Nonlinear association of the non–high-density lipoprotein cholesterol-to-high-density lipoprotein cholesterol ratio with cognitive function in older Chinese adults: A prospective cohort study

Objective Although the non–high-density lipoprotein cholesterol-to-high-density lipoprotein cholesterol ratio (NHHR) has emerged as a novel indicator of lipid metabolism, its specific correlation with cognitive function remains unclear. This study aimed to comprehensively explore this association in an aging population. Methods This prospective cohort study comprised both cross-sectional (2015, n = 4605) and longitudinal (2018, n = 2362) analyses using data from the China Health and Retirement Longitudinal Study. Regression analysis was performed to assess the association of the NHHR with cognitive performance and cognitive impairment. Restricted cubic spline models explored potential nonlinear associations. A logistic regression model was employed in the longitudinal research to examine the correlation between baseline NHHR levels and cognitive impairment during follow-up. Results NHHR was positively correlated with episodic memory (regression coefficient = 0.23, p < 0.01) and total cognition (regression coefficient = 0.28, p < 0.01) and inversely correlated with cognitive impairment (odds ratio = 0.89, p = 0.013). Restricted cubic spline analysis confirmed significant nonlinear relationships for these outcomes ( p < 0.05). The protective effect of an elevated NHHR was most pronounced in prediabetic individuals, showing improved memory (regression coefficient = 0.33), total cognition (regression coefficient = 0.42), and reduced cognitive impairment (odds ratio = 0.79) (all p < 0.01). Longitudinal associations with incident cognitive impairment lost significance after full covariate adjustment. Conclusions NHHR exhibits a nonlinear association with cognitive function in older Chinese adults. Maintaining optimal NHHRs may benefit cognitive health, particularly in prediabetic individuals.