Association between cerebral microbleeds and cognitive function: a systematic review.

Background: Cerebral microbleeds (MBs), defined as haemorrhagic microvascular lesions or microangiopathy in the brain, have traditionally been considered clinically silent. Recent studies, however, suggest that MBs are associated with a decline in cognitive function.
Objective: To determine whether an association between MBs and cognitive function exists, we conducted a systematic review of the literature using the Cochrane Library, MEDLINE, EMBASE and the China National Knowledge Infrastructure database. We also searched the reference lists of relevant studies and review articles.
Results: A total of seven studies were included. Qualitative meta-analysis of two studies suggested that the presence of MBs was significantly associated with cognitive impairment, while quantitative meta-analysis revealed an association between MBs and cognitive dysfunction in two studies (OR 3.06, 95% CI1.59 to 5.89) and implicated MBs as important in cognitive function decline in three other studies (standardised mean difference -1.06, 95% CI -2.10 to -0.02). MBs in the frontal or temporal region and the basal ganglia might also be related to cognitive dysfunction.
Conclusions: These results suggest that rather than being clinically silent, cerebral MBs might be a factor inducing cognitive function decline.