An interesting study conducted at Duke University explored the connection between exercise and depression. Duke researchers found that 30 minutes of brisk exercise three days per week was just as good at lowering depression as medication.1 Not only that, the study participants who simply exercised (as opposed to taking medication only, or exercising plus medication) had a much lower rate of relapse. Just 8% of exercisers had a return of depression, but in the groups that included medication (both medication only and medication plus exercise) the relapse rate was much higher: 38% and 31% respectively.
Exercise boosts production of serotonin
Exercise increases levels of BDNF, and BDNF boosts production of a neurotransmitter called serotonin. Serotonin is the neurotransmitter involved in thinking, feeling, sensitivity to pain, sleep and hunger. This neurotransmitter is strongly associated with depression and self-esteem, and is the neurotransmitter most frequently targeted by antidepressant medication. Furthermore, decreases in BDNF are associated with depression. Patients with mood disorders such as depression and anxiety, or patients under a lot of stress have lower levels of BDNF in their blood. Patients with stress-induced depression show less BDNF in the hippocampus.2
Adherence to the treatment is key
Other studies have also found that exercise improves depression3, even if only a little bit. But some of the studies that showed exercise had a relatively small effect on depression also included people who might have exercised as little as half the time they were supposed to.4 This is not a problem with the exercise intervention—it’s a problem with adherence to the intervention. In other words, if you don’t do the treatment, you can’t say it didn’t work.
Finally, depression is also associated with an atrophying hippocampus.5 Since BDNF can increase new cells in the hippocampus, thus reversing this atrophy, it seems even more clear that exercise is a great way to treat depression. In fact, I consider exercise to be the most effective treatment for depression out there!
1. Merritt R. (2000 Sept. 22). Study: Exercise has long-lasting effect on depression. Duke Today. Retreived from http://today.duke.edu/2000/09/exercise922.html
2. Artinowich K, Lu B. Interaction between BDNF and Serotonin: Role in Mood Disorders. Neuropsychopharmacology Reviews (2008) 33, 73—83; doi:10.1038/sj.npp.1301571; published online 19 September 2007
3. Rimer J, Dwan K, Lawlor DA, Greig CA, McMurdo M, Morley W, Mead GE. (2012, Jul.) Exercise for depression. Cochrane Database Syst Rev. 11(7).
4. http://summaries.cochrane.org/CD004366/exercise-for-depression. Retrieved 10/10/2013.
5. Warner-Schmidt JL, Duman RS. (2006). Hippocampal neurogenesis: Opposing effects of stress and antidepressant treatment. Hippocampus 16(3), 239-49.