem in the brain-behavior connection. The Wechsler Scales are the tests most often used to determine level of intelligence. The variety of scales available, the nature of the tasks, as well as a wide gap in verbal and performance scores can give clues to whether there is a learning disability or damage to a certain area of the brain.

Testing other areas

Other areas are also tested when a patient goes through neuropsychological assessment. These can include sensory perception, motor functions, attention, memory, auditory and visual processing, language, problem solving, planning, organization, speed of processing, and many others. Neuropsychological assessment can test many areas of cognitive and executive functioning to determine whether a patient's difficulty in function and behavior has a neuropsychological basis.

Information gathered from assessment

Tsatsanis and Volkmar assert that neuropsychological assessment can yield valuable insights into the specific nature of a psychological or neurological disorder, thereby informing the development of an appropriate treatment plan. Such assessments assist in clarifying the characteristics of the disorder and in evaluating the cognitive functioning associated with it. Furthermore, neuropsychological evaluations can help clinicians monitor the developmental trajectory of a disorder, enabling the prediction of potential future complications and the formulation of comprehensive treatment strategies.

Various forms of assessment may also be utilized to identify an individual's risk for developing specific conditions. However, a single assessment at one point in time may not provide sufficient information for long-term treatment planning, given the potential variability in behavioral and cognitive functioning. Consequently, repeated assessments are often necessary to determine whether the current treatment approach remains appropriate. Through neuropsychological testing, researchers can identify specific brain regions that may be impaired, based on observed cognitive and behavioral patterns.

Benefits of assessment

Neuropsychological assessment serves as a valuable tool in providing an accurate diagnosis, particularly in cases where the clinical presentation is unclear. Such assessments enable psychologists to identify the specific disorder affecting the patient, thereby informing more targeted and effective treatment strategies. These evaluations also assist in determining the severity of cognitive or neurological deficits, facilitating informed decision-making for both clinicians and patients. Additionally, neuropsychological assessments are useful in monitoring the progression of degenerative conditions through repeated evaluations over time.

These assessments also have important applications in the field of forensic psychology, particularly in cases where a defendant's mental competency is under scrutiny due to suspected brain injury or neurological impairment. In such contexts, neuropsychological testing may reveal cognitive deficits that are not detected through neuroimaging. Moreover, it can aid in the identification of malingering, wherein an individual may be feigning symptoms to obtain a reduced sentence.

Typically, the administration of neuropsychological tests requires between 6 and 12 hours, depending on the scope and complexity of the evaluation. This timeframe does not include the additional tasks performed by the psychologist, such as scoring, interpretation of results, case formulation, and the preparation of a comprehensive written report.

Qualifications for conducting assessments

Neuropsychological assessments are typically conducted by doctoral-level psychologists (Ph.D. or Psy.D.) who have received specialized training in neuropsychology. These professionals are referred to as clinical neuropsychologists. The qualifications, training requirements, and scope of practice for clinical neuropsychologists are defined by the widely recognized Houston Conference Guidelines. These individuals typically complete postdoctoral training in areas such as neuropsychology, neuroanatomy, and brain function. The majority are licensed psychologists practicing within their respective jurisdictions.

Advancements in the field have enabled certain tasks, such as the administration of specific neuropsychological instruments, to be performed by trained professionals known as psychometrists. However, the interpretation of test results and the formulation of clinical conclusions remain under the purview of the supervising clinical neuropsychologist.

Psychological evaluation

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

Psychological evaluation is a method to assess an individual's behavior, personality, cognitive abilities, and several other domains. A common reason for a psychological evaluation is to identify psychological factors that may be inhibiting a person's ability to think, behave, or regulate emotion functionally or constructively. It is the mental equivalent of physical examination. Other psychological evaluations seek to better understand the individual's unique characteristics or personality to predict things like workplace performance or customer relationship management.

History

Modern psychological evaluation has been around for roughly 200 years, with roots that stem as far back as 2200 B.C. It started in China, and many psychologists throughout Europe worked to develop methods of testing into the 1900s. The first tests focused on aptitude. Eventually scientists tried to gauge mental processes in patients with brain damage, then children with special needs.

Ancient psychological evaluation

Earliest accounts of evaluation are seen as far back as 2200 B.C. when Chinese emperors were assessed to determine their fitness for office. These rudimentary tests were developed over time until 1370 A.D. when an understanding of classical Confucianism was introduced as a testing mechanism. As a preliminary evaluation for anyone seeking public office, candidates were required to spend one day and one night in a small space composing essays and writing poetry over assigned topics. Only the top 1% to 7% were selected for higher evaluations, which required three separate session of three days and three nights performing the same tasks. This process continued for one more round until a final group emerged, comprising less than 1% of the original group, became eligible for public office. The Chinese failure to validate their selection procedures, along with widespread discontent over such grueling processes, resulted in the eventual abolishment of the practice by royal decree.

Development of psychological evaluation in 1800-1900-s

In the 1800s, Hubert von Grashey developed a battery to determine the abilities of brain-damaged patients. This test was also not favorable, as it took over 100 hours to administer. However, this influenced Wilhelm Wundt, who had the first psychological laboratory in Germany. His tests were shorter, but used similar techniques. Wundt also measured mental processes and acknowledged the fact that there are individual differences between people.

Francis Galton established the first tests in London for measuring IQ. He tested thousands of people, examining their physical characteristics as a basis for his results and many of the records remain today. James Cattell studied with him, and eventually worked on his own with brass instruments for evaluation. His studies led to his paper "Mental Tests and Measurements", one of the most famous writings on psychological evaluation. He also coined the term "mental test" in this paper.

As the 1900s began, Alfred Binet was also studying evaluation. However, he was more interested in distinguishing children with special needs from their peers after he could not prove in his other research that magnets could cure hysteria. He did his research in France, with the help of Theodore Simon. They created a list of questions that were used to determine if children would receive regular instruction, or would participate in special education programs. Their battery was continually revised and developed, until 1911 when the Binet-Simon questionnaire was finalized for different age levels.

After Binet's death, intelligence testing was further studied by Charles Spearman. He theorized that intelligence was made up of several different subcategories, which were all interrelated. He combined all the factors together to form a general intelligence, which he abbreviated as "g". This led to William Stern's idea of an intelligence quotient. He believed that children of different ages should be compared to their peers to determine their mental age in relation to their chronological age. Lewis Terman combined the Binet-Simon questionnaire with the intelligence quotient and the result was the standard test we use today, with an average score of 100.

The large influx of non-English speaking immigrants into the US brought about a change in psychological testing that relied heavily on verbal skills for subjects that were not literate in English, or had speech/hearing difficulties. In 1913, R.H. Sylvester standardized the first non-verbal psychological test. In this particular test, participants fit different shaped blocks into their respective slots on a Seguin form board. From this test, Knox developed a series of non-verbal psychological tests that he used while working at the Ellis Island immigrant station in 1914. In his tests, were a simple wooden puzzle as well as digit-symbol substitution test where each participant saw digits paired up with a particular symbol, they were then shown the digits and had to write in the symbol that was associated with it.

When the United States moved into World War I, Robert M. Yerkes convinced the government that they should be testing all of the recruits they were receiving into the Army. The results of the tests could be used to make sure that the "mentally incompetent" and "mentally exceptional" were assigned to appropriate jobs. Yerkes and his colleagues developed the Army Alpha and Army Beta tests to use on all new recruits. These tests set a precedent for the development of psychological testing for the next several decades.

After seeing the success of the Army standardized tests, college administration quickly picked up on the idea of group testing to decide entrance into their institutions. The College Entrance Examination Board was created to test applicants to colleges across the nation. In 1925, they developed tests that were no longer essay tests that were very open to interpretation, but now were objective tests that were also the first to be scored by machine. These early tests evolved into modern day College Board tests, like the Scholastic Assessment Test, Graduate Record Examination, and the Law School Admissions Test.

