Subnormal intellectual functioning which originates during the developmental period. This has multiple potential etiologies, including genetic defects and perinatal insults. Intelligence quotient (IQ) scores are commonly used to determine whether an individual is mentally retarded. IQ scores between 70 and 79 are in the borderline mentally retarded range. Scores below 67 are in the retarded range. (Joynt, Clinical Neurology, 1992, Ch55, p28)

Synonyms: Mental Retardation, Psychosocial Psychosocial Mental Retardations Deficiency, Mental Mental Deficiency Psychosocial Mental Retardation Disability, Intellectual Retardation, Mental Mental Deficiencies MENTAL DEFIC Retardation, Psychosocial Mental Intellectual Disabilities Idiocy DEFIC MENTAL Deficiencies, Mental Retardations, Psychosocial Mental Disabilities, Intellectual Intellectual Disability Mental Retardations, Psychosocial