Oligophrenia. Etiology and pathogenesis of oligophrenia The main etiological factors in the occurrence of oligophrenia

2. Etiology of oligophrenia

The etiology of oligophrenia is diverse. According to G. Allen and J. D. Murken, various forms of mental retardation with a clearly established etiology (the so-called differentiated forms) account for about 35%. In contrast, oligophrenia with an unclear etiology is designated as "undifferentiated", or "idiopathic".

All etiological factors of oligophrenia are usually divided into endogenous-hereditary and caused by exogenous (organic and social-environmental) influences. Along with predominantly hereditary or exogenous forms of oligophrenia in clinical practice, there are often cases in which the role of hereditary and exogenous factors appears in a complex interaction.

The significantly higher concordance (up to 90%) for oligophrenia among monozygotic twins compared with dizygotic twins (about 40%) convincingly testifies to the significant role of the hereditary factor in the etiology of oligophrenia. The hereditary factors contributing to the development of mental retardation are heterogeneous, just as the clinical manifestations of the diseases they cause are heterogeneous. A certain pattern has been established, which consists in the fact that deep degrees of mental retardation are more often observed with a recessive type of inheritance, while in oligophrenia with a shallow defect, dominant and polygenic hereditary factors play a decisive role. Most autosomal recessive forms of mental retardation are metabolic diseases, in the pathogenesis of which metabolic disorders (protein, fat, carbohydrate, etc.) play a major role.

Recessively inherited forms of mental retardation include such diseases as phenylketonuria, galactosemia, gargoylism, Cornelia de Lange syndrome, etc. Dominantly inherited forms of oligophrenia are characterized by relatively less profound mental underdevelopment, since the mutant gene manifests itself in a heterozygous state and its action is controlled to a certain extent and is compensated by a full-fledged allele. In this case, half of the children in the family and one of the parents are sick.

Along with inherited recessive and dominant types, polygenically conditioned forms of oligophrenia are also distinguished. The results of studies by B. A. Ledenev, G. S. Marinicheva, V. F. Shalimov, J. Roberts and others give grounds to classify mild cases of intellectual underdevelopment in children from those families in which parents in childhood had a shallow mental retardation or low subclinical level of intellectual development, well compensated with age.

Chromosomal pathology is of great importance in the etiology of oligophrenia. It is known that under certain, unfavorable environmental conditions, chromosome damage occurs, which leads to the appearance of zygotes with abnormal chromosome complexes. A numerical or structural change in the human chromosomal complex relatively often causes oligophrenia. The causes of chromosomal mutations are still poorly understood. There are indications in the literature that ionizing radiation, many chemical toxic substances, some drugs, endogenous metabolic disorders, aging of the body, viral infections and other environmental factors have mutagenic properties.

Another group of etiological factors of oligophrenia are exogenous hazards, either acting on the developing fetus through the mother's body during pregnancy, or damaging the child's brain in the first years of postnatal life. A certain importance in the genesis of brain underdevelopment and congenital dementia is given to intranatal hypoxia and birth trauma. Severe chronic diseases of the mother during pregnancy, such as cardiovascular insufficiency, blood diseases, kidney diseases, endocrinopathies, etc., can lead to oxygen starvation and impaired fetal development.

Among the pathogenic factors that can lead to brain development disorders in the prenatal period of development, an important place belongs to infections. The pathogenic effect of maternal infectious diseases on the fetus is associated with the possibility of penetration of microbes and viruses through the placenta into the bloodstream of the fetus, which has been proven by a number of studies. The most dangerous for the fetus are viral infections (measles rubella, influenza, infectious hepatitis, listeriosis, cytomegaly, etc.), which have a selective neurotropic effect. There are numerous data on the role of toxoplasmosis in the occurrence of mental retardation. However, V. V. Kvirikadze and I. A. Yurkova emphasize the need to carefully evaluate the role of toxoplasmosis in the etiology of oligophrenia. Syphilis of parents can also be one of its causes.

In the genesis of oligophrenia, some drugs taken by the mother during pregnancy (antibiotics, sulfa drugs, barbiturates, etc.), as well as fetal drugs, can play a role. A. P. Belkina found that the effects of quinine on pregnant animals often lead to the appearance of anencephaly and microcephaly in offspring. In the 60s, Y. Pliers, W. Lenz and other authors drew attention to the fact that the sedative and hypnotic drug “contergan” (thalidomide) released in 1958 caused focomelin, which in most cases was combined with intellectual disability.

