The motor disorders of mental handicap. An overlap with the motor disorders of severe psychiatric illness.

Among 236 in-patients in one hospital for the mentally handicapped, there was a significant relationship between the amount of motor disorder (rated using a comprehensive check-list) and the severity of mental handicap, the presence of associated psychiatric disorder and the use of neuroleptic medication. The population was fairly evenly divided between those currently, previously and never having received neuroleptic medication. All categories of motor disorder, including abnormal movements, were present in all three subgroups. Neuroleptic medication appeared to modify the expression of motor disorder rather than producing it de novo. The range and frequency of motor disorders was comparable with that in patients with severe psychiatric illness. A common cerebral basis for the motor disorders of patients with mental handicap and severe psychiatric illness is suggested.