Background We investigated the prevalence of and risk factors for cerebral microbleeds (CMBs) in a cross-sectional study of a general population of Japanese elderly. Methods In 2012, brain MRI scanning at 1.5T and comprehensive health examination were conducted for 1281 residents aged 65 years or older. CMBs were defined as ovoid hypointensity lesions less than 10 mm in diameter on T2-weighted images and classified into deep/infratentorial or lobar CMBs. Age- and sex-specific and overall prevalence of CMBs were estimated, and the associations of traditional cardiovascular risk factors and APOE polymorphism with the presence of CMBs were examined using a logistic regression analysis. Results The crude prevalences of total, deep/infratentorial, and lobar CMBs were 18.7% (n = 240), 13.5% (n = 173), and 9.6% (n = 123), respectively. The prevalence of total CMBs was 23.0% in men and 15.5% in women and increased with aging in both sexes (both p for trend <0.01). Hypertension was significantly associated with the presence of both deep/infratentorial and lobar CMBs. Lower serum total cholesterol was a significant risk factor for deep/infratentorial CMBs, but not for lobar CMBs, while APOE ϵ4 carriers had a significantly higher likelihood only of lobar CMBs compared with noncarriers. Conclusions Our study suggests that approximately 1 of 5 Japanese elderly people have CMBs, and that risk factors for deep/infratentorial and lobar CMBs are different, indicating the distinct pathologic backgrounds of these lesions.
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