Exercise has long been known to have beneficial effects on cardiovascular and musculoskeletal health. It has also been increasingly recognized for its positive effect on mental health, and psychiatrists often encourage their patients to develop an exercise routine. A comprehensive review recently published in Molecular Psychiatry by Ryan Ross and colleagues conclude that physicians should be more forceful when discussing exercise with their patients as a treatment for depression.
Review of the Research
The authors detail studies addressing exercise both as a stand-alone treatment for depression and as an augmentation strategy supplementing other treatments. They review data pertaining to both aerobic exercise and resistance exercise. They define aerobic exercise as “activities performed in a continuous or interval nature with the intention of improving the efficiency of the cardiovascular and pulmonary system and increasing aerobic capacity.” Resistance exercise involves “activities that require sustained or intermittent exertion of forces against resistance with the intention of improving musculoskeletal function and enhancing muscular strength or endurance.”
The overall conclusion of their review was that exercise “3 to 5 sessions per week, for 45 to 60 minutes per session, and at a moderate to vigorous intensity” has antidepressant properties similar to that of medications in reducing depressive symptoms in individuals with unipolar depression . Exercise in combination with pharmacotherapy is also effective. Although some evidence suggests the possibility that vigorous exercise is more effective than moderate exercise, both intensities of exercise are superior to no exercise at all. Most of the studies in this review were between one and four months in duration.
Most studies examined the benefits of aerobic exercise; however, available data suggest that resistance-based exercise is also helpful. The authors encourage exercise regimens that include both aerobic and resistance-based workouts.
Another recent report by Hiral Master and Evan Brittain examined the association of long-term exercise, as measured by Fitbit fitness trackers, and the incidence of chronic illness. They concluded, “Higher daily step counts in data collected over several years of Fitbit fitness tracker use were associated with lower risk of common, chronic diseases, including hypertension, diabetes, gastroesophageal reflux disease, depression, obesity and sleep apnea.”
Mechanisms for Antidepressant Effects of Exercise
How does exercise exert its antidepressant effects? Although numerous studies have attempted to determine possible mechanisms, data are inconsistent. Two mechanisms of interest involve the anti-inflammatory properties of exercise and its influence on levels of brain-derived neurotrophic factor (BDNF). BDNF is a chemical produced by the brain that influences cell connectivity and growth. A variety of antidepressant treatments influence BDNF levels.
Depression is common and is a leading cause of disability both in the United States and globally. Not everyone responds adequately to current treatment options or has access to mental health care. Adding such a low-cost option as exercise to the treatment arsenal for depression could have wide-ranging implications. We would add that other efforts focusing on lifestyle can also be beneficial in improving and perhaps preventing episodes of depression. These “therapeutic lifestyle changes” include diet, stress reduction, and sleep hygiene in addition to exercise.
Motivating patients to exercise
It is often difficult to motivate a person with depression to start an exercise regimen. Psychotherapeutic techniques and phone apps may be helpful. This review should motivate clinicians to be more rigorous either in encouraging exercise as an augmentation therapy or, especially in those unwilling to participate in psychotherapy or pharmacotherapy, as a sole therapy. In the words of the authors: “This is not a call for exercise to replace existing therapeutic strategies but for exercise to be consistently integrated as an additional first-line treatment for depression.”
Eugene Rubin, MD, Ph.D., and Charles Zorumski, MD, wrote this post.