Is schizophrenia inherited?

The tasks of psychiatry include the study of the etiology and pathogenesis, causes and conditions of the occurrence of mental disorders and, in particular, schizophrenia. The ability to recognize schizophrenia at an early stage, before a detailed picture of the psychopathological state (psychosis), is necessary for the timely provision of psychiatric care, as well as measures to prevent the negative impact of the disease on the quality of life in general, on the formation of distorted adaptation mechanisms to life in the family and in society. Thus, progress in studying the question of whether Is schizophrenia inherited?, helps to open up new opportunities for preventive treatment of the disease in the prodromal period, expanding its boundaries.

The clinical descriptive method today remains one of the leading methods for studying schizophrenia in fact. Its principles were outlined at the beginning of the last century by a domestic psychiatrist, a student of S.S. Korsakov and V.P. Serbsky, professor at Moscow University, A.B. Gannushkin. The principles of the method include identifying the characteristics of the patient’s personality, behavior in the environment and in relationships with other people, and compiling a life history. This approach is justified and is successfully used in the diagnostic and treatment practice of a psychiatrist. However, for obvious reasons, he does not pay sufficient attention to the factor of heredity in schizophrenia, which is important for identifying the prerequisites for the development of the disease in the period preceding the prodromal period.

In other words, in addition to the above principles of studying schizophrenia in fact, when a doctor deals with a specific patient with his own individual symptoms, interest in genetics and heredity is also important. The origins of the study of the genetic factor in domestic psychiatry were T.I. Yudin, founder of the genetics of mental illness, MD, professor, as well as D.S. Sarkisov, Doctor of Medical Sciences, Professor, Academician of the Russian Academy of Medical Sciences. The latter emphasized that changes at the molecular and subcellular level, as well as the influence of exogenous factors, indirectly affect regulatory mechanisms and the body as a whole. At the same time, the leading factor in the pathophysiology of schizophrenia, according to scientists, must still be considered disruption of the central nervous system, weakening of its epicritic function and the predominance of protopathic function.

Genetic factor and risk of developing schizophrenia

Since the beginning of the 21st century, geneticists have new, more accurate tools for diving into the human “code.” With their help, scientists test hypotheses about the likelihood of inheritance of schizophrenia. However, so far the gene or variation of genes responsible for heredity has not been discovered. To understand the scope of such research, you can familiarize yourself with the SZGene database, which contains more than 2,000 genes that can be tested for involvement in the inheritance of the disease. However, testing some of them in a genome-wide association study (GWAS) failed to establish a clear link between the candidate genes and schizophrenia.

In recent decades, there has been great interest in genetic research aimed at identifying the molecular causes responsible for the occurrence of schizophrenia. For example, among 6,429 scientific papers published on the website of The National Center for Biotechnology Information, 960 (15%) are devoted to the genetics of schizophrenia.

Genetic mutations in people with schizophrenia, compared to healthy people, are observed at the levels of:

chromosomal mutations;
point mutations in genes.

Chromosomal mutations in patients with schizophrenia include genomic aneuploidy and mosaic autosomal aneuploidy. These results obtained by domestic geneticists became the basis for the theory of chromosomal instability. Point mutations in genes are observed at the level of nucleotide replacement (single-nucleotide polymorphism) and copy number variations - replacement of pairs, genes, and their combinations. It is important to emphasize that genetic theories do not answer the question of whether schizophrenia is inherited, but only indicate the risk of the disease in carriers of chromosomal mutations and their children.

Genetic markers of schizophrenia are not absolute, since similar DNA changes are observed in genes responsible for various biological processes, for example: development of cells of the nervous system, neurotransmission, cellular respiration, transmission of nerve impulses. In addition, the putative genetic markers are found in only 1–5% of patients with schizophrenia.