Formal and informal evaluation

Formal psychological evaluation consists of standardized batteries of tests and highly structured clinician-run interviews, while informal evaluation takes on a completely different tone. In informal evaluation, assessments are based on unstructured, free-flowing interviews or observations that allow both the patient and the clinician to guide the content. Both of these methods have their pros and cons. A highly unstructured interview and informal observations provide key findings about the patient that are both efficient and effective. A potential issue with an unstructured, informal approach is the clinician may overlook certain areas of functioning or not notice them at all. Or they might focus too much on presenting complaints. The highly structured interview, although very precise, can cause the clinician to make the mistake of focusing a specific answer to a specific question without considering the response in terms of a broader scope or life context. They may fail to recognize how the patient's answers all fit together.

There are many ways that the issues associated with the interview process can be mitigated. The benefits to more formal standardized evaluation types such as batteries and tests are many. First, they measure a large number of characteristics simultaneously. These include personality, cognitive, or neuropsychological characteristics. Second, these tests provide empirically quantified information. The obvious benefit to this is that we can more precisely measure patient characteristics as compared to any kind of structured or unstructured interview. Third, all of these tests have a standardized way of being scored and being administered. Each patient is presented a standardized stimulus that serves as a benchmark that can be used to determine their characteristics. These types of tests eliminate any possibility of bias and produce results that could be harmful to the patient and cause legal and ethical issues. Fourth, tests are normed. This means that patients can be assessed not only based on their comparison to a "normal" individual, but how they compare to the rest of their peers who may have the same psychological issues that they face. Normed tests allow the clinician to make a more individualized assessment of the patient. Fifth, standardized tests that we commonly use today are both valid and reliable. We know what specific scores mean, how reliable they are, and how the results will affect the patient.

Most clinicians agree that a balanced battery of tests is the most effective way of helping patients. Clinicians should not become victims of blind adherence to any one particular method. A balanced battery of tests allows there to be a mix of formal testing processes that allow the clinician to start making their assessment, while conducting more informal, unstructured interviews with the same patient may help the clinician to make more individualized evaluations and help piece together what could potentially be a very complex, unique-to-the-individual kind of issue or problem .

Modern uses

Psychological assessment is most often used in the psychiatric, medical, legal, educational, or psychological clinic settings. The types of assessments and the purposes for them differ among these settings.

In the psychiatric setting, the common needs for assessment are to determine risks, whether a person should be admitted or discharged, the location the patients should be held, as well as what therapy the patient should be receiving. Within this setting, the psychologists need to be aware of the legal responsibilities that what they can legally do in each situation.

Within a medical setting, psychological assessment is used to find a possible underlying psychological disorder, emotional factors that may be associated with medical complaints, assessment for neuropsychological deficit, psychological treatment for chronic pain, and the treatment of chemical dependency. There has been greater importance placed on the patient's neuropsychological status as neuropsychologists are becoming more concerned with the functioning of the brain.

Psychological assessment also has a role in the legal setting. Psychologists might be asked to assess the reliability of a witness, the quality of the testimony a witness gives, the competency of an accused person, or determine what might have happened during a crime. They also may help support a plea of insanity or to discount a plea. Judges may use the psychologist's report to change the sentence of a convicted person, and parole officers work with psychologists to create a program for the rehabilitation of a parolee. Problematic areas for psychologists include predicting how dangerous a person will be. The predictive accuracy of these assessments is debated; however, there is often a need for this prediction to prevent dangerous people from returning to society.

Psychologists may also be called on to assess a variety of things within an education setting. They may be asked to assess strengths and weaknesses of children who are having difficulty in the school systems, assess behavioral difficulties, assess a child's responsiveness to an intervention, or to help create an educational plan for a child. The assessment of children also allows for the psychologists to determine if the child will be willing to use the resources that may be provided.

In a psychological clinic setting, psychological assessment can be used to determine characteristics of the client that can be useful for developing a treatment plan. Within this setting, psychologists often are working with clients who may have medical or legal problems or sometimes students who were referred to this setting from their school psychologist.

Some psychological assessments have been validated for use when administered via computer or the Internet. However, caution must be applied to these test results, as it is possible to fake in electronically mediated assessment. Many electronic assessments do not truly measure what is claimed, such as the Meyers-Briggs personality test. Although one of the most well known personality assessments, it has been found both invalid and unreliable by many psychological researches, and should be used with caution.

Within clinical psychology, the "clinical method" is an approach to understanding and treating mental disorders that begins with a particular individual's personal history and is designed around that individual's psychological needs. It is sometimes posed as an alternative approach to the experimental method which focuses on the importance of conducting experiments in learning how to treat mental disorders, and the differential method which sorts patients by class (gender, race, income, age, etc.) and designs treatment plans based around broad social categories.

Taking a personal history along with clinical examination allow the health practitioners to fully establish a clinical diagnosis. A medical history of a patient provides insights into diagnostic possibilities as well as the patient's experiences with illnesses. The patients will be asked about current illness and the history of it, past medical history and family history, other drugs or dietary supplements being taken, lifestyle, and allergies. The inquiry includes obtaining information about relevant diseases or conditions of other people in their family. Self-reporting methods may be used, including questionnaires, structured interviews and rating scales.

Personality Assessment

Personality traits are an individual's enduring manner of perceiving, feeling, evaluating, reacting, and interacting with other people specifically, and with their environment more generally. Because reliable and valid personality inventories give a relatively accurate representation of a person's characteristics, they are beneficial in the clinical setting as supplementary material to standard initial assessment procedures such as a clinical interview; review of collateral information, e.g., reports from family members; and review of psychological and medical treatment records.

Main article: Minnesota Multiphasic Personality Inventory

MMPI

History

Developed by Starke R. Hathaway, PhD, and J. C. McKinley, MD, The Minnesota Multiphasic Personality Inventory (MMPI) is a personality inventory used to investigate not only personality, but also psychopathology. The MMPI was developed using an empirical, atheoretical approach. This means that it was not developed using any of the frequently changing theories about psychodynamics at the time. There are two variations of the MMPI administered to adults, the MMPI-2 and the MMPI-2-RF, and two variations administered to teenagers, the MMPI-A and MMPI-A-RF. This inventory's validity has been confirmed by Hiller, Rosenthal, Bornstein, and Berry in their 1999 meta-analysis. Throughout history the MMPI in its various forms has been routinely administered in hospitals, clinical settings, prisons, and military settings.

MMPI-2

The MMPI-2 consists of 567 true or false questions aimed at measuring the reporting person's psychological wellbeing. The MMPI-2 is commonly used in clinical settings and occupational health settings. There is a revised version of the MMPI-2 called the MMPI-2-RF (MMPI-2 Restructured Form). The MMPI-2-RF is not intended to be a replacement for the MMPI-2, but is used to assess patients using the most current models of psychopathology and personality.

MMPI-2 and MMPI-2-RF Scales

Version	Number of Items	Number of Scales	Scale Categories
MMPI-2	567	120	Validity Indicators, Superlative Self-Presentation Subscales, Clinical Scales, Restructured Clinical (RC) Scales, Content Scales, Content Component Scales, Supplementary Scales, Clinical Subscales (Harris-Lingoes and Social Introversion Subscales)
MMPI-2-RF	338	51	Validity, Higher-Order (H-O), Restructured Clinical (RC), Somatic, Cognitive, Internalizing, Externalizing, Interpersonal, Interest, Personality Psychopathology Five (PSY-5)

MMPI-A

The MMPI-A was published in 1992 and consists of 478 true or false questions. This version of the MMPI is similar to the MMPI-2 but used for adolescents (age 14–18) rather than for adults. The restructured form of the MMPI-A, the MMPI-A-RF, was published in 2016 and consists of 241 true or false questions that can understood with a sixth grade reading level. Both the MMPI-A and MMPI-A-RF are used to assess adolescents for personality and psychological disorders, as well as to evaluate cognitive processes.

