Can exercise improve symptoms of depression?

Background: Current literature on the benefits of exercise in managing depression is confusing at best. The topic is incredibly complex to begin with, and many studies lack the scientific rigor necessary to provide concrete results (Lawlor, 2011; Ströhle, 2008). As such, researchers have performed systematic reviews to combine results from previously conducted studies and make stronger, better justified conclusions. A recent review by Cochrane published in 2013 looked at 39 randomized trials to determine the effect of exercise interventions in the treatment of depression (Cooney et al., 2013).

Defining Our Question: There are several questions that might come to mind when we ask, “can exercise improve symptoms of depression”?

What kind of exercise are we talking about?: Several exercise interventions are referred to in this paper. Most are aerobic exercises involving walking or running. It’s difficult to know if different types of exercise offer varying benefits to depression management as it does not seem to be properly investigated.

What do we mean by “improve symptoms”?: Improvement can refer to beneficial changes on both biochemical and psychological levels. For instance, exercise could affect the body’s endorphin and monoamine (e.g. dopamine) concentrations or reduce levels of the stress hormone cortisol (Chen, 2013). Exercise can also boost a person’s sense of self efficacy, which is linked with self esteem and overall well- being (Craft, 2011).

How do we know if improvements are significant?: Studies can use several measures such as the Beck Depression Inventory (BDI) or the Hamilton Rating Scale for Depression (HAMD). These require participants to answer multiple-choice questions which are meant to address depressive symptoms, including “sadness, hopelessness, self-blame, guilt, fatigue, and loss of appetite” (Warmenhoven et al., 2011). Patients undergoing exercise treatment are compared with patients without treatment or patients taking antidepressants/psychological treatments. More objective measures of depression (e.g. fMRI that looks at brain activity) have not been common, likely due to a lack of conclusive evidence on their reliability.

Results of this Paper: “Exercise is moderately more effective than no therapy for reducing symptoms of depression.” Furthermore, exercise by itself is less effective than antidepressants/psychological treatments for reducing symptoms of depression.

The Take-Away Message: Given the quality of evidence, we cannot make any strong arguments for the benefit of exercise in managing depression. More accepted treatments such as antidepressants are likely to be more effective in treating depression and its symptoms (Cooney et al., 2013). Nevertheless, exercise has been shown to be slightly more effective versus no treatment, suggesting that it can still contribute to patient well-being.

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Sources:

1. Lawlor, D. (2001). The effectiveness of exercise as an intervention in the management of depression: systematic review and meta-regression analysis of randomised controlled trials. BMJ, 322(7289), 763–763. http://dx.doi.org/10.1136/bmj.322.7289.763
2. Ströhle, A. (2008). Physical activity, exercise, depression and anxiety disorders. Journal Of Neural Transmission, 116(6), 777–784. http://dx.doi.org/10.1007/s00702-008-0092-x
3. Cooney, G., Dwan, K., Greig, C., Lawlor, D., Rimer, J., & Waugh, F. et al. (2013). Exercise for depression. Cochrane Database Of Systematic Reviews. http://dx.doi.org/10.1002/14651858.cd004366.pub6
4. Chen, MJ (2013). The neurobiology of depression and physical exercise. Handbook of Physical Activity and Mental Health. London: Routledge, 169–84
5. Craft, L. (2005). Exercise and clinical depression: examining two psychological mechanisms. Psychology Of Sport And Exercise, 6(2), 151–171. http://dx.doi.org/10.1016/j.psychsport.2003.11.003
6. Warmenhoven, F., van Rijswijk, E., Engels, Y., Kan, C., Prins, J., van Weel, C., & Vissers, K. (2011). The Beck Depression Inventory (BDI-II) and a single screening question as screening tools for depressive disorder in Dutch advanced cancer patients. Support Care Cancer, 20(2), 319–324. http://dx.doi.org/10.1007/s00520-010-1082-8