Association of cerebral microbleeds with risks of cognitive impairment and dementia: A systematic review and meta-analysis of prospective studies

Abstract

BackgroundCognitive impairment and dementia is a universal phenomenon in the older. And as a feature of cerebral small vessel disease (CSVD), cerebral microbleed (CMB) plays a role in the process of cognitive decline. AimsWe aim to identify the association of CMBs with risks of cognitive impairment and dementia prospectively. MethodsFrom database inception to Sept. 12, 2020, we systematically searched PubMed, Embase and Ovid databases to obtain relative articles which have exact values in the relationship between CMB and dementia. In primary analysis, we divided the cognitive normal subjects at baseline into dementia and mild cognitive impairment (MCI) groups as outcomes. In the dementia group, we conducted subgroup analysis according to the number and locations of CMBs. ResultsA total of 32641 articles were identified and 14 articles with 11407 participants were included. The presence of CMBs increased the risk of dementia (relative risk (RR) =1.32, 95% confidence interval (CI) =1.00-1.72, I2=21.2%, P=0.268), as well as the risk of VaD (vascular dementia) (RR=2.41, 95%CI=1.28-4.54, I2=0%, P=0.381). Subgroup analyses showed that ≥2 CMBs (RR=2.27, 95%CI=1.71-3.01, I2=0%, P=0.627) and deep and/or mixed CMBs (RR=1.75, 95%CI=1.09-2.80, I2=23.3%, P=0.012) were associated with the risk of dementia. ConclusionResults indicated that as CMB numbers increased, the associations with dementia were more significant. The present of CMBs in specific cerebral areas helps in understanding the pathogenesis of dementia. Future work will focus on finding treatments to improve long-term prognosis of patients with CMBs.