Thus, genetic studies give reason to believe that heredity in schizophrenia is determined by deviations in the development of the body at various levels. A variety of variations in biopsychological abnormalities can cause the development of schizophrenia, but at the genetic level they are always heterogeneous and cannot be reduced to a single basis. Perhaps it is for this reason that various pictures of endogenous psychoses are encountered in clinical practice.

Rice. 1. Lifetime risk of developing schizophrenia

Heredity factors for epilepsy

Epilepsy is inherited only in the idiopathic form. In this case, recessive or dominant genes are transmitted from the mother or father. Often, such epilepsy occurs in childhood, and the frequency of seizures increases as one gets older. The Rolandic epilepsy gene stimulates the formation of a focus of the disease in the Rolandic sulcus of the brain. Transmission occurs through both women and men through one or more generations. There is a disorder of brain activity, pathological personality changes, mental disorders and neuropathy. In this case, the child can only be a carrier, but the disease will not be detected.

The second type of hereditary epilepsy is the juvenile myoclonic form, which is directly inherited, but is rare, since its formation requires both parents to act as carriers of this gene. But it can also be detected if one of the parents is healthy and the other is sick. This is the rarest type of epilepsy.

Genetic diseases are almost impossible to predict and are difficult to study. The principle of inheritance of epilepsy has not yet been established. It is clear that the possibility of transmission of the disease exists, but it is still not possible to understand how hereditary factors and epilepsy are connected, to form an exact mechanism of inheritance that takes into account all deviations and the influence of external conditions, and even more so to manage the disease.

Also, mental illnesses such as neuroses, psychoses, psychopathy, alcohol and drug addiction, affective disorders, autism, hypochondria, various manias, delusions, dementia, Alzheimer's disease and a number of others are inherited.

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The likelihood of inheriting schizophrenia

To date, genetic research and clinical practice do not provide any basis for a positive answer to the question of whether schizophrenia is inherited. In most cases, schizophrenia is diagnosed in people who have healthy parents and do not have people with mental disorders in their family tree. In addition, Mendel's laws (in particular, the transfer of genetic information from parents to children) do not work in terms of predicting the inheritance of the disease, even in cases where both parents have schizophrenia.

The number of people with schizophrenia from the entire population does not exceed 1%. According to a large Swedish study published in 2013 in the journal JAMA Psychiatry, those who were able to start a family have children - 1/4 of families where the father has schizophrenia, 1/2 of families where the mother has schizophrenia. In particular, it is associated with low fertility in men with schizophrenia and frequent miscarriages or stillbirths in women with schizophrenia. The results of the study correlate with the data obtained by domestic scientists (R.A. Nadzharov, A.V. Snezhnevsky - the following are the figures of this study), published in 1983.

Possibility of transmitting schizophrenia from father

The probability of inheriting schizophrenia from father to child does not exceed 3.1%. If there are two children in such families, unfavorable heredity is more likely to affect male children. Girls, as a rule, may be predisposed to the disease if they have a brother in the family.

The risk of developing schizophrenia in a child in families where the father is ill:

2 sisters - tends to 0%;
2 brothers - no more than 6.4%;
brother and sister - 1.8% for sister, 5.1% for brother.

Rice. 2. The likelihood of transmitting schizophrenia from the father

Possibility of maternal transmission of schizophrenia

The probability of inheriting schizophrenia from mother to child does not exceed 14.8%. If such a family has two children, then the risk of a hereditary factor increases if there are two female children. However, boys in such families still have a greater predisposition to the disease compared to families where the father has schizophrenia.

The risk of developing schizophrenia in a child in families where the mother is ill:

2 sisters - tends to 17.8%;
2 brothers - no more than 11.1%;
brother and sister - 16.3% for sister, 7.4% for brother.

Rice. 3. The likelihood of transmission of schizophrenia from the mother

Chances of transmitting schizophrenia if both parents are sick

If both parents in a family have schizophrenia, the risk of inheriting the disease tends to be 15%. However, it is necessary to understand that these figures vary from study to study (the limit value is 45%) and in most cases the likelihood of transmitting the disease, even seemingly due to such aggravating heredity, is still doubtful.

