Depression Across the Lifetime Often Traces U-Shaped Curve

The trajectory of depressive symptoms across the adult life span follows a “U”-shaped pattern, with such symptoms being highest in young adulthood, decreasing during the middle years, and then increasing again in later years.

So reported Angelina Sutin, Ph.D., an assistant professor of medical humanities and social sciences at Florida State University College of Medicine, and colleagues online June 12 in JAMA Psychiatry.

In 1958, the Baltimore Longitudinal Study of Aging was launched by the National Institute on Aging. In 1979, participating subjects started to be assessed periodically for depressive symptoms with the CES-D scale—a commonly used measure of depressive symptoms. By the end of 2011, more than 10,000 depressive-symptom assessments had been conducted on some 2,300 subjects. Each subject had been assessed five times on average. The average amount of time between assessments was three years.

Sutin and her colleagues used these assessment results to determine the trajectory of depressive symptoms across the adult life span.

They found that depressive symptoms were highest in early adulthood, declined in middle adulthood, and then increased somewhat in older adulthood. Moreover, this was the case whether the depressive symptoms were depressed affect (e.g., “I felt sad”), somatic complaints (e.g., “My sleep was restless”), or interpersonal problems (e.g., “I felt that people disliked me”).

The researchers also found that women reported experiencing more depressive feelings in early adulthood than men did, but that men reported experiencing more depressive feelings in late adulthood.

Furthermore, higher level of education was associated with fewer depressive symptoms, especially fewer somatic complaints and interpersonal problems. The data pointed to racial differences as well, with whites experiencing more interpersonal problems and somatic complaints in older age than African Americans and individuals of other ethnicities.

Sutin and her colleagues also examined other data that had been collected about the cohort to see if they could identify clues to the uptick in depressive symptoms in the senior years. They found, not surprisingly, that subjects with greater disease burden and more functional limitations reported more depressive symptoms than those without, as did those who were approaching death. Yet even after the researchers accounted for disease burden, functional limitations, and approaching death in their analysis, there was still an increase in depressive symptoms among the older age cohort.

One explanation for their age-related findings, the researchers speculated, was loss—loss of loved ones, social support, employment, income, feeling valued, and personal control.

As Sutin told Psychiatric News, “Actually I expected to see a bigger effect of disease and disability on depressive symptoms, but the effects were modest. Even among the physically healthiest participants in the sample, feelings of sadness increased at older ages. This suggests that other factors associated with old age—such as death of a spouse, loss of social support networks— may be more important for depression in old age than the individual’s physical health.”

Their findings have clinical implications, the researchers believe. “There are periods of adulthood when people are more or less prone to depressive symptoms, although it is important to note that for any single individual, depression can happen at any time,” Sutin stated. “Even if older adults do not pass the threshold for a diagnosis of major depression, they are still at risk for elevated symptoms of depression. Second, health care providers should not assume that depressive symptoms in old age are due to declines in health; other factors may be contributing to symptoms of depression at older ages. And third, individuals with a history of depressive symptoms are at greatest risk for elevated depressive symptoms in old age.”

“This is an interesting study,” Dilip Jeste, M.D., a former APA president and chair in aging at the University of California, San Diego, told Psychiatric News. “The…findings are consistent with an increased prevalence of subsyndromal (but not major) depression in older age. It should be noted, however, that the increase in depressive symptoms in the present study was relatively small. Also, the overall trajectory of symptoms, especially around middle age, is at variance with several other studies from various countries showing a worsening of quality of well-being from age 20 to age 50, with improved self-reported mental functioning thereafter. The reasons for the discrepant results are not obvious and need further research.” ■