Life's essential 8 and non-alcoholic fatty liver disease: unmasking depressive symptoms' mediating role

Aimed to reveal the complex associations between Life's Essential 8 (LE8), depressive symptoms and nonalcoholic fatty liver disease (NAFLD), and to explore the mediating role of depressive symptoms in the pathways of LE8 components affecting NAFLD.

Based on nationally representative data of 8908 adults ≥ 20 years from the 2005-2018 National Health and Nutrition Examination Survey (NHANES), weighted logistic, regression, restricted cubic spline(RCS), threshold effect and bootstrap mediated-effects analyses were used to assess the association between LE8, NAFLD and depressive symptoms associations, and stratified analysis reveals the heterogeneity of the association in population.

Each one-point increase in the LE8 was associated with a reduced risk of NAFLD, OR (95% CI) = 0.19(0.16, 0.23), with health factor score showing particularly protective effect, OR (95% CI) = 0.09 (0.07, 0.10). These associations were stronger among women, older, and PIR (poverty-to-income ratio) > 3.5. A dose-response relationship was evident, with a positive correlation between severe depression and NAFLD, OR (95% CI) = 2.01(1.05, 3.85). Crucially, depressive symptoms constituted a significant mediating pathway in health behaviors, accounting for 46.78%, 17.74%, and 5.79% of the protective effects of optimal sleep health, adequate physical activity, and diet on NAFLD, respectively. Regarding nicotine exposure, depressive symptoms exerted a partial inhibitory effect, with the mediating effect accounting for -27.55%. However, for the association between health factors and NAFLD, depressive symptoms do not play a mediating role in the association.

This study is the first to confirm that depressive symptoms mediate the relationships between specific LE8 components and NAFLD. LE8 components are significantly correlated with NAFLD, possibly via depression-supporting a "physiological-psychological" integrated approach to NAFLD management. Targeted interventions for depressive symptoms may augment the benefits of optimized LE8 in high-risk populations.