Mental disorders that are inherited

Their occurrence cannot always be predicted. A child whose parents had similar disorders does not necessarily have to be born unhealthy - he can only have a tendency that will remain “unrealized” for the rest of his life.

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The list of hereditary mental illnesses is as follows:

depression - a person is constantly in a depressed mood, feels despair, his self-esteem becomes lower, and he is not interested in the people around him, loses the ability to rejoice and experience happiness;
schizophrenia – deviations in behavior, movements, thinking, emotional and other areas;
autism – occurs in young children (under 3 years of age), manifests itself in disturbances and delays in social formation, abnormal reactions to the outside world and monotonous behavior;
epilepsy – characterized by seizures of a sudden nature.

Note 1

The genetic aspect also plays a significant role in the occurrence of manic and affective disorders.

Pathological heredity, which a child acquires from his parents, is considered the leading condition in the emergence of mental illnesses. It is not the disease itself that is inherited, but changes in the “substrate” of heredity – the DNA molecule, and there is a predisposition to a certain type of disease, which develops through the interaction of hereditary factors and environmental conditions.

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Risk of schizophrenia in children of healthy parents

In recent decades, researchers in the field of genetics of mental disorders have come to the conclusion that the hereditary factor is not the leading one. Therefore, it is impossible to answer the question of whether schizophrenia is inherited using only a genetic factor, without taking into account many others that determine the results of related studies. In particular, the probability of developing schizophrenia in a child in families where both parents are not burdened with severe mental disorders is 5–7% (E. Zerbin-Rudin, 1967; V.M. Gindilis, 1979).

Due to the fact that healthy parents may give birth to a child with a predisposition to schizophrenia, there is interest in research emphasizing the relationship between the risk of developing a mental disorder and external, exogenous factors - family income level, social status, type of settlement and character of the area, accessibility medical care (in particular during childbirth) and education, social environment, level of cultural development.

Rice. 4. Biopsychosocial model of schizophrenia development

Developed and developing countries

Studies attempting to identify patterns in cases of schizophrenia in developed and developing countries have not yielded clear results, although there is a tendency for the number of hospitalizations to increase in developed countries. Locally, this % increases due to the migration factor - adaptation features, difficult living conditions and social isolation, including life on the “periphery” (Crocetti, 1971; Torrey, 1984; Nuallain, 1987).

Place of residence

Living in cities is associated with a high risk of TBI, intoxication, and adverse effects on the human body. Some cities are affected by hazardous enterprises and have high levels of gas pollution. Living in such an environment differs from life in the countryside - with clean air, water and farm-quality food, outside the acoustic “background” of the city (urban residents get used to it, stop noticing its negative impact), without stress, without artificial tension in the information field .

Pregnancy and childbirth

The connection between the risk of developing schizophrenia in the fetus and the seasonality of childbirth is also reflected in many scientific publications devoted to this topic. These studies highlight the fact that late winter and spring births predominate among patients with schizophrenia (Eaton, 1988). Among the hypotheses explaining the seasonal factor are the following:

seasonal endocrine effect (Hafner, 1990);
high percentage of older women giving birth (Dalen, 1990);
the influence of environmental temperature on gestation and childbirth (Pasamanick, 1986; Kendell, Adams, 1991);
previous FLU, other seasonal diseases (Watson, 1984; Torrey, 1988; Barr, 1990);
the influence of medications taken during pregnancy (Beiser, Iacono, 1990).

Family income level

The socioeconomic factor that determines the risk of developing schizophrenia is associated with belonging to low-income, poorly educated and marginal groups (Faris and Dunham, 1939; Schroeder, 1942; Gardner and Babigian, 1966; Giggs and Cooper, 1987). In such families, children have to deal with “real life” much earlier than their peers, for example, endure psychological and often physical violence, observe pathological relationships between father and mother.

