Research into hereditary and environmental causes of mental disorders. Vartanyan M.E. ‹‹Biological psychiatry. Genetic factors of developmental disorders in children

Mental illnesses in the modern world are not uncommon and the trend is that more and more new syndromes, unstudied by science, are appearing. Prolonged, unhealthy habits, a deteriorating environment - all these causes of illnesses of the soul are just the tip of the iceberg.

What illnesses are mental?

Since ancient times, mental illnesses have been called diseases of the soul. These illnesses are in direct opposition to normal mental health and personality functioning. The course of the disorder can be mild, then the person can exist normally in society, but in severe cases, the personality is completely “eroded.” The most terrible mental illnesses (schizophrenia, epilepsy, alcoholism in the stage of withdrawal syndrome) lead to psychosis, when the patient can harm himself and others.

Types of mental illness

The classification of mental illnesses is presented in the form of two large groups:

1. Endogenous mental disorders - caused by internal factors of ill-being, often genetic (bipolar disorder, Parkinson's disease, senile dementia, age-related functional mental disorders).
2. Exogenous mental illnesses (the influence of external factors - traumatic brain injuries, severe infections) - reactive psychoses, neuroses, behavioral disorders.

Causes of mental illness

The most common mental illnesses have long been studied by specialists, but sometimes it remains difficult to identify the reason why this or that deviation occurred, but in general there are a number of natural factors or risks for the development of the disease:

• unfavorable environment;
• heredity;
• unsuccessful pregnancy;
• traumatic brain injuries;
• child abuse in childhood;
• neurointoxication;
• severe psycho-emotional trauma.

Are mental illnesses inherited?

Many mental illnesses are inherited; it turns out that there is always a predisposition, especially if both parents have mental illnesses in their family tree, or the spouses themselves are unhealthy. Hereditary mental illnesses:

• schizophrenia;
• bipolar disorder;
• depression;
• epilepsy;
• Alzheimer's disease;
• schizotypal disorder.

Symptoms of mental illness

The presence of several symptoms allows one to suspect that a person is mentally ill, but only a competent consultation and examination by a specialist can reveal whether it is a disease or personality traits. Common signs of mental illness:

• auditory and visual hallucinations;
• rave;
• dromomania;
• prolonged state of depression, avoidance of society;
• sloppiness;
• alcohol and drug abuse;
• malice and vindictiveness;
• desire to cause physical harm;
• auto-aggression;
• emasculation of emotions;
• violations of will.

Treatment of mental illness

Mental illnesses – this category of illnesses require drug therapy no less than any somatic illnesses. Sometimes only a competent selection of medications or effective psychotherapy help slow down the disintegration of personality in severe forms of schizophrenia and epilepsy. Mental illnesses, drug therapy:

• neuroleptics– reduce psychomotor agitation, aggression, impulsivity (aminazine, sonapax);
• tranquilizers– reduce anxiety, improve sleep (phenozepam, buspirone);
• antidepressants– activate mental processes, improve mood (miracetol, ixel).

Treatment of mental illness with hypnosis

Common mental illnesses are additionally treated with. The disadvantage of hypnosis treatment is that only a small percentage of mentally ill patients are hypnotizable. But there are also successful cases of long-term remissions after several sessions of hypnosis. It is important to remember that mental illnesses such as schizophrenia and dementia are incurable, therefore conservative drug treatment is the main one, and hypnosis helps to find old traumas in the subconscious and “rewrite” the course of events, which will soften symptoms.

Disability due to mental illness

Mental deviations and diseases seriously limit a person’s work activity, his worldview changes, withdrawal into himself and desocialization occur. The patient is not able to live a full life, so it is important to consider such an option as disability and the assignment of benefits. In what cases is disability due to mental illness established, list:

• epilepsy;
• schizophrenia;
• dementia;
• Alzheimer's disease;
• Parkinson's disease;
• dementia;
• severe dissociative identity disorder;
• bipolar affective disorder.

Prevention of mental illness

Mental disorders or diseases are becoming increasingly common today, so prevention issues are becoming increasingly relevant. Diseases associated with the psyche - what measures are important to take to prevent the development of the disease or to mitigate the destructive manifestations of already progressive ones? Psychohygiene and mental hygiene are a set of measures aimed at supporting mental health:

• proper organization of work and rest;
• adequate mental stress;
• timely detection of stress, neurosis, anxiety;
• studying your ancestry;
• pregnancy planning.

Uncommon mental illnesses

Manic-depressive psychosis, schizophrenia - many have heard about these disorders, but there are rare mental illnesses that are not heard of:

• bibliomania– obsession with acquiring books by a specific author and the entire circulation of the book;
• hysterical fantasizing– an uncontrollable desire to lie, to make up various stories about oneself;
• koro or genital retraction syndrome - the patient is convinced that his genitals are inexorably retracted into the body, and when they are completely retracted, death will occur - the person stops sleeping, watches the penis;
• Cotard's delirium– a person with this disorder is convinced that he is dead or does not exist at all; it may seem to the patient that his organs are decomposing and his heart is not beating;
• prosopagnosia– a person orients himself in the surrounding environment, but does not perceive or recognize people’s faces.

Celebrities with mental illness

Exacerbation of mental illnesses or disorders does not go unnoticed - after all, stars have everything in plain sight, hiding such things is not an easy thing for a celebrity, and famous personalities themselves prefer to speak openly about their problems, attracting attention to themselves. Celebrities with different mental disabilities:

1. Britney Spears. The behavior and actions of Britney, who had gone off the rails, were not discussed except by the lazy. Suicide attempts and impulsive head shaving are all the result of postpartum depression and bipolar personality disorder.


