Associations of cognitive impairment and physical disability with the risk and reversibility of depressive symptoms in Chinese older adults.

BACKGROUND: Cognitive impairment (CI) and physical disability (PD) frequently co-occur in older adults and are both significant risk factors for depressive symptoms. However, their combined impact on the risk and reversibility across different depressive symptom states remains unclear. METHODS: Utilizing data from five waves (2011-2020) of the China Health and Retirement Longitudinal Study (CHARLS), we included 8,473 adults aged 60 and above. A continuous-time multi-state Markov model was used to analyze transition probabilities and intensities among states of no (NDS), mild (MDS), and severe depressive symptoms (SDS), and to examine the effects of CI and PD on these transitions. Cox proportional hazards models were employed to estimate hazard ratios (HRs) for the associations of CI and PD with the risk and reversibility of depressive symptoms. Restricted cubic splines (RCS) were further applied to assess dose-response relationships. RESULTS: Among 8,473 older participants (mean age 67.91 ± 6.59 years; 49.3% female), 14.0% had CI, 17.5% had PD, and 6.5% had both at baseline. Multi-state Markov models showed dynamic transitions of depressive symptoms, with reversion generally exceeding progression. Both CI and PD were associated with increased progression risk and reduced likelihood of reversion, with PD showing stronger associations and a lower likelihood of symptom reversal. Their co-occurrence showed the strongest effects (NDS → MDS: HR = 1.76, 95% CI: 1.42-2.18; MDS → SDS: HR = 1.79, 95% CI: 1.30-2.46), alongside reduced reversion probabilities (MDS → NDS: HR = 0.82, 95% CI: 0.66-0.92; SDS → MDS: HR = 0.74, 95% CI: 0.57-0.91). Additive interactions were observed across all transition pathways (all P < 0.05). Findings were consistent in prospective analyses, and restricted cubic spline analyses supported dose-response relationships. CONCLUSION: This study highlights the dynamic nature of depressive symptoms in older Chinese adults. CI and PD were independently associated with a higher likelihood of symptom progression and jointly associated with a lower probability of reversion. These findings suggest that approaches focusing on cognitive and physical function may hold promise for informing strategies to modify depressive symptom trajectories.