Counter-Messaging Downplays Effectiveness of Exercise for Depression

A new article, published in the Journal of Sports Sciences, illustrates how counter-messaging has misrepresented the evidence for exercise as a treatment for depression. The lead author, Panteleimon Ekkekakis, a professor of kinesiology at Iowa State University, reports that despite substantial research evidence that exercise can relieve depression, exercise is often not recommended by primary care practitioners.

“Our review suggests that media portrayals of RCTs allegedly showing that exercise has no antidepressant effect tend to state this conclusion with a definitiveness that is unjustified by the methodological limitations of the trials,” the authors write.

“Stepped cared” models for depression recommend that individuals start with lower-intensity interventions (e.g., easily accessible, non-pharmacological, low cost), and build up to higher-intensity treatments (e.g., pharmacotherapy) only if the lower ones are ineffective. These types of models are increasingly recommended in clinical practice guidelines for depression.

Many recent studies have substantiated the benefits of physical activity for relieving and preventing depression. Based on randomized controlled trial (RCT) evidence, many countries recommend exercise as a lower-intensity, first line intervention (e.g., UK, Canada, Netherlands, Australia). Yet, the American Psychiatric Association does not include exercise in their recommended treatments, and primary care practices still favor antidepressants as first-line treatments. Studies suggest that clinicians are unaware of the evidence that exercise is effective for depression or believe the evidence is weak.

“Confusion about the research evidence may be one of the factors that preclude the application of physical activity and exercise as options for the treatment of depression, even in countries in which they are explicitly recommended in stepped-care guidelines,” write the researchers.

The authors suggest that one cause of this confusion is “counter-messaging,” which is “the dissemination of information by researchers, university communication offices, and journalists of information that runs counter to the bulk of the research evidence and thus appears to conflict with ‘conventional wisdom’ on this topic.” Additionally, the lack of “critical appraisal by researchers, clinicians, and the public” of the sources of this counter-messaging allows the counter-messages to be more pervasive.

In the present study, the authors examine the effect of counter-messaging and deficient critical appraisal of that messaging for the TREAD-UK trial. The TREAD (treating depression with physical activity) trial, published in 2012, is the largest RCT to study the effects of physical activity for reducing depression in a primary care setting. In the abstract of the study’s publication, the authors conclude, “This physical activity intervention is very unlikely to lead to any clinical benefit in terms of depressive symptoms or to be a cost-effective treatment for depression.” Likewise, in a press release, the senior investigator is quoted saying, “this carefully designed research study has shown that exercise does not appear to be effective in treating depression.”

However, the researchers summarize a number of methodological issues and misinterpretations of the findings for the TREAD-UK trial. First, although the intervention group did not have significantly reduced depression compared to the control group, both groups had significant improvements in their depression symptoms. In fact, the control group had considerably more improvement than other control groups in similar studies.

The authors explain this result by outlining a number of ways the control group may differ from control groups in other trials. For one, participants were recruited to the study after having a conversation about the benefits of exercise with their physician. Additionally, participants were asked to record their physical activity during the study (tracking physical activity has been shown to result in increased activity). As a result, participants in the control group engaged in more physical activity than participants in any other study on physical activity promotion. The authors explain, “given the failure to manipulate physical activity, the trial could not fulfill its original purpose” to evaluate the effectiveness of physical activity for depression since both groups engaged in substantial levels of physical activity.

Another issue is that the TREAD-UK researchers revised the study’s hypothesis after the study had been completed. They changed the independent variable (the variable that distinguishes the control group from treatment group) from “physical activity” to “facilitated physical activity.” Although this may appear a minor revision, according to the present study authors it “fundamentally changed the nature of the research question” from whether participation in exercise reduces depression to whether participation in the study’s specific intervention was effective. The biggest problem is that this distinction was not made clear in press releases and media discussions of the study, leading to a misinterpretation of the findings by the general public.

In the current study, the researchers examined media and academic representations of the TREAD-UK trial for five years post-publication. To do this, they first examined the number of Google searches for “exercise” and “depression from 2012-2017. Findings show that search was conducted 3.5 times as frequently during the month the TREAD-UK study was published compared to the average number of searches during that five-year period.

Additionally, the authors reviewed 68 articles that cited the TREAD-UK trial in the five years post-publication. Of those studies, 47 specifically discussed the results. The authors examined whether the TREAD-UK results were portrayed accurately or erroneously and whether the articles provided critiques of the trial’s methodology.

The researchers find, “the majority (57%) of the remaining 47 articles cited the TREAD-UK as having shown that ‘exercise’ or ‘physical activity’ failed to lower depression. Only 17% were critiques.”

The authors briefly review three other studies on physical activity for depression that similarly had significant methodological flaws, but were marketed as definitive evidence for the ineffectiveness of exercise for depression. Like the TREAD-UK study, control groups in the DEMO and DEMO-II studies engaged in high levels of exercise and experienced comparable reductions in depression to the intervention groups. The OPERA study had the opposite problem. It was conducted in nursing homes, and most participants were too frail to engage in the moderate exercise planned in the study. The authors write, “despite the fact that it was impossible to implement ‘regular moderately intense group exercise sessions,’ the [OPERA] researchers concluded that ‘regular moderately intense group exercise sessions do not live up to their promise as a treatment for depression in elderly residents of care homes.’”

According to the researchers, rather than evidence-based medicine, we see “press release-based medicine” where critical appraisal of research methodology is absent, and findings are oversimplified. The researchers highlight how financial incentives can bias study design, interpretation of results, and dissemination of research as the pharmaceutical industry has much to lose if exercise replaces pharmacotherapy as a first-line intervention for depression. Therefore, the authors suggest that studies should undergo more scrutiny both pre- and post-publication.

They recommend, “critical appraisal should be applied with equal scrutiny to empirical evidence portrayed as having shown exercise to be ineffective and evidence portrayed as having demonstrated that exercise benefits health.”

 

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Ekkekakis, P., Hartman, M. E., & Ladwig, M. A. (2018). Mass media representations of the evidence as a possible deterrent to recommending exercise for the treatment of depression: Lessons five years after the extraordinary case of TREAD-UK. Journal of Sports Sciences, 36(16), 1860-1871. doi:10.1080/02640414.2018.1423856 (Link)