2. Amanda Bynes. A bright star of the late 90s. of the last century suddenly disappeared from the screens. Massive consumption of alcohol and drugs became the debut of developing paranoid schizophrenia.


3. David Beckham. The soccer star suffers from obsessive-compulsive disorder. For David, clear order is important, and if the arrangement of objects in his house changes, this provokes severe anxiety.


4. Stephen Fry. The English screenwriter suffered from depression and a feeling of worthlessness from a young age, attempting suicide several times, and only at the age of 30 was Stephen diagnosed with bipolar disorder.


5. Herschel Walker. An American football player was diagnosed several years ago with dissociative personality disorder. Since adolescence, Gerchel felt several personalities within himself and, in order not to go crazy, he began to develop a tough leading authoritarian personality.

Films about mental illness

The topic of mental personality disorders is always interesting and in demand in cinema. Neuropsychiatric diseases are like mysteries of the soul - actions, motives, actions, what motivates people with psychopathology? Films about mental disorders:

1. « Mind Games / A Beautiful Mind" The brilliant mathematician John Forbes Nash suddenly begins to behave strangely, communicates on the phone with a mysterious CIA agent, and takes letters to the appointed place. It soon becomes clear that the contact with the CIA is a figment of John's imagination and things are much more serious - paranoid schizophrenia with visual and auditory hallucinations.
2. « Shutter Island" The gloomy atmosphere of the film keeps you in suspense until the very end. Bailiff Teddy Daniels and his partner Chuck arrive on Shutter Island, where there is a psychiatric hospital specializing in the treatment of particularly severely mentally ill patients. Rachel Solando, a child killer, disappears from the clinic and the task of the bailiffs is to investigate this disappearance, but during the investigation, Teddy Daniels' inner demons are revealed. The film demonstrates the emasculation of personality in schizophrenia.
3. « Natural Born Killers" Crazy couple Mickey and Mallory travel across the USA and leave behind corpses. A controversial film illustrating dissocial personality disorder.
4. « Fatal Attraction" What might a casual weekend fling lead to with someone with borderline personality disorder? Dan's whole life goes downhill after his betrayal: attractive Alex turns out to be a maniac and threatens to commit suicide if Dan is not with her and kidnaps his son.
5. « Two Lives / Passion On Mind" Martha, a widow with two children, lives an ordinary life in a small French town, taking care of children, housekeeping and writing reviews for magazines. Everything changes at night, when Martha falls asleep - there is another bright life, where she is the beautiful vamp Marty, the head of a literary agency. Both lives: the real one and the one that happens in a dream are intertwined, and Martha can no longer separate which is reality and which is a dream. The heroine suffers from dissociative identity disorder.

The practical conclusions that we can draw based on the presented figures and facts are the following: having information about the presence of mental illness in the pedigree of an adopted child will help adoptive parents anticipate potential difficulties in the child’s development and possibly avoid them.
If you discover that there have been cases of mental illness in the family of an adopted child, you should not be immediately frightened by this information - it is more advisable to get advice from a geneticist about the degree of risk of developing this disease in the child. Remember that although mental disorders are inherited, the development of the disease is no less strongly influenced than genetic factors by the environment in which the child grows up - the level of education, the child’s social environment, school, and especially the influence of parents and the general family climate. Various mental and behavioral disorders in children arise precisely in orphanages and children's homes, which is associated with a lack of attention to children in these institutions. The very fact of living in a family, and not in an institution, has a decisive impact on the mental health of the child. As an example, we can cite the results of one long-term study carried out in Israel. Scientists observed two groups of children born to a parent with schizophrenia. Children from one group were raised in their family of origin, while children from the other group grew up in a kibbutz, where they were provided with conditions of life and upbringing that were close to ideal, according to the founders of the kibbutz. However, after 25 years, it turned out that the pupils of such an ideal orphanage had schizophrenia and affective illnesses more often than children who grew up in a family, even if it was not entirely successful due to the illness of a parent.
The first symptoms of mental illnesses, such as schizophrenia, can appear long before the onset of the illness itself. Up to 10 years can pass between their appearance and the development of the disease. Characterization of these symptoms is not the subject of this article, since such recommendations should come from a psychiatrist. However, it should be noted that changes in the child’s behavior, general weakness, sleep disturbances, impaired perception, and decreased performance at school should alert parents and serve as a reason to contact the appropriate doctor. At the same time, given the general nature of the listed signs, you should not be too wary of their manifestation in a child. A real cause for concern may arise only if he had close relatives with schizophrenia. If you are sure that the child is really showing symptoms of an impending illness, remember that, according to many psychiatrists, early intervention in the development of psychosis is more effective, as it contributes to the patient’s better adaptation to social life.
It can also be noted that of all the listed mental disorders, schizophrenia seems to be the most severe. The clinical manifestations of this disease are very diverse - its development may be limited to one attack, which will not affect the patient’s life in any way. In the most severe cases, schizophrenia causes irreversible personality changes, complete elimination from social life, when the patient not only cannot work, but also stops taking care of his appearance and communicating with people around him.
It should also be realized that molecular genetic tests for identifying mental illnesses are a matter of the future. If any medical institution offers you a test for schizophrenia or other mental disorders, keep in mind that, at best, this will be a determination of gene polymorphism that may influence the development of mental disorders. At the same time, no scientist can currently say unambiguously what contribution these genes make to the development of the disease. We also recommend that you be very careful about messages that appear from time to time in the media about the discovery of an aggression gene, a kleptomania gene, or another schizophrenia gene. These reports are nothing more than a misinterpretation of the discovery of an increased frequency of occurrence of any altered candidate gene variant in a group of patients compared to a control group.
In conclusion, I want to digress from the scientific presentation and move to the plane of assessing the problem from the point of view of common everyday sense and the humanitarian positions taken by a person who decides to raise a child. When connecting your life with a sick child or with a child whose heredity is burdened with severe mental illness, first of all you must recognize the existence of a problem and be prepared to solve it. In such a situation, it is wiser to help the child rather than push him away, especially since violations of the parent-child relationship only aggravate the problem. Remember that the influence of heredity, although great, is not infinite, and many problems are not associated with organic mental disorders. In other words, you shouldn’t blame genes and “bad heredity” for everything. As stated in one foreign textbook on psychogenetics, genes are good or bad cards dealt to each of us largely by chance, and how they will be implemented in the game depends on many surrounding factors that we can control to one degree or another under control.

