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Causes and pathogenesis of mental retardation
Last reviewed: 06.07.2025
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Epidemiology
The prevalence of mental retardation among different age groups of the population varies significantly, which explains the importance of the social adaptation criterion when making a diagnosis. The maximum values of this indicator fall on the age of 10-19 years, at which time society places high demands on the cognitive abilities of the population (schooling, conscription for military service, etc.).
The incidence rate of mental retardation worldwide ranges from 3.4 to 24.6 per 1000 people.
Causes of mental retardation
Underdevelopment of the brain can be a consequence of the influence of many factors. Among exogenous harmful substances alone, more than 400 agents are known whose action during pregnancy can disrupt the processes of embryogenesis. Pathogenic factors of the perinatal and early postnatal periods are important - hypoxia, neuroinfections, various somatic diseases. Hereditary factors, different in their mechanisms of action and nature of manifestations, play a particularly important role in the development of mental retardation. The occurrence of mental retardation is influenced by a deficit of sensory stimulation at an early age (mental deprivation).
Pathogenesis of mental retardation
When speaking about the pathogenesis of mental retardation, it is more correct to speak about the pathogenesis of diseases in which one of the symptoms is a disorder of brain development. The complexity of this problem is obvious, since even with such a well-studied disease as Down's syndrome, the pathogenesis of the intellectual defect itself has not been established.
Screening
Screening is used for early diagnosis of mental retardation caused by metabolic disorders. Along with phenylketonuria, screening can be aimed at identifying homocystinuria, histidinemia, maple syrup urine disease, tyrosinemia, galactosemia, lysinemia, and mucopolysaccharidoses. A special diet can help avoid or significantly reduce the severity of intellectual disabilities. Preventive measures include improving care for pregnant women, including obstetrics, preventing neuroinfections and traumatic brain injuries in young children, and iodine prophylaxis for people living in iodine-deficient areas.
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