Depression Increases Risk For and Accrual of Long-Term Health Disorders

Adults with a history of depression developed long term physical health conditions at a rate approximately 30% faster than those without a history of the disorder, according to new research published online February 13 in PLOS Medicine.1

The findings come from a study of more than 170 000 adults aged 40 to 71 years participating in the UK Biobank study that also reported participants with depression accrued a mean 0.2 additional conditions per year compared with 0.16 for those without depression.1

The strength of the observed association is underscored by persistence of the higher rate of condition accrual among participants with depression after multivariable adjustment for sociodemographic characteristics (RR 1.30, 95% CI, 1.28-1.32). Although the association was attenuated after additional adjustment for number of conditions at baseline and social and lifestyle factors, it remained statistically significant, according to the study results (RR 1.10, 95% CI, 1.09-1.12).

According to lead author Kelly Fleetwood, MSc, from the Centre for Population Health Sciences of the University of Edinburgh, United Kingdom, and colleagues, common conditions developed over time included osteoarthritis, hypertension, and acid reflux.1

Depression is frequently observed in multimorbidity, yet its precise relationship with various diseases within complex disease networks remains unclear. Evidence suggests that depression may both precede the onset of certain medical conditions and co-occur with or follow other diseases, highlighting a bidirectional association. Understanding these dynamic interactions is crucial for clarifying the role of depression in multimorbidity and guiding more effective interventions.2

The strength of the observed association is underscored by persistence of the higher rate of condition accrual among participants with depression after multivariable adjustment for sociodemographic characteristics. Although the association was attenuated after additional adjustment for number of conditions at baseline and social and lifestyle factors, it remained statistically significant.

While previous studies have investigated the association between depression and physical comorbidities and the rate and number to develop over time, the majority of them have included 15 or fewer conditions, Fleetwood et al wrote. Recommendations now call for including at least 50 conditions in multimorbidity measures. Results of existing research are also limited by relatively short follow-up (3-4 years) and limited adjustment for potential confounding variables, according to Fleetwood’s team.

The current study was designed to quantify the association between depression and the rate of accrual of 69 long-term health conditions in middle and older age. The final cohort of 172,566 UK Biobank participants were aged 40 to 71 years at baseline (mean 57 years) assessment between 2006 and 2010 and had linked primary care data available. The 69 prespecified health conditions were assessed at UKB baseline and during a mean follow-up of 6.9 years, according to the study.

FINDINGS

The authors found that 17.8% of participants had a history of depression at baseline. Approximately two-thirds of participants with a history of depression were women vs half the participants without a history. Those with depression had more comorbid physical conditions at baseline compared to those who were depression-free (mean 2.9 vs 2.1).

The three most common physical health conditions present at UKB baseline among those with and without depression, respectively, were:

• Hypertension (33.4% vs 29.6%)
• Allergic and chronic rhinitis (32.4% vs 26.7%)
• Osteoarthritis (27.0% vs 19.1%)

The most common comorbid mental health conditions present at baseline were anxiety (41.8% versus 6.3%) and alcohol misuse (4.1% versus 1.7%)

A host of unhealthy characteristics were reported more frequently among those with depression at baseline including chronic multisite pain, sleeplessness, stressful life events, loneliness, smoking and obesity. A history of depression was also associated with more markers of frailty, the authors reported.

Contemporary health care systems have been designed to treat individual conditions, instead of individual people with multiple conditions, and they especially struggle to treat people with both physical and mental health conditions, Fleetwood and colleagues observed. “Better identification and management of depression in physical healthcare is needed, but mental health services also need to involve themselves in supporting their patients to maintain or improve their physical health,” wrote the team.

They also emphasized that the higher rate of accrual of conditions comorbid with depression was driven, in part, by “differences in modifiable risk factors like smoking, high BMI and low physical activity, meaning that there are potential opportunities for preventive care to improve future health.”

The authors acknowledge several limitations to the study including healthy volunteer selection bias, given just 5.5% of people invited to join the UK Biobank participated, which may limit the generalizability of the findings to the wider population. It is also likely that baseline condition counts and rates of accrual of new conditions are underestimated compared with the general population.

Nonetheless, they emphasize the role the study findings play in encouraging a view of depression as a “whole body” condition and call for future research to more carefully “explore the causal relationship between depression and the subsequent accrual of long-term physical health conditions in order to identify potential interventions.”

References
1. Fleetwood KJ, Guthrie B, Jackson CA, et al. Depression and physical multimorbidity: A cohort study of physical health condition accrual in UK Biobank. PLOS Medicine. 22(2):e1004532.
doi:10.1371/ journal.pmed.100453
2. Birk JL, Kronish IM, Moise N, et al. Depression and multimorbidity: considering temporal characteristics of the associations between depression and multiple chronic diseases. Health Psychol. 2019;38(9):802–811. doi: 10.1037/hea0000737