Bottom line

1. In medicine, three factors are considered as possible causes of mental disorders: the presence of traumatic events, prolonged exposure to an unfavorable environment, the internal state of the body, including hereditary predisposition.

2. In psychogenetics, much attention is paid not only to the search for hereditary mechanisms of various mental disorders, but also to the study of environmental risk factors and the possibilities of environmental therapeutic influences (“environmental engineering”). Recently, along with the term “genome,” the term “envirome” (from the English environment) has begun to be used - a concept that includes environmental risk factors.

3. Schizophrenia is one of the most common mental illnesses, characterized by disturbances in the processes of thinking, perception, emotional and volitional spheres.

a. The incidence of schizophrenia among the population is about 1%. Among relatives of patients with schizophrenia, the incidence of the disease is higher than in the population. The risk of the disease increases with increasing degree of relationship. For MZ twins it is about 50%. This suggests the existence of a hereditary component to the disease.

b. To date, there is no single model of genetic transmission of schizophrenia. Most researchers believe that the inheritance of schizophrenia may be based on a multifactorial polygenic threshold model with possible epistasis effects.

4. Depressive disorder

a. Depression is a mental disorder characterized by depression, disturbances in attention, sleep and appetite. Depression can be accompanied by feelings of anxiety and agitation or, conversely, lead to apathy and indifference to the environment. About 5% of the population suffers from depression.

b. Depression tends to concentrate in individual families. Relatives of depressed patients have a higher susceptibility to the disease than the general population.

c. The results of genetic studies of depression vary widely depending on the diagnostic approaches and methods used.

d. In affected families, anxiety disorders often occur in addition to depressive disorders. There is reason to believe that anxiety and depressive disorders have common causes. Depression, like schizophrenia, appears to be a multifactorial hereditary disease of a complex nature.

5. Learning disability

a. Specific learning disabilities - learning disabilities - are often identified with the concept of mental retardation. SNO combines a number of cognitive disorders that interfere with school learning, despite intact intelligence. The number of children suffering from specific reading, writing, and arithmetic disorders, according to some estimates, is 20-30%.

b. Among SNOs, the most studied is specific reading disability (dyslexia), or congenital “word blindness.” Dyslexia is believed to be caused by specific abnormalities in brain cells. Cases of dyslexia run in families.

c. In genetic studies, dyslexia is considered as a complex multifactorial trait with a threshold effect. The phenotypic variability of dyslexia is extremely large and changes with age. Currently, it is possible to detect possible zones of chromosomal localization of dyslexia.

Articles used in this work

1. Alfimova M.V. “The influence of genetic inheritance on behavior” (Ph.D. in Psychology, leading researcher at the Laboratory of Clinical Genetics of the Scientific Center for Mental Health of the Russian Academy of Medical Sciences).

2. Vakharlovsky V.G. “Genetic diseases and their diagnosis in adopted children” (candidate of medical sciences, medical geneticist).

3. Golimbet V.E. “The influence of heredity on people’s mental health” (Doctor of Medical Sciences).

4. Nikiforov I.A."Factors contributing to the development of substance dependence"

5. Rudenskaya G.E. “Medical genetics: how it can help adoptive parents and children” (Doctor of Medical Sciences, Chief Researcher of the Russian Academy of Medical Sciences).

Instructions

The exact mental disorders are not known. Recent research in this area has shown that the development of these diseases is associated with several factors, among which genetic, biological, and psychological influences are most often mentioned. It is worth noting that mental disorders are not associated with personal weakness and the absence of certain character traits, and recovery from an experienced illness is not possible only through self-discipline and willpower.

Genetic predisposition is the main factor that determines the possibility of developing a mental disorder. Modern research is aimed at identifying genes that can provoke a particular mental disorder. It is the genetics of the body that is responsible for the functioning of the psyche in general and behavioral characteristics in particular. However, the presence of a mental disorder in the mother or father does not automatically mean that the child and his future children will inherit the disease. Genetic predisposition only increases the risk of developing the corresponding disease. Thus, a child may inherit a vulnerability to a particular type of disease, but never develop it throughout his life. As a rule, the disease occurs not only as a result of some vulnerability, but also under the influence of environmental factors.

