Associations between depressive symptoms and cognitive function in China older adults based on a dual-trajectory model.

BACKGROUND

Cognitive decline and depressive symptoms often co-occur in older adults, but research on the trajectories of these two conditions and their interrelationships remains limited.

METHODS

Using data from 2,823 adults aged ≥ 60 years in the China Health and Retirement Longitudinal Study (CHARLS, 2011–2018), we identified depressive-symptom and cognitive-function trajectories using group-based trajectory modeling (GBTM) and then used a group-based dual-trajectory modeling (GBDTM) to quantify their interdependence by estimating conditional and joint probabilities across trajectory groups. Multinomial logistic regression was used to examine how baseline characteristics predicted the likelihood of membership in each trajectory group.

RESULTS

Three distinct trajectories were identified for depressive symptoms (low: 31.0%, moderate: 46.2%, high: 22.8%) and cognitive function (high: 47.8%, declining: 34.6%, low: 17.6%). Depressive symptom trajectories mainly differed by symptom level with small fluctuations, whereas cognitive trajectories differed more in decline patterns, with modest decline in the high-functioning group and steeper declines in the other groups. Conditional and joint probabilities showed clear cross-domain linkage between depressive-symptom and cognitive-function trajectories. Dual-trajectory analysis revealed that 61.1% of participants in the low depressive symptoms group had high cognitive function, while 49.1% of the low cognition group had moderate depressive symptoms. The joint probability results showed that older adults with milder depressive symptoms were more likely to maintain high cognitive function. Higher education, better ADL function, and self-rated health were associated with favorable trajectory membership (P < 0.05).

CONCLUSION

Depressive symptoms and cognitive function were negatively associated among older Chinese adults. Interventions targeting depressive symptoms may help preserve cognitive health in aging populations.