Cerebral Microbleeds Are Associated with Impairments in Executive Function and Processing Speed.

Abstract

Cerebral microbleed (CMB) is an increasingly important risk factor for cognitive impairment due to population aging. Controversies, however, remain regarding the exact association between CMB and cognitive dysfunction. We aimed to determine the relationship between CMB burden and cognitive impairment, and also explore the characteristics of cognitive decline in CMB patients for middle-aged and elderly people. The present cross-sectional study included 174 participants (87 CMB patients and 87 controls) who underwent brain magnetic resonance imaging and a battery of neuropsychological test. Global cognitive function was measured using Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Compound z-scores were calculated for three cognitive subdomains: memory, executive function and processing speed. CMB patients had lower scores of MMSE (p < 0.001) and MoCA (p < 0.001). Patients at each category of CMB count had worse performance in global cognitive function and all three cognitive subdomains (p < 0.001). In multiple linear regression models, CMB patients had significantly greater declines in executive function (p < 0.001), processing speed (p < 0.001), and MoCA (p = 0.003) with increasing number of CMB. We found no relationship between CMB location and cognition (p > 0.05). CMB is associated with impairment in global cognition as well as for all tested subdomains. Strongest effect sizes were seen for tests which rely on executive functioning, where performance deficits increased in proportion to degree of CMB burden. Prospective studies are needed to evaluate whether the association between CMB and executive dysfunction is causal.