Extreme drought and risk of depressive symptoms among middle-aged and older chinese adults

Extreme drought events have become increasingly frequent under climate change, yet their potential impact on mental health, particularly the development of depressive symptoms, remains insufficiently understood. This study aimed to investigate the longitudinal association between drought exposure and incident depressive symptoms among middle-aged and older adults in China. We conducted a prospective cohort study using data from the China Health and Retirement Longitudinal Study (CHARLS). Participants without depressive symptoms at baseline were included and followed through subsequent survey waves. Extreme drought exposure was assessed using extreme drought days (EDD) derived from meteorological data. Associations between EDD exposure and incident depressive symptoms, defined as CESD-10 scores ≥ 10 during follow-up, were examined using Cox proportional hazards models and time-varying Cox models. K-means clustering was applied to identify long-term drought exposure trajectories. Restricted cubic spline analyses were performed to assess potential dose–response relationships. Multiple sensitivity analyses, including Fine–Gray competing risk models, landmark analyses, province-clustered robust standard errors, and adjustment for PM2.5 exposure, were conducted. Among 3,222 participants, 1,546 developed incident depressive symptoms during follow-up. Higher EDD exposure was associated with an increased risk of depressive symptoms in both conventional Cox models (HR = 1.004, 95% CI: 1.000–1.009) and time-varying Cox models (HR = 1.004, 95% CI: 1.001–1.008). Trajectory analysis identified two distinct drought exposure patterns. Compared with participants in the low-EDD trajectory group, those in the high-EDD trajectory group had a higher risk of incident depressive symptoms in both the conventional Cox model (HR = 1.21, 95% CI: 1.08–1.34) and the time-varying Cox model (HR = 1.22, 95% CI: 1.09–1.35). Restricted cubic spline analysis suggested a nonlinear exposure–response relationship between EDD and depressive symptoms. The associations remained broadly similar across multiple sensitivity analyses. Long-term exposure to higher levels of extreme drought was associated with an increased risk of incident depressive symptoms among middle-aged and older Chinese adults. These findings provide epidemiological evidence that may inform further research and mental health surveillance in drought-prone settings.