Major degrees of mental retardation according to international classification


Attention! In the catalog of finished works you can see theses on this subject.

Depending on the depth of the mental defect in oligophrenia, there are three degrees of mental underdevelopment: debility, imbecility and idiocy, which is of practical importance in determining the possibility of learning and social adaptation of these children. The ratio of moronity, imbecility and idiocy is about 75%, 20%, 5% (M.S. Pevzner, 1973).

Morbidity - mild degree of mental underdevelopment (IQ = 50-70). With good attention and good mechanical memory, children are capable of learning through a special program of auxiliary schools, based on concrete visual teaching methods, acquire certain work skills and can be independent in simple labor processes. Mental underdevelopment usually becomes less noticeable over the years.

As noted by S.Ya. Rubinstein (1986), at preschool age there is a primitive concept in the game, the possibility of its simplest organization, at school age - a definite assessment of a specific situation, in simple practical matters. In speech, phrasal speech is used, but their phrases are primitive, speech often suffers from agrammatism, tongue-tied. Verbal definitions that are not related to a specific situation are perceived slowly. In such children, the level of abstract thinking, logical processes, associations rises, everyday speech becomes little different from the speech of intellectually full children and adolescents. All this contributes to the acquisition of a certain stock of information, mastering the skills of reading, writing, counting.

The thinking of moron children has a visual-figurative character. Genuine education concepts is not available. Ability to distraction and generalization is very weak. The meaning of the read is poorly understood. Correctly perceiving objects and their images, children suffering from retardation, find it difficult to compare them, establishing the internal relations existing between them. When learning to count children, it is difficult for them to assimilate the concept of the quantitative content of a number, the meaning of conditional arithmetic signs. Without prior clarification, they often do not understand the condition of a simple task. When solved, it is “stuck” in the previous mode of action. Difficult to learn the rules of spelling.

The intellectual immaturity of a person is closely related to intellectual hypoplasia. The lack of curiosity, the weakness of the initiative are distinctly pronounced. With a general sufficient preservation of the emotional sphere, there are no complex shades of experiences. There is a lack of subtle, differentiated movements, expressive facial expressions. Scattered neurological signs, physique dysplasias are common, cerebroendocrine disorders are common (S.Ya. Rubinstein, 1986).

But at the same time, in the opinion of most researchers (TA Vlasov, MS Pevzner, 1973, S.Ya. Rubinstein, 1986, SD Zabramnaya, 1995, B.P. Puzanov, 2003, etc. .), with proper upbringing and education, timely inculcation of labor skills, the absence of neuropsychiatric disorders that complicate an intellectual defect, the social prognosis in the formation of the personality of children suffering from debility is favorable.

Imbecility - moderate and severe mental retardation (IQ = 20-50). S.Y. Rubinstein (1986) points out that imbecile thinking is concrete, inconsistent, tightly mobile. The formation of abstract concepts is essentially unavailable. The stock of information and ideas is limited to a narrow circle of purely domestic, everyday issues. There is a sharp underdevelopment of perception, attention, memory. Speech is tongue-tied and agrammatic, vocabulary is poor and consists of the most frequently used words and expressions in everyday life.

Imbeciles are not trained by the program of auxiliary schools. With relatively good mechanical memory, some of them can master letters and ordinal count, but use them mechanically. The lack of visual and auditory analysis and synthesis is clearly manifested in the difficulties in memorizing letters that are similar in spelling or sound, when merging sounds into syllables and syllables into words. Reading is mechanical, understanding of the meaning of reading is missing. It is possible to learn the ordinal count within the first ten, mechanical learning of the multiplication table. An abstract account, the concept of number is not available. They have access to self-service skills and elementary work processes, but in most cases they are incapable of self-employment. Synkinesia, slowness, lethargy, awkwardness of movements exacerbate the difficulties of mastering the letter, physical labor.

Imbeciles easily give inadequate reactions, sometimes they are malicious and aggressive. Some have increased and distorted drives. Increased suggestibility and imitativeness often contribute to the manifestation of asocial forms of behavior. At imbeciles, simple, immediate emotions, as well as expressions of sympathy, the desire to help, are relatively preserved. These patients also have the beginnings of self-esteem: the experience of their physical weakness, motor awkwardness.