MMPI-A and MMPI-A-RF Scales

Verson	Number of Items	Number of Scales	Scale Categories
MMPI-A	478	105	Validity Indicators, Clinical Scales, Clinical Subscales (Harris-Lingoes and Social Introversion Subscales), Content Scales, Content Component Scales, Supplementary Scales
MMPI-A-RF	241	48	Validity, Higher-Order (H-O), Restructured Clinical (RC), Somatic/Cognitive, Internalizing, Externalizing, Interpersonal, Personality Psychopathology Five (PSY-5)

NEO Personality Inventory

The NEO Personality Inventory was developed by Paul Costa Jr. and Robert R. McCrae in 1978. When initially created, it only measured three of the Big Five personality traits: Neuroticism, Openness to Experience, and Extroversion. The inventory was then renamed as the Neuroticism-Extroversion-Openness Inventory (NEO-I). It was not until 1985 that Agreeableness and Conscientiousness were added to the personality assessment. With all Big Five personality traits being assessed, it was then renamed as the NEO Personality Inventory. Research for the NEO-PI continued over the next few years until a revised manual with six facets for each Big Five trait was published in 1992. In the 1990s, now called the NEO PI-R, issues were found with the personality inventory. The developers of the assessment found it to be too difficult for younger people, and another revision was done to create the NEO PI-3.

The NEO Personality Inventory is administered in two forms: self-report and observer report. It consists of 240 personality items and a validity item. It can be administered in roughly 35–45 minutes. Every item is answered on a Likert scale, widely known as a scale from Strongly Disagree to Strongly Agree. If more than 40 items are missing or more than 150 responses or less than 50 responses are Strongly Agree/Disagree, the assessment should be viewed with great caution and has the potential to be invalid. In the NEO report, each trait's T score is recorded along with the percentile they rank on compared to all data recorded for the assessment. Then, each trait is broken up into their six facets along with raw score, individual T-scores, and percentile. The next page goes on to list what each score means in words as well as what each facet entails. The exact responses to questions are given in a list as well as the validity response and amount of missing responses.

When an individual is given their NEO report, it is important to understand specifically what the facets are and what the corresponding scores mean.

• Neuroticism
  • Anxiety
    • High scores suggest nervousness, tenseness, and fearfulness. Low scores suggest feeling relaxed and calm.
  • Angry Hostility
    • High scores suggest feeling anger and frustration often. Low scores suggest being easy-going.
  • Depression
    • High scores suggest feeling guilty, sad, hopeless, and lonely. Low scores suggest less feeling of that of someone who scores highly, but not necessarily being light-hearted and cheerful.
  • Self-consciousness
    • High scores suggest shame, embarrassment, and sensitivity. Low scores suggest being less affected by others' opinions, but not necessarily having good social skills or poise.
  • Impulsiveness
    • High scores suggest the inability to control cravings and urges. Low scores suggest easy resistance to such urges.
  • Vulnerability
    • High scores suggest inability to cope with stress, being dependent, and feeling panicked in high stress situations. Low scores suggest capability to handle stressful situations.
• Extraversion
  • Warmth
    • High scores suggest friendliness and affectionate behavior. Low scores suggest being more formal, reserved, and distant. A low score does not necessarily mean being hostile or lacking compassion.
  • Gregariousness
    • High scores suggest wanting the company of others. Low scores tend to be from those who avoid social stimulation.
  • Assertiveness
    • High scores suggest a forceful and dominant person who lacks hesitation. Low scores suggest are more passive and try not to stand out in a crowd.
  • Activity
    • High scores suggest a more energetic and upbeat personality and lead a quicker paced lifestyle. Low scores suggest the person is more leisurely, but does not imply being lazy or slow.
  • Excitement-Seeking
    • High scores suggest a person who seeks and craves excitement and is similar to those with high sensation seeking. Low scores seek a less exciting lifestyle and come off more boring.
  • Positive Emotions
    • High scores suggest the tendency to feel happier, laugh more, and are optimistic. Low scorers are not necessarily unhappy, but more so are less high-spirited and are more pessimistic.

• Openness to Experience
  • Fantasy
    • Those who score high in fantasy have a more creative imagination and daydream frequently. Low scores suggest a person who lives more in the moment.
  • Aesthetics
    • High scores suggest a love and appreciation for art and physical beauty. These people are more emotionally attached to music, artwork, and poetry. Low scorers have a lack of interest in the arts.
  • Feelings
    • High scorers have a deeper ability to experience emotion and see their emotions as more important than those who score low on this facet. Low scorers are less expressive.
  • Actions
    • High scores suggest a more open-mindedness to traveling and experiencing new things. These people prefer novelty over a routine life. Low scorers prefer a scheduled life and dislike change.
  • Ideas
    • Active pursuit of knowledge, high curiosity, and the enjoyment of brain teasers and philosophical are common of those who score high on this facet. Those who score lower are not necessarily less intelligent, nor does a high score imply high intelligence. However, those who score lower are more narrow in their interests and have low curiosity.
  • Values
    • High scorers are more investigative of political, social, and religious values. Those who score lower and more accepting of authority and honor more traditional values. High scorers are more typically liberal while lower scorers are more typically conservative.
• Agreeableness
  • Trust
    • High scores are more trusting of others and believe others are honest and have good intentions. Low scorers are more skeptical, cynical, and assumes others are dishonest and/or dangerous.
  • Straightforwardness
    • Those who score high in this facet are more sincere and frank. Low scorers are more deceitful and more willing to manipulate others, but this does not mean they should be labeled as a dishonest or manipulative person.
  • Altruism
    • High scores suggest a person concerned with the well-being of others and show it through generosity, willingness to help others, and volunteering for those less fortunate. Low scores suggest a more self-centered person who is less willing to go out of their way to help others.
  • Compliance
    • High scorers are more inclined to avoid conflict and tend to forgive easily. Low scores suggest a more aggressive personality and a love for competition.
  • Modesty
    • High scorers are more humble, but not necessarily lacking in self-esteem or confidence. Low scorers believe they're more superior than others and may come off as more conceited.
  • Tender-Mindedness
    • This facet scales one's concern for others and their ability to empathize. High scorers are more moved by others' emotions, while low scorers are more hardheaded and typically consider themselves realists.

• Conscientiousness
  • Competence
    • High scores suggest one is capable, sensible, prudent, effective, and are well-prepared to deal with whatever happens in life. Low scores suggest a potential lower self-esteem and are often unprepared.
  • Order
    • High scorers are more neat and tidy, while low scorers lack organization and are unmethodical.
  • Dutifulness
    • Those who score highly in this facet are more strict about their ethical principles and are more dependable. Low scorers are less reliable and are more casual about their morals.
  • Achievement Striving
    • Those who score highly in this facet have higher aspirations and work harder to achieve their goals. However, they may be too invested in their work and become a workaholic. Low scorers are much less ambitious and perhaps even lazy. They are often content with their lack of goal-seeking.
  • Self-Discipline
    • High scorers complete whatever task is assigned to them and are self-motivated. Low scorers often procrastinate and are easily discouraged.
  • Deliberation
    • High scorers tend to think more than low scorers before acting. High scorers are more cautious and deliberate while low scorers are more hasty and act without considering the consequences.

