Longitudinal trajectories of depressive symptoms: the role of multimorbidity, mobility and subjective memory

The high prevalence of depression among older people in China places a heavy burden on the health system. Multimorbidity, mobility limitation and subjective memory impairment are found to be risk indicators for depression. However, most studies on this topic focused on depression at a single point in time, ignoring the dynamic changes in depressive symptoms and the relationship between the trajectories and these three conditions. Therefore, we aimed to identify distinct trajectories of depressive symptoms in older people and investigate their associations with multimorbidity, mobility limitation and subjective memory impairment. Data was drawn from China Health and Retirement Longitudinal Study conducted during 2011-2018. A total of 5196 participants who completed 4 visits, conducted every 2-3 years were included in this study. Group-based trajectory modeling was conducted to identify distinct trajectories of depressive symptoms z-scores. Multinomial logistic regression was used to investigate the relationships. Four distinct trajectories of depressive symptoms z-scores were identified, labeled as persistently low symptoms (68.69%, n = 3569), increasing symptoms (12.14%, n = 631), decreasing symptoms (14.05%, n = 730) and persistently high symptoms (5.12%, n = 266). Participants with multimorbidity had unfavorable trajectories of depressive symptoms compared with those without multimorbidity, with adjusted odds ratios (95% CIs) of 1.40 (1.15, 1.70), 1.59 (1.33, 1.90) and 2.19 (1.65, 2.90) for the increasing symptoms, decreasing symptoms and persistently high symptoms, respectively. We also observed a similar trend among participants with mobility limitations. Compared with participants who had poor subjective memory, participants with excellent/very good/good subjective memory had a lower risk of developing unfavorable trajectories of depressive symptoms. The adjusted odds ratios (95% CIs) of the increasing symptoms, decreasing symptoms and persistently high symptoms were 0.54 (0.40, 0.72), 0.50 (0.38, 0.65) and 0.48 (0.31, 0.73), respectively. Multimorbidity, mobility limitation and subjective memory impairment were found to be potential risk factors for unfavorable depression trajectories.