Socioeconomic differences of psychological health and the potential benefit of eliminating food insecurity: longitudinal and counterfactual evidence from the health and retirement study

Background Food insecurity (FI) is strongly socially patterned and may contribute to socioeconomic differences in psychological health. However, it remains unclear whether lower socioeconomic status (SES) groups would derive greater psychological health benefits from achieving food security and whether such differences reflect greater exposure to FI, greater vulnerability to FI, or both. Methods We analyzed 6,695 participants from the U.S. Health and Retirement Study. SES was constructed from household wealth, household income, and educational attainment. FI was assessed in 2013 using the U.S. Department of Agriculture Six-Item Short Form Food Security Survey Module. Psychological health was assessed using standardized, direction-reversed scores from the 8-item Center for Epidemiologic Studies Depression Scale in 2014, 2016, 2018, and 2020. Linear mixed-effects models examined longitudinal associations and temporal interactions. G-computation was used to estimate SES-specific population intervention benefits (PIB) and conditional average treatment effects (CATE) under hypothetical food-security scenarios. Results FI showed a pronounced socioeconomic gradient, affecting 40.8% of participants with low SES, 14.2% with middle SES, and 2.4% with high SES. Higher SES was associated with better psychological health, while FI was associated with poorer psychological health. The FI-related psychological health difference narrowed over time (FI × time: β = 0.065, 95% confidence interval [CI] 0.044–0.085; P < 0.001). The overall SES × FI × time interaction was significant ( P = 0.014), indicating temporal heterogeneity across SES groups without a consistent socioeconomic gradient. Counterfactual analyses showed that the average PIB associated with eliminating economically driven barriers to adequate food access was greatest in the low-SES group (0.097 standard deviation [SD] units, 95% CI 0.068–0.126), compared with the middle-SES (0.023 SD, 95% CI 0.011–0.035) and high-SES groups (0.003 SD, 95% CI −0.002–0.007). CATEs showed less consistent SES differences over time. Conclusions FI was strongly concentrated among adults with lower SES and was consistently associated with poorer psychological health. The greater potential population-level benefit of achieving food security among lower-SES adults appeared to reflect primarily their greater burden of FI, with more limited evidence for consistently greater vulnerability to FI.