There are several theories explaining the pathological influence of the “social environment” and low income:

theory of social drift - schizophrenia leads a person to socio-economic collapse;
social stress theory - stress inherent in low-income people leads to the development of schizophrenia;
neuroontogenetic theory - diseases and other harmful factors that accompany the life of immigrants and marginalized sections of the population create the preconditions for the development of schizophrenia.

Children born into such families usually do not have the opportunity to get an education, advance up the career ladder, or reach a higher socio-economic standard of living. However, the increasing level of unemployment and other socio-economic shocks can affect society as a whole, therefore, in times of crisis, an increase in the number of cases of schizophrenia is observed not only in low-income and vulnerable sections of the population.

Psychotraumatic events and stress

It is traumatic events that in most cases lead to the development of schizophrenia, and not the amount of stress that accumulates over a long period of time (Brown, Birley, 1986; Norman, Malla, 1993). One of the major WHO studies (Study on the determinants of outcome of severe mental disorder, 1987) emphasizes the dominant role of severe traumatic events 2–3 weeks before the development of signs of an acute psychotic state.

Immigration

Immigration is always a big stress. And if adults come to such a decision, as a rule, consciously, thinking through the move, then children find themselves truly unprotected in the face of unexpected changes in life. Unfortunately, the psychological preparation of children only partially smoothes out the immigration process, not allowing the child to fully ensure a comfortable transition. It should be noted here that a larger number of cases of schizophrenia is characteristic of the second generation of immigrants (Harrison, 1988).

Family (schizophrenogenic mother)

The concept of a family where parents create conditions under which a child develops schizophrenia is not new. The hypothesis was expressed by Freud and subsequently developed in the works of prominent psychiatrists, for example, the famous clinician F. Fromm-Reichmann (1948), B. Suran and D. Rizzo (1979). The key figure in such a family is the schizophrenogenic, or schizogenic, mother:

despotic, domineering woman;
shows hyperprotection over the child;
does not allow the child’s personality to develop;
rejects the child emotionally;
provokes anxiety and fears in the child;
does not allow the child to express “I”.

The father in such a family plays a secondary role; he is not involved in raising children and does not have the “right to vote.” A child in such a family finds himself in a situation where his personality has been suppressed since childhood. Against the background of pathological overprotection, the formation of natural adaptation mechanisms is disrupted, the development of the emotional-volitional sphere and, as a consequence, the personality with its inherent individual characteristics is blocked.

Ultimately, such a person turns out to be incapable of independent life in society and does not have healthy skills for creating and living in his own family. His “I,” suppressed over decades of life under the control of a schizophrenogenic mother, structures an irrational “adaptation” picture of the world (an analogue of the second “I”), including fears and, accordingly, prerequisites for the development of a psychotic state. As a rule, such people live under the care (for example, of parents or spouses, if they manage to start a family) and leaving the comfort zone, which involves a conflict between the pathological picture of the world and real life, can provoke the development of schizophrenia.

In 1992, the results of a prospective field study of five populations were obtained (AY Tien, WW Eaton), which refute the common belief that 1% of people with schizophrenia in the population. In other words, outside of clinical statistics, the percentage of patients with schizophrenia varies from 0.24 to 7.1% per 1000 people, depending on the region. This percentage includes people with a socially acceptable form of the disease, “adapted” to life in society, and who have not turned to a psychiatrist for help.

Schizophrenia

18638 May 13

IMPORTANT!

The information in this section cannot be used for self-diagnosis and self-treatment.
In case of pain or other exacerbation of the disease, diagnostic tests should be prescribed only by the attending physician. To make a diagnosis and properly prescribe treatment, you should contact your doctor. Schizophrenia: causes, symptoms, diagnosis and treatment methods.

Definition

Schizophrenia is one of the most common mental disorders, characterized by a combination of productive (hallucinatory, delusional, catatonic, affective, etc.) and negative (apathy, abulia, alogia, emotional and social withdrawal, etc.) symptoms, behavioral and cognitive disorders (memory disorders , attention, thinking, etc.).