Mental illness may be biologically determined due to defects in the structure of the brain that are associated with thinking, mood and behavior. Disorders of the nervous system can cause psychiatric symptoms. Scientists say that certain neurons in the brain can control the symptoms of the disease. Inflammation that occurs as a result of a certain disease can also play a role in the development of mental disorders. In this case, infections (for example, meningitis) that enter the human brain can cause brain damage and cause mental abnormalities.

Psychological trauma can also cause mental illness. Most often, such disorders occur in childhood, when the child’s psyche is not completely stable. Physical, emotional and sexual violence can cause mental defects, which later turn into characteristic diseases. Serious losses (such as the death of a parent) can also cause problems. Lack of control can also cause abnormal development of the child’s behavior and mental disorders.

GENETICS OF MENTAL DISEASES

B. Morel (1857) was the first to speak quite clearly about the role of degeneration. He cited clinical evidence of the accumulation of various stigmas of degeneration in degenerating families, so that in the third or fourth generations already mentally ill children may be born, exhibiting, for example, signs dementia praecox(premature dementia). Since the second half of the 20th century, the study of the role of heredity in the origin of psychoses has become increasingly important. With the development of genetics as an exact science, clinical experience began to be supported by evidence-based information about disturbances in the structure of certain genes that make up the set of human chromosomes. However, a direct, rigid connection between genetic “breakdowns” and the occurrence of mental disorders has been established only for a small number of mental illnesses. These currently include such as Huntington's chorea (the presence of a pathological gene on the short arm of chromosome 4), a number of differentiated oligophrenias with a clear clinical and genetic diagnosis. This group includes phenylketonuria (autosomal dominant mode of inheritance), Down's disease (trisomy XXI), Klinefelter's disease (XXY or XXXY syndrome), Martin-Bell disease (fragile 10 syndrome), "cry the cat" syndrome (missing part chromosomes of the fifth pair), XYY syndrome with signs of mental retardation and aggressive behavior in men.

The involvement of several genes (their pathology) has recently been proven in relation to Alzheimer's disease. Damage to genes localized on chromosomes 1, 14, 21 leads to the early onset of atrophic dementia with amyloid deposition in brain structures and neuronal death. A defect in a specific gene on chromosome 19 determines the late onset of sporadic cases of Alzheimer's disease. With most endogenous mental illnesses (schizophrenia, epilepsy, manic-depressive psychosis - MDP), a certain diathesis and predisposition are inherited. The manifestation of the pathological process is often provoked by psychogenies and somatogenies. For example, in schizophrenia, changes are found in a number of genes - such as NRG (8p21-22), DTNBI (6p22), G72 (13q34 and 12q24 locus), etc. In addition, various alleles of glutamate receptor genes.

One of the earliest methods of genetic research is considered to be the genealogical method, which consists of analyzing the pedigree, starting with the patient himself (proband). The significant role of genetic factors in the development of psychoses is indicated by an increase in the frequency of the pathological symptom in the proband’s immediate relatives and a decrease in its frequency in distant relatives. Population-based studies, especially international multicenter ones, are of great importance.

The twin method allows us to more accurately judge the degree of contribution of hereditary and environmental factors to the etiology of psychoses. It is generally accepted that concordance reflects the contribution of genetic factors to the occurrence of human disease, and, conversely, discordance between identical twins is determined by environmental factors. M. E. Vartanyan (1983) provided generalized (averaged) data on the concordance of identical twins (ET) and fraternal twins (DT) for schizophrenia, MDP, epilepsy (Table 1).

Table 1. Generalized data on the concordance of identical and fraternal twins for a number of diseases, %

As can be seen from table. 1, in none of the studied endogenous diseases does the concordance in OB pairs reach 100%. Interpretation of twin concordance data faces a number of difficulties. For example, according to psychologists, “mutual mental induction” cannot be ruled out, which is much more pronounced in OB than in DB. It is known that OBs strive more for mutual imitation than DBs. This explains the difficulties of absolutely precise determination of the contribution of genetic and environmental factors in endogenous psychoses. In this regard, the developed methods of family-twin analysis help (V. M. Gindilis et al., 1978).

The most significant achievement of recent times is considered to be a complete study of the human genome, which made it possible to form a new field in psychiatry - molecular psychiatry with molecular genetic research (DNA diagnostics). If previously, for example, psychiatrists may have had difficulty clinically distinguishing between Huntington's chorea and catatonic schizophrenia due to individual preferences and differences in schools of researchers, now it is possible to accurately diagnose Huntington's chorea with evidence of damage to a number of loci in the short arm of chromosome 4.

History of psychogenetics of disordered behavior.

Eugenic measures and their consequences. Modern trends in eugenics.

The main factors underlying mental disorders.

"Environmental Engineering".

Genome and environment.

Genetics of mental retardation.

Hereditary disorders and diseases.

