Date Published: April 8, 2019
Publisher: Public Library of Science
Author(s): Rebecca Lys, Emmanuelle Belanger, Susan P. Phillips, Stephen D. Ginsberg.
Older adults experience increasing physical illness with age, but paradoxically, they frequently describe improvements in mood and self-rated health. The role of declining physical health as a risk for depression in elderly men and women remains unclear. We assessed whether declining physical health predicted changes in depression over time among seniors using data from the International Mobility in Aging Study (IMIAS).
IMIAS is a longitudinal population-based study of older adults in Canada, Colombia, and Brazil. We assessed change in depression by comparing Center for Epidemiology–Depression (CES-D) scores for 1161 men and women between 2012 and 2016, and used multiple regression to identify whether changes in chronic health conditions, grip strength and self-rated health predicted change in depression over time.
Despite worsening physical health measured as chronic health conditions and grip strength, mean CES-D scores decreased from 8.15 (95% CI 7.70–8.60) in 2012 to 7.15 (95% CI 6.75 to 7.56) in 2016. Counterintuitively, women reported increased self-rated health despite having declining physical health, p = 0.004. Decreases in depressive symptoms were aligned with higher CES-D in 2012 and with increases in self-rated health among women and overall, and with high CES-D 2012 and increases in chronic health conditions in men, ps < 0.05. Mental health appears to be a fundamentally different construct than physical health in older adults, allowing seniors to experience improved mood despite declining physical health. Clinicians should not consider depression in elderly populations as an inevitability of aging.
Among those with depression, it is older adults who are most likely to attempt and complete suicide. The role of concomitant physical disease, and the etiology of depression among seniors are poorly understood and confusing. Older adults are more likely than the young to have chronic illnesses such as cardiovascular disease, diabetes, or respiratory compromise, all recognized both as risk factors for and complications of depression.[2–5] Yet, paradoxically, most research demonstrates a decrease in prevalence of depression with increasing age.[6–8] There is evidence that some individuals, including seniors, with physical illness may experience a response shift of recalibrating their physical health expectations, reprioritizing their values, or reconceptualizing constructs in order to maintain their quality of life while experiencing a decline in health.[9–12]
Visual inspection with histograms, normal Q-Q plot, and box plots showed that the majority of data were approximately normally distributed.  Change in depression was within the normal range for males (skewness -0.260, SE 0.104, kurtosis 2.958, SE 0.209) and females (skewness -0.556, SE 0.099, kurtosis 2.689, SE 0.197).
As respondents aged, they reported fewer depressive symptoms despite declining physical health. This improvement in mood was consistent for men and women, and across high- and middle-income settings. The most consistent predictor of a decrease in depression was a higher initial CES-D. This could demonstrate nothing more than regression to the mean, however the consistency of the finding across settings and groups suggests something more. While objectively-measured physical health declined and number of chronic diseases increased, SRH increased or remained stable, implying that subjective assessments of one’s health sometimes extend beyond a count of chronic diagnoses to include elements of mental well-being.
Our longitudinal, international study demonstrates that decreased mood is not an inevitable consequence of physical illness in older adults. While risk factors such as sex/gender, chronic illness, and income insufficiency can contribute to a higher baseline prevalence of depressive symptoms, adults across middle and high income settings appear to have improvements in mood as they age. Health care providers treating older adults should not dismiss depression as an expected consequence of aging. Instead they might help patients develop a sense of successful aging despite increasing physical comorbidities.