Prevalence and Associations of Cognitive Impairment in Adult Patients with Moyamoya Disease: A Systematic Review and Meta-Analysis

Background: Cognitive impairment, and in the long term Alzheimer's disease, vascular, or mixed dementia, are potential complications of moyamoya disease (MMD), of which the prevalence and associations are not well established. Objective: We performed a systematic review and meta-analysis to investigate the prevalence of cognitive impairment in adult patients with MMD as well as its clinical and demographic correlates. Methods: We performed a systematic search of four electronic databases: PubMed (MEDLINE), EMBASE, Scopus, and Cochrane Library, profiling studies from inception until 7 May 2023. Clinical data consisting of population characteristics, comorbidities, cognitive assessment tools used, and prevalence of cognitive impairment was extracted. Results: Seventeen studies were included in the meta-analysis, with a total study population of 1,190 patients. All studies assessed cognition, and the overall prevalence of cognitive impairment in MMD patients was 54.59%. A subgroup analysis identified that the prevalence of executive dysfunction in MMD patients was 31.55%. We performed a meta-regression analysis which identified that cognitive impairment was not associated with age, education level, or a history of ischemic or hemorrhagic stroke. Conclusions: A substantial proportion of MMD patients have cognitive impairment, and cognitive impairment was found to have no association with a history of stroke. Further research is necessary to investigate the longitudinal relationship of MMD and cognitive impairment, and the impact of bypass surgery on cognitive impairment.