Mental retardation and organic brain damage

general description

Oligophrenia, when considered, requires its distinction from the acquired form of dementia, which is classified as such a pathology as dementia. This form of it means a decrease in intelligence due to certain reasons with concomitant brain damage, that is, intelligence decreases from normal levels corresponding to the patient’s age. As for the condition of oligophrenia that interests us, then with it the intelligence of a physically adult person is not subject to development, that is, there is no tendency to achieve normal indicators.

Oligophrenia was identified as a separate disease only in the last century, and before its isolation, the definition of “dementia” was used in practice for any group of patients, be it with a congenital form of the disease with mental underdevelopment, or with an acquired form (dementia).

There are some difficulties in trying to determine the prevalence of oligophrenia, which is explained, first of all, by the distinctive features of the diagnostic approaches used. In addition, the degree of tolerance on the part of society in relation to mental abnormalities, as well as the degree of accessibility to the use of specialized medical care, plays an important role in this issue. Predominantly in industrialized countries, mental retardation occurs in 1% of the population, and 85% of patients have a mild form of mental retardation. The share of moderate mental retardation, as well as severe retardation and profound retardation, accounts for 10%, 4% and 1% in a similar sequence. As for the ratio of the incidence of oligophrenia depending on gender, the indicator varies between men and women within the range of 1.5:1-2:1.

It should be noted that mental retardation (again, unlike dementia) is not a progressive process, but a process that determines the subsequent outcome of the disease.

Classification of oligophrenia

The classification of current forms of oligophrenia exists in several versions, each of which takes into account the severity of this disease and has its own characteristics of isolation. In the traditional version, the degrees of oligophrenia can manifest themselves in three variants:

• debility (a mild form of mental retardation);
• imbecility (moderate severity of mental retardation);
• idiocy (extreme severity of mental retardation).

Increasingly, today, the ICD-10 classification is used in accordance with IQ indicators (intelligence quotient indicators, the identification of which occurs through specialized tests), which determine the severity of oligophrenia, which is offered in the following versions:

• mild degree of oligophrenia - with IQ scores in the range of 50-70 points;
• moderate degree of mental retardation – with IQ scores in the range of 35-50 points;
• severe mental retardation – with IQ scores ranging from 20-35 points;
• deep degree of oligophrenia - with IQ scores not reaching 20 points.

In general, there is no uniform classification for this disease today. Based on the etiological factors that provoked the development of oligophrenia, undifferentiated oligophrenia and differentiated oligophrenia (undifferentiated mental retardation and differentiated mental retardation) are distinguished. The differentiated form refers to etiologically defined variants of the disease; the undifferentiated form, respectively, refers to diseases whose development was provoked by unknown causes.

Causes of mental deviation

Among the factors that influence the occurrence of mental pathology are the following:

• genetic predisposition to the disease. In approximately half of cases, mental retardation is inherited;
• chromosomal disorders, gene abnormalities, their mutation due to radiation, infectious diseases, maternal use of toxic substances during gestation;
• severe labor, which led to injury to the child (especially in the case of head injury), asphyxia, cerebral hypoxia;
• premature birth;
• infectious diseases affecting the central nervous system;
• lack of education, negative atmosphere in the family, psychological trauma at an early age, late diagnosis of the disease, etc.

It should be noted that to date scientists have not been able to find a single cause of mental retardation. As a rule, the occurrence of the disease is associated with several unfavorable factors that occur simultaneously or alternately.

Oligophrenia: symptoms

Undifferentiated oligophrenia either manifests itself as a result of damage to the rudiment of the brain, or as part of a later stage of its intrauterine damage. The degrees of oligophrenia noted above (debility, imbecility and idiocy) refer to varieties of undifferentiated forms of oligophrenia; the determination of compliance with a particular of the three forms is made on the basis of compliance of IQ indicators with certain boundaries, discussed above. Let us consider the indicated degrees of mental retardation separately in combination with the symptoms inherent in each of them.

• Mental retardation: debility

Moronism is the mildest degree of manifestation of the patient’s mental underdevelopment. It, in turn, manifests itself in several forms, the determination of which is made on the basis of compliance with IQ indicators. Thus, in a mild form, IQ corresponds to indicators in the range of 65-69 points, in a moderate form - in the range of 60-64 points, in a severe form - in the range of 50-59 points. Scores are determined during a comprehensive clinical examination.

