A recently published study in the Canadian Medical Association Journal provides further evidence for the link between mortality and depression, while also suggesting women may be increasingly vulnerable to early death.
In 2015 alone, 16.1 million American adults experienced at least one major depressive episode, according to the National Institute of Mental Health. During these episodes, people may notice a range of symptoms, from low mood and anhedonia to changes in sleeping and eating habits. Depression accounts for a greater rate of disability than any other mental health condition and significantly impacts the ability to care for oneself. Even more concerning, the Canadian Medical Association Journal study shows that just one depressive episode raises a person’s risk of death, and this risk can remain elevated for up to 20 years after each episode.
An Unsettling Evolution
Studies about the association between mortality and depression are often limited in duration to 10 years or less, according to study corresponding author Stephen Gilman, ScD, Investigator and Acting Branch Chief, Health Behavior Branch, Division of Intramural Population Health Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development. That led researchers involved in the current study to wonder how the association persists and evolves over time.
To conduct their review, researchers analyzed data from the Stirling County Study. Launched in 1952, the Stirling County Study includes 60 years worth of mental health data obtained from 3,410 adults living in Atlantic Canada.
“The Stirling County Study was unique in that it used two different approaches,” Gilman says. “First, it enrolled representative samples of the adults in the county at three different time periods: 1952, 1970 and 1992. Second, it conducted follow-up interviews in 1970 and 1992 of participants enrolled in earlier waves. At each time point in the study, assessments were used to determine participants’ experiences with mental health problems — depression and anxiety were a major focus. To determine the vital status of participants, we cross-referenced the Stirling County data with the Canadian [Human] Mortality Database.”
As part of the investigation into how the association changed over time, researchers examined depression and mortality among men and women separately. The team found that depression was associated with an increased risk of death in men during all three study periods; however, mortality risk declined in men from the 1950s to the early 2010s. Researchers observed the opposite effect in women. A higher mortality risk was not apparent among women with depression in the 1950s and 1970s. Between 1992 and 2011, however, researchers observed a 50 percent increase in the mortality risk among women with depression.
The Quest to Understand Why
The current study was not designed to determine reasons for the lingering association between depression and early death, particularly among women. Behaviors, such as alcohol use and smoking, did not seem to play a role in the association, according to Gilman. Instead, researchers hypothesize that women’s evolving roles may contribute to the association.
“[S]ocietal roles are changing, and those changes are putting more pressure on women, making it more difficult for women to get help when they are depressed,” says study author Ian Colman, PhD, Canada Research Chair in Mental Health Epidemiology at the University of Ottawa. “Most notably, the proportion of women in the workforce has increased dramatically in recent decades. This is a good thing for women’s equality, but if expectations for women are not changing outside of the office, then that may be putting a particularly heavy burden on them, especially if they are struggling with their mental health.”
Takeaways for the Future
The findings of this study highlight the continual need for public education about depression and place greater emphasis on not only treating depression, but also preventing recurrent depressive episodes. For physicians, this means caring for people in body and mind, according to Rudy Nydegger, PhD, ABPP, Professor Emeritus of Management and Psychology at Union Graduate College and Union College, and Chief, Division of Psychology, at Ellis Hospital in Schenectady, New York.
“There is a relationship — and everybody knows this — between physical and mental health,” says Nydegger, who was not involved in the study. “But it’s very easy for us to get into the oftentimes time-pressure-based approach where we just take care of the presenting problem, do the best we can and [move] on to the next patient. ... [I]f we’re not looking at some of these psychological factors that may be complementing the medical condition, we may not be able to treat the medical condition as effectively.”