Nonlinear Relationship of Non-High-Density Lipoprotein Cholesterol and Cognitive Function in American Elders: A Cross-Sectional NHANES Study (2011–2014)

BACKGROUND: Serum non-high-density lipoprotein-cholesterol (non-HDL-C) levels may be associated with cognitive function. OBJECTIVE: The objective of this study was to evaluate the association between non-HDL-C and cognitive function among American elders. METHODS: We used data from the 2011 to 2014 U.S. National Health and Nutrition Examination Survey (NHANES). A total of 3,001 participants aged over 60 years were enrolled in our analysis. The cognitive function was evaluated with the word learning subtest from the Consortium to Establish a Registry for Alzheimer's disease (CERAD W-L), the Animal Fluency Test (AFT), and the digit symbol substitution test (DSST). We also created a composite cognitive z-score to represent a global cognition. We applied multivariate linear regression analyses to estimate the associations between non-HDL-C levels and all domains of cognitive function. Further, the generalized additive model and the smooth curve were conducted to investigate the dose-response relationship between non-HDL-C and global cognition. RESULTS: Serum non-HDL-C was positively associated with global cognition (β= 0.20, 95% CI: 0.11, 0.28), AFT score (β= 0.54, 95% CI: 0.33, 0.76), and DSST score (β= 1.13, 95% CI: 0.56, 1.69) after fully adjusted. While non-HDL-C was not related to CERAD W-L score. In addition, an inverted U-shape curve was observed in the dose-response relationship between non-HDL-C and global cognition (p for non-linearity < 0.001). CONCLUSION: Serum non-HDL-C is positively and nonlinearly associated with cognitive function among American older adults. Maintaining serum cholesterol levels at an appropriate range may be helpful to the cognitive health of the elderly.