Back in the 19th century. Psychiatrists considered three main factors as possible causes of mental disorders: the presence of traumatic events, prolonged exposure to an unfavorable environment and the internal state of the body, including hereditary predisposition. The corresponding cumulative combination of internal predisposition to the disease and any life circumstances can lead to the fact that a certain threshold is exceeded, after which the picture of the disease develops. Since the beginning of the development of psychogenetics, with the advent of the twin method, research began aimed at studying the role of heredity in the occurrence of various mental illnesses, mental retardation, deviant behavior, including alcoholism, crime, etc. But even before the scientific study of heredity began, eugenics had just emerged called for a healthier society. Eugenics, not based on a truly scientific theory, proclaimed almost as a religion, convinced and convinced others of the effectiveness of artificial selection and hereditary determination of diseases, led to the deployment of practical measures related to mass sterilization and discrimination in a number of countries in Europe, Asia, Africa and America. Moreover, these measures were aimed primarily against people with mental disabilities, and not with physical illnesses. Eugenic ideas continue to live in the minds of people... And research related to the Human Genome Project has only revived them. For example, in China in 1994 they adopted eugenic laws, aimed at reducing the birth rate in economically underdeveloped areas. In the United States, to this day, one can find publications trying to influence public opinion regarding the need for genetic screening for employment, encouraging abortion in the poor, etc. To counter this, the Human Genome Project allocates significant funds to humanitarian causes. programs (educational, cultural, medical, ethical, legal).

Psychogenetics today is engaged not only in the search for hereditary mechanisms of various mental disorders, but also in the study of environmental risk factors and the possibilities of environmental therapeutic influences (environmental engineering, according to R. Plomin). Today, as we have already written, along with the term genome the term began to be used envir(from the word environment – environment) is a concept that includes environmental risk factors in the occurrence of mental disorders. Shifting the emphasis to more thorough environmental studies will likely make it possible to more correctly establish and understand the causes of disorders, based on the recognition of the indivisibility and complex mutual influence of heredity and environment - in fact, the problem of the role of heredity and environment in the development of various mental illnesses and behavioral disorders becomes the main one.

We have already talked about schizophrenia above, so now let us just recall what is most important in working with the origins of this disease in the light of what has been said above about the complex mutual influence of heredity and environment:

1) clarification of psychiatric genetic classification (identification of particular nosological phenotypes for linkage analysis);

2) study of neurobiological dysfunctions (endophenotypes) accompanying schizophrenia, with the aim of involving them in linkage analysis;

3) development of statistical models to study the multifactorial etiology and heterogeneous nature of schizophrenia;

4) continued study of groups of relatives to identify the loci involved;

5) combining the efforts of many laboratories and international cooperation.

This is schizophrenia, but depression!.. Depression is a mental condition characterized by depression, disturbances of attention, sleep and appetite. Depression can be accompanied by feelings of anxiety and agitation or, conversely, lead to apathy and indifference to the environment. People suffering from depressive disorder feel despair and helplessness, and often have suicidal thoughts, so clinically significant depression also requires treatment.

There are several forms of depression, of which the most well-known and common are major (unipolar) depression and bipolar affective disorder (manic-depressive psychosis). In bipolar disorder, periods of depression and bad mood are followed by phases of increased activity and elation, often accompanied by inappropriate behavior. Depression is a common illness and is sometimes called cold among mental illnesses. But due to the variety of manifestations and the impossibility of recording all patients - not everyone goes to the doctor - it is quite difficult to establish the exact incidence of the disease. In the USA, for example, it is believed that at least 5% of the population suffers from depression. Women suffer from depression approximately 2 times more often than men. Bipolar disorder affects 1% of the population. By the way, let us remind you: it has been noted that depression tends to concentrate in individual families. Parents, children, and siblings of depressed patients have a much higher risk of the disease than in the general population. Twin studies show much higher concordance MZ twins versus DZ twins. Particularly noticeable differences apply to bipolar disorder. But, as we know, research methods also influence the results: the heritability of bipolar psychosis is comparable to the heritability of schizophrenia, while the data for unipolar depression are very contradictory; The heritability of recurrent depression is higher than that of single episodes. But there is no complete clarity on the question of whether unipolar depression is a single disease or represents a whole group of disorders. Depressive disorders vary so much in the nature of symptoms, severity, and connections with other disorders that many are inclined to consider depression heterogeneous disease. In the families studied, along with depressive disorders, anxiety states (generalized anxiety, panic and phobic disorders) were often found. Twin studies conducted in recent years around the world suggest that anxiety and depressive disorders share common genetic causes. And some researchers believe that Both anxiety and depression are quantitative traits that have a normal population distribution and depend on the action of many genes with small effects.

Let's talk about Alzheimer's disease - a progressive disease of the central nervous system, accompanied by loss of short-term memory, loss of skills, and slowness of thinking. The disease develops in older people, and studies indicate an excess of amyloid protein in the brain cells of such patients. The disease tends to progress: irritability and intolerance increase, hygiene skills are lost, and problems with speech arise. The progressive nature of the disease results from extensive cell death in certain areas of the brain. But what triggers the development of the disease is still unclear. Alzheimer's disease affects approximately 3-5% of people over 65 years of age and 20% of people over 80 years of age. Much less commonly, the disease begins at 40–50 years of age. It is known that Alzheimer's disease is familial - the probability of the disease is higher for first-degree relatives and reaches 50% for older people. The familial nature of the disease is especially clear for rare variants (frequency 1:10,000) with early onset (before 65 years). Although conducting twin studies of older people is often associated with great difficulties, nevertheless, in the USA and Scandinavian countries, data have been obtained on twins indicating the presence of a hereditary component of the disease. The concordance of MZ twins was significantly higher than that of DZ twins, but varied widely (from 21% to 83%).