A certain role in the origin of oligophrenia is assigned to chronic alcoholism of parents. However, this point of view is not generally accepted. A. Roc showed that two groups of children (from alcoholics and healthy parents) did not differ from each other in terms of the level of intellectual development. L. Penrose emphasizes that in order to damage human hepsrative cells, the concentration of alcohol in the blood must be very high; in reality, such a concentration is never achieved. At the same time, the toxic effect on the fetus of alcohol consumed by the mother during pregnancy is not excluded.

In the postnatal period, neuroinfections (meningitis, encephalitis, meningoencephalitis), dystrophic diseases, severe intoxication, craniocerebral trauma, as well as other hazards suffered in the first years of life, which can cause brain damage and abnormalities of its development, often act as etiological factors for oligophrenia. .

Exogenous factors contributing to the occurrence of oligophrenia also include the immunological incompatibility of the blood of the mother and fetus in terms of the Rh factor and ABO factors.

In foreign literature, the etiological role of cultural and social factors in the occurrence of mental retardation is widely discussed. The fact that sociocultural deprivation, especially in the first years of a child's life, can lead to mental development disorders is beyond doubt. This point of view is confirmed by those rare cases when children are brought up outside of human society ("Mowgli children"). However, the problem of the so-called socio-cultural mental retardation has a lot of controversial and unclear. The American Association for Mental Insufficiency points out that socioculturally determined mental retardation can only be diagnosed when there is no clinical or anamnestic evidence that points to an organic cause of mental disability. Based on these ideas, it is practically impossible to diagnose socio-cultural mental retardation, since there are almost no children who do not suffer from somatic diseases. In addition, the widespread use of the concept of socially conditioned mental retardation is the source of classifying a significant number of children from low-income strata of society with a low cultural level as intellectually handicapped. In domestic psychiatry, factors of social deprivation are more often considered as one of the conditions that can have an additional influence on the formation of oligophrenia. At the same time, sociocultural deprivation can be the cause of one of the variants of borderline intellectual insufficiency in the so-called microsocial-pedagogical neglect (V.V. Kovalev).

Thus, the etiology of oligophrenia is extremely diverse. Mental underdevelopment can be caused by a number of hereditary, exogenous-organic and micro-socio-environmental factors. In some cases, the disease occurs as a result of the influence of one of these factors, in others - as a result of a complex interaction of many pathogenic hazards. The establishment of the main etiological factor in each case is important for the correct treatment and prevention of various forms of mental retardation.

The pathogenesis of various forms of oligophrenia is not the same, but there are also common pathogenetic mechanisms. A particularly important role among them belongs to the so-called time factor, or chronogenic factor, that is, the period of ontogeny in which the developing brain is affected. Various pathogenic factors, both genetic and exogenous, acting in the same period of ontogenesis, can cause the same type of changes in the brain, which are characterized by identical or similar clinical manifestations, while the same etiological factor, acting at different stages ontogenesis, can lead to various consequences. The nature of the response reactions of the brain largely depends on the level of morphological and functional development and maturity of the organism and may be typical for each ontogenetic period.

The severity of clinical manifestations of oligophrenia varies considerably with brain lesions in the early or late prenatal, natal or postnatal periods of ontogenesis. Damage during the period of blastogenesis can cause the death of the germ or lead to a gross violation of the development of the whole organism or many organs and systems. During the period of embryonic development, characterized by intensive organogenesis, pathogenic factors cause malformations not only of the brain, but also of other organs, especially those that are in a critical stage of development. Multiple anomalies and dysplasias that occur during embryogenesis are mostly nonspecific due to immature mechanisms of embryonic reactivity. Under the action of exogenous factors in this period, congenital anomalies and dysplasias arise, similar to genetic dysmorphias and representing phenocopies of the latter. However, the pathogenesis of embryopathies caused by chromosomal aberrations is more complex. In these forms, along with nonspecific symptoms that are noted in embryopathies of any origin, specific morphological and biochemical disorders are also detected due to changes in the genotype, which lead to impaired synthesis of enzymes and proteins of the developing organism.

