Numerous studies have examined the relationship between mental health and physical activity over the past few decades. Some have focused on the connection between walking and depression and its symptoms. But there’s a problem: Despite the wealth of experiments and analyses, some have produced conflicting results.
Getting the science right. To address this problem, a team of experts conducted a meta-analysis, a quantitative study based on previous research. They found that when they looked at the scientific literature as a whole, these analyses showed a negative association between walking and the onset of symptoms associated with depression.
Researchers from the University of Castilla la Mancha led the study. They published details of the methodology and results of this analysis in an article in the journal JAMA Network Open.
This “study of studies” began with a systematic review of the scientific literature to find relevant analyses published to date (May 2024). From this search, the researchers found 33 observational studies with 96,173 participants in 13 different countries.
Estimating an association. Based on the results of the previous research, the team responsible for this new study made new estimates of the relationship between the steps taken and the occurrence of depressive symptoms. They found that people who walked at least 10,000 steps a day had fewer depressive symptoms than people who walked 5,000 steps or less.
In addition, they calculated that an increase of 1,000 steps per day was equivalent to a 9% reduction in the risk of experiencing these symptoms.
Caution in interpretation. These types of quantitative studies are good at identifying correlations between variables. Still, their ability to establish cause-and-effect relationships is limited because they tend to be cross-sectional studies, which are highly dependent on the type of studies included.
Establishing a cause-effect relationship in this case is particularly difficult because the inverse relationship is specific: Having depression makes people less likely to walk, so this fact already presupposes the existence of a correlation between the variables.
“This study shows that people with more depressive symptoms tend to have lower step counts and vice versa. The authors write, ‘the objective measurement of daily steps may represent an inclusive and comprehensive approach to public health that has the potential to prevent depression’ but this study can’t tell us whether this would prevent depression,” David Curtis, an honorary professor at University College London who wasn’t involved in the study, said.
“It just shows that people who are less depressed walk more but of course that might just be because they’re more cheerful and active. In fact, inactivity is actually listed as a symptom of depression so it’s only to be expected that observational studies would see this association,” Curtis added.
Good advice. Researcher Brendon Stubbs of the National Institute for Health and Care Research shares Curtis’ view: “While it shows a clear association between higher step counts and lower depression symptoms, we can’t definitively say that walking more reduces depression, as most studies only looked at one point in time.”
But even this possibility can’t be ruled out. “However, the findings align well with existing evidence about physical activity’s benefits for mental health,” Stubbs stated. As such, maintaining an active lifestyle helps reduce the risk of developing these problems and mitigates their effects if they do occur.
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