Research this month points to a mental health benefit from regularly exercising. The review found that people who reported being physically active were noticeably less likely to later be diagnosed with depression. This association was most apparent in people who appeared to meet the recommended amount of exercise a week, but it could still be seen in people who exercised half as much.
Exercise is one of the healthiest things a person can do, and many studies in recent years have found that it can keep both the body and brain sharp. Physical activity is known to help people acutely suffering from mental health problems as well, in conjunction with other treatments. But this new research, published in JAMA Psychiatry this April, tries to quantify the protective effect that different levels of exercise may have in preventing depression.
The study reviewed data from 15 population studies, involving nearly 200,000 people. Importantly, these were prospective studies, meaning that people’s health outcomes were intentionally tracked from the very start—in contrast, a retrospective study can only look back in time, making it harder to confirm a cause-and-effect link between a factor and a health outcome. As part of these reviewed studies, participants were asked about their level of physical activity and had their history of clinical depression recorded as well.
Compared to people who didn’t report being physically active, people who reported being physically active had a significantly lower risk of depression, the study found. More specifically, people who met the minimal duration of exercise recommended by many public health organizations—about the equivalent of two-and-a-half hours of brisk walking per week—had a 25% lower risk of depression. But those who exercised half as much still had a 18% lower risk, while only “minor additional benefits” were seen in people who exercised more. Based on their modeling, they also estimated that if less-active people could meet the recommended level of physical activity, up to 11% of future cases of depression would be prevented.
The authors do note that their work might overestimate the effect of exercise on depression risk. One possibility, for example, is that people who were depressed but not yet diagnosed at the start of the study would also be less likely to exercise. To help mitigate this possible issue, they only analyzed studies with longer follow-up times (at least three years), but they note that some bias may still exist. And the authors do call for more studies that can better rule out any confounding factors and bolster a causal link between exercise and prevention of depression.
That said, plenty of studies have found that exercise can have direct and indirect effects on people’s well-being and risk factors for depression, from the mood boosts that people feel while exercising (the well-known runner’s high) to the social bonding it can create for those who join a gym class or running group. This is also only the latest study to suggest that any amount of exercise, however you get it, is much better than none at all.
The findings, the authors say, show that “substantial mental health benefits can be achieved at physical activity levels even below the public health recommendations.”