The distribution of cerebrovascular amyloid in Alzheimer’s disease varies with ApoE genotype

We performed a comparative study to assess cerebral amyloid angiopathy and ApoE genotype in cases of Alzheimer’s disease (AD). Ten ApoE 3,3 and ten ApoE 4,4 AD brains, as well as ten normal control brains, were selected after matching for age, sex, and duration of disease. Sections of middle frontal and inferior parietal cortex including white matter sections were stained with an antibody against amyloid beta (Aβ), and extensive analysis of arteriolar Aβ deposition was performed using digital image analysis. Quantification of the staining revealed a larger cross-section of arteriolar walls occupied by Aβ in ApoE 4,4 and ApoE 3,3 AD subjects compared to controls. Our results show Aβ deposition in gray matter and white matter arterioles was predominantly found in ApoE 4,4 brains and, overall, Aβ deposition was greatest in these cases. This observation implies that there is greater vascular amyloid deposition (particularly in the white matter arterioles) in ApoE 4,4 AD individuals compared to ApoE 3,3 AD. These observations may give insight into the etiology behind the increased risk for AD associated with the ApoE-ε4 allele and the pathogenesis of vascular Aβ deposition.