Sex-specific associations between lipids and cognitive decline in the middle-aged and elderly: a cohort study of Chinese adults

Background Studies regarding the lipid-cognition relationship have increasingly gained popularity but have generated much mixed results. To date, few studies have focused on the difference between sexes. Methods This study included 6792 Chinese adults aged over 45 years (women, 48.56%; mean age, 57.28 years), who were free of severe conditions known to affect cognitive function at the baseline (2011). Blood concentrations of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), and triglycerides (TG) were assessed at baseline, and both continuous and categorical values were used in final analyses. Global cognitive functions were assessed by the word recall test and the mental status test in 2011, 2013, and 2015, respectively. We graded participants into three groups according to the cognitive change slopes: no decline (>= 0), moderate decline (median to 0), and severe decline (< median). Sex-specific associations between blood lipids and cognitive decline were analyzed using ordinal logistic models, adjusting for sociodemographic information, lifestyle behaviors, and health status. Results Higher baseline TC and LDL-C concentrations exhibited no significant association with 5-year cognitive decline in men but were significantly associated with greater 5-year cognitive decline in women [odds ratio (OR) 1.026, 95% confidence interval (CI) 1.003, 1.050; OR 1.026, CI 1.002, 1.051, respectively]. For higher serum HDL-c levels, a significantly protective effect on cognition was observed in men, but a slightly adverse effect was found in women (not significant after Bonferroni correction). TG presented almost no effect on later cognition in either sex. Conclusion Different associations between sexes were observed for the lipid-cognition relationship, and maintaining serum cholesterol levels at an appropriate range may have a positive effect on cognitive health.