Abstract
BackgroundStudies 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.MethodsThis 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.ResultsHigher 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.ConclusionDifferent 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.
Highlights
Studies regarding the lipid-cognition relationship have increasingly gained popularity but have generated much mixed results
This study aimed to explore the sex-specific associations of serum lipids with 5-year cognitive decline in a community-based longitudinal study of Chinese elderly individuals derived from the China Health and Retirement Longitudinal Study (CHARLS) based on its large sample, containing middle-aged participants and its thorough and detailed information on the exposure and outcome
Higher total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were noted in the high high-density lipoprotein cholesterol (HDL-C) grade (Supplementary Table 1)
Summary
Studies regarding the lipid-cognition relationship have increasingly gained popularity but have generated much mixed results. 20–30% of Americans and 8% Chinese aged over 65 years are affected by cognitive impairment, ranging from mild deficits to dementia [1, 2]. Since atherosclerosis and vascular diseases are important contributing factors to cognitive decline and dementia [3, 4], exploring the relationship of dyslipidemia with cognitive decline has aroused increasing interest in recent years. A few epidemiological studies suggested that high serum total cholesterol (TC) levels predicted subsequently greater cognitive decline or the onset of dementia in general populations [5,6,7,8], and lipid lowering agents might have protective effects [9]. Other studies showed no [10,11,12] or reverse associations [13,14,15]
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