The main clinical forms of oligophrenia

Mental and psychological underdevelopment (deficiency, retardation) of the individual, caused by many reasons, which is commonly called oligophrenia, is manifested by an equally extensive and varied complex of symptoms.

To distinguish the main features of each type of abnormal intellectual and mental state in clinical psychiatry, specific forms of oligophrenia have been defined and their classification has been developed.

Classification of forms of oligophrenia

As is often the case with any attempt to systematize a significant volume of phenomena similar in manifestation but different in etiology, the most difficult thing is to choose a single classification criterion, which is especially important in medicine. Obviously, it is the lack of common views on the principles of systematization that can explain the multivariance that the classification of forms of oligophrenia has. Although an important role in the emergence of new interpretations is played by achievements in the study of the pathogenesis of this condition.

The author of the term “oligophrenia”, the German psychiatrist Emil Kraepelin (1856-1926), believed that when classifying mental illnesses, it is necessary to take into account their etiology (primarily pathological changes in the structures of the brain), characteristic signs and a typical clinical picture.

There have been many attempts to classify forms of mental retardation, but in the end the criterion was the scale of the existing mental and psychological underdevelopment (in a milder formulation, an intellectual disability). The traditional forms of oligophrenia, debility, imbecility and idiocy, do not appear in the 2010 edition of the International Classification of Diseases: they were decided to be removed, since these medical terms acquired derogatory connotations (they began to be used in everyday speech as a definition of a negative attitude towards a person and his or her actions).

According to the provisions adopted by WHO and enshrined in ICD-10, depending on the degree of cognitive dysfunction, oligophrenia can be mild (F70), moderate (F71), severe (F72) and profound (F73). Such a distinction structures the pathology in a simplified manner, without taking into account many distinctive characteristics that have several dozen different forms of this abnormal condition.

For example, in the pathogenetic classification of mental retardation, developed in the 1960-70s by Professor M.S. Pevzner (one of the founders of clinical defectology), the main principle was the relationship between certain cerebral lesions and their clinical manifestations.

The following forms of oligophrenia are distinguished according to Pevzner:

• an uncomplicated form of oligophrenia, in which the emotional-volitional sphere of patients is not very pronounced;
• complicated forms of oligophrenia (complications are caused by disruption of neurodynamic processes in the central nervous system, which can lead to excessive excitability, inhibition or weakness);
• oligophrenia with speech, hearing, and motor impairments;
• oligophrenia with manifestations similar to psychopathy;
• oligophrenia with obvious underdevelopment and insufficiency of the cortex and subcortical structures of the anterior lobes of the brain (which, in fact, is associated with most extrapyramidal disorders, intellectual disabilities and mental abnormalities).

According to Sukhareva, forms of oligophrenia differ in etiology and features of the impact of pathogenic factors. Based on many years of observations of clinical manifestations of oligophrenia in children, Professor G.E. Sukhareva (child psychiatrist, 1891-1981) identified:

• oligophrenia caused by hereditary-genetic factors (Down syndrome, microcephaly, phenylketonuria, gargoylism, etc.);
• oligophrenia associated with the impact of a number of negative factors (viruses, treponema, toxoplasma, toxins, immunological incompatibility of the mother and fetus, etc.) during the period of intrauterine development;
• oligophrenia caused by postpartum factors (asphyxia, birth injuries, infectious and inflammatory diseases of the brain).

In its modern form (at least half a century has passed since Sukhareva's classification was developed), the pathogenesis-based division of intellectual disabilities distinguishes between hereditary or endogenous forms of oligophrenia: all syndromes associated with gene aberrations, as well as disorders affecting metabolic processes, hormone synthesis, and enzyme production. Accordingly, acquired (postnatal) exogenous forms of oligophrenia are also distinguished, arising from alcoholism or drug addiction of the mother, after rubella suffered during pregnancy (rubeolar oligophrenia), with transplacental infection of the fetus with toxoplasma present in the pregnant woman, with iodine deficiency, etc.

There are oligophrenias of mixed etiology. For example, microcephaly, which accounts for more than 9% of diagnoses of mental retardation, is an endogenous-exogenous oligophrenia, since it can be either genetically determined (true) or secondary, arising from the effect of ionizing radiation on the fetus.

Hydrocephalus (water on the brain) can be a consequence of intrauterine infection of the fetus by cytomegalovirus, and can also develop after a traumatic brain injury in a newborn, meningitis or encephalitis.

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Characteristics of forms of oligophrenia

Despite all the terminological innovations, the characteristics of the forms of oligophrenia take into account the same morphological features, etiology and clinical manifestations. And as a basis for describing individual forms, as is customary, the main complex of the most characteristic symptoms is used.

A mild form of oligophrenia (mental retardation in the form of debility) is diagnosed if:

• the level of mental development on the scale of “intelligence quotient” (IQ) fluctuates between 50-69 on the Wechsler scale;
• speech is underdeveloped and its lexical range is limited;

Fine motor skills are not sufficiently developed, there may be problems with coordination of movements, as well as various movement disorders;

• there are craniofacial or musculoskeletal congenital defects (abnormal growth or size of the head, distorted proportions of the face and body, etc.);
• the ability to think abstractly is very low, the predominance of objective thinking and mechanical memorization is obvious;
• evaluation, comparison and generalization (of objects, phenomena, actions, etc.) cause serious difficulties;
• the range of emotions and ways of expressing them is insufficient; emotions are often expressed in the form of affects;
• suggestibility is increased, independence is decreased, self-criticism is absent, and stubbornness is frequent.

In moderate oligophrenia (mild imbecility), the IQ is 35-49 points, and severe oligophrenia (clearly expressed imbecility) is defined as an IQ of 34 and below (up to 20 points). The line between them is very conditional, given the obvious presence of mental pathology. However, in moderate oligophrenia, patients can formulate the simplest phrases and master basic actions, while in severe oligophrenia, all this is no longer possible. It should be borne in mind that this degree of cognitive dysfunction (which is diagnosed in early childhood) leads to a lack of attention, as well as complete internal lack of control over behavior (including sexual) and the expression of emotions. Therefore, imbecile patients quickly fall into a state of psychomotor agitation and can be aggressive towards others; they also have seizures similar to epilepsy.

Deep oligophrenia (idiocy) is characterized by: IQ below 20; complete lack of ability to think, understand what others say and speak; extremely low emotional threshold and lack of all types of sensitivity (including taste, smell and touch); atony and limitation of movements to reflexive gesticulation.

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Atypical forms of oligophrenia

Any violation of the “standard” clinical picture of mental retardation results in so-called atypical forms of oligophrenia.

According to psychiatrists, the reasons are multifactorial damage to brain structures during its intrauterine development, in which the combined negative impact of both internal (genetic) and external factors is not excluded. It is difficult to establish with absolute accuracy which symptom is a manifestation of one or another pathogenic influence.

Oligophrenia with obvious hydrocephalus can be considered atypical: a child - against the background of a hypertrophied skull shape, hearing loss and strabismus - may have a good ability for mechanical memorization.

The way in which “atypical dementia” manifests itself largely depends on the local factor – that is, on which structure of the brain is damaged and how critical this damage is for the functioning of individual areas of the cortex, cerebellum and pituitary-hypothalamic zone of the brain.

In atypical forms of oligophrenia, specialists include emotional and sensory deprivation, which children are subjected to when placed in conditions of prolonged external isolation or in difficult family conditions (families of alcoholics).

Moderate forms of mental retardation (IQ 50-60) are almost always evident during the first years of life. These people face difficulties at school, at home, in society. In many cases – after specialized training – they can lead a virtually normal life.

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