Chronic schizophrenic males receiving both antipsychotic and antiparkinson medication had the latter replaced by placebo for a sixweek study period. To provide a double-blind control, a smaller group received matching tablets of benztropine mesylate. Of 403 patients receiving placebos, 7% were withdrawn from the study because of substantial return or appearance of extrapyramidal symptoms. Another 11% were judged to be worse from the rating scale data, but the remaining 82% seemed to get along quite well without antiparkinson medication, experiencing at most some temporary symptoms of extrapyramidal system disturbance. From these and other data, it is recommended that clinicians reconsider their prescribing habits, particularly prophylactic and long-term use of antiparkinson drugs.
Klett CJ, Point P, Caffey E. Evaluating the Long-Term Need for Antiparkinson Drugs by Chronic Schizophrenics. Arch Gen Psychiatry. 1972;26(4):374–379. doi:10.1001/archpsyc.1972.01750220084016