More than 20 million people suffer from schizophrenia worldwide.
Causes of schizophrenia The
leading causes of schizophrenia include heredity, unfavorable environment and social living conditions.

The risk of developing schizophrenia in children, one of whose parents suffers from this disease, is 7–13%, and if both parents are sick, then 27–46%. In each subsequent generation, the risk decreases. Men and women develop schizophrenia equally often, but in men the disease usually appears earlier - at the age of 18-25 years, while in women - at 25-30 years.

Environmental factors are important in the development of schizophrenia - scientists have found that urban residents are diagnosed with the disease more often than rural residents. There is a risk of this mental disorder among migrants. Obstetric and gynecological complications (premature birth, fetal hypoxia), infectious diseases and malnutrition of the mother in the first and early second trimester of pregnancy, infectious diseases during pregnancy (influenza, rubella, toxoplasmosis, herpes), as well as early childhood psychological trauma can also cause schizophrenia.

Many scientists are of the opinion that schizophrenia develops as a result of a disorder in the metabolism of neurotransmitters, in particular dopamine, in the brain. Neurotransmitters are biologically active substances that are produced by nerve cells (neurons) and transmit information from neuron to neuron and to other cells.

Classification of the disease

The International Classification of Diseases (ICD-10) identifies several forms of schizophrenia:

paranoid (F20.0),
hebephrenic, or hebephrenic (F20.1),
catatonic (F20.2),
undifferentiated (F20.3),
post-schizophrenic depression (F20.4)
residual schizophrenia (F20.5)
simple (F20.6).

In addition, schizophrenia is divided according to the type of course: first episode, episodic course, episodic course with an increasing defect, low-progressive course, etc.
In the clinical picture of schizophrenia, separate symptom complexes are distinguished:

positive symptoms
negative symptoms
disorganization of speech and thinking,
affective symptoms,
cognitive impairment,
catatonic symptoms, etc.

Symptoms of schizophrenia
The most active period of the disease is the first 5 years after the first psychotic episode.

Before the development of an acute psychotic episode, the patient may experience so-called prodromal phenomena (harbingers) for weeks, months or even years. The patient loses interest in work, social activities, his appearance, and hygienic habits; cognitive impairment occurs (impaired thinking, attention, memory, speech), and changes in motor skills. Perceptual disturbances, unexplained anxiety, and mild depression may occur.

In 75% of patients, the prodromal period lasts more than 5 years.
The paranoid form of schizophrenia
is characterized by severe hallucinations and/or delusions. The patient may hear various sounds, hallucinatory voices of a threatening or imperative nature (when a voice orders a person to do something), feel non-existent smells, tastes, sexual or other bodily sensations. In the paranoid form of schizophrenia, delusions may arise - a system of false beliefs built on erroneous, illogical conclusions. A person may suffer from delusions of persecution (to be sure that he is being listened to or being plotted), he may have delusions of influence (the patient thinks that he is being influenced by some devices, energies, hypnosis) or delusions of relation (when everything that happens around him is a sign or a hint), or delusions of grandeur (the patient is sure that he has extraordinary abilities, considers himself a famous person). In addition, there are delusions of meaning, high origin, special purpose, bodily changes, guilt, jealousy, etc.

Hebephrenic form of schizophrenia

usually appears in adolescence or young adulthood. This form of the disease is accompanied by pronounced and prolonged emotional flatness - the patient’s strength of experienced emotions decreases (patients note that they cannot be happy or upset, they become indifferent), they lose the ability to understand the emotions of other people, their facial expressions lose expressiveness. There is also emotional inadequacy - a person can rejoice at sad events and be upset about joyful ones. The behavior of a patient with the hebephrenic form of schizophrenia is characterized by foolishness, there are thought disorders in the form of broken speech (schizophasia) - when there is no semantic connection between words and sentences, sentences are not grammatically consistent, words and terms are used inappropriately.