A study of families with early-onset disease has identified three gene mutations that may cause the disease. One of them, the amyloid beta precursor protein gene, is localized on chromosome 21. It is designated APP (Amiloid Precursor Protein). By the way, people with Down syndrome, who have an extra chromosome 21, tend to develop Alzheimer's disease at a relatively young age. Two other genes, located on chromosomes 14 and 1, turned out to be associated with the synthesis of presenilin proteins, which may be related to the regulation of intracellular protein transport, including APR.

Thus, the main risk factors for Alzheimer's disease are: older age, familial cases, especially with early onset, and Down's disease. Others include traumatic brain injury, thyroid disease, birth to a mother over 30 years of age, and low level of education. Interestingly, smokers have a lower risk of developing Alzheimer's disease than non-smokers. Active creative activity and a high level of education also lead to lower risks of the disease.

And one more thing: under mental retardation is understood persistent irreversible impairment of intelligence. Clinically, there are two main forms of mental retardation: mental retardation And dementia.

Mental retardation includes several groups of persistent intellectual disabilities due to underdevelopment of the brain at an early age.

Under dementia refers to the collapse of already formed intellectual functions as a result of various brain diseases.

Mental retardation milder forms of intellectual underdevelopment are considered, often accompanied by only partial (partial) impairment of higher mental functions.

As is known from the history of the world and science, mental retardation was one of the indications for forced sterilization during the period of eugenic laws. This suggests that even before systematic research on the genetics of mental retardation was carried out, there was a belief in the possibility of inheritance of intellectual underdevelopment.

One well-known historical example that supports the belief that mental retardation runs in families is the alleged history of the Kallikak family, which is often cited as evidence of the role of heredity in the determination of mental abilities.

"The doctrine of the heredity of dementia" (The Kallikak Family: A Study in the Heredity of Feeble-Mindedness) – a book by Henry G. Goddard, an American psychologist and eugenicist, written in 1912. This work examines in detail the problem of inheritance of dementia, which refers to various mental disorders: mental retardation, learning disability and mental disorder. Goddard concluded that all mental traits are heritable and that society should avoid reproducing unhealthy people. The book begins with a discussion of the case of Deborah Kallikak (Kallikak is a pseudonym derived from the Greek (kalos) Fine And Badly), women at the Goddard Institute, a home for the education and care of mentally retarded children in New Jersey. As Goddard researched her genealogy, he made some curious and surprising discoveries. Goddard's book examines the genealogy of Martin Kallikak, Deborah's great-great-great-great-grandfather and American Revolutionary War hero. On the way home after the war, normal Martin once had an affair with weak-minded bartenders. Young Martin later became a respected New Englander and the father of a large and prosperous family. But according to Goddard, a child was born from a relationship with an “unknown, weak-minded bartender.” An only child, a boy, from whom even more children were born, who then gave birth to their own, and so on from generation to generation. The children from the "feeble-minded" side of the Kallikak family grew up weak, restless, feeble-minded, and criminals. Goddard wrote about the invisible threat of recessive "feeble-minded" genes carried by apparently intelligent-looking people (Mendel's laws were discovered ten years later). On the “healthy” side of the Kallikak family, the children grew up successful, smart and well-mannered. They became lawyers, ministers and doctors. Goddard came to the conclusion that the weak-minded should not be allowed to reproduce, otherwise it would lead to an increase in crime and poverty in society. The work presents complex family trees, with designations of negative and positive qualities. It is not surprising that Goddard recommended that such children be kept in institutions like the one he led, where they would be trained in simple work in the service sector. By now, The Kallikak Family is widely known and has been reprinted many times, considered one of the classic works in American eugenics.

Mental retardation can be caused by both endogenous and exogenous causes. It is believed that approximately 75% of cases of mental retardation are hereditary. Among them, 15% are chromosomal abnormalities. Chromosomal abnormalities are associated with a change in the number of chromosomes or a restructuring of their structure. Anomalies can affect both autosomes and sex chromosomes. Violation of the number and structure of autosomes leads to more serious consequences and is accompanied, in addition to mental retardation, by multiple developmental defects affecting various organs and tissues. A change in the number of sex chromosomes causes less severe mental retardation. Among the chromosomal abnormalities associated with mental retardation, Down syndrome is the most common (1:700). Down syndrome is a consequence nondisjunction of chromosomes. The karyotype of patients shows an extra 21st chromosome. The IQ of people with Down syndrome ranges from 20 to 60 units. Most of these patients are not able to live independently.

Severe mental retardation can also occur as a result of hereditary diseases associated with metabolic errors. One of the most famous among them is phenylketonuria – a recessive autosomal monogenic disease associated with a disorder of the metabolism of the amino acid phenylalanine. Some time ago, children born with this diagnosis were doomed to severe mental retardation, since phenylalanine supplied with food did not undergo the necessary transformations - as a result, brain function suffered. Now, in principle, such severe consequences can be avoided if, immediately after the birth of a sick child, foods containing phenylalanine are excluded from food, and such diets have been developed and used. Diagnosis of phenylketonuria in newborns is not difficult, therefore, with universal screening of newborns and the use of dietary therapy, the incidence of mental retardation due to phenylketonuria can be reduced. The phenylketonuria gene is localized on chromosome 12. Recently, it has been established that the cause of phenylketonuria can be more than 100 different mutations of this gene, which can cause varying degrees of mental retardation.

The study of the genetics of severe mental retardation indicates the heterogeneity of this group of diseases - some of them are of an exogenous nature, the rest are associated with chromosomal disorders and various hereditary diseases.

