Keep the Black Dog on the leash

There are heavy clouds darkening the path ahead for many people, and depression is a known risk for tripping us up.

But research shows that the risk is much higher for sedentary people.

According to a recent study, even people genetically vulnerable to depression are protected from it by three hours of physical activity each week.

Researchers at Harvard Medical School examined the health records of 8000 people who had volunteered information to a biobank in the Boston area.

They looked at their exercise habits, at DNA for markers associated with inherited depression, and at their medical history of any treatment for depression.

They found that physically active people had less risk than people who were sedentary, and the type of exercise mattered little.

If someone spent at least three hours a week participating in any activity he or she was less likely to become depressed than sedentary volunteers, and the risk fell another 17 percent with each additional 30 minutes or so of daily activity.

This link between movement and improved mental health held true for people who had experienced depression in the past. If they reported exercising now, their risk for a subsequent episode of depression fell, compared to the risks for inactive people with a history of depression.

Exercise also substantially altered the risk for people whose DNA predisposed them to depression: if their genes suggested susceptibility to depression,  they none-the-less were no more likely to develop depression than inactive people with little genetic risk.

“Our findings strongly suggest that, when it comes to depression, genes are not destiny and that being physically active has the potential to neutralise the added risk of future episodes in individuals who are genetically vulnerable,” said Karmel Choi, the lead author of the study.

“On average, about 35 additional minutes of physical activity each day may help people to reduce their risk and protect against future depression episodes.”

In effect, physical activity “neutralised” much of the added risk for people born with a propensity for depression, Dr Choi said. If depression runs in your family, she says, you might help to manage any heightened risk by moving more.

The paper is published in the journal Depression and Anxiety, behind a paywall.