Patterns of Association between Depressive Symptoms and Chronic Medical Morbidities in Older Adults

Abstract

Objectives: To investigate the association between depressive symptoms and several medical morbidities, and their combination, in a large older population.

Design: Cross-sectional study of baseline data from the ASPirin in Reducing Events in the Elderly (ASPREE) trial.

Setting: Multicentric study conducted in Australia and the United States.

Participants: A total of 19,110 older adults (mean age = 75 years [standard deviation = ±4.5]).

Measurements: Depressive symptoms were measured using the Center for Epidemiological Studies Depression (CES-D 10) scale. Medical morbidities were defined according to condition-specific methods. Logistic regression was used to calculate odds ratios (ORs) with 95% confidence intervals (CIs) to test associations before and after accounting for possible confounders.

Results: Depressive symptoms were significantly associated with obesity (OR = 1.19; 95% CI = 1.07-1.32), diabetes (OR = 1.22; 95% CI = 1.05-1.42), gastroesophageal reflux disease (GERD) (OR = 1.41; 95% CI = 1.28-1.57), metabolic syndrome (OR = 1.16; 95% CI = 1.03-1.29), osteoarthritis (OR = 1.41; 95% CI = 1.27-1.57), respiratory conditions (OR = 1.25; 95% CI = 1.10-1.42), history of cancer (OR = 1.19; 95% CI = 1.05-1.34), Parkinson's disease (OR = 2.56; 95% CI = 1.83-3.56), polypharmacy (OR = 1.60; 95% CI = 1.44-1.79), and multimorbidity (OR = 1.29; 95% CI = 1.12-1.49). No significant association was observed between depressive symptoms and hypertension, chronic kidney disease, dyslipidemia, and gout (P > .05). A significant dose-response relationship was evident between the number of medical comorbidities and the prevalence of depression (OR = 1.18; 95% CI = 1.13-1.22).

Conclusion: Late-life depressive symptoms are significantly associated with several medical morbidities, and there appears to be a cumulative effect of the number of somatic diseases on the prevalence of depression. These findings augment the evidence for a complex relationship between mental and physical health in an otherwise healthy older population and might guide clinicians toward early recognition of high-risk individuals. J Am Geriatr Soc 68:1834-1841, 2020.

Keywords: depression; late-life depression; medical comorbidity; polypharmacy; somatic conditions.

Figure 1.

Association between number of medical comorbidities and prevalence of depression (defined as CES-D score ≥8). The figure shows the cure prevalence of depression stratified by number of medical comorbidities, using a multivariable-adjusted logistic regression accounting for age, sex, race, education, smoking, alcohol use, living status, and body mass index. A statistically significant dose-response relationship was found between depression and the number of medical comorbidities (P < .001).

Figure 2.

Relationship between depression, number of medical comorbidities, and mean number of concomitant medications. The figure shows the mean number of concomitant drug use stratified by depression status and number of medical comorbidities excluding depression. A linear model was fitted to assess the effect of depression on the association between the number of medical comorbidities and number of concomitant drugs, with the number of drugs as the outcome variable and the number of comorbidities, depression status, and their interaction term as the main predictors. The model was adjusted for age, sex, race, education, smoking, alcohol use, living status, and body mass index. Based on this model, there is significant evidence of an association between the number of medical comorbidities and increased number of concomitant drugs in those with depression as compared with those without depression (P = .009). Antidepressants were excluded from this analysis.