Prevalence of Psychotic Symptoms in a Community-based Parkinson Disease Sample

Objectives: : To determine the prevalence of psychotic phenomena, including minor symptoms, in a Parkinson disease (PD) sample and compare the clinical correlates associated with the various psychotic phenomena. To evaluate the extent to which cases met National Institute of Neurological Diseases and Stroke (NINDS)/National Institute of Mental Health (NIMH)-proposed criteria for PD-associated psychosis.

Methods: : A total of 250 patients with idiopathic PD and Mini Mental State Exam scores greater than 23 from three community-based movement disorder clinics underwent comprehensive research diagnostic evaluations by a geriatric psychiatrist as part of a study on mood disorders in PD. Psychotic symptoms were categorized using a checklist, which included a breakdown of hallucinations, delusions, and minor symptoms. Clinical characteristics of groups with minor and other psychotic symptoms were compared. The NINDS/NIMH criteria for PD-psychosis were retrospectively applied.

Results: : Of the total sample, 26% of patients were found to have any current psychotic symptoms, with 47.7% of those having isolated minor symptoms, and 52.3% having hallucinations and/or delusions. Compared to those with no current psychiatric symptoms, minor symptoms were associated with more depressive symptoms and worse quality of life, and 90.8% of those with psychotic symptoms fulfilled the NINDS/NIMH proposed criteria.

Conclusions: : Psychotic symptoms are common in PD patients, with minor psychotic phenomena present in nearly half of affected patients in a community-based sample. Psychotic symptoms, including minor phenomena, were clinically significant. The NINDS/NIMH PD-psychosis criteria captured the clinical characteristics of psychosis as it relates to PD. Longitudinal studies are needed to determine whether minor psychotic symptoms represent a precursor to hallucinations and delusions, and to further validate diagnostic criteria.