Idiocy - The deepest mental retardation (IQ less than 20), in which almost completely undeveloped thinking and speech. The reaction to the environment is sharply reduced, the perceptions are poorly differentiated. In the speech addressed, it is not the meaning that is perceived, but the intonation and the accompanying mimicry and gestures. Emotions are elementary and are mainly determined by instinctive life - a feeling of pleasure and displeasure. Forms of expression of passion are primitive: joy manifests itself in motor arousal, expressive cry. Static and locomotor functions are grossly underdeveloped, many patients cannot stand or walk. With idiocy, some patients are sluggish, have low mobility, stay in a monotonous position for a long time, others are restless, motor-excitable. Often there is an increase and a perversion of drives (stubborn masturbation, eating impurities, etc.). With idiocy, gross defects in physical development and marked neurological symptoms are usually observed.

The life of oligophrenics in the degree of idiocy proceeds at the instinctive, unconditioned reflex level. They do not develop the skills of tidiness and self-service. They constantly need care and supervision.

In the somatic status of patients with oligophrenia, there are often signs of physical underdevelopment, dysgenesis and dysplasia, many of which correspond to embryonic stages of the development of organs and systems. In some cases, they make it possible to judge the time of exposure to a pathogenic factor, and their typical combination allows you to isolate individual differentiated forms of oligophrenia (Down's syndrome, microcephaly, etc.). Physical development of patients with oligophrenia often lags behind the age norm and is characterized by disproportion in the structure of the trunk and extremities, curvature of the spine, signs of cerebral endocrine insufficiency (obesity, underdevelopment of the sexual organs, violation of the pace and timing of the formation of secondary sexual characteristics) (S.Ya. Rubinstein, 1986) .

In conclusion, it must be said that in some forms of oligophrenia the structure of mental underdevelopment is uneven and is not exhausted only by the main, characteristic symptoms of dementia. In this connection, atypical and complicated variants of oligophrenia are distinguished. The atypical forms include cases of oligophrenia with an uneven structure of the mental defect, which manifests itself either in the unilateral development of a mental function or in signs of partial mental underdevelopment. In complicated forms, in the structure of mental underdevelopment, additional psychopathological syndromes that are not specific to oligophrenia (asthenic, epileptiform, psychopathic, etc.) are observed (TA Vlasova, MS Pevzner, 1973).


1. Vlasov, TA, Pevzner, MS Teacher about children with developmental disabilities. - M .: Enlightenment, 1973. - 173s.
2. Zabramnaya S.D. Psychological and pedagogical diagnosis of mental development of children. - M .: Enlightenment, 1995. - 112 p.
3. Education of children with intellectual disabilities (oligophrenopedagogics) / ed. B.P. Puzanov. - M .: Academy, 2003. - 272с.
4. Rubinstein S.Ya. The psychology of the mentally retarded student: Proc. student manual ped. in-Tov 3rd ed., Pererab. and add. - M .: The Enlightenment, 1986. - 192 p.

Classification of mental retardation

Mental retardation, or insanity, is classified according to the severity and forms of clinical signs that manifest themselves in this disorder. One of the traditional classifications includes the following types of mental retardation:

  • Debility - mild mental retardation, characterized by the presence of smoothed clinical signs of oligophrenia, thereby causing some difficulties in the diagnosis,
  • Imbecility - moderate mental retardation,
  • Idiocy is a severe form of mental retardation, combining, in addition to the obligate signs of almost zero intelligence, the symptoms of complex psychopathological states.

The international classification of diseases of the tenth revision (ICD-10) provides for a separate classification of mental retardation, based on testing the level of intelligence test Isaac (IQ) and distinguishes, depending on the test results, mild, moderate, severe and deep oligophrenia. In Russia, this approach is used in extremely rare cases in order to determine the level of moronity. For more severe forms, the use of IQ test is impractical. For making a diagnosis of mental retardation and its quality, Wexler’s methods and various verbal and non-verbal scales have been adopted in our country, which with a certain accuracy allow us to determine the level of intelligence of the subject.

