Criteria for Alzheimer's Disease and the Nosology of Dementia with Lewy Bodies

Dementia with brainstem and neocortical Lewy bodies (LB) is a source of ongoing nosologic controversy and confusion. Differing opinions about concomitant Alzheimer's disease (AD) have produced competing nomenclatures. We applied neocortical plaque-based criteria for the diagnosis of AD from the National Institute on Aging and from the Consortium to Establish a Registry for AD for definite, probable, and possible AD to 58 dementia brains with LB, 10 elderly nondemented controls, and 58 brains with neuropathologically pure AD. We also employed diagnostic criteria requiring both neocortical plaques and tangles, and assessed the extent of neurofibrillary pathology in all 126 specimens using a modified version of the Braak and Braak staging protocol for changes related to AD. The percentages of mixed LB disease and AD versus pure LB disease varied from 91% mixed and 9% pure to 34% mixed and 66% pure, depending upon which diagnostic criteria for AD were employed. Most dementia brains with LB occupied higher modified Braak stages than controls, but lower ones than pure AD specimens. A minority of the dementia brains with LB had no more AD-type pathology than controls.