Body composition, anxiety, and fitness test performance in Chinese college students: biopsychosocial association patterns across gender-differentiated testing contexts.

Depression is a leading contributor to the global burden of disease and a major public health concern worldwide []. It is associated with substantial disability, reduced quality of life, and increased risk of morbidity and mortality [, ]. In low- and middle-income countries, including South Africa, depression occurs within contexts characterised by persistent socioeconomic inequality, labour-market instability, and constrained access to mental health services [–]. These structural conditions heighten vulnerability to poor mental health outcomes and pose significant challenges for prevention and early intervention efforts. Public health research has consistently demonstrated that depression is socially patterned, with a higher risk observed among individuals exposed to adverse social and economic conditions [–]. The Social Determinants of Health framework emphasises the role of structural, socioeconomic, and contextual factors, such as education, employment, income security, social relationships, and living environments, in shaping mental health outcomes [, ]. Empirical studies from diverse settings have linked these determinants to depression prevalence; however, much of the existing evidence is based on cross-sectional designs, limiting understanding of the temporal processes through which social disadvantage contributes to the onset of depression [–]. Distinguishing between prevalence and incidence is critical for public health planning. While prevalence describes the burden of depression at a given point in time, incidence reflects the emergence of new cases and provides additional insight into population mental health dynamics. Although depression is widely studied, population-level evidence on temporal changes in incidence is scarce, and recent syntheses of “trends over time” have been largely limited to prevalence, as eligible incidence studies were not identified []. The present study contributes a longitudinal perspective by examining depression at follow-up among individuals without depression at baseline within a historically disadvantaged subpopulation in South Africa, complementing national-level evidence by describing patterns of depression at follow-up and associated social determinants within this group.