HEXACO-PI

The HEXACO-PI, developed by Lee and Ashton in the early 2000s, is a personality inventory used to measure six different dimensions of personality which have been found in lexical studies across various cultures. There are two versions of the HEXACO: the HEXACO-PI and the HEXACO-PI-R which are examined with either self reports or observer reports. The HEXACO-PI-R has forms of three lengths: 200 items, 100 items, and 60 items. Items from each form are grouped to measure scales of more narrow personality traits, which are them grouped into broad scales of the six dimensions: honesty & humility (H), emotionality (E), Extraversion (X), agreeableness (A), conscientiousness (C), and openness to experience (O).The HEXACO-PI-R includes various traits associated with neuroticism and can be used to help identify trait tendencies. One table which give examples of typically high loaded adjectives on the six factors of HEXACO can be found in Ashton's book "Individual Differences and Personality"

Adjective relating to the six factors within the HEXACO structure

Personality Factor	Narrow Personality Traits	Related Adjectives
Honesty-Humility	Sincerity, fairness, greed-avoidance, modesty	Sincere, honest, faithful/loyal, modest/unassuming, fair-minded versus sly, deceitful, greedy, pretentious, hypocritical, boastful, pompous
Emotionality	Fearfulness, anxiety, depenence, sentimentality	Emotional, oversensitive, sentimental, fearful, anxious, vulnerable versus brave, tough, independent, self-assured, stable
Extraversion	Social self-esteem, social boldness, sociability, liveliness	Outgoing, lively, extraverted, sociable, talkative, cheerful, active versus shy, passive, withdrawn, introverted, quiet, reserved
Agreeableness	Forgivingness, gentleness, flexibility, patience	Patient, tolerant, peaceful, mild, agreeable, lenient, gentle versus ill-tempered, quarrelsome, stubborn, choleric
Conscientiousness	Organization, diligence, perfectionism, prudence	Organized, disciplined, diligent, careful, thorough, precise verus sloppy, negligent, reckless, lazy, irresponsible, absent-minded
Openness to Experience	Aesthetic appreciation, inquisitiveness, creativity, unconventionality	Intellectual, creative, unconventional, innovative, ironic versus shallow, unimaginative, conventional

One benefit of using the HEXACO is that of the facet of neuroticism within the factor of emotionality: trait neuroticism has been shown to have a moderate positive correlation with people with anxiety and depression. The identification of trait neuroticism on a scale, paired with anxiety, and/or depression is beneficial in a clinical setting for introductory screenings some personality disorders. Because the HEXACO has facets which help identify traits of neuroticism, it is also a helpful indicator of the dark triad.

Temperament Assessment

In contrast to personality, i.e. the concept that relates to culturally- and socially-influenced behaviour and cognition, the concept of temperament' refers to biologically and neurochemically-based individual differences in behaviour. Unlike personality, temperament is relatively independent of learning, system of values, national, religious and gender identity and attitudes. There are multiple tests for evaluation of temperament traits (reviewed, for example, in, majority of which were developed arbitrarily from opinions of early psychologists and psychiatrists but not from biological sciences. There are only two temperament tests that were based on neurochemical hypotheses: The Temperament and Character Inventory (TCI) and the Trofimova's Structure of Temperament Questionnaire-Compact (STQ-77). The STQ-77 is based on the neurochemical framework Functional Ensemble of Temperament that summarizes the contribution of main neurochemical (neurotransmitter, hormonal and opioid) systems to behavioural regulation. The STQ-77 assesses 12 temperament traits linked to the neurochemical components of the FET. The STQ-77 is freely available for non-commercial use in 24 languages for testing in adults and several language versions for testing children

Pseudopsychology (pop psychology) in assessment

Although there have been many great advancements in the field of psychological evaluation, some issues have also developed. One of the main problems in the field is pseudopsychology, also called pop psychology. Psychological evaluation is one of the biggest aspects in pop psychology. In a clinical setting, patients are not aware that they are not receiving correct psychological treatment, and that belief is one of the main foundations of pseudopsychology. It is largely based upon the testimonies of previous patients, the avoidance of peer review (a critical aspect of any science), and poorly set up tests, which can include confusing language or conditions that are left up to interpretation.

Pseudopsychology can also occur when people claim to be psychologists, but lack qualifications. A prime example of this is found in quizzes that can lead to a variety of false conclusions. These can be found in magazines, online, or just about anywhere accessible to the public. They usually consist of a small number of questions designed to tell the participant things about themselves. These often have no research or evidence to back up any claims made by the quizzes.

Ethics

Concerns about privacy, cultural biases, tests that have not been validated, and inappropriate contexts have led groups such as the American Educational Research Association (AERA) and the American Psychological Association (APA) to publish guidelines for examiners in regards to assessment. The American Psychological Association states that a client must give permission to release any of the information that may come from a psychologist. The only exceptions to this are in the case of minors, when the clients are a danger to themselves or others, or if they are applying for a job that requires this information. Also, the issue of privacy occurs during the assessment itself. The client has the right to say as much or little as they would like, however they may feel the need to say more than they want or even may accidentally reveal information they would like to keep private.

Guidelines have been put in place to ensure the psychologist giving the assessments maintains a professional relationship with the client since their relationship can impact the outcomes of the assessment. The examiner's expectations may also influence the client's performance in the assessments.

The validity and reliability of the tests being used also can affect the outcomes of the assessments being used. When psychologists are choosing which assessments they are going to use, they should pick one that will be most effective for what they are looking at. Also, it is important for the psychologists are aware of the possibility of the client, either consciously or unconsciously, faking answers and consider use of tests that have validity scales within them.

Vitamin D and neurology

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Vitamin_D_and_neurology 

 

Vitamin D
Cholecalciferol (D3)

Vitamin D shows associations between low levels of vitamin D, or hypovitaminosis D, and neuropsychiatric disorders, including Alzheimer's disease, autism, epilepsy, multiple sclerosis, Parkinson's disease, and schizophrenia.

Physiology

Vitamin D (the inactive version) is mainly from two forms: vitamin D₃ and vitamin D₂. Vitamin D₃, or cholecalciferol, is formed in the skin after exposure to sunlight or ultra violet radiation or from D₃ supplements or fortified food sources. Vitamin D₂, or ergocalciferol, is obtained from D₂ supplements or fortified food sources. These two forms of vitamin D are metabolized in the liver and stored as 25-hydroxyvitamin D. Before biological use, the storage form must be converted into an active form. One common active form is 1,25-dihydroxyvitamin D. The term vitamin D in this article means cholecalciferol, ergocalciferol, 25-hydroxyvitamin D, and the active forms. The role of vitamin D is best characterized as enabling calcium absorption and regulating calcium homeostasis. Vitamin D also play a role in phosphate absorption.

Hypovitaminosis D

Hypovitaminosis D is any deficiency of vitamin D. A vitamin D blood-concentration standard for diagnosing hypovitaminosis D does not exist. In the past, hypovitaminosis D was defined by blood concentrations lower than 20 ng/mL. However, in more recent literature many researchers have considered 30 ng/mL to be an insufficient concentration of vitamin D. Subnormal levels of vitamin D are usually caused by poor nutrition or a lack of sun exposure. Risk factors for hypovitaminosis D include premature birth, darker skin pigmentation, obesity, malabsorption, and older age.

Vitamin D and the central nervous system

Location in the central nervous system

The brain requires the use of many neurosteroids to develop and function properly. These molecules are often identified as one of many common substances including thyroid hormones, glucocorticoids, and sex hormones. However in recent studies, throughout the brain and spinal fluid, vitamin D has begun to surface as one of these neurosteroids.

• Metabolites: Several vitamin D metabolites are found in cerebral spinal fluid and have the ability to cross the blood brain barrier. This is similar to many of the previously known neurosteroids. These vitamin D metabolites include 25-hydroxyvitamin D₃, 1,25-dihydroxyvitamin D₃, and 24,25-dihydroxyvitamin D₃. Derivatives of these metabolites are highly expressed in the substantia nigra and the hypothalamus. These two brain structures are responsible for motor functions and linking the nervous system to the endocrine system, respectively. The expression of these metabolite derivatives in these areas suggests that these structures have the ability to synthesize these products from vitamin D.

Location of brain regions related to vitamin D

• Receptors: In addition to vitamin D metabolites, vitamin D receptor (VDR) proteins are also found in the brain; more specifically, they are found in the cerebellum, thalamus, hypothalamus, basal ganglia, and hippocampus. The highest density of VDR is in substantia nigra, one of the primary areas of dopamine production. Another significant portion of the receptors is located in the hypothalamus (supra optic and paraventricular nuclei) and external granule cell layer of the prefrontal cortex. VDR are also found in the hippocampus (CA1 and CA2) areas, in slightly lower densities.

