Psychiatric features in diffuse Lewy body disease: a clinicopathologic study using Alzheimer's disease and Parkinson's disease comparison groups.

We conducted a retrospective study to determine the frequency of depression, hallucinations, and delusions in patients with diffuse Lewy body disease (DLBD) and to compare these findings with those in Alzheimer's disease (AD) and Parkinson's disease (PD). One hundred twelve subjects were included in the study. Of these, 28 subjects were diagnosed with DLBD, 58 with AD, and 26 with PD at autopsy. Main outcome measures included the percentages of subjects in each of the three categories in whom depression, hallucinations, or delusions were reported at any time during the course of the illness. Hallucinations and delusions were further classified by type. We found that depression was more common in DLBD (50.0%) than in AD (13.8%) (chi 2 = 13.00, p = 0.0003). There was no difference in the frequency of depression in DLBD and PD (57.7%) (chi 2 = 0.32, p = 0.57). Hallucinations were reported more frequently in DLBD (60.7%) than in AD (34.5%) (chi 2 = 5.30, p = 0.021). There was no difference in the frequency of hallucinations in DLBD and PD (53.8%) (chi 2 = 0.26, p = 0.61). Delusions were more common in DLBD (57.1%) than in PD (15.4%) (chi 2 = 10.08, p = 0.0015). There was no difference in the frequency of delusions in DLBD and AD (53.4%) (chi 2 = 0.10, p = 0.75). There was a male predominance of DLBD cases and PD cases; AD cases were predominantly women. We conclude that psychiatric features are very common in DLBD and should be a central diagnostic criterion for the disease.