An autopsied case of dementia with diffuse Lewy bodies was reported. The onset was at the age of 55-year-old. The initial symptoms of the patient had been depression for several years. The following clinical course showed fluctuating neuropsychological symptoms with hallucinations, delusions and parkinsonism with muscular rigidity and hypokinesis.

Head MRI showed progressive brain atrophy of the medial temporal lobes and MIBG-scan revealed low uptake findings. Total duration of the illness was 22 years.

Neuropathologically, the brain weight was 1,320g. Macroscopic findings showed atrophy of the medial temporal lobes. Brain stem revealed marked reduction of pigmentation in the substantia nigra. The main histological findings were the presence of abundant LB throughout the central nervous system and brain stem. Cortical LBs were found in the small neurons of the deeper cortical layers, mainly in the temporal, frontal and insular cortices and parahippocampal region. In the brain stem, wide spread presence of LBs were found including the substantia nigra, locus caeruleus and dorsal raphae nuclei. A few NFTs were observed in the hippocampal region. Brain-stem pathology proceeds first to cortical pathology from clinical symptoms. These findings suggest that Lewy body related pathology is associated with initial depressive symptoms. Clinicopathologically, it should be concluded that a common form with Alzheimer's pathology and a pure form without it could be differentiated.