The Problem: There have been lots of studies looking at whether being active, and more specifically, exercising regularly can reduce the risk of you getting depressed. Recent reviews that compare the results across many of these studies suggest that indeed, higher exercise levels are related to a lower risk of depression. What’s more, this relationship does not merely reflect the fact that when someone gets depressed, they tend to step back from valued activities. Exercise itself seems to exert a direct effect on your mood such that you feel better overall, and it is preventive when it comes to mood problems.
The question that Matthew Pearce and his colleagues brought to the table with their study was how much exercise is required to have a beneficial effect? In other words, what is the dosage of exercise that’s required to significantly lower the risk of depression?
The Method: To answer this question, a careful review of recent research studies on the topic was conducted. Studies of adults 18 years of age and older were considered so long as they included at least 3 levels of exposure to exercise, followed participants for at least 3 years, reported risk levels for depression as measured by diagnostic criteria or a recognized screening test, and included at least 3,000 participants. In all, 15 studies were included in the final analysis, with a total of close to 200,000 participants.
Key Findings: Findings suggest that it is at the lowest dosage of exercise that the greatest effects on depression are observed. In other words, moving from no activity to at least some activity gives you the most benefit. How much is meant by “some activity”? Based on their analyses, Pearce and his colleagues estimate that a volume equal to 2.5 hours of brisk walking each week could reduce the risk of depression by 25%. At half that dose, or just 10-15 minutes each day, the reduction in risk was just under 20% when compared to no activity. Interestingly, increasing the amount of exercise you get beyond 2.5 hours per week resulted in only minor additional benefits.
Why Does This Matter? This study is important because for many people the idea of getting regular exercise is very intimidating. Knowing that the amount of change needed to make to get substantial benefits is relatively small - amounting to just 15-30 minutes each day of brisk walking - could make a huge difference in a person’s willingness to change their behaviour. Think about it - how much exercise do you get each day? Could you make this relatively small change in your lifestyle knowing that it could have a big impact on how you feel over the long term? Think of it as a lifestyle prescription that costs nothing, has a lot of benefits, and unlike most medications, has few if any unpleasant side effects.
Pearce M, Garcia L, Abbas A, Strain T, Barreto Schuch F, et.al. (2022). Association Between Physical Activity and Risk of Depression: A Systematic Review and Meta-analysis. JAMA Psychiatry. Doi:10.1001/jamapsychiatry.2022.0609
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