In the second half of pregnancy (the stage of fetogenesis), when the laying of organs is basically completed and differentiation and integration of functional systems are intensively occurring, gross developmental anomalies and dysplasia do not occur, and developmental disorders often manifest themselves in functional disorders. An exception is the brain, in which in this period the formation of its most complex structures takes place, and changes can be not only functional, but also morphological. In the second half, especially towards the end of pregnancy, due to the development of differentiated innervation and vascularization of the central nervous system of the fetus, as well as the maturation of immunological systems and the improvement of other adaptive mechanisms in response to the action of pathogenic factors, local reactions of the fetus may occur. It becomes possible the appearance of local inflammatory processes, focal necrosis, cicatricial changes and other limited lesions of the brain and meninges. In the fetal period, the tropism of many pathogenic agents for certain brain structures begins to appear. Therefore, anomalies in the development of the brain that occur in late pregnancy may be characterized by uneven lesions and more pronounced underdevelopment of the most late-forming brain structures, such as the structures of the frontal and parietal cortex. Clinically, this manifests itself in the unevenness of the intellectual defect, in the presence of a variety of concomitant psychopathological disorders (psychopathic, cerebrasthenic, etc.) characteristic of the so-called complicated and atypical oligophrenia.

In the last stages of pregnancy and in the perinatal period, due to the increased sensitivity of mature neurons to oxygen starvation, hypoxia is a common common pathogenetic factor. With the consequences of hypoxia, signs of underdevelopment of the brain systems give way to disturbances in the processes of myelination and the development of the capillary network of blood vessels and the brain. Severe intrauterine hypoxia, fetal intoxication, asphyxia during childbirth, as well as mechanical birth trauma, can lead to intracerebral hemorrhage. In more severe cases, not only the cortex is affected, but also the subcortical ganglia. Various encephalitis and meningitis transferred in utero or in the postnatal period also lead in some cases to focal lesions of the brain. However, even minor limited morphological lesions in the prenatal and postnatal periods may be accompanied by a delay in the development of the entire brain and, first of all, the cortex as the youngest area in evolutionary terms, the processes of specialization and differentiation of which continue into the first years of a child's life. With a violation of the development of the most complex cerebral structures of the cortex, especially its frontal and parietal sections, the lack of analytical and synthetic functions characteristic of oligophrenia is predominantly associated.

Exogenous factors contributing to the occurrence of oligophrenia also include the immunological incompatibility of the blood of the mother and fetus in terms of the Rh factor and ABO factors.

The severity of clinical manifestations of oligophrenia varies considerably with brain lesions in the early or late prenatal, natal or postnatal periods of ontogenesis. Damage during the period of blastogenesis can cause the death of the germ or lead to a gross violation of the development of the whole organism or many organs and systems. During the period of embryonic development, characterized by intensive organogenesis, pathogenic factors cause malformations not only of the brain, but also of other organs, especially those that are in a critical stage of development. Multiple anomalies and dysplasias that occur in embryogenesis, more partly non-specific due to immature mechanisms of reactivity of the embryo. Under the action of exogenous factors in this period, congenital anomalies and dysplasias arise, similar to genetic dysmorphias and representing phenocopies of the latter. However, the pathogenesis of embryopathies caused by chromosomal aberrations is more complex. In these forms, along with nonspecific symptoms that are noted in embryopathies of any origin, specific morphological and biochemical disorders are also detected due to changes in the genotype, which lead to impaired synthesis of enzymes and proteins of the developing organism.

Oligophrenia (from the Greek oligos - baby, phren - mind) is a special form of mental underdevelopment, expressed in a persistent decrease in cognitive activity in children due to physical damage to the cerebral cortex in the perinatal (intrauterine) and early postnatal (up to 2-3 years) periods.

Signs of oligophrenia are:

1) durability;

2) irreversibility;

3) organic origin of the defect;

4) non-progressive (not progressive).

The pathogenesis of various forms of oligophrenia is not the same, but there are common mechanisms.

An important role is played by the course of the period of ontogenesis, during which the developing brain of the child is damaged.

Various pathogenic factors, both endogenous, exogenous, and mixed, can cause changes even in infancy. Throughout the first year of a child's life, a tendency to the progression of dementia is found, after 3-7 years the condition stabilizes.

Homodistainuria associated with impaired methionine metabolism, inherited in a recessive manner, manifested by convulsions, muscle weakness, and sometimes increased readiness for muscle spasms. There is a delay in psychomotor development. There are changes in the eyes. These include cataracts, retinal degeneration, ectopia of the lens, etc. The skin around the eyes is reddened.

Galactosemia, fructosuria, sucrose are inherited in a recessive manner. Children have malnutrition, diarrhea and other severe somatic disorders that lead to death. Mental underdevelopment is strongly expressed, accompanied by lethargy, convulsions.