A significant contribution to the pedagogical areas of work with mentally retarded children belongs to M. S. Pevzner, who, in 1979, offered her own variety of classifications of oligophrenia based on the etiological and pathogenetic features of the disease:

  • Uncomplicated form of oligophrenia,
  • Mental retardation against the background of disturbances in neurodynamic processes directed towards excitation or inhibition,
  • Mental retardation against the background of dysfunctions of the analyzers - auditory. Visual, tactile,
  • Mental retardation, combined with psychopathological manifestations of patient behavior,
  • Mental retardation on the background of severe frontal insufficiency.


This term in modern psychiatry is used less and less, it is recommended to replace it with - “mild mental retardation”. Like all types of mental retardation, the mild form depends on the biological characteristics of the brain laid down at birth.

This form of the disorder is diagnosed only with the use of specialized tests to determine the level of intelligence, since the clinical picture is expressed rather weakly. Symptoms are especially pronounced in childhood, children with this disorder retain mechanical memory and emotional-volitional sphere. Getting new knowledge and consolidating the received is very difficult with the loss of large volumes, which have to be learned again and again.

Ability to abstract thinking is practically absent, but the descriptive type of thought processes is well developed.

It is extremely difficult for children to link the logical threads of two different objects together, the concept of "time" and "space" is inaccessible for understanding.

Verbal manifestation demonstrate a very poor vocabulary, narrow forms and minority. Retelling or memorizing is fraught with very high physical costs, and given the lack of functionality in the permanent memory, what has been learned quickly disappears from it.

Often, with debility, certain endowments in one area or another are manifested - a child can successfully perform complex mathematical calculations or draw quite nicely. Emotional manifestation is rigidly tied to a specific situation, actions, as a rule, do not have long-term achievement of the goal, negativism prevails in the reasoning.

In English-speaking countries, the term "moron" is similar in meaning to the concept of "moron", which was used for a long time in English and American psychology, denoting approximately the same picture that is characteristic of debility or mild intellectual disability. That is how the US refers to the mild form of mental retardation.

Today, the “moron” is gradually emerging from the psychiatric American nomenclature, as well as the “moron” from the Russian, because these terms have become offensive in the form of frequent use in everyday life.


This term applies to moderate mental retardation, which is intermediate between mild and severe oligophrenia.

The stage of imbecility is characterized by the patients understanding of the surrounding reality, in their colloquial speech there are logically correct selected words reflecting the superficial essence of their requirements against the background of a very poor vocabulary and short words - from two or three words and sentences. The undeveloped will, emotional paucity, inability to concentrate and obtain new knowledge are clearly visible. Actually, the last point is out of the question, as a rule, the actions of imbeciles are limited to acquired reflexes.

At a certain level of effort, patients can be trained in general reading, writing and counting skills. For mathematical calculations it is possible to use the first ten and elementary arithmetic operations.

The reaction to praise or censure is expressed logically correctly, the emotions are more pronounced than in the last stage of mental retardation. Attachment to loved ones or to those people who take good care of them or give other positive emotions is also well seen. Such manifestations of character as initiative, adaptation, sociality are not familiar to imbeciles.

Patients suffering from this form of oligophrenia are given government support in the form of pension payments and preferential treatment.

Idiocy refers to the most severe form of oligophrenia and is expressed by a complete lack of understanding and awareness of the environment and the severity of logically correct emotions.

In the overwhelming majority of cases, idiocy is accompanied by serious motor, physiological, and psychopathological dysfunctions. Patients, as a rule, move with difficulty and have anatomical problems of internal organs. Meaningful activity is not available. Verbal manifestations are incoherent, practically do not contain words - they are replaced by high vocal notes of individual syllables or sounds. Patients do not tend to distinguish the people around them, they do not respond to the semantic load of the messages, limiting their response to mimic manifestations and shouts.

Emotional satisfaction is limited only by obtaining primitive pleasure from eating, releasing the intestines, as well as pathological dependencies in the form of masturbation, sucking fingers or chewing inedible objects.

