Is supervised aerobic exercise effective for people with depression or depressive symptoms?
This study is difficult to parse, given the nonspecificity of the diagnosis of depression, the low quality of half the included studies, the small numbers of participants in each study, and the high degree of heterogeneity among the interventions and results. But here goes: With an NNT of between 2 and 3, it seems worth a try to offer a supervised exercise program to patients with less severe depression to help reduce symptoms.
Self-funded or unfunded
These investigators searched 7 databases, as well as a trials database and reference lists of identified studies, to identify randomized controlled studies of adults with a diagnosis of depression (or who screened positive for depressive symptoms) that compared an exercise intervention group with a nonexercising control group. Articles were selected and abstracted by 3 independent researchers and risk of bias was assessed by 3 investigators. The authors identified 41 studies that enrolled a total of 2264 participants. Half the studies enrolled patients who were given a diagnosis (severity not specified) of depression and half the studies enrolled patients with depressive symptoms. Most of the studies evaluated the effect of aerobic exercise alone (n = 30) or in combination with resistance training (n = 10).
Lots of problems with this literature. Heterogeneity was high for both interventions and outcomes. There was a high risk of bias in half the studies. Three of the studies included patients with dysthymia. Overall, an exercise intervention produced a greater reduction in symptoms than nonexercise comparators, with an overall number needed to treat (NNT) of 2.0; the NNT was slightly higher (2.8) in studies with a low risk of bias. The effect was larger in patients with depression and when a supervised exercise program was recommended.
Allen F. Shaughnessy, PharmD, MMedEd
Professor of Family Medicine