Neuropsychiatric disturbances in Parkinson's disease clusters in five groups with different prevalence of dementia

Objective: To investigate the inter-relationship of neuropsychiatric disturbances in Parkinson's disease (PD) by cluster analysis and describe the properties of the clusters. Method: A total of 139 patients were assessed using the neuropsychiatric inventory (NPI). A cluster-analysis was used to investigate the inter-relationship of NPI items. The clusters were profiled regarding dementia (PDD) and major depression. Results: A total of 39 patients showed no neuropsychiatric symptoms. The remaining 100 patients (43% PDD) were divided in to five clusters. The largest group (42, 31% PDD) showed symptoms of mild depression, followed by a group (29, 79.3% PDD) with hallucinations and mild other symptoms. The third group (14, 7.1% PDD) had sleep disturbances exclusively. The fourth group (8, 25% PDD) showed apathy, anxiety and depression. The smallest group (7, 57.1% PDD) had high scores on several NPI items. Conclusion: Our PD sample can be divided in to clusters based on the NPI, with different prevalence of dementia and depression.