A comparative study of psychiatric symptoms in dementia with Lewy bodies and Parkinson's disease with and without dementia

Objectives: To compare the frequency and clinical correlates of neuropsychiatric symptoms in patients with Parkinson's disease (PD) with and without dementia and in those with dementia with Lewy bodies (DLB).

Methods: Neuropsychiatric symptoms during the month prior to assessment were assessed in clinically diagnosed PD patients with dementia (PDD; n = 48) and without dementia (PDND; n = 83) and in 98 DLB patients (33% autopsy confirmed) using standardized instruments.

Results: Delusions and hallucinations were significantly more common in DLB (57% and 76%) than PDD (29% and 54%) and PDND (7% and 14%) patients (p < 0.001). In all groups, auditory and visual hallucinations and paranoid and phantom boarder delusions were the most common psychotic symptoms. Frequency of major depression and less than major depression did not differ significantly between the three groups. Clinical correlates of hallucinations in PD were dementia (odds ratio (OR) = 3.9; 95% confidence interval (CI) 1.5-10.4) and Hoehn-Yahr stage 3 or more (OR 3.4; 95% CI 1.0-12.0), whereas no significant clinical correlates of hallucinations were found in DLB patients.

Conclusions: Delusions and hallucinations occur with increasing frequency in PDND, PDD and DLB patients, but the presentation of these symptoms is similar. These findings support the hypothesis that psychiatric symptoms are associated with cortical Lewy bodies or cholinergic deficits in the two disorders.