Current impairments in the cognitive sphere in patients with oligophrenia to the considered degree manifest themselves in the form of an inability to develop concepts in a complex form, as a result of which attempts at complex generalization are impossible; limitations in abstract thinking (mild degree) or its impossibility are also relevant.

Patients are characterized by the predominance of a concrete-descriptive type of thinking; it is difficult for them to fully comprehend the situation - mainly only the external side of the events required for consideration can be covered. Based on the degree of severity of debility in patients, this inability manifests itself in each of them to varying degrees, while disturbances in abstract thinking are noted in them in any case. The possibility of studying at school in such patients is allowed, but the material must be mastered with great effort; mathematics is a particularly difficult subject for them.

Moronic patients lack their own judgment and inquisitive mind, they constantly adopt other people's point of view and views. When memorizing expressions, rules, etc., they are used in a template form; often they themselves begin to teach the information acquired in this way to those people who surround them. And although such patients are not characterized by subtle analysis in combination with the necessary generalization, this does not exclude, in case of debility (this is especially true with its mild degree), the dexterity of orientation within the conditions of ordinary situations.

A pronounced delay in mental development in debilitated patients in some cases determines the possibility of partial giftedness for them. It can manifest itself, for example, in excellent mechanical memory (but with the exception of their comprehension of the repeated information). Similar skills in hearing, drawing, dexterous handling of large numbers in performing certain mathematical operations (for example, multiplication), etc. are not excluded.

A characteristic feature of patients with debility is their easy susceptibility to being influenced, an increased form of suggestibility. This feature determines a significant danger both for them and for the environment, because in certain situations they can become a tool in various types of fraud and crimes due to the impossibility of comprehending the situation in the required way. Yielding to the instructions of someone else's will, moronic patients can break, kill, set fire, etc. - any action in this case is performed at the level of automatism, without taking into account the consequences.

Debilitated patients are often characterized by increased manifestation of primitive forms of drives. This can be vulgar and dissolute behavior; primitive instincts also include the sexual side of their behavior.

As for character traits, patients with debility have common traits with imbeciles (we will consider them below), in particular, they can be friendly, friendly and good-natured. The opposite option is also possible, in which they are characterized by vindictiveness, aggressiveness, malice and stubbornness. Behavioral characteristics are dominated by inactivity or motor excitability.

• Oligophrenia in the stage of imbecility

Imbecility determines the average degree of manifestation of oligophrenia with an IQ in the range of 35-39 points. A violation of cognitive activity determines the possibility of the formation of ideas, but the formation of concepts, as a slightly higher level of mental activity, becomes either a significantly difficult process or completely impossible.

Generalization and abstract thinking are excluded in this case. Imbeciles have the opportunity to acquire a standard type of skills related to self-service (independent food consumption, dressing, neatness); in addition, they can perform simple work activities, which is ensured through training in performing imitative actions. For example, they may be involved in cleaning the yard or premises, they may be engaged in rewinding threads or perform some other operations that involve performing the same action.

Patients with imbecility have an understanding of simple speech, and they themselves can learn a certain set of words. Similar to the previous form of mental underdevelopment, the severity of imbecility falls under three main options (mild, moderate and severe), each of which corresponds to certain levels of manifestation.

When considering the speech of imbeciles, it can be noted that it consists of standard and extremely short phrases (a noun with a verb or a simple adjective).

As for the possibility of learning something new, this is given to patients with enormous effort, often only within the framework of certain specific ideas that exclude any form of generalization. Imbeciles lack independent thinking, which is why they can only adapt to the conditions of an environment that is familiar and sufficiently familiar to them. Even with minimal deviations from plans, actions or situations, significant difficulties arise that require constant guidance.

In addition, imbeciles are also characterized by an increased degree of suggestibility. Their personal interests are mostly very primitive, boiling down mainly to satisfying ordinary physiological needs. Often they are characterized by particular gluttony and sloppiness in food consumption. As for the other side, related to satisfying the needs for sex, here only in some cases there is an increased degree of sexual desire, which in this case manifests itself in combination with promiscuity in behavior.

Depending on the behavior inherent in oligophrenics at this stage, they are divided into two main groups. Thus, the first group includes very mobile, energetic and active patients, the second group - on the contrary, apathetic and lethargic, indifferent patients, they do not react to anything and are only interested in satisfying those needs that are important to them.

