Dyslipidaemia Associated with Cognitive Impairment in Comorbidity-Free Chinese Adults: A Systematic Review and Meta-Analysis

Abstract Amidst China’s aging population, cognitive impairment poses a critical public health challenge, yet evidence linking dyslipidaemia to cognitive decline in comorbidity-free adults remains inconsistent. This meta-analysis systematically evaluated 13 case-control studies (17,417 participants) from seven databases, excluding populations with confounding comorbidities. Hyperlipidaemia was associated with a 24% increased risk of cognitive impairment (OR = 1.24, 95%CI:1.12–1.38), with marked age- and sex-specific effects. Elevated total cholesterol conferred an 88% higher risk in adults ≥ 60 years (OR = 1.88, 95%CI:1.54–2.29), while hypertriglyceridemia tripled risk in male-predominant cohorts (OR = 2.78, 95%CI:2.28–3.39). Paradoxically, high-density lipoprotein cholesterol (HDL-C) also correlated with increased cognitive impairment risk (OR = 1.31, 95%CI:1.08–1.60), suggesting nonlinear dose-response dynamics. Sensitivity analyses confirmed low-density lipoprotein cholesterol (LDL-C) as a risk factor (OR = 1.23, 95%CI:1.16–1.30) after excluding outliers. Methodological rigor—comorbidity exclusion, Chinese-language database inclusion, and stratified analyses—strengthened validity. These findings highlight the necessity of age- and sex-stratified lipid management for cognitive preservation. Future research should prioritize longitudinal designs and mechanistic studies to elucidate causal pathways, informing personalized interventions for China’s aging population.