Is Exercise an Efficacious Treatment for Depression? A Comment upon Recent Negative Findings

Exercise is receiving substantial and increasing attention as a potential treatment for depression. Despite the many positive meta-analytical findings and recommendations of some guidelines to incorporate exercise as a treatment for depression (National Institute for Health and Clinical Excellence, 2009), most clinical trials have significant methodological flaws that limit the generalizability of their findings (Daley, 2008; Rethorst et al., 2009). Furthermore, recent meta-analyses show that, when only robust clinical trials are included, the effects of exercise are " moderate at best " or statistically insignificant (Rimer et al., 2012). Similarly, four recent, robust, ran-domized controlled trials (RCTs) have failed to find any antidepressant effects of exercise: the DEMO (Krogh et al. compared aerobic exercise, anaerobic exercise , and relaxation (control) groups; after 4 months of intervention, no differences in depressive symptoms, as assessed by the Hamilton scale for depression (HAM-D17) (Hamilton, 1967), were found between the groups. Subsequently, the DEMO II trial (Krogh et al., 2012) compared aerobic exercise and stretching (control) groups; after 3 months, the authors found reductions in HAM-D17 scores in both groups but failed to find differences between the groups. In both studies, the authors concluded that exercise was as effective as placebo and had no biological antidepressant effects. Corroborating the DEMO and DEMO II findings, the TREAD (Trivedi et al., 2011) found a non-significant trend (p < 0.06) toward a remission rate of 16 kcal/kg/ week for aerobic exercise versus 4 kcal/ kg/week for aerobic exercise (control) after 3 months of intervention. Lastly, the TREAting Depression with physical activity (TREAD-UK) (Chalder et al., 2012) evaluated the cost-effectiveness of a strategy for promoting and increasing the physical activity levels of depressed patients in primary care. After 8 months, physical activity was shown to be an ineffective and more costly strategy than conventional primary care assistance and resulted in a non-cost-effective strategy according to willingness-to-pay thresholds. Considering these recent results, the answer to the question " is exercise an effi-cacious treatment for depression? " appears to be " No. " However, before this question is answered, some issues must be highlighted. Similar to the findings regarding exercise , several meta-analyses have shown that the benefits of antidepressants are " minimal or non-existent, " as they are as effective as placebo. Other meta-analyses have shown that antidepressants are effective only in severe, but not in moderate or mild depression (Kirsch et al., 2008; Fournier et al., 2010; Khan …