Patients necessarily need the presence of caring people, so they are always on the maintenance of the state in special boarding schools throughout their lives.


The first attempt to differentiate mental retardation belongs to Philip Pinel, who introduced the concept of "idiocy" and identified four of its main types. But the main thing is that Pinel divided dementia into congenital and acquired, and this distinction is also relevant today. Thus, the pathological abnormalities of the level of intelligence can be divided into oligophrenia and dementia. Under the first understand the birth defect, in under the second - acquired. When oligophrenia mental abilities of a person have never been normal, and when dementia was, but then because of something decreased. According to the traditional classification, there are three degrees:

The last is the hardest. However, in modern ICD-10, 4 degrees are indicated. Imbecility is divided into two levels. In general, it is:

  • lightweight
  • moderate,
  • heavy
  • deep

mental retardation. At the same time, the terms moronity, imbecility and idiocy disappeared in ICD-10, since they were recognized as going beyond the scope of medicine labels, but they were also in ICD-9. Once stood out and some kind of marginal mental retardation. It was still in the years of the USSR, and the ICD-8 criteria existed in the world at that time. Frontier mental retardation is IQ 68-85, but only too much optimist can consider this level abnormal, therefore this state has been fairly removed from all medical reference books and classifiers.

Mental retardation: forms

The concept of form is needed to classify the manifestation of backwardness. For example, Maria Semyonovna Pevzner proposed the following classification of states:

  1. uncomplicated oligophrenia,
  2. олигофрения, осложнённая нарушением нейродинамики (возбудимые, тормозные и с выраженной слабостью основных нервных процессов),
  3. олигофрения в сочетании с нарушениями различных анализаторов,
  4. олигофрения с психопатоподобными формами поведения,
  5. олигофрения с нарушениями функции лобных долей мозга.

They also speak about forms when they try to point out special cases or single out something clinical. The first is reflected in the ICD diagnosis F78 "other forms". It is placed if the situation is considered when the child has any other defects that do not allow him to be attributed to the general series. For example, there is reason to believe that a child has a low level of mental development, but he is deaf and dumb, blind, or suffers from some other diseases, which makes it difficult to diagnose according to common criteria. They also speak about clinical forms of mental retardation. This refers to the need for treatment. Most often, this occurs when the patient commits bad deeds, and his behavior requires correction. The degrees of correspondence of chronological age to the mental are not the basis for the gradation according to the principle “these are treated, but these are not treated”.

Special forms of mental retardation are often considered because of the need for differentiation. So, with the atonic form, affective immaturity and instability, mixing of emotions, lack of interest in the environment, weakening of instincts, randomness of activity, stereotypical movements come out on top. All this can be taken for autism or schizophrenia. However, in an atonic oligophrenia, children may try to make contact, but they fail. Similarly, productive symptoms of schizophrenia are not seen.

It is impossible to unambiguously answer the question of what is the most common clinical form of mental retardation. This is due to the different approaches to diagnosing and the general attitude to the problems. It is possible that such figures will be fair. In one way or another, low mental development concerns about 1% of children, and from 68.9% to 88.9% of them have a slight degree of mental retardation.

Moderate mental retardation: a brief description

At first about the easy form. This is a mental age of 9-10 years, and an IQ of 50-69. The fate of these children can be very different. It is possible to attend a regular kindergarten and secondary school. Of course, then we will most likely deal with the Losers, since a program designed for normal children is too difficult for such.

We note another difficulty. Some kind of problematic may not necessarily be associated with oligophrenia. Above, we said about the age of 9-10 years. So, if this is oligophrenia, and the degree of manifestation is debility, to say the same, the patient will never reach the mental age of 14-15 years, never look at the world with adult eyes, and his childishness should not be confused with the lyrical reluctance to grow up. It's all different.

But there is also a delay in mental development, which may be reversible. In other words, in the period from 7 to 9 years old, the child developed with great delay, but then “made up” the loss and became equal to his peers. Certain differences from them may persist, but not as pathological as with oligophrenia.