Function in the central nervous system

The presence of vitamin D, its activating enzyme, and VDR in the brain leads researchers to question what role vitamin D plays in the brain. Research suggests that vitamin D may function as a modulator in brain development and as a neuroprotectant. In recent studies, vitamin D has exhibited an association with the regulation of nerve growth factor (NGF) synthesis. NGF is responsible for the growth and survival of neurons. This relationship has also been studied in embryonic and neonatal rats. Developmental vitamin D deficient (DVD) rats have decreased levels of neurotrophic factors, increased mitosis, and decreased apoptosis. These findings suggest that vitamin D potentially affects the development of neurons as well as their maintenance and survival. Current research is underway investigating whether vitamin D is a factor contributing to normal brain functioning.

Vitamin D and neurological disorders

Hypovitaminosis D is associated with several neuropsychiatric disorders including dementia, Parkinson's disease, multiple sclerosis, epilepsy, and schizophrenia. There are several proposed mechanisms by which hypovitaminosis D may impact these disorders. One of these mechanisms is through neuronal apoptosis. Neuronal apoptosis is the programmed death of the neurons. Hypovitaminosis D causes this specific apoptosis by decreasing the expression of cytochrome C and decreasing the cell cycle of neurons. Cytochrome C is a protein that promotes the activation of pro-apoptotic factors. A second mechanism is through the association of neurotrophic factors like nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF). These neurotrophic factors are proteins that are involved in the growth and survival of developing neurons and they are involved in the maintenance of mature neurons.

Dementia: Alzheimer's disease

"Dementia" is a term referring to neurodegenerative disorders characterized by a loss of memory and such brain functions as executive functioning. Included under this umbrella term is Alzheimer's disease. Alzheimer's disease is characterized by the loss of cortical functions like language and motor skills. Patients with Alzheimer's disease exhibit an extreme shrinkage of the cerebral cortex and hippocampus with an enlargement of the ventricles. In several recent studies, higher vitamin D levels have been associated with lower risks of developing Alzheimer's disease. Alzheimer's disease is associated with a decrease in vitamin D receptors in the Cornu Ammonius areas (CA 1& 2) of the hippocampus. The hippocampus is a portion of the limbic system responsible for memory and spatial navigation. Additionally, certain VDR haplotypes were detected with increased frequency in patients with Alzheimer's disease while other VDR haplotypes were detected with decreased frequency, suggesting that specific haplotypes may increase or decrease risk of developing Alzheimer's. It is hypothesized that this lack of VDRs in the hippocampus prevents the proper functioning (ie. memory) of this structure.

Parkinson's disease

This image depicts the circuits of the basal ganglia in patients with Parkinson's disease. Pay close attention to the role of the substantia nigra and the dopaminergic neurons

Parkinson's disease is characterized by progressive deterioration of movement and coordination. Patients with Parkinson's disease lose dopaminergic (DA) neurons in the substantia nigra, a part of the brain that plays a central role in such brain functions as reward, addiction, and coordination of movement. Studies suggest that low vitamin D levels could play a role in PD, and in one case report, vitamin D supplements lessened parkinsonian symptoms. In a study of vitamin D receptor knockout mice, mice without VDR exhibited motor impairments similar to impairments seen in patients with Parkinson's disease. One proposed mechanism linking vitamin D to Parkinson's disease involves the Nurr 1 gene. Vitamin D deficiency is associated with decreased expression of the Nurr1 gene, a gene responsible for development of DA neurons. It is therefore plausible that a lack of Nurr1 expression leads to impaired DA neuronal development. Failure to form DA neurons would lead to lower dopamine concentrations in the basal ganglia. Additionally, rats lacking Nurr1 exhibited hypoactivity followed by death shortly after birth.

Multiple sclerosis

Multiple sclerosis (MS) is an autoimmune disease causing demyelination within the central nervous system. In the central nervous system, there are many cells encased in a fatty coating called the myelin sheath. This sheath allows for informational signals to be transmitted at greater speeds down through the cell. In multiple sclerosis, this sheath deterioration causes a slower transmission of nerve signals. This ultimately results in severe motor deficits.

The prevalence of MS is associated with latitude. In this image, red indicates a high prevalence of MS while yellow indicates a lower prevalence

There is a well-established global correlation between multiple sclerosis and latitude; there is a higher multiple sclerosis prevalence in northeastern regions than in the south and western regions. At the same time, on average higher vitamin D levels are found in the south and western regions than in the northeast. Based on this correlation and other studies, the higher intake of vitamin D is associated with a lower risk for MS. Research has also shown that in relation to geological position (latitude), patients who later developed MS saw an earlier age of onset of symptoms in the more northern latitudes than in the southern hemisphere. The mechanism for this association is not fully established, however, a proposed mechanism involves inflammatory cytokines. Hypovitaminosis D is associated with an increase in proinflammatory cytokines and decrease in anti-inflammatory cytokines. The increase in these specific cytokines is associated with the degradation of the myelin sheath.

The increase of vitamin D into the body has shown to increase the amount of anti-inflammatory cytokines and molecules within the body. As this research progresses, the understanding grows of how vitamin D and its complementary receptor (vitamin D receptor, VDR) are incorporated in expressing and regulating 900 genes within our bodies, as well as how this pair interacts genetically. For example genes can be upregulated or downregulated when the highly active form of vitamin D, 1,25-alpha dihydroxyvitamin D₃ binds to the VDR on chromosomal regions of gene expression that manage the balance or ratio between differentiating immune cells into Th₁ and Th₂ T cell proteins. The upregulation of Th₂ T cell proteins, like IL-4 and TGF-β, are the main focus of some research which aims to minimize the effects seen in the model organism disease EAE (experimental autoimmune encephalomyelitis), studied for its similarities to multiple sclerosis. Though this study of gene regulation is observed within murine models, it focuses on MS orthologs to humans and research has shown that it may also help to manage: rheumatoid arthritis (RA), type 1 diabetes (T1D), systemic lupus erythematosus (SLE), cardiovascular disease (CVD), and other chronic inflammatory diseases.

Epilepsy and seizures

Seizures are disturbances in brain activities where neurons fire abnormally. Epilepsy is a condition in which a person experiences repeated seizures. In one small pilot study (Christiansen, 1974, BMJ), vitamin D supplementation, but not placebo treatment was associated with decreased seizures. Vitamin D regulates proconvulsant and anticonvulsant factors. More specifically, Vitamin D is involved in the down regulation of cytokine IL-6, which is a proconvulsant. Additionally, vitamin D is associated with the up regulation of neurotrophic factors: GDNF and TN3. These neurotrophic factors are anticonvulsant. In the absence or depletion of vitamin D, research suggests that the proconvulsant factors will not be down regulated and the anticonvulsant factors will not be up regulated. It is hypothesized that this disturbance in homeostasis may lower the threshold for convulsive activity. Lastly, vitamin D has also been shown to promote the expression of calcium binding proteins that are known to possess anti-epileptic properties.

Schizophrenia

Map of deficits in neural tissue throughout the human brain in a patient with schizophrenia. The most deficient areas are magenta, while the least deficient areas are blue.

Schizophrenia is a neuropsychiatric disorder characterized by the inability to perceive reality and think clearly. This condition has genetic and developmental causes. In this disorder, vitamin D is believed to be involved in the development of the brain during the gestational period. Gestational vitamin D deficiency in rats is associated with reduced levels of neurotrophic factors NGF and GDNF. NGF is the nerve growth factor, which is involved in neurotransmission. GDNF is the glial cell lined derived neurotrophic factor, which is involved in the survival and differentiation of dopaminergic neurons.

Other hypovitaminosis D associations

Hypovitaminosis D has also been associated with many other conditions, including both neurological and non neurological conditions. These include but are not limited to autism, diabetes, and osteoporosis.

Future research: cause or effect

Hypovitaminosis D has been associated with many neurological conditions. However, an actual mechanism of action for each of the conditions has yet to be solidified. Many researchers have questioned whether the depletion of vitamin D actually causes these disorders or if vitamin D deficiency is a symptom of these disorders.

