Psychiatric morbidity in dementia with Lewy bodies: A prospective clinicaland neuropathological comparative study with Alzheimer's disease

Objective: The literature reports considerable variation in the rates of ps ychiatric morbidity for patients with dementia with Lewy bodies. The author s intended to clarify the frequency of psychiatric morbidity in dementia wi th Lewy bodies and how it differs from probable Alzheimer's disease. Method : The study incorporated two groups-a clinical case register cohort (98 wit h dementia with Lewy bodies; 92 with Alzheimer's disease) and 80 (40 with d ementia with Lewy bodies; 40 with Alzheimer's disease) prospectively studie d, neuropathologically confirmed cases. Diagnoses were made by using the Mc Keith et al. consensus criteria for dementia with Lewy bodies and the Natio nal institute of Neurological and Communicative Disorders and Stroke and th e Alzheimer's Disease and Related Disorders Association criteria for Alzhei mer's disease. Neuropathological diagnoses were made by using the consensus criteria for dementia with Lewy bodies and the Mirra et al. protocol for A lzheimer's disease. Results: The occurrence of psychiatric symptoms was rep orted over 1 month. Hallucinations, depression, delusions, and delusional m isidentification were ail significantly higher for patients with dementia w ith Lewy bodies. The differences in frequency between dementia with Lewy bo dies and Alzheimer's disease for auditory and visual hallucinations were es pecially pronounced for patients with mild cognitive impairment. The presen ce of psychiatric symptoms at presentation was a better discriminator betwe en dementia with Lewy bodies and Alzheimer's disease than occurrence over t he course of dementia. Conclusions: Delusional misidentification and halluc inations in the early stages of dementia may improve differentiation betwee n patients with dementia with Lewy bodies and those with Alzheimer's diseas e and have important treatment implications.