We’ve known for decades that even a single bout of exercise can elevate our mood, but is it enough to be used as treatment for major depression? Well, we know physical activity has been associated with decreased symptoms of depression. If you look at a cross-section of 8,000 people across the country, those that exercised regularly were less likely to have a major depression diagnosis.
That’s just a snapshot in time, though. If you look at that study, the researcher openly admits this may be a case of reverse causation. Maybe exercise didn’t cut down on depression, maybe depression cut down on exercise. The reason depression may be associated with low physical activity is that patients feel too lousy to get out of bed. What we need is an interventional study, where you take people who are already depressed and randomize them into an exercise intervention and see if they get better. And that’s what we got.
Men and women over 50 with major depression were randomized to either do an aerobic exercise program for four months or take an antidepressant drug called Zoloft. This is where they started out before, with Hamilton Depression scores up around 18—anything over seven is considered depressed—but within four months, the drug group came down to normal, which is exactly what the drugs are supposed to do. What about the exercise only group, no drugs? Same powerful effect.
They conclude that an exercise training program may be considered an alternative to antidepressants for treatment of depression in older persons, as long as that group program of aerobic exercise is feasible and effective.
Not so fast, though. A group program? Patients in this exercise group come in three times a week for a group class. Maybe the only reason the exercise group got better is because they were forced to get out of bed, interact with people—maybe it was the social stimulation that made them feel better, maybe it had nothing to do with the actual exercise. Before you could definitively say that exercise can work just as well as drugs, what you’d like to see is the same study but with an additional group, the same two plus a home exercise group that can exercise on their own at home, no extra social interaction. But nothing like that had ever been done - until it was.
The largest exercise trial of patients with major depression conducted to date included a home exercise group in addition to the supervised group exercise and drug group as before. And they all worked just about as well in terms of forcing the depression into remission.
So we can say with confidence that exercise is comparable to antidepressant medication in the treatment of patients with major depressive disorder.
Putting all the best studies together, they indicate that exercise, at least, has a moderate antidepressant effect, and at best, exercise has a large effect on reductions in depression symptoms and could be categorized as a very useful and powerful intervention. Unfortunately, while studies support the use of exercise as a treatment for depression, exercise is rarely prescribed as a treatment for this common and debilitating problem.