Association of the atherogenic index of plasma with cognitive function and oxidative stress: A population-based study

Background Atherosclerosis contributes to cognitive dysfunction and Alzheimer's disease-related pathologies. Atherogenic index of plasma (AIP) is a novel and composite biomarker can predict atherosclerosis. Objective This study aims to (1) examine the association between the AIP and cognitive performance, and (2) explore the mediating role of oxidative stress biomarkers in this relationship. Methods 1466 participants over the age of 60 were included from 2011–2014 NHANES. AIP was calculated through log-transformed triglyceride to high-density lipoprotein cholesterol ratios. The assessment of cognition was conducted using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) test. Weighted linear regression model and restricted cubic spline were carried out to determine the associations between AIP and CERAD scores. The mediation analyses were conducted to assess whether oxidative stress mediates the association. Results Higher AIP levels were associated with lower CERAD learning scores. The highest quartile of AIP showed a 0.67-fold decrease (95%CI: −1.30, −0.03; p = 0.041) on the CERAD total score than that in the lowest quartile. Each 1-unit increase in AIP corresponded to reductions in CERAD total and delayed recall scores of approximately 1.09 and 0.54 points, respectively, in the sub-population under 70 years. Moreover, 25(OH)D, an oxidative stress indicator, partially mediated 24% of the association between AIP and the CERAD total score. Conclusions AIP has the potential to indicate the risk of cognitive aging, especially that for young-old or female older adults. The supplementation of 25(OH)D may reduce atherosclerosis-related cognitive decline, which could provide some strategies for the prevention of dementia.