Depression's heavy toll: Unraveling its impact on overall health in US adults

In a recent study published in JAMA Network Open, researchers assessed the associations between depression and mortality among adults in the United States (US).

Depression is prevalent in the US, with about 21 million adults estimated to have experienced ≥ 1 depressive episode in 2020. Multiple adverse outcomes are associated with depression, such as a higher incidence of cardiovascular disease (CVD) and premature death. The majority of previous studies examining depression and CVD or mortality focused on older or middle-aged adults and specific subsets of the population and were unable to capture CVD- or IHD-related causes of death.

Study: Depressive Symptoms and Mortality Among US Adults. Image Credit: Black Salmon / Shutterstock

About the study

The present study examined the associations of depressive symptoms with IHD, CVD, and all-cause mortality in the US. The researchers used National Health and Nutrition Examination Survey (NHANES) mortality files from 2005 to 2018 linked to the 2019 National Death Index records. Subjects were followed up until death, and those who died from non-IHD or -CVD causes were censored.

The Patient Health Questionnaire (PHQ)-9 was used to assess depressive symptoms, which evaluates depressive symptom frequency over the past two weeks, with higher scores reflecting increased severity. The prevalence of depressive symptoms was assessed. Clinical and sociodemographic characteristics were compared across depression categories using analysis of variance and chi-squared test for continuous and categorical variables, respectively.

Hazard ratios and 95% confidence intervals for CVD, IHD, and all-cause mortality were estimated using multivariable Cox proportional models. Mediation analysis examined whether alcohol use and the American Heart Association’s Life’s Essential (LE)-8 cardiovascular health metrics (body mass index [BMI], nicotine use, physical activity, sleep health, blood glucose, blood lipids, blood pressure, and diet) mediate associations.

Findings

The study included 23,694 adults aged 44.7, on average, including 49.8% of males. Most subjects were non-Hispanic White (66.2%), followed by Hispanics (15.3%), non-Hispanic Black (11%), and other race/ethnicity (7.6%). Most individuals (77.9%) had none or minimal depressive symptoms, 14.9% had mild depression, and 7.2% had moderate to severe depression.

Female, never married, separated, divorced, or widowed individuals, subjects with less than 12 years of education, and those without health insurance were more likely to be depressive. Depressive adults had significantly lower scores in six cardiovascular health metrics. The mean follow-up period was 7.72 years.

Overall, 1495, 497, and 209 all-cause, CVD, and IHD deaths occurred. All-cause mortality rates were 5.62, 7.79, and 9.48 per 1000 person-years for none/minimal, mild, and moderate-to-severe depression, respectively. Depression was significantly associated with an increased all-cause mortality risk.

The hazard ratios were 1.35 for mild depression and 1.62 for moderate-to-severe depression relative to those without depression. For CVD mortality, the hazard ratios were 1.49 and 1.79 for mild and moderate-to-severe depressive symptoms relative to those without. Likewise, the hazard ratios for IHD mortality were 0.96 for mild depressive symptoms and 2.21 for moderate-to-severe depressive symptoms. These associations were consistent by sex, age, poverty subgroups, and diabetes status.

The most prevalent depressive symptoms were feeling tired, having trouble sleeping, having little energy, overeating, poor appetite, and feeling hopeless. Mediators explained 11% and 14.2% of the association between mild depression and CVD and all-cause mortality, respectively. Similarly, they explained 14.3%, 12%, and 16.1% of the association between moderate-to-severe depression and IHD, CVD, and all-cause mortality, respectively.

BMI, diabetes, smoking, and physical activity were the primary mediators of IHD and CVD mortality. In contrast, physical activity, sleep health, and smoking were the primary mediators of all-cause mortality. In sensitivity analyses, the associations between depression and mortality were consistent when individuals with a history of cancer or CVD were included or when those who died within the first follow-up year were excluded.

Conclusions

Taken together, the findings illustrate that 14.9% and 7.2% of participants had mild and moderate-to-severe depression. Individuals with mild depression had about 49% and 35% excess risk of death from CVD and all-cause, relative to those without depressive symptoms. IHD, CVD, and all-cause mortality risks were 121%, 79%, and 62% higher for people with moderate-to-severe depression than those without depressive symptoms. Overall, public health efforts to improve awareness and treatment of depressive symptoms and risk factors could help reduce the burden of depression.

Written by

Tarun Sai Lomte

Tarun is a writer based in Hyderabad, India. He has a Master’s degree in Biotechnology from the University of Hyderabad and is enthusiastic about scientific research. He enjoys reading research papers and literature reviews and is passionate about writing.