Daily smoking linked to depression

OTTAWA, Oct. 24 (UPI) -- Previous depression, smoking and a lack of control over life circumstances are risk factors for repeat episodes of depression, Canadian researchers say.

Dr. Ian Colman of the University of Ottawa and colleagues identified risk factors associated with a long-term prognosis of depression.

The researchers looked at 585 adults from Statistics Canada's National Population Health Survey who had suffered depression in 2000/2001 -- 65 percent women, average age 38.5 years and 82 percent in the middle- to high-income bracket. More than half the patients had one or more episodes of depression in six years.

The study, published in the Canadian Medical Association Journal, found age, sex and income were not associated with future depressive episodes but daily smoking and low mastery were associated with long-term depression. Mastery is the sense that people have control over their lives and their circumstances -- in this study, high levels of mastery appeared to be protective against further depression.

Being an immigrant appeared to have protective status against relapse in people with severe depression, the study said.

"History of depression is a well-known clinical indicator of future depressive episodes; however, smoking and mastery are more novel prognostic factors that are not well accounted for in current clinical practice," Colman said in a statement.