A child with a moderate form of mental retardation is the mental age of 6–9 years, his IQ is 35–49, and the traditional term for the designation is “unsharply expressed imbecility”. It's much worse. Patients differ in appearance, and in an ordinary school they would have nothing to do, but they will not get into it. They understand those around them, of course, if they don’t talk about quantum physics, they can express their thoughts themselves. Only their thoughts are very simple, and the expression is reduced to one or two words. Usually the vocabulary consists of several dozen words, but it can reach 200-300 words.

With moderate mental retardation, children study in special schools, where they manage to teach reading simple texts, writing individual phrases, and counting to ten. The main way of learning is to impart imitative skills. In this way, the youngest are taught to dress themselves and perform basic self-care activities, and older children as part of an extremely simplified school program. However, the author is aware of cases in which even handicraft skills were inculcated in children with a moderate degree of mental retardation. But for independent life in society, they are completely unsuitable.

Severe mental retardation: a brief description

This is pronounced imbecile. Speaking of moderate mental retardation, we started with a mild degree. And this time we start deep, i.e., idiocy. With idiocy, IQ is referred to as “up to 20”. In some cases, its definition is impossible, because the hero who can determine such an indicator for a child who does not understand or speak at all is not born. Immediately everything is not so scary, but not at all rosy. IQ is somewhere at the level of 20-34, and its definition, speaking the truth, depends on the diagnostician, and not on the patient himself. The mental age is 3-6 years old, but such imbeciles are not such children as healthy at 6 years old. Some of the usual 6 read and write, sing and dance, recite poems and collect not the cubes, but the designers. With severe mental retardation, children know a minimum of words, and also - they do not always know why they are actually needed, if you can show it with your hand.

However, they are different. They may be lethargic, apathetic, unresponsive or paradoxical. They can also be active, energetic and restless. Individual features are also different - someone is angry, aggressive, often there are flashes of anger, and someone is friendly, kind and helpful, loves praise and affection.

All that can be achieved from such children is to inculcate in them the skills of elementary self-service, and also to express their needs not with mysterious sounds, but with some words. Sometimes teachers consider it a great achievement when a pupil learns to designate his discomfort with the words “cold”, “hot”, “to the toilet”, “hurts”, or begins to use the words “good”, “satisfied” with meaning. There can be no talk of any independence in society.

In all cases, it is necessary to take into account the fact that mental retardation, although an independent nosological unit, may be a consequence of not something that happened before birth or during childbirth, but one of the consequences of the current disease. Some of these are incurable, and medicine can only somehow alleviate the overall severity of the situation.

Features of children with mental retardation

The main signs of a mentally retarded child are:

  1. Cognitive activity is low, so he does not want to know anything.
  2. Motility is poorly developed.
  3. The underdevelopment of all types of speech is observed: incorrect pronunciation of words, inability to construct sentences, poor vocabulary, etc.
  4. Slow thought processes, and often their absence. As a result, the child does not form abstract thinking, he cannot do a logical operation, a generalization is carried out only elementary.
  5. Productive activity is imitation, so all games are elementary. It gives preference to light labor, since there can be no willful effort.
  6. The emotional-volitional sphere is infantile, sharp changes in mood are possible without any reason. Excitability is quite high or, conversely, low.
  7. There are considerable difficulties in the perception of the world, which is caused by the fact that such children cannot single out the main thing, they do not understand the process of composing the whole from the parts that are located inside. They are hard to imagine. Therefore, they are poorly oriented in space.
  8. Attention focus is not long, switching to other objects and operations slow.
  9. Memory is arbitrary. More focused on the external signs of the subject than on the internal.

Oligophrenia and dementia - forms of the disease

The time of manifestation of signs of mental retardation determine two forms of the disease:

  • oligophrenia,
  • dementia.

Oligophrenia is a lesion of the cerebral cortex in the prenatal, natal and postnatal (only up to 3 years of age) periods, as a result of which mental or mental underdevelopment occurs.

Unlike physical defects, mental abnormalities, such as mental retardation, are difficult to determine in a child at an early age. Signs Beliefs of the disease begin to manifest in the process of further development of the baby.

