General Psychology Psychiatry Psychologists Thinkers Crib

Psycology » Articles » Common Questions » Types and causes of mental retardation

  • Mental retardation (mental retardation)
  • Mental retardation: classification
  • Types and causes of mental retardation
  • Diagnosis and treatment of mental retardation

In regard to mental retardation is Etiopatogenetichesky heterogeneous group. Very significant hereditary factor, as well as exogenous organic stigma (damage to the body during early ontogeny). Currently valid reasons of mental retardation can be installed in 30-35% of patients with mental retardation. The remaining cases are regarded as "undifferentiated form." Diagnostic difficulties are directly proportional to the severity of intellectual defect. According to E. Reed and S. Reid (1965), 29% of the total cohort of patients have mental retardation hereditary nature of pathology, 19% greater likelihood of discovering the prevalence of genetic factors in 9.5% excel external environmental factors in the etiology of 42.5% is not clear. Various forms of mental retardation are genetic nature is confirmed kolichestvmo large (at least 200) of hereditary diseases and syndromes involving mental retardation. Causes of mental retardation, a significant part of undifferentiated diagnoses of the disease may also have a genetic basis.
Among the external factors that contribute to adverse effects on the brain with mental retardation, a significant role is played by various toxins, alcohol, ionizing radiation and radionuclides action. Dangerous risk factor for mental retardation is the use of alcohol in the mother during pregnancy. Particularly serious consequences are possible when exposed to toxins on the fetus in the first trimester of pregnancy. Exogenous factors acting on the fetus during pregnancy and capable of leading to mental retardation may be viral infection (influenza, hepatitis, syphilis), intoxication, various somatic diseases in the mother, placenta pathology, etc. Factors associated with childbirth themselves - prematurely born, rapid delivery, birth asphyxia, mechanical injury.

Genetically caused mental retardation

Chromosomal aberrations are fairly common causes of oligophrenia. Defects largest chromosomes (first to twelfth pair) lead to the non-viability of the embryo and abortion. Trisomy thirteenth to eighteenth chromosome pairs leads to the death of a child in the first year of life. Deletion of the short arm of chromosome 5 generates mental retardation "cat cry syndrome" deletion long arm of chromosome 18 generates syndrome Lejeune. These syndromes manifest severe mental retardation - idiocy, imbecility pronounced. In adults, the most common trisomy of chromosome 21 (Down syndrome) and sex chromosome defects.
Down syndrome is the cause of its development, chromosomal aberration (error), expressed in trisomy of chromosome 21. First case of this disease described L. Down in 1866. The frequency of the disease in newborns is an average of one case per 600-700 births. Genetic causes breaking special metabolic disorders, thereby developing the characteristic clinical manifestations. Cases of Down's syndrome are often observed at birth mother after 35-45 years.
The clinical picture is characterized by severe mental retardation, which is combined with the typical physical anomalies, whereby patients are very similar to each other ("children of the same mother.") Their appearance is very characteristic: round face, the nose is small, flattened, thickened nasal bridge, massive cheeks, red eyes properly planted, have skin folds at the inner corner with Epicanthus, the presence of areas of depigmentation on the periphery of the iris, tongue thick, barely fits in the mouth cavity, mouth slightly open, teeth rare head is flattened in the anteroposterior direction, sloping skull (brachycephaly). Ears small size, deformed, low located. Often there is hypoplasia of the mandible (or top), the high sky. Expressed korotkopalost, small growth, reducing the size of genitals, flatulence ("belly gorilla"), hair loss. Flat brush, fingers wide, short, short, curved inward pinky phenomena seam fingers (syndactyly). Pronounced hypotonia, joint laxity, "guttaperchivost." Marked impairment in cardiovascular pathology. Mental retardation in the majority expressed in degrees imbecility, 20% - of idiocy and only 5% - debility.
In such patients, the vocabulary is small, inarticulate speech, clumsy movements, awkward, inaccurate, sometimes found inappropriate restlessness. They are very prone to imitation, so deeply demented patients the wanton copying (ehokinezii), in mild cases, they deliberately and accurately repeated gestures, manners of speech of others, their gait and action. This is combined very often with good humor, kindness, affability. But can occur indifferent, sluggish, angry, irritable patients.

Syndrome Fragile-X syndrome (Martin-Bell).

Frequency in the population observed indicators 1,8:1000 boys and girls 1:2000. Specific features are the large protruding ears, high arcuate palate, nose with a tapered tip and broad base, high prominent forehead, dolihotsefalichesky skull, elongated face. Giperelastichny skin, joints have an increased ability to extension (looseness). Characteristic feature is the increase in testicular size (makroorhizm) that are not accompanied by a disturbance of endocrine functions. Psyche patients has a characteristic mental deficiency with specific speech disorders (fast paced, perseveration with fast repetition of individual phrases or endings).
Diagnostic difficulties at an early stage of the disease depend on the autistic behaviors, echolalia, motor phenomena katatonopodobnyh character. This in some cases gives grounds for suspecting the onset of schizophrenia, but the presence of intellectual decline helps to accurately diagnose mental retardation.

Syndrome XXY (Klinefelter's syndrome).

In 1942 he described a congenital disorder Klinefelter men, which was characterized by eunuchoid body structure, gynecomastia, hypogonadism and azoospermia (absence of sperm).

© 2008-2021 Psychology online.: en, es, de, fr, cz