Prevalence of cerebral microbleeds in Alzheimer’s disease, dementia with Lewy bodies and Parkinson’s disease dementia: a systematic review and meta‐analysis

Abstract

AbstractBackgroundCerebral microbleeds (CMB) are often associated with vascular risk factors and/or cerebral amyloid angiopathy and are frequently identified in people with dementia. This study aimed to estimate the pooled prevalence of CMB across the three most common late‐onset dementia diagnoses, Alzheimer’s disease (AD), dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD).MethodA systematic search with pre‐defined search terms was performed on Medline, EMBASE and PubMed, from inception to 19th October 2022. Identified articles were manually screed for titles and abstracts by independent reviewers. Relevant MRI studies that reported raw prevalence data of CMB in AD, DLB or PDD were included. Studies which investigated Parkinson’s disease without dementia or people with mild cognitive impairment were excluded. Prevalence data were manually extracted, and study quality was assessed using the Joanna Briggs Institute Checklist for Prevalence Studies. Data were pooled using random‐effect models. The predefined primary outcome was prevalence of CMB in AD, DLB and PDD. Secondary outcomes were associations between CMB and vascular risk factors as well as amyloid‐β burden.ResultA total of 65 studies met the inclusion criteria for data extraction. CMB, predominantly lobar, were present in 32% of AD (n = 5409; 95% CI 29‐35%), 36% of DLB (n = 348; 95% 26‐45%) and 31% of PDD participants (n = 236; 95% CI 23‐40%). The prevalence estimates of CMB in AD and DLB increased with higher field strength and the use of susceptibility‐weighted imaging. CMB in AD were associated with a history of hypertension (odds ratio [OR] 1.74, 95% CI 1.33‐2.28) and amyloid‐β burden (standardised mean difference [SMD] 0.41; 95% CI 0.25‐0.57). CMB in DLB were associated with hypertension (OR 1.95; 95% CI 1.00‐3.83), but not amyloid‐β burden (SMD 0.05; 95% CI ‐0.32‐0.42).ConclusionThe prevalence of CMB was similar across AD, DLB and PDD (31‐36%). The underlying pathophysiology of CMB in DLB might differ from that of AD. More studies evaluating CMB in DLB and PDD are needed.