Introduction: Cerebral microbleed (CMB) location may predict underlying pathology. Deep CMBs are more associated with hypertensive vascular disease, while lobar CMBs are more associated with cerebral amyloid angiopathy (CAA). The objective of this study was to determine the neuroimaging pathology associated with CMBs.
Methods: We analyzed 1,831 nondemented ARIC participants (mean age=76.3 ±5.3 years, 40% male, 27% black) with 3T MRI scans at the fifth exam (2011-13). We fit multinomial logistic regression models to assess the effect of brain volumes (AD signature region atrophy, total gray matter, frontal, and log2-transformed white matter hyperintensities (WMH) volume), infarct frequencies (lacunar, non-lacunar, and total), and APOE (number of ε4 alleles) on CMB location (no, any deep, or lobar only CMBs). Models were weighted for the sample selection scheme and adjusted for age, male, education, hypertension, ever smoking status, diabetes, race-site membership, and estimated intracranial volume (brain volume models only).
Results: The frequency of CMBs was 24.1%. A larger WMH volume, greater total infarct frequency, and smaller total grey volume increased the relative risks (RR) of both deep and lobar CMBs compared to no CMBs; increasing the WMH volume also increased the RR of deep to lobar CMBs. Additional lacunar infarcts increased the RR of deep compared to no CMBs, whereas AD signature region atrophy and APOE ε4 homozygosity increased the RR of lobar CMBs.
Conclusion: CMBs are a common vascular pathology in the elderly. Deep CMB presence is associated with MRI features of hypertensive small vessel disease, while lobar CMB presence is associated with MRI features of CAA and Alzheimer’s disease.