Depending on their character, imbeciles are also divided into two groups, thereby dividing into friendly, good-natured, sociable and flexible, and into aggressive and evil ones.

Despite the fact that imbeciles have the ability to perform primitive actions, they are not able to live independently; they require constant supervision of qualified personnel.

• Oligophrenia: idiocy

Idiocy represents the most profound degree of mental retardation with an IQ score of less than 34 points. In this case, the patients are absolutely unteachable, their movements are characterized by clumsiness and lack of purposefulness, and speech is also practically absent (only slurred pronunciation of individual words becomes possible). The manifestation of emotions comes down to the reproduction of the simplest reactions (pleasure or, respectively, displeasure). The cause of idiocy lies in genetic pathology. In the vast majority of cases, patients are inactive, they are unable to control urination and defecation, this also applies to eating, and they are often unable to distinguish edible from inedible. Such patients can only master visual-spatial forms of coordination and basic skills.

Idiocy, as a rule, is accompanied by severe forms of structural damage to the brain, severe and varied neurological symptoms, defects associated with the sensory organs, epileptic seizures, structural defects of internal organs and the body as a whole. If adequate care is provided for such patients, some of them can live up to the age of 30-40 years, but mostly they die in childhood or adolescence due to the development of an intercurrent type of disease.

Considering that such patients cannot develop intellectually, as well as being unable to independently meet their own needs, they need constant help, care and supervision in specialized institutions.

Criteria and symptoms of UO

Mental retardation means a stable, difficult to reversible slowdown in the development of the mental, intellectual, emotional and volitional sphere, which is characterized by the presence of congenital or acquired pathologies during life.

Significant limitations in skills that accompany dementia entail problems in the field of adaptive human behavior. This implies a low adaptability of the individual to the environment and difficulties in interacting with society.

The issue of intellectual disability must be considered in combination with the individual characteristics of the person. When diagnosing this mental disorder, one should also take into account the environmental conditions in which the patient is located. It is this that determines not only the individual’s adaptation in society, but also the psychological support that such people need throughout their lives.

Mental retardation in an adult is determined by the following criteria:

• deficiency of intellectual development. It manifests itself through difficulties in solving everyday problems, the inability to think abstractly, reason, and learn from experience;
• low level of adaptive behavior. It lies in the inability to adapt to cultural and social stereotypes generally recognized in society. People with mental pathology are little or not at all adapted to independent life and experience difficulties in the process of communication and leading social life. Therefore, they require regular help and support from others;
• Difficulties in the field of intellectual education and adaptive capabilities in oligophrenics develop throughout the entire period of the disease. Therefore, it is very important to diagnose the disease in a timely manner, the first symptoms of which can be seen in early childhood. The child’s further biological, psychological and social development must be structured in such a way as to minimize the worsening of pathology in adulthood.

In addition to the main signs indicating the presence of mental retardation, experts note auxiliary ones that can be noticed by people around the patient:

• inability to solve mathematical and logical problems, especially if it is necessary to additionally use reading, speech, etc. Concentration of attention and memory is low, which leads to a low degree of learning ability;
• a person often does not understand his thoughts and cannot clearly express them to others. Problems arise with communication - due to the lack of necessary experience in interpersonal relationships, it is difficult for him to get close to others and make friends. If it does happen that the patient is prone to excessive suggestibility and subordination to strangers;
• low level of independence - an individual may take poor care of himself, is unable to organize his leisure time, is often irresponsible when it comes to work, and does not know how to competently manage personal finances;
• poor behavior control. Outbreaks of aggressiveness, irritability, anger can arise due to various factors - discomfort caused by communication difficulties or the inability to express personal needs and desires, social isolation, social discrimination, etc.;
• severe cases of mental retardation in adults are accompanied by inhibited motor skills, slurred speech, and a low level of vocabulary;
• the rhythm of development of oligophrenics is slow, so mental retardation is most easily determined when the child is at school age;
• in the case of genetic intellectual disability syndrome, patients have a specific appearance;
• people with this pathology are more susceptible than others to mental, neurological and physical disorders (sleep problems, obesity, diabetes, etc.).

