EFFECT OF CLOZAPINE ON MOTOR FUNCTION IN SCHIZOPHRENIC-PATIENTS

It is well established that clozapine is less likely than typical anti psychotic drugs to cause clinically discernible extrapyramidal side-ef fects. There is a paucity of data, however, on clozapine's motor effec ts. In this report we compare normal controls to groups of chronic sch izophrenic patients treated with either typical antipsychotic drugs or with clozapine. Motor function was measured with a target-matching ta sk, a test relying on submaximal sustained force control. Results indi cated that patients on clozapine performed with significantly lower ac curacy (greater variability) of force control. Even though the clozapi ne patients were treatment resistant to typical antipsychotic drugs, a nd many had a history of tardive dyskinesia, we postulate that the obs erved deficit is likely due to clozapine treatment rather than to earl ier treatments or other factors. The observed force control deficit ma y be the result of an increase in myoclonus and a generally lower leve l of overall motor activity.