Having a general level of intellectual function that is significantly below average and that exists concurrently with deficits in adaptive behavior. These behavioral changes may first appear in childhood or may develop after head trauma or stroke. This condition is sometimes called “organic brain syndrome” in adults or “mental retardation” in children. Chronically neurologically impaired children are often grouped epidemiologically with persons who have other developmental disabilities including chronic epilepsy, autism, and cerebral palsy.