Recently, the attention of specialists has been drawn to the study X-linked mental retardation (fragile or fragile X syndrome, Martin-Bell syndrome). The name of the syndrome is explained by the special shape of the structure of the X chromosome, which has a clearly visible constriction at the end of the long arm. After identifying this hereditary form of mental retardation, the high incidence of intellectual underdevelopment in boys became clear. This recessive disorder is transmitted with the X chromosome through the mother, as boys receive their only X chromosome from their mother. Boys, unlike girls, have only one X chromosome, so recessive X-linked diseases are observed much more often in them. Fragile X syndrome is one of the most common inherited diseases, comparable in frequency to Down syndrome (approximately 1 in 2000 men). In addition to the fragile X chromosome, patients are characterized by some morphological features that are not always clearly visible (high convex forehead, large ears and jaws, large hands, enlarged testicles). Mental development fluctuates between IQ values ​​from 30 to 65 (sometimes within the normal range). Speech is replete with repetitions, and a kind of stuttering is common. Children are characterized by motor disinhibition and some symptoms of autism (the child avoids eye contact, makes stereotypical movements with his hands, and experiences fears). Even with a mild degree of intellectual disability, children have difficulty mastering counting and writing skills. Children with a fragile X chromosome have a unique electroencephalogram. Due to the fact that the symptoms of the disease are varied, an erroneous diagnosis is often made (schizophrenia, early childhood autism, epilepsy, attention deficit hyperactivity disorder). As a result, children do not receive appropriate treatment, and the family remains in the dark about the true causes of developmental disorders. The genetic mechanism of the disease is associated with the expansion of trinucleotide repeats (CGG - cytosine-guanine-guanine) in the corresponding constriction region of the X chromosome. Normally, the number of repeats should not exceed 50. The number of repeats from 50 to 200 is considered a premutation, and a pronounced picture of the disease is observed in the presence of more than 200 repeats. This disease is characterized by the phenomenon of anticipation, i.e., an increase in the severity of the disease from generation to generation, which is associated with an increase in the number of trinucleotide repeats in the mutated region of the chromosome. Since the disease is widespread, its early diagnosis is important for the timely organization of therapeutic and corrective measures and medical and genetic counseling of the family in order to prevent the risk of having children with the same diagnosis.

Mild forms of mental retardation represent a qualitatively different group in terms of heredity than its severe forms. Pathology of exogenous origin is much less represented here, although unfavorable environmental factors play an undoubted role. Mild mental retardation is usually not accompanied by noticeable changes in physical appearance or behavioral reactions. However, familial accumulation is observed for these forms of mental retardation. Intelligence assessments of relatives with mild forms of mental retardation in probands represent a normal distribution with some bias towards lower values, which indicates a tendency for intelligence to decline in this group. Intelligence scores in relatives of probands with severe forms of mental retardation are distributed bimodally. This means that severe mental retardation often occurs in families with a normal level of intelligence and is the result of exogenous causes or rare mutations and chromosomal disorders.

Research into the genetics of mental retardation is fraught with many difficulties, since it involves a whole group of diseases with different etiologies. Severe forms of mental retardation fall under the purview of medical genetics. Mild forms are the subject of study by psychogeneticists, since, apparently, they can be classified as extreme variants of normal variability in intelligence.

A special group of cognitive impairments is specific learning disability(SNO). In the English-language literature these disorders are called learning disabilities. We do not yet have a generally accepted term for this group of developmental disorders. They are often identified with the concept of mental retardation (MDD); sometimes you can find such designations as school difficulties or school difficulties. It is clear that failure at school can be explained by various reasons - low motivation, pedagogical neglect, mental retardation itself, diseases not related to the mental sphere, etc. And school failure should not be confused with SSS. Specific learning disability comprises a range of cognitive disorders that interfere with school learning despite intact intelligence. Most often, there are difficulties in mastering basic school skills (reading, writing, counting). The number of children experiencing serious learning difficulties, according to experts, is 20–30%. Of these, up to 20% are due to specific disorders of reading, counting, and writing. This could mean that in any given class, about a quarter of children are struggling with the standard curriculum, with specific developmental disabilities rather than poor application being the main cause. Unfortunately, lack of understanding of this on the part of teachers and parents leads to a decrease in self-esteem in such children and is often the cause of school maladaptation and deviant behavior. If we consider that the number of children with SNO throughout the world tends to increase, it becomes clear that the problem of early diagnosis and correction of SNO is extremely acute.

Among the various cognitive impairments leading to difficulties in school learning, the most well-known and studied is dyslexia(reading disability). Dyslexia, or congenital verbal blindness, was first described in the mid-90s of the 19th century. The main symptom of dyslexia is the inability to master reading, despite intact intelligence, the absence of visual and hearing impairments or brain injuries (dyslexia should not be confused with the child’s reluctance to learn to read due to inadequate pedagogical influence, reduced motivation, etc.). Characteristic symptoms of dyslexia are the inability to break down words into phonemes and the inability to quickly name simple visual stimuli (objects, colors, letters, numbers). Dyslexics also have mild but distinct visual and hearing impairments and some coordination problems. Dyslexia is believed to be caused by specific abnormalities in brain cells. At the beginning of the 20th century. It has been observed that cases of dyslexia run in families. In 1950, the first family study of dyslexia was conducted. Since then, genetic studies of dyslexia have become systematic. Twin studies have shown higher concordance among MZ twins (68%) compared with DZ twins (38%). The results here indicate the role of heredity and general environment. When calculating simple concordance, dyslexia is considered a qualitative, alternative trait, a complex trait that requires quantitative assessment and the development of standard criteria. Unfortunately, there are no unified psychometric criteria for dyslexia yet - the reason is variable symptoms, age-related changes, and the lack of a clear definition of dyslexia itself. Genetic analysis of dyslexia is challenging. Researchers use different experimental approaches to study dyslexia. The specificity of the language of the country in which the research is being conducted also leaves its mark (most of the work was carried out on English-speaking populations, but research is being conducted in Germany and Scandinavian countries).

