Prevalence and impact of cerebrovascular lesions in Alzheimer and lewy body diseases

Background: Data on the prevalence of cerebrovascular lesions (CVLs) and their impact on cognitive decline in Alzheimer disease (AD) and Lewy body disease are conflicting.

Objective: Retrospective examination of the prevalence of CVL in a consecutive autopsy series.

Material and methods: 1,339 cases of autopsy-proven AD, Parkinson disease (PD), dementia with Lewy bodies (+ or - AD), and 486 age-matched controls were examined according to standardized neuropathologic methods including immunohistochemistry. Diagnoses followed current consensus criteria, classification of CVLs and of cerebral amyloid angiopathy (CAA) in 5 grades [Acta Neurol Scand 2006;114:38-46; Acta Neuropathol 2005;110:345-359].

Results: Lewy body variant of AD and AD showed significantly more frequent CVLs (91.9 and 67.8%) than the other groups (29.4 to 45.7%), with the highest frequency of severe CVLs (old, recent infarcts and hemorrhages) in AD (23.6%), but 2.0-8.3% in the other groups. Severe CAA was most frequent in AD and the Lewy body variant of AD (97.9 and 85%), less in PD (36%) and controls (30%). CAA was more frequent/severe in demented than in nondemented cases. CVLs in cortico-subcortical and hippocampal areas were most frequent in AD; subcortical CVLs (lacunes) in both AD and PD were more frequent than in controls. The incidence and severity of CVLs significantly correlated with neuritic Braak stages. Cognitive impairment was largely independent of coexisting CVLs, but related to the severity/location of AD and/or Lewy pathology.

Conclusions: The present data confirm the importance of CVLs in AD and in dementia with Lewy bodies with severe AD, and the little impact of CVLs alone, but show a close association of CAA with clinical dementia associated with AD pathology.