Vitamin D deficiency

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Vitamin_D_deficiency 

 

Vitamin D deficiency
Other names	Hypovitaminosis D
The normal process of Vitamin D absorption
Specialty	Endocrinology
Symptoms	Usually asymptomatic
Complications	Rickets, osteomalacia, other associated disorders
Causes	Lack of vitamin D, inadequate sunlight exposure
Risk factors	Age, people with dark skin, obesity, malabsorption, bariatric surgery, breastfed infants
Diagnostic method	Measuring the concentration of calcifediol in the blood
Prevention	Sufficient sunlight exposure, dietary intake
Treatment	Supplements
Medication	Cholecalciferol, ergocalciferol, calcifediol
Frequency	Severe deficiency (<30 nmol/L): Europe 13%, US 5.9%, Canada 7.4%. Deficiency (<50 nmol/L): Europe 40%, US 24%, Canada 37%

Vitamin D deficiency or hypovitaminosis D is a vitamin D level that is below normal. It most commonly occurs in people when they have inadequate exposure to sunlight, particularly sunlight with adequate ultraviolet B rays (UVB). Vitamin D deficiency can also be caused by inadequate nutritional intake of vitamin D; disorders that limit vitamin D absorption; and disorders that impair the conversion of vitamin D to active metabolites, including certain liver, kidney, and hereditary disorders. Deficiency impairs bone mineralization, leading to bone-softening diseases, such as rickets in children. It can also worsen osteomalacia and osteoporosis in adults, increasing the risk of bone fractures. Muscle weakness is also a common symptom of vitamin D deficiency, further increasing the risk of falls and bone fractures in adults. Vitamin D deficiency is associated with the development of schizophrenia.

Vitamin D can be synthesized in the skin under exposure to UVB from sunlight. Oily fish, such as salmon, herring, and mackerel, are also sources of vitamin D, as are mushrooms. Milk is often fortified with vitamin D; sometimes bread, juices, and other dairy products are fortified with vitamin D. Many multivitamins contain vitamin D in different amounts.

Classifications

Mapping of several bone diseases onto levels of vitamin D (calcidiol) in the blood

Normal bone vs. osteoporosis

Vitamin D deficiency is typically diagnosed by measuring the concentration of the 25-hydroxyvitamin D in the blood, which is the most accurate measure of stores of vitamin D in the body. One nanogram per millilitre (1 ng/mL) is equivalent to 2.5 nanomoles per litre (2.5 nmol/L).

• Severe deficiency: <12 ng/mL = <30 nmol/L
• Deficiency: <20 ng/mL = <50 nmol/L
• Insufficient: 20–29 ng/mL = 50–75 nmol/L
• Normal: 30–50 ng/mL = 75–125 nmol/L

Vitamin D levels falling within this normal range prevent clinical manifestations of vitamin D insufficiency as well as vitamin D toxicity.

Signs and symptoms

Child with rickets

In most cases, vitamin D deficiency is almost asymptomatic. It may only be detected on blood tests but is the cause of some bone diseases and is associated with other conditions:

Complications

• Rickets, a childhood disease characterized by impeded growth and deformity of the long bones. The earliest sign of vitamin D deficiency is craniotabes, abnormal softening or thinning of the skull.
• Osteomalacia, a bone-thinning disorder that occurs exclusively in adults and is characterized by proximal muscle weakness and bone fragility. Women with vitamin D deficiency who have been through multiple pregnancies are at elevated risk of osteomalacia.
• Osteoporosis, a condition characterized by reduced bone mineral density and increased bone fragility
• Increased risk of fracture
• Myopathy: Muscle aches, weakness, and twitching (fasciculations) due to reduced blood calcium (hypocalcemia); impaired muscle glycogen metabolism (abnormal glycogen accumulation), atrophy of type II (fast-twitch/glycolytic) muscle fibres, and diminished calcium uptake by the sarcoplasmic reticulum (needed for muscle contraction).
• Periodontitis, local inflammatory bone loss that can result in tooth loss.
• Pre-eclampsia: There has been an association between vitamin D deficiency and women who develop pre-eclampsia in pregnancy. The exact relationship of these conditions is not well understood. Maternal vitamin D deficiency may affect the baby, causing overt bone disease from before birth and impairment of bone quality after birth.
• Respiratory infections and COVID-19: Vitamin D deficiency may increase the risk of severe acute respiratory infections and COPD. Emerging studies have suggested a link between vitamin D deficiency and COVID-19 symptoms. A review has shown that vitamin D deficiency is not associated with a higher chance of having COVID-19 but is associated with a greater severity of the disease, including 80% increases in the rates of hospitalization and mortality.
• Schizophrenia: Vitamin D deficiency is associated with the development of schizophrenia. People with schizophrenia generally have lower levels of vitamin D. The environmental risk factors of seasonality of birth, latitude, and migration linked to schizophrenia all implicate vitamin D deficiency, as do other health conditions such as maternal obesity. Vitamin D is essential for the normal development of the nervous system. Maternal vitamin D deficiency can cause prenatal neurodevelopmental defects, which influence neurotransmission, altering brain rhythms and the metabolism of dopamine. Vitamin D receptors, CYP27B1, and CYP24A1 are found in various regions of the brain, showing that vitamin D is a neuroactive, neurosteroid hormone essential for the development of the brain and normal function. Inflammation as a causative factor in schizophrenia is normally suppressed by vitamin D.

• Parkinson's disease: Many studies have confirmed the association between Parkinson's disease and low levels of vitamin D. Because vitamin D has neuroprotective functions, it is possible that vitamin D deficiency can cause Parkinson's disease, but firm conclusions remains uncertain.
  

Risk factors

Those most likely to be affected by vitamin D deficiency are people with little exposure to sunlight. Certain climates, dress habits, the avoidance of sun exposure, and the use of too much sunscreen protection can all limit the production of vitamin D.

Age

Elderly people have a higher risk of having a vitamin D deficiency due to a combination of several risk factors, including decreased sunlight exposure, decreased intake of vitamin D in the diet, and decreased skin thickness, which leads to further decreased absorption of vitamin D from sunlight.

Fat percentage

Since vitamin D₃ (cholecalciferol) and vitamin D₂ (ergocalciferol) are fat-soluble, humans and other animals with a skeleton need to store some fat. Without fat, the animal will have a hard time absorbing vitamin D₂ and vitamin D₃, and the lower the fat percentage, the greater the risk of vitamin deficiency, which is the case in some athletes who strive to get as lean as possible.

Malnutrition

Although rickets and osteomalacia are now rare in Britain, osteomalacia outbreaks in some immigrant communities included women with seemingly adequate daylight outdoor exposure wearing typical Western clothing. Having darker skin and reduced exposure to sunshine did not produce rickets unless the diet deviated from a Western omnivore pattern characterized by high intakes of meat, fish, and eggs and low intakes of high-extraction cereals. In sunny countries where rickets occurs among older toddlers and children, rickets has been attributed to low dietary calcium intakes. This is characteristic of cereal-based diets with limited access to dairy products. Rickets was formerly a major public health problem among the US population; in Denver, almost two-thirds of 500 children had mild rickets in the late 1920s. An increase in the proportion of animal protein in the 20th-century American diet coupled with increased consumption of milk fortified with relatively small quantities of vitamin D coincided with a dramatic decline in the number of rickets cases. One study of children in a hospital in Uganda, however, showed no significant difference in vitamin D levels of malnourished children compared to non-malnourished children. Because both groups were at risk due to darker skin pigmentation, both groups had vitamin D deficiency. Nutritional status did not appear to play a role in this study.

Obesity

There is an increased risk of vitamin D deficiency in people who are considered overweight or obese based on their body mass index (BMI) measurement. The relationship between these conditions is not well understood. Different factors could contribute to this relationship, particularly diet, and sunlight exposure. Alternatively, vitamin D is fat-soluble, so excess amounts can be stored in fat tissue and used during winter when sun exposure is limited.

