Exercise is not only beneficial for your physical health, but can improve mental health as well. Depression is more common than people may think. It is the leading cause of disability for ages 15-44 and affects 6.7% of U.S. adults .6.7% may not sound like much, but it is equivalent to about 14.8 million people. Unfortunately, nearly half of those diagnosed with depression do not receive adequate treatment. One option for people is to go on an anti-depressant, which can be costly and may have adverse effects. Another option is cognitive behavioral therapy…also costly and very time consuming. Although exercise may be a bit time consuming, it can be free, has several other benefits for your physical and mental health, and generally little to no adverse effects.
Rethorst and colleagues (2009) conducted a meta-analysis using 58 randomized control trials (RCTs) and included 2,982 subjects. The studies included in this meta were required to have their subjects use a form of moderate to vigorous exercise, be an RCT and their control groups could not participate in any exercise including walking or stretching. The main findings of this meta were:
- Both aerobic exercise and resistance training alone can significantly improve depression, but a combination of both yields the greatest results.
- There are greater improvements in people who are clinically depressed vs. mildly depressed.
- In a clinically depressed population, longer exercise interventions yield greater improvements.
- Exercise worked just as well as psychotherapy or medication. There were no significant differences between psychotherapy, medication, and exercise.
- The dropout rate for exercise (14.6%) was less than the dropout rate of medication (21-33%)
For the OVERALL population the following yielded the BEST results:
- 20-29 minute bouts
- 3-4 days a week
- 4-9 weeks & 10-16 weeks…better than 17-26 weeks (weird…I would think that longer is better, but they suggest that this could be due to a floor effect…so they achieved their greatest improvements in the first 16 weeks of exercise.)
- >75% max HR…..but 50-60% yielded good results too…(better than 61-74%…also weird.)
For the CLINICALLY DEPRESSED population, the following yielded the BEST results:
- 45-59 minute bouts
- 5 days a week
- 10-16 week intervention
- No significant differences between intensity levels (% max HR)
Rethorst and colleagues suggest that exercise may cause physiological changes to the brain that make it effective for treating depression. These neurophysiological changes include:
- Neurogenesis
- Increases in BDNF…(Anti-depressants also increase BDNF to treat depression)
- Increase in endorphins
- Increase in serotonin
- Endocannabanoids
- Altered HPA functioning
Psychosocial factors as a result of exercise including an increase in self-esteem, improved body image, and improved sense of mastery may also help relieve depression.
While this specific study found 3-4 days a week (in overall population) and 5 days a week (in clinical population) to be best, and 4-9 week or 10-16 week interventions to be best; I would guess that more days a week is better and a lifelong intervention would be the ultimate best. I believe this to be the case because 1.) Research in mice suggests that there are greater effects in 7 days a week compared to 5 days a week (Duman et al., 2008….[I will be blogging more about this study later]) & 2.) If one were to stop exercising and receiving that stimulus to physiologically change the brain, then it is likely that their depression will return. I also expect that higher intensity is better in either population.
In conclusion, exercise (either aerobic, anaerobic, or both) is an effective treatment for individuals with depression. Although the U.S. hasn’t quite caught up yet, the UK and Australia are pro exercise as treatment for depression. In 2005, the UK’s Mental Health Foundation released a report encouraging general practitioners to use exercise as a frontline treatment for mild to moderate depression. In Australia, the government allows general practitioners to refer patients to an exercise physiologist under their Medicare program for treatment for depression. Exercise is a lot cheaper than medication or psychotherapy and has less adverse effects. Not only that, but while you are improving your mental health it yields several other health benefits such as: (i) reduced risk of cardiovascular disease, high blood pressure, colon, breast and prostate cancers, (ii) improved mortality rates and cognitive functioning, (iii) maintenance of normal strength, joint structure and function, and peak bone mass.
Feel free to comment/ ask questions as always!
#SOE
References:
Duman, C.H., Schlesinger, L., Russell, D.S., Duman, R.S. (2008). Voluntary exercise produces antidepressant and anxiolytic behavioral effects in mice, Brain Research, 1199, 148-158.
Kessler, R. C., Walters, E. E., Rush, A. J., Demler, O., Merikangas, K. R., Jin, R., . . . National Comorbidity Survey Replication. (2003). The epidemiology of major depressive disorder: Results from the national comorbidity survey replication (NCS-R). JAMA, 289(23), 3095-3105
Rethorst, C., Wipfli, B., Landers, D. (2009). The antidepressive effects of exercise: A meta-analysis of randomized trials. Sports Medicine, 39(6), 491-511.
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