Summary

In 1980 we proposed Lewy body disease (LBD) as a disease entity and classified it into three types: brainstem, transitional, and diffuse. The brainstem type is identical to Parkinson's disease, and the diffuse type is now called diffuse LBD (DLBD).

DLBD has become the subject of much attention since the publication of our studies on DLBD. It has recently been reported that DLBD is the second most common cause of dementia among the elderly. Our recent study of 79 consecutive autopsied dementia cases suggests that also in Japan DLBD is the second most common degenerative dementia, following Alzheimer-type dementia (ATD). In 1990, we divided DLBD into two forms: a pure form and a common form. Then, it was noted that in 30% of the common form DLBD cases no parkinsonism was detected, although Parkinson pathology was present. Very recently, we proposed cerebral type of LBD as yet another type of LBD, in which cortical dementia without parkinsonism is the predominant symptom and there are as many cortical Lewy bodies as in DLBD, but Parkinson pathology is absent. This feature suggests that the development of cortical Lewy bodies can precede Parkinson pathology. Therefore, this might explain why cortical dementia precedes Parkinson symptoms in many DLBD cases. Thus, LBD is now classified into four types, and DLBD is understood within the spectrum of LBD. The frequency of cortical Lewy bodies is important. More than five or ten cortical Lewy bodies per x 100 visual field in the predilection sites are necessary for the diagnosis of DLBD or cerebral type LBD in HE or ubiquitin-immunostained sections, respectively.