Dementia with Lewy bodies: reclassification of pathological subtypes and boundary with Parkinson's disease or Alzheimer's disease.

The present study is an attempt to reclassify the pathological subtypes of DLB based on both Lewy pathology and Alzheimer pathology, and to clarify the pathological boundary between DLB and Parkinson's disease (PD) or Alzheimer's disease (AD) in autopsied cases, using pathological and immunohistochemical methods. Dementia with Lewy bodies was classified into the limbic type and neocortical type according to the degree of Lewy pathology, including Lewy bodies (LB) and LB-related neurites, by our staging and was classified into the pure form, common form and AD form according to the degree of Alzheimer pathology including NFT and amyloid deposits by Braak staging. These combined subtypes were lined up on a spectrum not only with Lewy pathology but also with other DLB-related pathologies including Alzheimer pathology, neuronal loss in the substantia nigra, spongiform change in the transentorhinal cortex and LB-related neurites in the CA2-3 region. There were some similarities in both Lewy pathology and other DLB-related pathologies between PD and DLB, although Lewy pathology of PD was below the lowest stage of Lewy pathology. In contrast, AD did not meet the stages of Lewy pathology, and there were also no similarities in other DLB-related pathologies between AD and DLB. In addition, LB of AD showed the characteristics different from those of DLB on the coexistence of LB with NFT. These present findings suggest that DLB has pathological continuity with PD, but can be pathologically differentiated from AD. The present study clarified the pathological entity of DLB, compared with PD and AD.