Incidence of cerebrovascular lesions in Alzheimer's disease: a postmortem study

Recent epidemiological and clinico-pathological data suggest overlaps between Alzheimer's disease (AD) and cerebrovascular lesions (CVL) that may show some synergistic effects, but the results of studies of the relationship between AD and stroke have been controversial. The objective of this study was to compare the frequency of cerebral infarcts, hemorrhages and minor cerebrovascular lesions in autopsy-confirmed AD and age-matched control brains. Using current routine and immunohistochemical methods 173 consecutive cases of autopsy-confirmed AD and 130 age-matched controls were compared. The total incidence of vascular pathology (56.5%) in AD was significantly less than in a previously reported smaller AD autopsy cohort (82.3%) (P<0.01), and was higher than in controls (42.4%). The incidence of severe CVL (old and recent infarcts, hemorrhages) in our cohort was slightly higher (12.7%) than in controls (8.5%), that of minor to moderate CVL (lacunes, cerebral amyloid angiopathy with or without minor vascular lesions) was more frequent in AD (43.8%) than in controls (33.9%), but the results were not statistically significant (P<0.03). The brain weight and severity of cognitive decline did not correspond to the degree of vascular pathology, but higher neuritic Braak scores and reduced brain weight contributed to the production of cognitive impairment. Like previous findings in Parkinson's disease, our data do not indicate a protective effect from stroke or a significantly greater susceptibility to death from stroke in AD in the population studied, but further prospective clinico-pathological studies are necessary.