A developmental disability is a mental or physical impairment that occurs before age 22, continues indefinitely and causes substantial difficulties in self-care, learning, mobility and economic independence.
Mental retardation is the most common developmental disability.
Others include cerebral palsy, autism, spina bifida, Tourette syndrome and epilepsy. Mental retardation and other developmental disabilities cut across all lines of race, educational, social and economic background. Any condition that impairs development before birth, during birth or in the early years can cause mental retardation and other developmental disabilities. In most instances, there is no known cause for an individual's disability. Mental retardation refers to below average intellectual functioning and can be expected to be permanent.