Neuropathological investigation of the hypometabolic regions on positron emission tomography with [18F] fluorodeoxyglucose in patients with dementia with Lewy bodies.

We performed a quantitative neuropathological examination of the hypometabolic regions on FDG PET in dementia with Lewy bodies (DLB), Alzheimer's disease (AD) and control cases. When the DLB cases were divided into two groups according to concomitant AD pathology (ADP), neuronal loss in the temporo-parietal association area was milder in the DLB groups than in the AD group, although there were no differences between the two DLB groups. Tau and Aβ immunoreactivities were observed in the AD group and the DLB group with ADP, but were rare in the DLB group without ADP. Tau and Aβ immunoreactivities as well as numbers of neurofibrillary tangles (NFTs) and neuritic plaques (NPs) were more common in the AD group than in the DLB group with ADP. There was no difference in neuronal loss in the occipital area among the three groups. α-Synuclein immunoreactivity was observed in the DLB groups but not in the AD group. There were no differences in α-synuclein immunoreactivity and number of Lewy bodies (LBs) between the two DLB groups. These findings indicate that the neuropathological bases of the hypometabolic regions in the temporo-parietal association and occipital area in DLB may be AD pathology and Lewy pathology, respectively.