Pharmacology of hallucinations induced by long-term drug therapy.

The authors studied 20 patients with Parkinson's disease and prominent hallucinations related to dopaminergic or anticholinergic therapy. The character of the hallucinations appeared distinct from the classic description of either acute anticholinergic or acute aminergic hallucinatory states. Manipulation of either kind of drug could precipitate or relieve hallucinations in a given patient, which suggests that the dopaminergic/cholinergic systems are reciprocally active in the pathophysiology of long-term drug-induced hallucinatory states in this population.