Sun exposure

The use of sunscreen with a sun protection factor of 8 can theoretically inhibit more than 95% of vitamin D production in the skin. In practice, however, sunscreen is applied so as to have a negligible effect on vitamin D status. Vitamin D sufficiency of those in Australia and New Zealand is unlikely to have been affected by campaigns advocating sunscreen. Instead, wearing clothing is more effective at reducing the amount of skin exposed to UVB and reducing natural vitamin D synthesis. Clothing that covers a large portion of the skin, when worn on a consistent and regular basis, such as the burqa, is correlated with lower vitamin D levels and an increased prevalence of vitamin D deficiency.

Regions far from the equator have a high seasonal variation of the amount and intensity of sunlight. In the UK, the prevalence of low vitamin D status in children and adolescents is found to be higher in winter than in summer. Lifestyle factors such as indoor versus outdoor work and time spent in outdoor recreation play an important role.

Additionally, vitamin D deficiency has been associated with urbanisation in terms of both air pollution, which blocks UV light, and an increase in the number of people working indoors. The elderly are generally exposed to less UV light due to hospitalisation, immobility, institutionalisation, and being housebound, leading to decreased levels of vitamin D.

Darker skin color

Because of melanin which enables natural sun protection, dark-skinned people are susceptible to vitamin D deficiency. Three to five times greater sun exposure is necessary for naturally darker skinned people to produce the same amount of vitamin D as those with light skin.

Malabsorption

Rates of vitamin D deficiency are higher among people with untreated celiac disease, inflammatory bowel disease, exocrine pancreatic insufficiency from cystic fibrosis, and short bowel syndrome, which can all produce problems of malabsorption. Vitamin D deficiency is also more common after surgical procedures that reduce absorption from the intestine, including weight loss procedures.

Critical illness

Vitamin D deficiency is associated with increased mortality in critical illness. People who take vitamin D supplements before being admitted for intensive care are less likely to die than those who do not take vitamin D supplements. Additionally, vitamin D levels decline during stays in intensive care. Vitamin D₃ (cholecalciferol) or calcitriol given orally may reduce the mortality rate without significant adverse effects.

Breastfeeding

Infants who exclusively breastfeed need a vitamin D supplement, especially if they have dark skin or have minimal sun exposure. The American Academy of Pediatrics recommends that all breastfed infants receive 400 international units (IU) per day of oral vitamin D.

Pathophysiology

Decreased exposure of the skin to sunlight is a common cause of vitamin D deficiency. People with a darker skin pigment with increased amounts of melanin may have decreased production of vitamin D. Melanin absorbs ultraviolet B radiation from the sun and reduces vitamin D production. Sunscreen can also reduce vitamin D production. Medications may speed up the metabolism of vitamin D, causing a deficiency.

The liver is required to transform vitamin D into 25-hydroxyvitamin D. This is an inactive metabolite of vitamin D but is a necessary precursor (building block) to create the active form of vitamin D.

The kidneys are responsible for converting 25-hydroxyvitamin D to 1,25-hydroxyvitamin D. This is the active form of vitamin D in the body. Kidney disease reduces 1,25-hydroxyvitamin D formation, leading to a deficiency of the effects of vitamin D.

Intestinal conditions that result in malabsorption of nutrients may also contribute to vitamin D deficiency by decreasing the amount of vitamin D absorbed via diet. In addition, a vitamin D deficiency may lead to decreased absorption of calcium by the intestines, resulting in increased production of osteoclasts that may break down a person's bone matrix. In states of hypocalcemia, calcium will leave the bones and may give rise to secondary hyperparathyroidism, which is a response by the body to increase serum calcium levels. The body does this by increasing the uptake of calcium by the kidneys and continuing to take calcium away from the bones. If prolonged, this may lead to osteoporosis in adults and rickets in children.

Diagnosis

See also: Reference ranges for blood tests § Vitamins

The serum concentration of calcifediol, also called 25-hydroxyvitamin D (abbreviated 25(OH)D), is typically used to determine vitamin D status. Most vitamin D is converted to 25(OH)D in the serum, giving an accurate picture of vitamin D status. The level of serum 1,25(OH)D (calcitriol) is not usually used to determine vitamin D status because it often is regulated by other hormones in the body such as parathyroid hormone. The levels of 1,25(OH)D can remain normal even when a person may be vitamin D deficient. Serum level of 25(OH)D is the laboratory test ordered to indicate whether or not a person has vitamin D deficiency or insufficiency. It is also considered reasonable to treat at-risk persons with vitamin D supplementation without checking the level of 25(OH)D in the serum, as vitamin D toxicity has only been rarely reported to occur.

Levels of 25(OH)D that are consistently above 200 nanograms per milliliter (ng/mL) (500 nanomoles per liter, nmol/L) are potentially toxic. Vitamin D toxicity usually results from taking supplements in excess. Hypercalcemia is often the cause of symptoms, and levels of 25(OH)D above 150 ng/mL (375 nmol/L) are usually found, although in some cases 25(OH)D levels may appear to be normal. Periodic measurement of serum calcium in individuals receiving large doses of vitamin D is recommended.

Screening

The official recommendation from the United States Preventive Services Task Force is that for persons that do not fall within an at-risk population and are asymptomatic, there is not enough evidence to prove that there is any benefit in screening for vitamin D deficiency.

Treatment

UVB exposure

Vitamin D overdose is impossible from UV exposure: the skin reaches an equilibrium where the vitamin degrades as fast as it is created.

Sun tanning

Further information: Sun tanning

Light therapy

Main article: Light therapy § Vitamin D deficiency

Exposure to photons (light) at specific wavelengths of narrowband UVB enables the body to produce vitamin D to treat vitamin D deficiency.

Supplement

Vitamin D₂ supplements

In the United States and Canada as of 2016, the amount of vitamin D recommended is 400 IU per day for children, 600 IU/d for adults up to age 70, and 800 IU/d for people over age 70. The Canadian Paediatric Society recommends that pregnant or breastfeeding women consider taking 2000 IU/day, that all babies who are exclusively breastfed receive a supplement of 400 IU/d, and that babies living north of 55°N get 800 IU/d from October to April.

Treating vitamin D deficiency depends on the severity of the deficit. Treatment involves an initial high-dosage treatment phase until the required serum levels are reached, followed by the maintenance of the acquired levels. The lower the 25(OH)D serum concentration is before treatment, the higher the dosage that is needed to quickly reach an acceptable serum level.

The initial high-dosage treatment can be given on a daily or weekly basis or can be given in form of one or several single doses (also known as stoss therapy, from the German word Stoß, meaning "push").

Therapy prescriptions vary, and there is no consensus yet on how best to arrive at an optimum serum level. While there is evidence that vitamin D₃ raises 25(OH)D blood levels more effectively than vitamin D₂, other evidence indicates that D₂ and D₃ are equal for maintaining 25(OH)D status.

Initial phase

Daily, weekly, or monthly dose

For treating rickets, the American Academy of Pediatrics (AAP) has recommended that pediatric patients receive an initial two to three months of treatment with "high-dose" vitamin D therapy. In this regime, the daily dose of cholecalciferol is 1000 IU for newborns, 1000 to 5000 IU for 1- to 12-month-old infants, and 5000 IU for patients over 1 year of age.

For adults, other dosages have been called for. A review of 2008/2009 recommended dosages of 1000 IU cholecalciferol per 10 ng/mL required serum increase, to be given daily over two to three months. In another proposed cholecalciferol loading dose guideline for vitamin D-deficient adults, a weekly dosage is given, up to a total amount that is proportional to the required serum increase (up to the level of 75 nmol/L) and within certain bodyweight limits, to body weight.

According to new data and practices relevant to vitamin D levels in the general population in France, to establish optimal vitamin D status and frequency of intermittent supplement dosing, patients with or at high risk for osteoporosis and vitamin D deficiency should start supplementation with a loading phase consisting of 50000 IU weekly of vitamin D for eight weeks in patients with levels <20 ng/mL and 50000 IU weekly for four weeks in patients with levels between 20 and 30 ng/mL. Subsequently, long-term supplementation should be prescribed as 50000 IU monthly. Should pharmaceutical forms suitable for daily supplementation become available, patients displaying good treatment adherence could take a daily dose determined based on the 25(OH)D level.

