An Inverse Association Between the Composite Dietary Antioxidant Index and Alzheimer's Disease: Evidence from an NHANES-Based Cross-Sectional Study.

INTRODUCTION: The relationship between the dietary Complex Antioxidant Index (CDAI) and Alzheimer's Disease (AD) is not clear. Our study is to investigate the relationship between CDAI and the risk of AD in general adults. METHODS: This study included 116876 participants from the National Health and Nutrition Survey (NHANES). CDAI was calculated based on the intake of six dietary antioxidants. We used multivariate logistic regression to examine the relationship between CDAI and AD prevalence, and used restricted cubic splines to examine the nonlinear association. RESULTS: The study showed that in the multivariate logistic regression model with fully adjusted confounding variables, the odds ratio (OR) of CDAI and AD was 0.9983 (95% confidence interval: 0.9969,0.9998; P=0.024). In addition, restricted cubic spline analysis revealed a linear correlation (P for non-linearity = 0.097). DISCUSSION: This cross-sectional study reveals a linear negative association between the CDAI and AD prevalence in U.S. adults, with vitamin E, carotenoids, and selenium showing independent protective effects. These findings align with the hypothesis that dietary antioxidants may mitigate oxidative stress-related neurodegeneration. However, due to the cross-sectional design, causal inference is not possible, and reverse causation cannot be excluded. The modest effect size and reliance on self-reported dietary data necessitate cautious interpretation. These hypothesis-generating findings underscore the need for prospective cohort studies to confirm whether antioxidant-rich diets could serve as a primary prevention strategy for AD. CONCLUSION: This cross-sectional study found a negative linear association between CDAI and AD prevalence in US adults. These hypothesis-generating findings require confirmation in prospective cohort studies.