Differentiated oligophrenia

In domestic medicine, a two-level classification is used, based primarily on the time within which the corresponding pathological effect was exerted, as well as on the quality of the damage by the harmful factor and its overall severity. Regarding the time of exposure (including the characteristic features and similarities of the onset of the disease and its development), this classification defines three main groups of oligophrenia, namely:

• familial and hereditary oligophrenia;
• embryonic or fetal damage;
• development of oligophrenia within the framework of certain harmful influences during labor and the first months/years of a child’s life.

Differentiated oligophrenia, that is, those oligophrenias whose etiology has already been studied, can thus be divided into the following groups:

• oligophrenia resulting from hereditary pathologies (chromosomal or genetic);
• oligophrenia resulting from exposure to a certain type of harmful substances and microorganisms (intoxication, infection, etc.) during the period of intrauterine development of the fetus;
• oligophrenia resulting from exposure to a certain type of harmful substances and microorganisms during the perinatal period, as well as the first months and years of the child’s life;
• oligophrenia resulting from exposure to a negative type of psychosocial phenomena.

Let us highlight some types of differentiated oligophrenia.

• Microcephaly

Microcephaly is characterized by a significant reduction in the size of the skull, which, accordingly, determines similar sizes for the brain (other parts of the body correspond to the norm). Thus, with a horizontal coverage of the skull, microcephaly determines a figure of less than 49 cm (the minimum indicators for the coverage of the skull are 22 cm). Brain mass indicators are also sharply reduced (ranging from 150 to 400 grams). The hemispheres are characterized by underdevelopment, underdevelopment is also noted in the gyri (this is especially true of the frontal gyri).

Microcephaly: comparison

Microcephaly in a newborn: photo

Simultaneously with these pathologies, it is often noted that the size of the cerebellum in combination with the subcortical nodes corresponds to the norm. As for the mental disorders that are relevant for microcephaly, they are very significant in manifestations, the degree of severity of the manifestations of oligophrenia is quite deep, due to which the patients’ condition is noted to be approaching the absolute form of idiocy (much less often the degree of idiocy manifests itself in this condition in a mild form). The causes of microcephaly are the effects of various types of harmful factors on the fetus during the initial stages of pregnancy (this includes diseases transmitted by the mother: Botkin’s disease, rubella, influenza, etc.; chronic intoxication (diabetes, tuberculosis, alcohol); the use of certain chemotherapy drugs ( such as sulfonamides, quinine, etc.); toxoplasmosis (see below).

• Toxoplasmosis

Toxoplasmosis is defined as a parasitic disease that develops as a result of exposure to toxoplasma; various types of domestic mammals, as well as wild mammals (dogs, cats, rabbits, various predators, rodents, herbivores, etc.) are considered as a source of infection. Toxoplasma penetrates the fetus through the placenta through an infected mother; infection of the child is also possible during the first years of his life.

With toxoplasmosis, the actual degree of oligophrenia for the patient can manifest itself in different ways. In addition, the possibility of manifestation of catatonic disorders and epileptiform seizures is also allowed. The development of oligophrenia against this background may also be accompanied by encephalitis/meningoencephalitis of toxoplasmosis nature. Toxoplasmosis can also occur in combination with pathologies such as hydrocephalus or microcephaly. The course of toxoplasmosis, in addition to the listed features, is accompanied by eye damage (retinal detachment, iridocyclitis, pigmentary choreoretinitis). In the bones of the skull and in the brain, areas of calcification form (calcification - that is, the deposition of calcium salts in these areas in the absence of them here normally).

• Phenylpyruvic oligophrenia

This form of pathology is associated with the fact that there is a disturbance in the body’s metabolism of phenylanine with the simultaneous formation of phenylpyruvic acid in significant quantities; its content can be determined in urine, blood, and sweat. The condition is accompanied by manifestations of deep degrees of oligophrenia (idiocy or imbecility), as well as hypopigmentation of the iris and skin. Phenylpyruvic oligophrenia is also accompanied by a pathological condition with impaired metabolism of B vitamins.

• Langdon Down disease

It is also known as trisomy 21, Down syndrome. This pathology is characterized by the presence of not 46, but 47 chromosomes in a sick person, which occurs for as yet unknown reasons (it is assumed that the development of the syndrome is caused by a pathological form of heredity or a chromosomal abnormality). The number of chromosomes is determined by the fact that the chromosomes represented by the 21st pair do not have a standard pair, but three copies (other variants of chromosome pathology are less often considered).

