O3-04-07: Prevalence and risk factors of cerebral microbleeds in the Rotterdam scan study

Abstract

Cerebral microbleeds (CMB) reflect small vessel disease and can be visualized with T2*–GRE magnetic resonance imaging (MRI). Their location may be related to different causative factors, since symptomatic deep grey matter hemorrhages are related to hypertension and lobar hemorrhages to cerebral amyloid angiopathy (CAA). Anticoagulants may be associated with CAA–related hemorrhages. Little is known on the occurrence of CMBs in the general population. We conducted an MRI study in healthy elderly persons to assess the prevalence and distribution of and the risk factors for CMBs. The study is based on 491 randomly selected participants (mean age 67.1; range 60.7–91.7) from the Rotterdam Study, a population–based cohort study among participants aged 55 years and older. We performed a custom–designed T2*–GRE susceptibility–weighted MR–sequence, with higher T2* weighting and smaller voxel size than commonly used T2*–GRE sequences, to increase the conspicuity of CMBs. Two raters scored the presence, location and number of CMBs. Intra–rater and inter–rater reliabilities were good to excellent. Cardiovascular risk factors were assessed by interview and physical examination, 5 years prior to and at the time of MRI. Associations between risk factors and CMBs were assessed by logistic regression and adjusted for age, sex, and relevant confounders. One or more CMBs were seen in 84 (17.1%) participants, with multiple microbleeds in 37, of whom 20 had five or more CMBs. Of participants with microbleeds, 80% had CMBs located in cortical grey and subcortical white matter, 24% in deep grey and white matter, and 27% had CMBs infratentorial. The prevalence of CMBs significantly increased with age (OR per year 1.05; 95%CI 1.01; 1.09). This association was particularly strong for multiple CMBs (OR per year 1.11; 95%CI 1.04; 1.17). Prior high systolic blood pressure was significantly related to CMBs in deep grey matter, but not to CMBs elsewhere, whereas use of antithrombotics showed a significant association with cortico–subcortical CMBs. Compared to previous studies, we found a two– to threefold higher prevalence of CMBs in a healthy elderly population. The prevalence of CMBs increased with age. Our initial analyses suggest an etiologic difference in CMBs in different locations.