Cognitive burden and excess Lewy-body pathology in the Lewy-body variant of Alzheimer disease.

Objectives Authors compared the degrees of cognitive deficit among individuals with Alzheimer disease (AD), the Lewy-body variant of AD (LBV), and "pure" dementia with Lewy bodies (DLB); and compared cortical Lewy body (LB) counts in LBV versus DLB and neuritic plaque and neurofibrillary tangle severity in LBV versus AD. Methods Authors examined brain specimens from consecutive autopsies of elderly nursing home subjects. Numbers and densities of plaques, Lewy bodies, and tangle severity were determined in multiple cortical regions, and demographic and clinical variables were compared among the three groups. Results The three groups did not differ in demographic or clinical variables. The LBV group was significantly more impaired than the other groups. Cortical LB counts were significantly higher in LBV than in DLB. There was no evidence of increased plaque or tangle severity in LBV than in AD. Conclusion The co-occurrence of AD and LB pathology is associated with higher numbers of LBs and more severe dementia than when classical AD or LB lesions occur alone.