Down syndrome: photo

Here, as in other cases considered, there is a manifestation of mental disorders and oligophrenia in particular; moreover, there are characteristic features that accompany this disease in combination with Down syndrome. Thus, mental retardation in Down syndrome determines the significant mobility of patients, their good nature and affection, they have expressive movements and facial expressions, and have a tendency to imitate.

Down syndrome: signs

The appearance of the patients is also very characteristic, it consists in a spherical shape of the head with widely spaced eyes, a characteristic fold (epicanthus) appears on the upper eyelid, the nose is somewhat flattened, upturned, short, the tongue is streaked. Patients also have decreased muscle tone, loose joints, and short stature.

• Pilvia mental retardation in combination with dyskeratosis

This form of the disease is caused by an insufficient amount of vitamin A in the expectant mother’s body during pregnancy, which is especially important during the first trimester. In addition to oligophrenia, ichthyosis subsequently develops against this background, and epileptiform seizures appear.

• Rubeolar embryopathy

This pathology is relevant if the expectant mother suffers a viral disease such as rubella during the first trimester. In this case, mental retardation manifests itself to a profound extent, accompanied by pathologies in the form of cataracts, congenital heart defects, and deaf-muteness.

• Oligophrenia developing against the background of a positive Rh factor

This pathology is relevant in case of a negative fetal factor. In this case, the causes of oligophrenia are associated with the fact that Rh antibodies reach the fetus through the placenta, resulting in subsequent damage to its brain. Oligophrenia, the symptoms of which develop in children against the background of exposure to this factor, is also accompanied by paralysis, paresis, and hyperkinesis.

• Residual oligophrenia

This form of the disease is observed in practice most often. In this case, the arrest of mental development is preceded by the patient suffering from infectious diseases (meningitis, meningoencephalitis) and injuries in early childhood. As for the degree of manifestation of oligophrenia here, it can be in any variant. The most common form of pathology that develops against the background of infections and injuries is hydrocephalus (the disease is accompanied by an increase in the volume of cerebrospinal fluid within the subarachnoid spaces (this is an external form of hydrocephalus) or an increase in its volume in the ventricles of the brain (internal hydrocephalus)).

In a circular coverage, the skull with hydrocephalus in size reaches about 70 cm or more, this is accompanied by weakening of vision, and often its complete loss, which is explained by the pressure exerted by the cerebrospinal fluid on the area of ​​​​the intersection of the visual tuberosities with a plastic form of their atrophy. As for the mental degree of underdevelopment, relevant for hydrocephalus, it can be different, manifesting itself both in the form of mild debility and in the form of achieving an absolute state of idiocy. In addition to the development of hydrocephalus against the background of infections and injuries, there is a possibility of its development as a manifestation of an actual progression process, which may imply pathologies in the form of congenital syphilis, tumor formation in the brain, etc.

Hydrocephalus

Hydrocephalus in a child: photo

Who is he, a person with mild dementia?

Moronism is the most common and mildest variant of mental disability.
The severity of the disease can be mild, moderate or severe. According to the dominant manifestations: atonic, sthenic, asthenic, dysphoric. Patients remember any information slowly and forget quickly. They do not know how to generalize, do not master abstract concepts. The type of thinking is concrete-descriptive. That is, they can only talk about what they saw, without making any conclusions or generalizations. Their understanding of logical connections between events and phenomena is impaired.

Patients with oligophrenia to the extent of debility are practically the most honest people in the world. But not for high moral reasons. These people are simply not capable of fantasizing. With the exception of rare, pathological cases described in judicial practice, they can only talk about what they saw.

During a conversation, one immediately notices: speech disturbances, monotony, lack of emotion, poor vocabulary, primitive sentence construction.

Sometimes such a phenomenon as giftedness in some areas is added against the background of general pathology: the ability to mechanically memorize large texts, absolute pitch, genius in mathematics, artistic gift.

Patients do not like change of environment. Only in a familiar environment do they feel confident, protected and even capable of independent life.

They are highly suggestible, which is why they are easy prey for criminals who use them like zombies. It is easy to convince a gullible oligophrenic of something, to impose your point of view, which they will perceive as their own. From among them often emerge uncontrollable and unreasoning fanatics who never change “their” beliefs.

Will and emotion are almost undeveloped. They are guided by instincts: sexual, food. Sexual promiscuity is an unpleasant phenomenon that causes disgust among others.

