Intracranial Atherosclerosis Disease (ICAD) Associated with Cognitive Impairment and Dementia: Systematic Review and Meta-Analysis.

Background Intracranial atherosclerosis disease (ICAD) alters cerebrovascular hemodynamics and brain structural integrity. Multiple studies have evaluated the link between ICAD and cognitive impairment with mixed results. This study aims to systematically review and summarize the current evidence on this link. Methods and Results PubMed, EMBASE, PsycInfo and Web of Science were searched from 2000 to 2023 without language restriction. Cross-sectional and prospective cohort studies as well as post-mortem studies were included. Studies containing data on the link between ICAD, defined at least 50% stenosis in one intracranial vessel, and cognitive impairment and dementia were screened by two independent reviewers. A total of 22 (17 observational and 5 post-mortem) unique studies comprising 11,184 individuals (average age range: 59.8 to 87.6 years, 45.7% female, 36.5% Asian) were included in the systematic review. Seven out of 10 cross-sectional studies and 5 out of 7 prospective studies showed a significant association between ICAD and cognitive impairment and. In the pooled analysis, ICAD was associated with greater cognitive impairment (measure of association: 1.87; 95% confidence interval 1.49-2.35). Meta-regression analyses did not show a significant impact of age, sex and race. All post mortem studies showed that patients with Alzheimer disease and vascular dementia had a higher burden of ICAD compared with controls. Conclusions This study shows that ICAD is associated with cognitive impairment and dementia across age, sex and race groups. Our findings may underscore the need to develop individualized dementia preventive care plans in patients with ICAD.