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Intellectual Disability: Biological Factors

Intellectual disability (ID) is a condition diagnosed prior to age 18 years that includes limitations in intellectual functioning (e.g., reading, learning, problem solving) and a decrease in adaptive behavior, including conceptual, social, and practical skills. ID is diagnosed utilizing standardized tests of intelligence and adaptive behavior. ID affects between 2% and 3% of the U.S. population. There are numerous biological factors involved in identified causes of ID; however, for up to 60% of cases, there is no identifiable cause. The biological factors can be categorized utilizing the following:

  • Infectious disease
  • Chromosomal abnormalities
  • Biomedical conditions
  • Prenatal, perinatal, and postnatal issues
Infectious Disease

Infections during pregnancy are important biological factors regarding ID in the unborn child; the most common relevant infectious processes include cytomegalovirus (a common virus that may not cause symptoms ...

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