It is not a medical disorder, nor a mental disorder. It is a particular state of functioning that begins in childhood and is characterized by limitations in both intelligence and adaptive skills. Definition of mental retardation from the American Association on Mental Retardation, 1992. Based on the 1990 census, an estimated 7 million individuals have mental retardation. Mental retardation is 10 times more common than cerebral palsy and 25 times more prevalent than blindness.
Mental retardation cuts across racial, ethnic, educational, social and economic backgrounds.
One out of every 10 American families is directly affected by mental retardation. The effects of mental retardation vary considerably. Eighty-seven percent of individuals will be mildly affected and will only be a little slower than average in learning. Thirteen percent will have serious limitations in functioning. Early intervention, a functional education, and appropriate supports as adults can enable satisfying lives in the community.