Morfan's syndrome- a disease caused by a violation of the exchange of polysaccharides. The basis of this hereditary disease is a systemic lesion of the connective tissue. This disease is equally common in both men and women. Symptoms appear from birth. These include:

1) anomalies in the development of the eyes;

2) anomalies in the development of the musculoskeletal system;

3) developmental anomalies, from the side of the cardiovascular system.

With this disease, not all children have an intellectual defect. For many, mental development corresponds to the age norm.

Gargoylism- a hereditary disease caused by a metabolic disorder involved in the formation of connective tissue. This disease is more common in men than in women. Clinical manifestations become noticeable in the first month of a child's life. These include an increase in the size of the skull, deformation of the auricles, deformation of the chest, thick short fingers, a wide palm, joints are affected. Mental development is sharply delayed, the deficiency of intellect increases with the passage of time, quite often the defect in intellectual development reaches the degree of idiocy.

Lawrence Syndrome- oligophrenia associated with dysfunction of the hypothalamus. With this disease, signs of disorders of fat and protein metabolism are manifested. Vegetative and endocrine changes appear. Mental defect ranges from mild oligophrenia to idiocy.

Oligophrenia- congenital or acquired in early childhood (up to 3 years) u / o, which arose as a result of an organic lesion of the GM and which manifests itself in the underdevelopment of all mental functions (totality) and mainly their higher levels (hierarchy) with special underdevelopment abstract thinking, which leads to a persistent violation of cognitive activity, underdevelopment of the personality as a whole and to social maladaptation. signs: Congenital (genetically caused by intrauterine trauma) / Acquired before the age of 3 (because phrasal speech is formed). Underdevelopment of all mental functions (total retardation). Oligophrenia is a combined group of pathological conditions that are different in etiology, pathogenesis, and hence the clinical and morphological picture, the course of which is characterized by non-progression (not accompanied by an increase in the intel defect). The disease proceeds according to general biological laws, but on a defective basis.

12. The prevalence of oligophrenia

Prevalence - epidemiology. Oligophrenia as a biological phenomenon is distributed relatively evenly. According to WHO - 1-3% of the population. Boys are more often affected. ¾ All oligophrenics - mild degree. Factors affecting the prevalence: ecology (BUT adaptation, immunity, evolution of the body), heredity, health status (BUT premature babies survive => risk group), lifestyle, diagnostic status (BUT improved diagnosis leads not only to an increase in the number of but also healthy children).

