Association of health literacy with depressive and anxiety symptoms in Korean adults: a dose–response analysis

This study aimed to examine the associations between health literacy and depressive and anxiety symptoms among Korean adults using data from the 2024 Korea National Health and Nutrition Examination Survey (KNHANES). This cross-sectional study included 3,456 Korean adults aged 19–64 years from the 2024 KNHANES. Health literacy was assessed using the 10-item KNHANES health literacy instrument, and participants were classified using a cut-off score of 28 points. This tool was developed through a Korea Disease Control and Prevention Agency (KDCA) policy research project in 2022. Depressive and anxiety symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9) and the Generalized Anxiety Disorder-7 scale (GAD-7), respectively. Multivariable logistic regression analyses were performed to estimate odds ratios (OR) and 95% confidence intervals (95% CI), and restricted cubic spline analyses were conducted to examine dose-response relationships. Lower health literacy was associated with higher PHQ-9 and GAD-7 scores and higher odds of depressive and anxiety symptoms. Each 1-point increase in health literacy score was associated with lower odds of depressive symptoms (OR: 0.945; 95% CI, 0.926–0.964) and anxiety symptoms (OR: 0.943; 95% CI, 0.925–0.961). Restricted cubic spline analyses showed an inverse dose-response relationship between health literacy and depressive symptoms (p for non-linear < 0.05), whereas a similar inverse pattern was observed for anxiety but did not reach statistical significance. Participants with lower health literacy also showed less favorable anthropometric and cardiometabolic profiles. Lower health literacy was significantly associated with poorer mental health among Korean adults, suggesting that enhancing health literacy may serve as a crucial strategy for mental health promotion and prevention.