There are no consistent data suggesting the ideal regimen of supplementation with vitamin D, and the question of the ideal time between doses is still of debate. Ish-Shalom et al. performed a study in elderly women to compare the efficacy and safety of a daily dose of 1500 IU to a weekly dose of 10500 IU and to a dose of 45000 IU given every 28 days for two months. They concluded that supplementation with vitamin D can be equally achieved with daily, weekly, or monthly dosing frequencies. Another study comparing daily, weekly, and monthly supplementation of vitamin D in deficient patients was published by Takacs et al. They reported equal efficacy of 1000 IU taken daily, 7000 IU taken weekly, and 30000 IU taken monthly. Nevertheless, these consistent findings differ from the report by Chel et al., in which a daily dose was more effective than a monthly dose. In that study, the compliance calculation could be questionable since only random samples of the returned medications were counted. In a study by De Niet et al., 60 subjects with vitamin D deficiency were randomized to receive 2000 IU vitamin D3 daily or 50000 IU monthly. They reported a similar efficacy of the two dosing frequencies, with the monthly dose providing more rapid normalization of vitamin D levels.

Single-dose therapy

Alternatively, a single-dose therapy is used for instance if there are concerns regarding the patient's compliance. The single-dose therapy can be given as an injection but is normally given in the form of oral medication.

Vitamin D doses and meals

The presence of a meal and the fat content of that meal may also be important. Because vitamin D is fat-soluble, it is hypothesized that absorption would be improved if patients are instructed to take their supplement with a meal. Raimundo et al. performed different studies confirming that a high-fat meal increased the absorption of vitamin D3 as measured by serum 25(OH) D. A clinical report indicated that serum 25(OH) D levels increased by an average of 57% over a 2-month to 3-month period in 17 clinic patients after they were instructed to take their usual dose of vitamin D with the largest meal of the day.

Another study conducted in 152 healthy men and women concluded that diets rich in monounsaturated fatty acids may improve and those rich in polyunsaturated fatty acids may reduce the effectiveness of vitamin D3 supplements. In another study performed by Cavalier E. et al., 88 subjects received orally a single dose of 50000 IU of vitamin D3 solubilized in an oily solution as two ampoules each containing 25000 IU (D‐CURE®, Laboratories SMB SA, Brussels, Belgium) with or without a standardized high‐fat breakfast. No significant difference between fasting vs. fed conditions was observed.

Maintenance phase

Once the desired serum level has been achieved, be it by a high daily or weekly or monthly dose or by a single-dose therapy, the AAP recommendation calls for a maintenance supplementation of 400 IU for all age groups, with this dosage being doubled for premature infants, dark-skinned infants and children, children who reside in areas of limited sun exposure (>37.5° latitude), obese patients, and those on certain medications.

Special cases

To maintain blood levels of calcium, therapeutic vitamin D doses are sometimes administered (up to 100000 IU or 2.5 mg daily) to patients who have had their parathyroid glands removed (most commonly kidney dialysis patients who have had tertiary hyperparathyroidism, but also to patients with primary hyperparathyroidism) or with hypoparathyroidism. Patients with chronic liver disease or intestinal malabsorption disorders may also require larger doses of vitamin D (up to 40000 IU, or 1 mg, daily).

Co-supplementation with vitamin K

The combination of vitamin D and vitamin K supplements has been shown in trials to improve bone quality. As high intake of vitamin D is a cause of raised calcium levels (hypercalcemia), the addition of vitamin K may be beneficial in helping to prevent vascular calcification, particularly in people with chronic kidney disease.

Epidemiology

The estimated percentage of the population with a vitamin D deficiency varies based on the threshold used to define a deficiency.

Percentage of US population	Definition of insufficiency	Study
69.5%	25(OH)D less than 30 ng/mL	Chowdury et al. 2014
77%	25(OH)D less than 30 ng/mL	Ginde et al. 2009
36%	25(OH)D less than 20 ng/mL	Ginde et al. 2009
6%	25(OH)D less than 10 ng/mL	Ginde et al. 2009

Recommendations for 25(OH)D serum levels vary across authorities, and probably vary based on factors like age; calculations for the epidemiology of vitamin D deficiency depend on the recommended level used.

A 2011 Institute of Medicine (IOM) report set the sufficiency level at 20 ng/mL (50 nmol/L), while in the same year The Endocrine Society defined sufficient serum levels at 30 ng/mL and others have set the level as high as 60 ng/mL. As of 2011 most reference labs used the 30 ng/mL standard.

Applying the IOM standard to NHANES data on serum levels, for the period from 1988 to 1994 22% of the US population was deficient, and 36% were deficient for the period between 2001 and 2004; applying the Endocrine Society standard, 55% of the US population was deficient between 1988 and 1994, and 77% were deficient for the period between 2001 and 2004.

In 2011 the Centers for Disease Control and Prevention applied the IOM standard to NHANES data on serum levels collected between 2001 and 2006 and determined that 32% of Americans were deficient during that period (8% at risk of deficiency, and 24% at risk of inadequacy).

History

The role of diet in the development of rickets was determined by Edward Mellanby between 1918 and 1920. In 1921, Elmer McCollum identified an antirachitic substance found in certain fats that could prevent rickets. Because the newly discovered substance was the fourth vitamin identified, it was called vitamin D. The 1928 Nobel Prize in Chemistry was awarded to Adolf Windaus, who discovered the steroid 7-dehydrocholesterol, the precursor of vitamin D. Potential anticancer roles of the vitamin D metabolite calcifediol were observed epidemiologically by Frank Garland and Cedric Garland in the 1980s which were later observed clinically by Michael F. Holick and Raphael E. Cuomo.

Before the fortification of milk products with vitamin D, rickets was a major public health problem. In the United States, milk has been fortified with 10 micrograms (400 IU) of vitamin D per quart since the 1930s, leading to a dramatic decline in the number of rickets cases.

Research

Some evidence suggests vitamin D deficiency may be associated with a worse outcome for some cancers, but evidence is insufficient to recommend that vitamin D be prescribed for people with cancer. Taking vitamin D supplements has no significant effect on cancer risk. Vitamin D₃, however, appears to decrease the risk of death from cancer but concerns with the quality of the data exist. Nevertheless, studies suggest that Vitamin D deficiency is associated with increased risk of development melanoma. Low levels of 25-hydroxyvitamin D, a routinely used marker for vitamin D, have been suggested as a contributing factor in increasing the risk the development and progression of various types of cancer. Vitamin D requires activation by cytochrome P450 (CYP) enzymes to become active and bind to the VDR. Specifically, CYP27A1, CYP27B1, and CYP2R1 are involved in the activation of vitamin D, while CYP24A1 and CYP3A4 are responsible for the degradation of the active vitamin D. CYP24A1, the primary catabolic enzyme of calcitriol, is overexpressed in melanoma tissues and cells. This overexpression could lead to lower levels of active vitamin D in tissues, potentially promoting the development and progression of melanoma. Several drug classes and natural health products can modulate vitamin D-related CYP enzymes, potentially causing lower levels of vitamin D and its active metabolites in tissues, suggesting that maintaining adequate vitamin D levels, that is, avoiding vitamin D deficiency, either through dietary supplements or by modulating CYP metabolism, could be beneficial in decreasing the risk of melanoma development.

Vitamin D deficiency is thought to play a role in the pathogenesis of non-alcoholic fatty liver disease.

Evidence suggests that vitamin D deficiency may be associated with impaired immune function. Those with vitamin D deficiency may have trouble fighting off certain types of infections. It has also been thought to correlate with cardiovascular disease, type 1 diabetes, type 2 diabetes, and some cancers.

Review studies have also seen associations between vitamin D deficiency and pre-eclampsia.