Causes of oligophrenia are:

  • mother-borne infectious diseases during pregnancy,
  • asphyxia (birth trauma),
  • mental retardation of parents or at least one of them,
  • blood incompatibility on the Rh factor of the child and the mother,
  • parental use of alcohol, drugs.

Dementia is an organic lesion of the brain as a result of a previous illness or injury after a period of normal development of the central nervous system. A child's memory, attention is disturbed, emotions become poor, and behavior is disturbed.

The causes of dementia are:

  • brain injury
  • schizophrenia,
  • meningitis,
  • epilepsy and others

Degrees of mental retardation: idiocy, imbicity, moronity

Mental retardation is classified not only by the time of manifestation, but also by the depth of the lesion. The place of the brain damage is also important. So, according to many scientists, the degree of mental retardation affects:


Coming out of this, there are such degrees of mental inferiority:

Idiocy: a characteristic of the disease

Idiocy is a severe (deep) form of mental retardation. Such children cannot comprehend the world around them. Their speech functions are rather limited.

Such children have disorders:

  • coordination of movements
  • motility
  • behavior,
  • of emotions.

Their desires are associated only with the satisfaction of their physiological needs. Such children are untrained. The main task is to teach them elementary self-service skills. In the behavior of such children, there is lethargy, lethargy, and sometimes motor restlessness is possible. Idiocy happens 3 types:

  • complete (lying, deep) idiots,
  • typical idiots
  • speech idiots.

In deep idiots completely missing sensations. They resemble animals in behavior: they shout, jump, give inadequate reaction to any stimuli. Cannot serve themselves.

In typical idiots, unlike deep instincts expressed. To meet their physiological needs, they emit separate sounds. But their speech is not developed.

Speech idiots react to the world around them. Can say some words. But there is no cognitive activity. They learn to walk very late. The movements are uncertain, coordination is low, there are obsessive movements in the form of swaying the body.

The stay of such children (with the consent of the parents) is possible in special orphanages.

Teaching children with mental retardation

The child calmly masters the program of the auxiliary school (the total is not under his power), is efficient, and socially adapts easily. In a comfortable environment is always good-natured, nervous processes are balanced, the emotional-volitional sphere is preserved.

Debility, complicated by violations of different analyzers

Child development is difficult as a result of mental retardation, and a secondary defect. Social and labor adaptation are rather limited. Life prospects are few.

Debility with severe frontal insufficiency

Children, as a rule, are lethargic, helpless, inactive, do not like to work. They have a violation of motility. Speech verbose, but empty. The development of cognitive processes is very slow.

Morbidity with psychopathic behavior

In such children, the emotional-volitional sphere is not stable. Personal components are underdeveloped. Subject to constant unpredictable actions. Such children tend to run away somewhere.

Raising children with mental retardation

Raising such children is due to certain difficulties. But the main thing in their life is not the amount of knowledge that they must master. Quite different values ​​come to the fore. They need warmth, love and understanding of people close to them. Growing up in a comfortable environment, they will be able to learn certain work skills that they will fulfill with pleasure. These are people who will remain kind and unwilling to lie to children for the rest of their lives. They are good household and house helpers. They are easy to teach handicraft, which they will perform with great pleasure. Spending time with them systematically in conversations, telling and reading educational books, watching TV shows, they will constantly evolve, not degrade.

Of course, children who have a deep and moderate degree of mental retardation are not subject to any training. But they also feel the love of loved ones. Such children like when they play with them, read books to them, listen to music with them, study. They understand everything, but in their own way.

It is clear that parents themselves can’t cope with raising such a child. They need the help of a pathologist, who will explain the child’s features, help the parents understand the development process of the baby, and be able to establish difficult family relationships.

An important role at the initial stage is played by the correction of the psychological state of the mother, which should be everything to the child. The future of the baby depends on it: calm, comfortable, interesting, serene. A specialist will help in this matter, and then he will demonstrate the methods and techniques for working with a child.

Over time, parents can be not only passive observers, but also active participants in the educational process. They will not invent lessons that will be informative and useful for their child.

Returning to the words of the scientist L. Vygotsky, I would like to remind you that you need to find in the mentally retarded children what is not affected, and develop it to the maximum.