Research identifies five pathways of depressive symptoms, with stable and increasing patterns significantly increasing the risk of all-cause mortality.
Study: Association between depressive symptom trajectories and all-cause mortality in middle-aged and older Chinese adults. Image credits: New Africa/Shutterstock.com
Depression is a widespread condition known to increase the risk of death from any cause. However, its progression varies considerably from person to person, highlighting the need for more detailed research.
A recent study published in Scientific reports examined how long-term patterns of depression in an older Chinese population influence the risk of all-cause mortality.
Depression – the global picture
About a third of adolescents worldwide have symptoms of clinical depression. In China, observation for one month revealed the presence of significant symptoms of depression in almost 20% of individuals.
Depression is a risk factor for cardiovascular disease, dementia and suicidal thoughts and worsens other medical conditions. It contributes 45 million disability-adjusted life years (DALYs) worldwide. Moreover, it increases the chance of death.
Most studies on this aspect have been cross-sectional, despite the fluctuating nature of depressive symptoms. Many depressed people recover thanks to inner resilience, appropriate treatment, social and family support, positive life events and/or biological changes.
Large changes in the intensity of depression were found in almost 20% of participants in one longitudinal study, but in most studies this has not been given sufficient weight. This motivated the current article.
About the study
The current study included 13,624 people over the age of 45. The data are from the China Health and Retirement Longitudinal Study (CHARLS). Depression was assessed using the Center of Epidemiological Studies Depression Scale-10 (CESD-10).
The trajectories of depression in different groups were modeled and examined for any association with all-cause mortality. Mortality was monitored at two points, in 2018 and 2020. Other demographic, lifestyle and medical factors were also used to stratify participants.
The model included five trajectories for depressive symptoms. These include stable-low, stable-moderate, increasing, decreasing and stable-high. The number of participants per process was 4,900, 5,250, 1,200, 1,500 and 750 respectively.
For example, 36% of participants had stable, low depressive symptoms, and 39% had stable, moderate symptoms. About 6% had high depressive symptoms. Symptoms increased by 9% and decreased by 11% over time.
There were 1,194 deaths in the entire group, the mortality rate was 8.7%. After compensating for other confounders, mortality risk increased by 30% and nearly 60% among those in the increasing and stable-high symptom trajectory groups, respectively, compared with those with stable-low depression. The risk of mortality from any cause increased from the lowest to the highest symptom range.
There was no significant mortality risk in the groups with decreasing or stable to moderate depression trajectories. The sensitivity analyzes showed that the findings were robust for most groups.
The findings confirm and extend previous studies by showing the impact of decreasing or increasing symptoms over time on the risk of mortality.
The importance of identifying this group through long-term follow-up seems clear. Potential interventions targeting the risk groups include pharmaceutical, psychological, exercise-based and general strategies aimed at improving quality of life.
Plausible biological mechanisms have been suggested that link mortality to depression, such as disrupted biofeedback mechanisms, low-grade inflammation, and an increased likelihood of unhealthy lifestyles.
Conclusions
The findings of this study reveal different trajectories of depression among middle-aged and older Chinese individuals.
There was an increased risk of all-cause mortality among people who showed increasing or persistently high levels of depression, compared to those with low and stable levels.
No significant increase in risk was found among those who had depression at baseline but showed decreasing symptoms over time, or among those who had moderate but stable depressive symptoms. This suggests that previous mortality estimates for such groups were overestimated.
Future studies should follow individuals with depression at multiple time points to provide further insight into the association of depression with mortality.