Neurodevelopmental Disorders

Question 1

What are the requirements for a diagnosis of Intellectual Disability?

Answer 1

For this diagnosis, the person must have:
(a) deficits in intellectual functioning as determined by the results of a clinical assessment and a score that is about two standard deviations below the mean on an individualized, standardized intelligence test;
(b) deficits in adaptive functioning that cause a failure to meet community standards of personal independence and social responsibility and impair functioning in one or more activities of daily life in multiple contexts;
(c) an onset of the deficits during the developmental period.

*A specifier is used to indicate level of severity (mild, moderate, severe, or profound), which is based on adaptive functioning in conceptual, social, and practical domains and is useful for determining the amount of support the person needs.
*The cause of intellectual disability is known in 25 to 50% of all cases. Of cases with a known etiology, about 80 to 85% are due to prenatal factors (which includes chromosomal and other genetic causes), 5 to 10% are due to perinatal factors (e.g., asphyxia), and 5 to 10% are due to postnatal factors.
*The most common chromosomal causes are Down’s syndrome followed by fragile X syndrome, and the most common preventable prenatal cause is fetal alcohol syndrome (Kilgus, Maxmen, & Ward, 2015).