In persons suffering from debility, instincts are almost impossible to control and correct. Food instinct is the basis. They eat a lot, are indiscriminate in their food, and have a poorly developed sense of fullness.

In general, with successful socialization, they are excellent spouses (suggestibility), not prone to conflicts, and very obedient (no judgment of their own).

They are easy to manage. Because of their suggestibility and controllability, they can be both completely adequate members of society and absolutely asocial, maliciously vindictive and cruel.

They can have a very attractive character: kind, like children, warm-hearted, devoted to those who care about them. Along with them, there are individuals who are aggressive, angry, stubborn, and vindictive.

Moronism is expressed both in excessive excitability and in obvious inhibition (in common people the latter are called “brakes”).

Persons diagnosed with “moronism” do not serve in the army, do not drive cars, do not have the right to purchase and store weapons, and work in state and municipal institutions is not for them. Systematic observation by a psychiatrist increases their chances of adapting to the outside world.

Diagnostics

It should be immediately noted that IQ indicators alone cannot be used as the main and only criterion in the diagnosis of oligophrenia. The fact is that there are often cases in which people with low IQ scores and other signs of mental retardation in their own condition did not determine the basis for establishing such a diagnosis. Accordingly, the diagnosis of “oligophrenia” is established on the basis of a general assessment of the patient’s everyday skills and mental state, an assessment of the level of his social adaptation and a study of the anamnesis for previous diseases. Only an integrated approach determines the possibility of diagnosing a patient with mental retardation.

Oligophrenia in infancy, as well as in childhood, can manifest itself in a form of developmental delay that can be determined by a timely visit to the doctor. Within the context of preschool institutions, mental retardation in children is accompanied by problems with adaptation; it is difficult for children to maintain a daily routine, just as it is difficult for them to master classes with teachers - in this condition they become too complex.

Oligophrenia in school-age children can be detected through appropriate attention to the child and, in particular, alertness to his increased inattention, poor performance, and behavioral characteristics. Mental retardation is also often accompanied by symptoms in the form of frequent headaches, seizures, tics, and partial paralysis when limbs are affected.

Basically, mental retardation can be recognized at an early age. Mental retardation, which develops at the genetic level, is determined in the fetus during pregnancy (screening examination in a antenatal clinic and maternity hospital). If the symptoms characteristic of phenylketonuria (as a form of mental retardation) are identified and treatment started before the child reaches the age of two to three months, there is a chance of preserving intelligence. Taking this into account, pediatrician supervision is extremely necessary both during the neonatal period and during early childhood. In general, timely treatment, within the framework of possible measures, allows the child to achieve normal adaptation to the conditions that independent life implies.

Causes of pathology

Oligophrenia is a syndrome whose formation can be influenced by a large number of different factors. Among them:

1. Negative effects on the human body that occur during childbirth, as well as in the age period up to 3 years. This is fetal hypoxia or asphyxia during childbirth, infections of early childhood, traumatic brain injuries, etc.
2. Intrauterine harmful factors. These include viral infections (herpes, rubella), hormonal disorders, and microbial infections (syphilis and toxoplasmosis).
3. Chromosomal and genetic pathologies. These include Down's disease, various types of enzyme disorders and microcephaly.

Sometimes the classification of oligophrenia is made based on the causal factors listed above. In this case, there are three forms of mental retardation. Among them are genetic, intrauterine and perinatal.

In addition, medicine knows that oligophrenia is accompanied by diseases of a certain type. This list includes:

1. Hydrocephalus. This disease is caused by excessive accumulation of cerebrospinal fluid, which occurs in the ventricles of the brain. A similar phenomenon occurs due to excess production of this substance or difficulty in its outflow.
2. Microcephaly. This pathology is caused by the smaller size of the skull and brain.
3. Phenylketonuria. The disease occurs due to disturbances in the metabolism of phenylalanine. As a result, a significant volume of toxic substances is formed - products of the breakdown of this amino acid.
4. Toxoplasmosis. The cause of this disease is a parasitic infection of the body. Infection of the mother can penetrate the fetus and cause various developmental defects, including in the brain.
5. Down's disease. This pathology occurs due to the formation of an additional chromosome in the body. A person with such a disease is identified by his appearance. He may have delayed physical and mental development, and also have heart defects.