THE EFFECTS OF DRUG-INDUCED PARKINSONISM ON THE PSYCHOMOTOR PERFORMANCE OF CHRONIC SCHIZOPHRENICS

Abstract

Fourteen chronic schizophrenics were given a battery of five psychomotor tests under a medication regimen designed to provide clinically manifest symptoms of extrapyramidal motor dysfunction. It was hypothesized that (1) the level of psychomotor performance would be negatively related to the level of extrapyramidal motor dysfunction; and (2) drug-induced Parkin-sonism would cause a deficit in fine psychomotor performance, whereas gross psychomotor activity would be less affected. The results indicated that: (1) the medication produced clinically apparent evidence of extrapyramidal motor system dysfunction; (2) all of the psychomotor measures showed maximum effect in close temporal agreement with the maximum EPS dysfunction; and (3) all measures except the transport function of the transport manipulation test exhibited a decrement in performance. The latter showed an increment in performance. A possible explanation in terms of interaction with the manipulation element of the test was proposed. The conclusions were that: (1) the psychomotor tests are sensitive to the presence of drug-induced extrapyramidal motor system dysfunction, with the transport-manipulation test exhibiting the best differential effect, and (2) fine psychomotor co-ordination is more affected than are grosser measures.