In the hebephrenic form, hallucinations and delusions may be present, but they do not predominate in the clinical picture.

In
the catatonic form of schizophrenia,
the patient experiences alternating stupor and agitation. A person can freeze in one position, even a completely uncomfortable one, without reacting to external stimuli and without speaking. The patient retains consciousness, then he can talk about what happened, but at the moment of stupor he does not move, does not speak, does not perceive other people’s speech, does not eat or drink. With catatonic excitement, a person commits stereotypical aggressive actions, aimlessly destroying everything around him, so in order to avoid injury, he has to be tied up.

Both during the period of stupor and during the period of excitement, the patient may experience oneiric syndrome - fantastic visions with himself in the leading role.

In addition, with the catatonic form of the disease, negativism (a person perceives negatively everything that is offered), mutism (silence), obedience (automatic execution of instructions), stereotypy (automatically performs the same action over a significant period of time), echolalia (repetition heard words, phrases), Pavlov's symptom (reaction only to requests spoken in a whisper), etc.

For undifferentiated schizophrenia

symptoms are either insufficient to identify another form of schizophrenia or, conversely, so many that criteria for more than one form of the disease are identified.

With a simple form

There is a slow (over a year or more) development of three signs:

a distinct change in personality, which is manifested by loss of drives and interests, inactivity and aimless behavior, self-absorption and social withdrawal;
deepening of symptoms such as apathy, impoverished speech, hypoactivity, emotional flatness, passivity and lack of initiative, poverty of non-verbal communication (so-called negative symptoms),
a distinct decrease in social, educational or professional productivity.

In the residual or residual form of schizophrenia,
there is a transition from the active course of the process (psychotic episodes with a predominance of productive symptoms) to the chronic stage with persistent negative symptoms - psychomotor retardation, reduced activity, emotional flatness, passivity and lack of initiative; poor speech and non-verbal communications; lack of self-care skills and social productivity.

Diagnosis of schizophrenia

In making a diagnosis, communication with the patient and, if possible, his relatives plays an important role. In addition to complaints, family history, age at which symptoms appeared, the patient’s marital status, his social status, etc. are analyzed.

To make a diagnosis and establish the form of the disease, psychiatrists use special criteria by which they evaluate the presence of positive and negative symptoms, catatonic disorders, and changes in the patient’s behavior.

In some cases, people with suspected schizophrenia, to exclude an organic cause of psychotic disorders, are recommended to consult a neurologist and conduct laboratory tests to exclude other pathologies:

general blood analysis;

List of used literature

1. Tiganov A.S. "Manual of Psychiatry in 2 volumes."

2. Tiganov A.S. "Endogenous mental illnesses."

3. Gannushkin P.B. "Selected Works".

4. Snezhnevsky A.V. "Schizophrenia, a multidisciplinary study."

5. Reznik A.M., Kostyuk G.P., Khannanova A.N. “Problems of the preconditions of schizophrenia according to molecular genetic studies.”

6. Kolesnichenko E.V., Barylnik Yu.B., Golimbet V.E. "The influence of the BDNF gene on the phenotypic expression of paranoid schizophrenia."

7. Cardno AG, Gottesman II “Twin studies of schizophrenia: from bowand-arrow concordances to star wars Mx and functional genomics.”

8. Need AC, Goldstein DB “Next generation disparities in human genomics: concerns and remedies.”

9. Sullivan PF, Kendler KS, Neale MC “Schizophrenia as a complex trait: evidence from a meta-analysis of twin studies.”

10. Power RA, Kyaga S., Uher R. “Fecundity of patients with schizophrenia, autism, bipolar disorder, depression, anorexia nervosa, or substance abuse vs their unaffected siblings.”

11. Nadzharov R.A., Snezhnevsky A.V. "The risk of manifestation and clinical features of schizophrenia depending on the gender of parents and children."

12. Warner R., Giovanni de Girolamo. "Schizophrenia".

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