L-shaped association between lipid accumulation products and depression: Insights from the National Health and nutrition examination survey 2005-2018

Background: Increasing studies have indicated that insulin resistance is a risk factor for the development of depression. The lipid accumulation product (LAP) has emerged as a novel biomarker of insulin resistance. This cross-sectional study aimed to explore the relationship between LAP and the risk of depression. Methods: Data of adult participants from the 2005-2018 National Health and Nutrition Examination Survey were obtained. Depression presence and severity were evaluated using the 9-item Patient Health Questionnaire (PHQ9). The linear and non-linear associations between LAP and PHQ-9 scores were evaluated using multivariable logistic regression analysis, restricted cubic spline analysis, and piecewise regression analysis. Results: A total of 2073 participants with and 22,714 without depression were included. The association between LAP and risk of depression was L-shaped. Piecewise regression analysis showed that the odds ratio and 95 % confidence interval for the association between LAP and PHQ-9 score were 1.008 (1.004, 1.012) for LAP <140.16 cm x mmol/L and 1.001 (0.999, 1.004) for LAP >140.16 cm x mmol/L. Subgroup analysis indicated that the association between LAP and PHQ-9 score was more pronounced in women than in men, and more pronounced in never smokers than in former and current smokers. Limitation: Cross-sectional design that limited interpretation of causal relationships. Conclusions: LAP was an independent risk factor for depression in US adults when it was <140.16 cm x mmol/L, especially in women and never smokers. Prospective, longitudinal studies are needed to establish a causal relationship between LAP and depression.