Hallucinations in Parkinson's disease

The appearance of psychiatric symptoms is not rare in the course and treatment of Parkinson's disease. In particular, therapy with L-dopa or dopamine agonists leads to increased dream activity. As with sleep disturbances, this can be a warning signal of paranoid hallucinatory psychosis. However, isolated visual hallucinations before manifest psychosis in Parkinson's must generally be regarded as resulting from medication. They occur in up to 30% of Parkinson's patients and often involve visual and figurative hallucinations. Visual hallucinations most probably result from the combined effect on dopaminergic and serotonergic systems in the CNS. Therapy consists in normalization of H2O and electrolyte levels, control of the accompanying medication, reduction of the evening doses of anti-Parkinson's medications, and serotonin antagonists such as clozapine.