Moderate exercise not only treats, but prevents depression

This is the first longitudinal review to focus exclusively on the role that exercise plays in maintaining good mental health and preventing the onset of depression later in life.

Mammen -- who is supervised by Professor Guy Faulkner, a co-author of the review -- analyzed over 26 years' worth of research findings to discover that even low levels of physical activity (walking and gardening for 20-30 minutes a day) can ward off depression in people of all age groups.

Mammen's findings come at a time when mental health experts want to expand their approach beyond treating depression with costly prescription medication. "We need a prevention strategy now more than ever," he says. "Our health system is taxed. We need to shift focus and look for ways to fend off depression from the start."

Mammen acknowledges that other factors influence a person's likelihood of experiencing depression, including their genetic makeup. But he says that the scope of research he assessed demonstrates that regardless of individual predispositions, there's a clear take-away for everyone. "It's definitely worth taking note that if you're currently active, you should sustain it. If you're not physically active, you should initiate the habit. This review shows promising evidence that the impact of being active goes far beyond the physical."