The association between the ten-year trajectory of multimorbidity and depressive symptoms among the middle-aged and older adults: Results from the China Health and Retirement Longitudinal Study.

Background: Despite the established link between chronic conditions and depressive symptoms in recent decades, research into the temporal dynamics between multimorbidity and the occurrence of depressive symptoms remains scarce.

Methods: A total of 15,882 Chinese middle-aged and older adults with 63,246 observations from the China Health and Retirement Longitudinal Study were included in the present study. Depressive symptoms were evaluated using a 10-item CESD scale, with a threshold set at 12 points. Group-based trajectory modeling was used to examine the multimorbidity developmental trajectories. The risk of depressive symptoms was analyzed using mixed effect logistic regression models.

Results: Among the final included 15,896 participants, 37.6 % reported states of multimorbidity, and 25.7 % were detected as depressive symptoms. In the fully adjusted model, those with multimorbidity were 2.36 (2.24 to 2.49) times more likely to present depressive symptoms, and the likelihood increased 1.38 (1.36 to 1.40) times with each additional chronic condition. Four distinct multimorbidity trajectory groups were identified: no-new-condition group (32.6 %), slow growth group (42.9 %), steady growth group (19.7 %), and rapid growth group (4.9 %). Compared to the no-new-condition group, the likelihood of developing depressive symptoms was greater in the subsequent three groups, with ORs of 1.53 (1.39 to1.71), 2.54 (2.24 to 2.89), and 4.40 (3.62 to 5.34), respectively.

Conclusion: Our results highlight the substantial health effects of accumulating multimorbidity on depressive symptoms, showing a direct link between risk and accumulation rate. We urge focusing on depressive symptoms in those with multimorbidity to tackle the significant healthcare challenges arising from concurrent physical and mental health issues.