And, of course, we cannot ignore one of the most difficult issues - crime and heredity. It is a common belief that crime and alcoholism are hereditary traits. It is no coincidence that at the beginning of the 20th century. In those countries where eugenic laws were passed, criminals and alcoholics were subjected to forced sterilization. The problem of crime and violence, alcoholism, drug addiction and other forms of antisocial behavior in modern society is extremely acute.

Currently, a whole direction has emerged in criminology - biological criminology: studying the biological correlates of criminal behavior. Biochemical, physiological, and medical studies are carried out on persons with social maladjustment and socially dangerous forms of behavior. Research by geneticists and psychologists plays an important role here. Note that in a word criminal (criminal, delinquent) behavior combines a wide range of deviant behavior options. This is a term that comes from criminology, and there are no clear criteria for its use in psychogenetics. A complex phenotype requires careful description and identification of individual components, taking into account which groups for research should be formed, otherwise the reliability of the results may rightfully be questioned. It is known, for example, that individuals with criminal tendencies are characterized by lower intelligence; Some temperamental and personality traits are more common among them than in the general population (hot temper, hyperactivity, aggressiveness, tendency to violence, stubbornness). It is known that heredity plays an important role in the variability of intelligence, temperament and many personality traits - perhaps the similarity of twins in crime is explained by the hereditary nature of these particular traits or the greater similarity of environments in MZ twins, since there is a phenomenon of genotype-environmental covariation. Most of the evidence on the inheritance of crime comes from family, twin, and stepchild studies. In addition to common genes, the similarity of close relatives is also influenced by the common environment. MZ twins share much more environmental conditions than DZ twins due to their genetic similarity (mutual friends, a tendency to do the same activities, spend time together, etc.). All this leads to an overestimation of the similarity of MZ twins, resulting from common environmental influences. One might speculate that twins' strong attachment to each other may contribute to their shared involvement in criminal activities. But reliable conclusions about the inheritance of aggressiveness and crime cannot be made based on the twin method. There are too many vulnerable points for criticism. And as for adopted children, for example, those whose mothers were convicted of felonies, prostitution, theft and other offenses. There is practically no information about fathers here. The children were adopted after their mothers were found guilty of crimes, and most spent more than 12 months in orphanages, making them over 1 year old at the time of adoption. It turned out that in the group of adopted children from criminal mothers, convictions and arrests are more common. Psychopathological conditions recorded during a psychiatric examination are also more common among them. The results indicate a significant influence of the environment on the manifestations of delinquent behavior. It should also be taken into account that the majority of children who subsequently committed crimes spent the first year of their lives in an orphanage, that is, in conditions that were not conducive to normal development.

Today there is evidence that The combination of crime and alcoholism in biological parents is an aggravating circumstance for the manifestation of criminal behavior in adopted children. As a rule, their crimes involve violence.

When discussing the question of whether crime is inherited, it should be remembered that all the research conducted in this direction is far from perfect. The phenotype itself is completely undefined. In modern research, it is not crime as such that is studied, but types of behavior, personality characteristics associated with crime, biological correlates of the tendency to aggressive behavior, etc. It would be a mistake to assume that the tendency to criminal behavior is inherent in genes - there is a lot of evidence that favorable development environment is capable compensate undesirable characteristics of temperament and personality, which can lead to the development of deviant and delinquent behavior. And, on the contrary, an unfavorable environment can aggravate the consequences of even minor developmental disorders, such as, for example, nonspecific learning disorders, and lead to severe social maladjustment and behavioral deviations.

We have already mentioned alcoholism - one of the most sad socially significant diseases. Its prevalence is extremely high. Excessive addiction to alcohol (alcohol dependence) is observed in 3–4% of people in the population. Male alcoholism is much more common than female alcoholism - this difference can be explained by both biological and social reasons, but so far such differences between the sexes do not have a satisfactory explanation (by the way, attempts are being made to find genetic reasons for the differences between male and female alcoholism). Studies of families, twins and adopted children indicate a familial pattern of alcoholism with a high level of heritability (50-60% for men; data on the heritability of female alcoholism are less numerous and somewhat contradictory). The hereditary nature of alcoholism makes it necessary to look for specific genes related to the disease. Among them, the most famous is the recessive allele of acetaldehyde dehydrogenase, a liver enzyme involved in the metabolism of alcohol. Homozygous individuals who have two copies of this allele experience unpleasant symptoms (flushing, nausea) after drinking alcohol and therefore are much less likely to develop alcoholism. In 1990, the dopamine receptor gene was discovered, which, as reported then, is related to alcoholism - the media rushed to report that it had been found alcoholism gene however, the results were subsequently not confirmed.

Genes for other chemical dependencies are also being searched. One important aspect of addiction research is the study of individual differences in response to psychotropic drugs.