Influences of an Anticholinergic Antiparkinsonian Drug, Parkinsonism, and Psychotic Symptoms on Cardiac Autonomic Function in Schizophrenia

The arguments against the use of anticholinergic antiparkinsonian drugs for neuroleptic-induced parkinsonism have been based, in part, on their autonomic side effects. Except for anecdotal case reports, there is little evidence that antiparkinsonian drugs are the main factor causing autonomic dysfunction in schizophrenic patients with parkinsonism. Therefore, in the current study, the separate influences of the anticholinergic antiparkinsonian drug (biperiden), parkinsonism, and psychotic symptoms on cardiac autonomic function were investigated in 48 patients with schizophrenia. Biperiden was discontinued in 33 patients with or without parkinsonism and commenced in 15 patients with parkinsonism. Their parkinsonism and psychotic symptoms were assessed using rating scales, and their cardiac autonomic functions were assessed using the mean R-R interval and 3 methods of analyzing heart rate variability both before and after the change in medication. Consequently, the cardiac autonomic function was not affected by biperiden or the change in parkinsonism. Cardiac vagal function decreased when psychotic symptoms were more pronounced, but cardiac sympathetic function did not show a significant change. Therefore, it appeared that psychotic symptoms played the predominant role in modifying the cardiac autonomic function, implying the existence of autonomic changes associated with cognitive processing and a possible relation between psychotic symptoms and autonomic symptoms in schizophrenia.