The impact of cerebrovascular lesions in Alzheimer disease--a comparative autopsy study.

BACKGROUND: Recent epidemiological and clinico-pathological data suggest overlaps and some synergistic effects between Alzheimer disease (AD) and cerebrovascular pathology, but the results of studies of the relationship between the two types of lesion have been controversial.
OBJECTIVE: Comparison of the frequency of cerebral infarcts, hemorrhages and minor cerebrovascular lesions in AD and age-matched control brains. SUBJECTS AND METHODS: 730 consecutive cases of autopsy-proven AD and 535 age-matched controls were compared using current routine and immunohistochemical methods. Results The total prevalence of cerebrovascular pathology in AD was significantly higher than in controls (48.0 vs 32.8%, p<0.01). Minor to moderate cerebrovascular lesions (lacunes, amyloid angiopathy with and without minor vascular lesions) were more frequent in AD than in controls (31.6 vs 23.4 %), the frequency of severe vascular pathology (old and recent infarcts and hemorrhages) in AD was significantly higher than in controls (16.7 % and 7.4 % vs 2.1% and 3.2%, respectively, p<0.01). There was no correlation between the severity of cerebral amyloid angiopathy with minor to severe subcortical lacunes and Ammon's horn sclerosis or to acute and old ischemic infarcts. On the other hand, acute and old cerebral hemorrhages were significantly correlated with severe amyloid angiopathy. 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.
CONCLUSION: In accordance with previous findings in AD and in Parkinson disease, our data indicate a higher incidence of cerebrovascular lesions and greater susceptibility to death from stroke in AD in the population studied, but further prospective clinicopathological studies are warranted.