Prevalence and Risk Factors of Cerebral Microbleeds: An Analysis From the UK Biobank.

OBJECTIVE: To determine the prevalence and risk factors for cerebral microbleeds (CMB) at different locations in a large healthy community population. METHODS: 8159 subjects from UK Biobank with MRI scans suitable for CMB analysis were included. Brain susceptibility weighted imaging (SWI) data was acquired on two identical 3.0 T scanners. The Microbleed Anatomical Rating Scale (MARS) was used to identify definite CMB. Generalized linear models were used to determine independent associations with all CMB and lobar, deep and infratentorial CMB. RESULTS: The mean age at scan was 62.1±7.4 years. One of more definite CMB were detected in 572 (7.0%) of subjects. Of those with CMB 439 (76.7%) had lobar CMB, 103 (18.0%) had deep CMB, and 83 (14.5%) had infratentorial CMB. Age was an independent risk factor for CMB in all locations. ApoE4 and male sex were positively, and higher BMI were negatively associated, with lobar CMB. In contrast, hypertension, smoking and alcohol consumption were associated with deep CMB, but not with lobar CMB. Only age was associated with infratentorial CMB. The associations were unchanged after controlling for WMH lesion volume as a marker of small vessel disease severity. CONCLUSIONS: In this large population based study, the CMB prevalence detected using a low sensitivity and high specificity system was 7%. There were distinct risk factor profiles for CMB in lobar and deep locations consistent with different underlying pathophysiological processes