Therapeutic antagonism between anticholinergic antiparkinsonism agents and neuroleptics in schizophrenia. Implications for a neuropharmacological model.

Systematic data from three studies suggest that anticholinergic antiparkinsonism agents, when added to ongoing neuroleptic treatment in schizophrenics, have the effect of arresting or reversing therapeutic changes, and when given alone to untreated patients, tend to further worsen their psychosis. The countertherapeutic effects of anticholinergic drugs are reflected particularly in parameters which represent features of schizophrenic psychosis most consistently responsive to neuroleptics. It is proposed that these anticholinergic effects are central in origin and point to the involvement of cholinergic mechanisms in the expression of schizophrenic psychosis and its improvement with neuroleptic medication.