Psychosis in Parkinson's disease]

Psychosis is common in Parkinson's disease, and occurs with increasing frequency as the disease progresses. Assessment and treatment are often complicated and involve several clinical specialists in addition to the general practitioner. We describe the prevalence, form, causes and treatment of psychosis in Parkinson's disease.The article is based on a literature search in PubMed for controlled pharmacological treatment studies and a discretionary selection of articles based on the authors' clinical and research experience.About 1 % of patients with newly diagnosed Parkinson's disease have psychotic symptoms. In later stages, complicated by dementia, these symptoms occur in about half of the patients. A false sense of presence, optical illusions and visual hallucinations occur most frequently, but delusions and hallucinations involving other senses have been reported. Various theories to explain the underlying etiology and pathology are explored. A further medical assessment is recommended when psychotic symptoms occur. Clozapine is still the only antipsychotic drug documented effective against psychotic symptoms in Parkinson's disease.The prevalence of psychotic symptoms in various stages of Parkinson''s disease has been thoroughly documented. Non-pharmacological treatment is often effective, but the documentation is inadequate. Pharmacological treatment with clozapine has proved effective against psychosis in Parkinson's disease, but new drugs that are easier to administer are needed.