(Reuters Health) - People who suffer from depression may not live as long as individuals who don’t experience this mental health disorder, a Canadian study suggests.

Researchers examined six decades of mental health and mortality data on 3,410 adults during three time periods: 1952 to 1967, 1968 to 1990 and 1991 to 2011. Depression was associated with an increased risk of premature death in every decade of the study for men, and starting in the 1990s for women.

The connection between depression and a shorter lifespan appeared strongest in the years following a depressive episode, leading the researchers to conclude that at least part of the risk might be reversed by effectively treating the mental illness.

“For some individuals depression can be very serious condition,” said lead study author Stephen Gilman of the Eunice Kennedy Shriver National Institute of Child Health and Human Development.

“Given our finding that individuals whose depression was present at multiple time points in our study were at highest risk, it is very important to seek treatment for depression and to be vigilant about recurrences,” Gilman said by email.

Depression has long been linked to a variety of health problems, in part because it may lead to physiological changes in the body and also because it can contribute to unhealthy habits like a poor diet, inactivity, smoking and excessive drinking.

In the current study, however, researchers found a link between depression and premature death even after accounting for things like obesity, smoking and drinking habits.

“It is known that depression is associated with an increased risk of death from heart disease,” said Dr. Ralph Stewart, a researcher at the University of Auckland in New Zealand who wasn’t involved in the study.”

“This study suggests that this increased risk of death extends to other causes of premature death and persists over decades,” Stewart said by email.

The researchers examined data from the Stirling County Study, which began in 1952 in Canada and is one of the first community-based studies on mental illness.

People were about 50 years old on average when they joined the study. Across the three time periods examined, researchers followed half of the participants for at least 19 years.

Researchers calculated life expectancies at age 25 for men and women with and without depression in each wave of the study.

In the first wave, life expectancy with depression was 10 and 12 years shorter for women and men, respectively, researchers report in CMAJ. It was 7 years shorter for men with depression in the second wave, and 7 and 18 years shorter for women and men with depression, respectively, in the last group.

Men with depression were almost three times as likely to die early at the beginning of the study, but the increased risk declined to 52 percent by the end.

Women’s risk of a premature death increased, however. At the start of the study, women with depression were 8 percent more likely to die prematurely, and by the end their increased risk was similar to men’s odds at 51 percent.

Limitations include a long interval between participant interviews, which prevented the research team from determining the exact timing of depression and recurrences, the authors note.

Even so, the findings underscore the importance of diagnosing and treating depression, said Dr. Gjin Ndrepepa, a researcher at the German Heart Center and Technical University in Munich, Germany, who wasn’t involved in the study.

“Since the risk related to depression decays over time, great efforts should be made to improve treatment and prevent recurrences of depressive episodes,” Ndrepepa said by email.

Treating depression, Ndrepepa added, “can reduce depressive symptoms, improve quality of life and potentially prolong life.”

SOURCE: bit.ly/2zDrd1R CMAJ, online October 23, 2017.