13. Etiology and pathogenesis of oligophrenia

Very polymorphic and varied. There are: differentiated forms of oligophrenia - those forms where the etiology is precisely known, undifferentiated forms - the etiology is unknown + atypical forms of oligophrenia. 50% of pathologies are wrong lifestyle, 15-20% - unfavorable ecology, 15-20% - unfavorable heredity. Endogenous factors(hereditary conditions): Disorders associated with a change in the number or structure of chromosomes (breakage of X chromosomes, translocation, deletion, inversion, chromosomal mosaic ...)<= спонтанные мутации, индуцированные мутации <= Физич факторы: любой вид излучения (ионизирующие излучения); хим факторы (мутагены): лекарств средства; биологич факторы: угнетение репродуктив ф-ии женщин, вирусы…Exogenous factors(social-environmental): infections (viral: most contactogeous - more quickly transmitted to the fetus, stronger impact - measles rubella, mumps, cytomegalovirus, hepatitis, influenza; bacterial; protozoa: pale spirocheda => syphilis, toxoplasmosis => toxoplasmosis, listerella => listeriosis ) - the influence of the teratogenic factor on the degree of fetal deformity. Intoxication (poisoning - all those harmful substances that the cat enters the child's body with mother's milk). Injuries (hm: difficult diagnosis; generic: narrow pelvis, umbilical cord around the fetus => bending oxygen access => asphyxia - suffocation<= неправильное положение плода; затяжные роды; стремительные роды =>barotrauma - pressure) + hormonal disorders - more often the thyroid gland + in some cases mental trauma (d. b. a differentiated approach, since not all injuries lead to oligophrenia). The most vulnerable age is the prenatal period (75% of oligophrenia). Taking into account the various mechanisms of oligophrenic dementia in various clinical forms, it is customary to single out pathogenetic mechanisms common to all clinical forms. The main role is the defeat of the central nervous system. Various pathogenic factors (genetic and exogenous), acting in the same period of ontogenesis, can cause the same type of changes in the brain and will be characterized by similar clinical manifestations. On the other hand, the same pathogenic factor, acting at different stages of ontogenesis, leads to different changes in the GM. If the path factor affects the 1st half of pregnancy, congenital malformations of various organs and their systems are possible (congenital malformations of the heart, great vessels, kidneys, liver, gastrointestinal tract, skeleton, etc.) + pronounced lesions of the central nervous system. If the path factor is in the 2nd half of pregnancy, there are no gross malformations from the internal systems and organs (maybe only functional disorders). The most pronounced disorders - from the side of the central nervous system Clinical manifestations of oligophenia in different age periods: General: behavior - lethargy, drowsiness, indifference to the environment, violation of the formation of the revitalization complex, late reaction to any stimulus. 2-3 years: difficulties in mastering self-service skills, elementary manipulation of objects, primitive play activity (including non-play objects), children do not show interest in the environment, contact with peers is difficult, they are curious, but not inquisitive. Preschool age: increased ability to copy and imitate, a tendency to non-purposeful noisy and active games, difficulties in mastering school skills. Feeling: formed slowly, not enough. Lagging behind in the formation and inferiority of hearing, seeing and moving reflexes => destroying and distorting orientation in the external environment, establishing the attitude of m / y with phenomena and objects. Perception: characterized by insufficient activity => earthiness, inaccuracy and globality. Involuntary attention, easily distracted and unsteady. distorted cognitive system.Attractions: not able to control them - bulimia, hypersexuality, struggle of motives, escapes, departures ... Memory: reduced all types of memory, hypomnesia, fur memory, m.b. electoral. Emotions- direct experiences prevail, lower emotions are preserved, higher ones are underdeveloped or defective. More disturbing intellect than emotion. Speech- speech development delay, all aspects of speech suffer, a poor vocabulary stock, a large discrepancy between the m / y active and passive vocabulary, speech is poor, stereotyped, stamped, non-expanded, simple expressions, adjectives, conjunctions and prepositions are poorly used, verbs are poorly understood. Underdevelopment f-th motor Disinhibition, poor coordination, clumsiness. Thinking: no ability to abstract, only concretization. Does not understand the hidden meaning, sensory cognition suffers, but judgments are adequate (good or bad, but does not know why). There is no logical thinking, it is not possible to develop new or change old algorithms of actions. Rigid thinking, incapable of establishing cause and effect. connections. Underdevelopment personalities: increased self-esteem, mental infantilism Type temperament: excitable, erective, inability to retain information in memory + impulse drive manifestations / inhibited type of temperament - lethargy, reduced activity, urges, performance, increased fatigue.

Oligophrenia (synonym: dementia, mental underdevelopment) is a group of morbid conditions characterized by an intellectual defect congenital or acquired in early childhood, which does not increase throughout subsequent life. With oligophrenia, deviations are also observed in physical development: growth retardation, abnormal physique, internal organs and sensory organs (vision,), delayed or premature sexual development. The movements are poor, devoid of smoothness, accuracy, are performed either with excessive speed, or, on the contrary, with slowness. Facial expression is monotonous and inexpressive.

Clinical picture oligophrenia consists of various manifestations of mental underdevelopment, among which the leading role is played by a violation of cognitive activity. The most typical sign of oligophrenia is the underdevelopment of the complex functions of thinking - generalization, the formation of concepts, the establishment of cause-and-effect relationships. Speech is completely absent or, to a greater or lesser extent, underdeveloped (phonetic and articulatory defects, a meager vocabulary, primitive construction of phrases, etc.). In the sphere of feelings, primitive emotions and drives predominate, more complex differentiated emotions are underdeveloped. Characterized by extreme poverty of imagination, weakness of initiative, great imitation, suggestibility, a tendency to monotonous automatic activity. However, there is no complete parallelism between the degree of intellectual defect and emotional-volitional insufficiency. Depending on the characteristics of temperament, the behavior of patients may be different:
from motor retardation, lethargy (torpid patients) to extreme mobility, fussiness and often high mood (eretic).

Deviations from the norm are also noted in physical development: growth retardation, dysplastic physique, anomalies in the structure of the skull, malformations of internal organs and sensory organs (vision and hearing). Sexual development is often delayed (rarely premature). The motor sphere is underdeveloped. Violated pace, smoothness, rhythm and accuracy of movements. Synkinesis and stereotypic movements are noted. Facial expressions are monotonous and inexpressive. Neurological symptoms and signs of endocrine dysfunction are different depending on the pathogenesis of oligophrenia.

The degree of mental underdevelopment in oligophrenia can be different.