Background The mechanisms underlying vascular cognitive impairment remain poorly understood. Brain microbleeds may contribute, particularly to executive dysfunction. We investigated the cognitive effects of microbleeds and other neuroimaging markers for cerebrovascular disease in a large, hospital-based study.

Methods Consecutive, unselected patients referred to the stroke unit or clinic underwent clinical assessment, detailed neuropsychological testing and vascular MRI. Microbleeds, white matter changes (WMC) and brain infarcts were identified and their effects on cognition assessed.

Results 242 patients were included (N=60 with, N=182 without microbleeds). Executive impairment was more prevalent in patients with microbleeds than without (37% vs 20%; p=0.008). Patients with microbleeds were impaired in more cognitive domains than those without (p=0.007). The presence and number of lobar microbleeds, number of infarcts, and mean WMC score independently predicted executive impairment. The number of lobar microbleeds predicted impairment in multiple cognitive domains (OR 2.05, 95% CI 1.01 to 4.16, p=0.048), as did infarct number. Total microbleed count correlated with number of cognitive domains impaired (p=0.002).

Conclusion Lobar microbleeds were independently associated with executive dysfunction and extent of cognitive impairment; number of infarcts and WMC score also contributed, suggesting an interaction between these different imaging markers of cerebrovascular disease.