Behavioral and Psychological Correlates of Depressive Symptoms in Korean Women: Attenuation of the Perceived Body Size Association After Adjustment

Abstract

Aim: This study addressed two research questions. First, which sociodemographic, behavioral, and psychological factors are independently associated with elevated depressive symptoms among Korean women aged 20–59 years? Second, does subjective perception of one’s own body size retain an independent association with depressive symptoms after these factors are taken into account, and does this pattern differ between younger and midlife women? The primary outcome was elevated depressive symptoms, defined as a PHQ-9 score of 5 or above. Design: This cross-sectional study used pooled data from the four Korea National Health and Nutrition Examination Survey cycles in which the PHQ-9 was administered (2014, 2016, 2018, and 2020). All estimates incorporate the complex survey design and therefore refer to the national population of Korean women aged 20–59 years. Methods: We analysed data from Korean women aged 20–59 years who completed the PHQ-9 (n = 7595). Elevated depressive symptoms were defined as a PHQ-9 score of 5 or above, indicating mild or greater symptomatology. Design-based multivariable logistic regression models were constructed in sequential blocks: demographic variables (Model 1); behavioural and psychological factors added (Model 2); and perceived body size, entered as indicator contrasts against average body size, added (Model 3). Analyses were stratified by age group (20–39 and 40–59 years), and age-group interaction terms were fitted in a pooled model to test formally whether associations differed across the female lifespan. Results: The weighted prevalence of elevated depressive symptoms (PHQ-9 ≥ 5) was 24.1% (95% CI 22.8–25.3). In bivariate analyses, perceived body size differed significantly between women with and without elevated depressive symptoms (p < 0.001). After adjustment for behavioural and psychological factors, neither perceived thinness nor perceived obesity was associated with depressive symptoms in either age group (20–39 years, thin: OR 1.25, 95% CI 0.92–1.69; obese: OR 1.05, 95% CI 0.85–1.30; 40–59 years, thin: OR 1.21, 95% CI 0.84–1.73; obese: OR 0.99, 95% CI 0.80–1.22), and the joint two-degree-of-freedom test was non-significant in both groups. Perceived stress (OR 5.15 and 4.93), poor subjective health (OR 2.11 and 2.55), and lifetime smoking experience (OR 1.75 and 1.79) showed the strongest and most consistent associations in both groups (all p < 0.001). Lower household income was associated with depressive symptoms among women aged 40–59 years and heavy episodic drinking among those aged 20–39 years; in formal interaction testing, household income showed only a non-significant trend towards effect modification by age (p = 0.060), so the age differences are described rather than established. Conclusions: The crude association between perceived body size and depressive symptoms did not persist after adjustment for behavioral and psychological factors. Because perceived stress and subjective health may lie on a causal pathway from body size perception to depressive symptoms, this attenuation is consistent with either confounding or an indirect pathway, and the present cross-sectional design cannot distinguish between them. Perceived stress and subjective health showed the strongest associations across age groups, while lower household income remained an independent correlate in midlife. This finding points to a material condition that individual-level screening cannot by itself address.