The relationship between midlife dyslipidemia and lifetime incidence of dementia: A systematic review and meta-analysis of cohort studies

Introduction: We conducted a systematic review and meta-analysis to review the relationship between midlife dyslipidemia and lifetime incident dementia. Methods: The databases Medline, Embase, Scopus, Web of Science, and Cochrane were searched from inception to February 20, 2022. Longitudinal studies examining the relationship between midlife lipid levels on dementia, dementia subtypes, and/or cognitive impairment were pooled using inverse-variance weighted random-effects meta-analysis. Results: Seventeen studies (1.2 million participants) were included. Midlife hypercholesterolemia was associated with increased incidence of mild cognitive impairment (effect size [ES] = 2.01; 95% confidence interval [CI] 1.19 to 2.84; I-2 = 0.0%) and all-cause dementia (ES = 1.14; 95% CI: 1.07 to 1.21; I-2 = 0.0%). Each 1 mmol/L increase in low-density lipoprotein was associated with an 8% increase (ES = 1.08, 95% CI: 1.03 to 1.14; I-2 = 0.3%) in incidence of all-cause dementia. Discussion: Midlife dyslipidemia is associated with an increased risk of cognitive impairment in later life.