A recent updated Cochrane review suggests that exercise may reduce symptoms of depression to an extent comparable to psychological therapy and, with lower certainty evidence, antidepressant medication. The review, which analyzed 73 randomized controlled trials involving nearly 5,000 adults diagnosed with depression, highlights exercise as a low-cost, accessible option with additional health benefits, while also noting limitations in the current evidence, particularly regarding long-term effects and the specifics of optimal exercise interventions.
Background on Depression and Treatment Approaches
Depression is identified as a significant global cause of ill health and disability, affecting over 280 million individuals worldwide. Current treatment options typically include psychological therapies and antidepressant medications. Exercise, recognized in some global guidelines as a first-line treatment, offers a non-pharmacological approach that can be widely accessible.
Review Methodology and Findings
Researchers from the University of Lancashire, with support from the National Institute for Health and Care Research (NIHR) Applied Research Collaboration North-West Coast (ARC NWC), conducted the updated Cochrane review. They systematically analyzed 73 randomized controlled trials, encompassing approximately 5,000 adults with diagnosed depression. These studies compared the effects of exercise against no treatment, control interventions, psychological therapies, and antidepressant medications.
Key findings from the review include:
- Comparison to No Treatment/Control: Exercise demonstrated a moderate benefit in reducing depressive symptoms when compared with no treatment or a control intervention.
- Comparison to Psychological Therapy: Exercise exhibited a similar impact on depressive symptoms, supported by moderate-certainty evidence derived from ten trials.
- Comparison to Antidepressant Medication: Comparisons with antidepressant medication also suggested a similar effect; however, the supporting evidence for this specific comparison was categorized as low certainty.
Professor Andrew Clegg, lead author of the review, indicated that exercise appears to be a safe and accessible option for managing depression symptoms, though its effectiveness may vary among individuals, emphasizing the importance of sustainable approaches.
Potential Mechanisms of Action
Experts suggest several mechanisms by which exercise may alleviate depression symptoms. Dr. Stephen Mateka, medical director of psychiatry at Inspira Health, noted that exercise can improve neurotransmitter function, affecting compounds such as serotonin, dopamine, and endorphins, which is also a pathway for some antidepressant medications. Dr. Nicholas Fabiano of the University of Ottawa added that exercise can trigger the release of brain growth factors, such as Brain-Derived Neurotrophic Factor (BDNF), which are crucial for neuroplasticity and are sometimes observed at lower levels in individuals with depression.
Exercise Parameters and Types
The review indicated that light to moderate intensity exercise might be more beneficial than vigorous exercise. Improvements in depressive symptoms were associated with completing between 13 and 36 sessions of light to moderate intensity exercise.
While no single type of exercise was definitively superior, mixed exercise programs and resistance training appeared more effective than aerobic exercise alone. Specific forms of exercise, such as yoga, qigong, and stretching, were not included in this particular analysis.
Side Effects and Accessibility
Exercise is characterized as a low-cost, accessible option with minimal reported side effects. Occasional musculoskeletal injuries were noted among participants engaging in exercise. For those receiving antidepressants, typical medication-related effects such as fatigue and gastrointestinal issues were reported.
Dr. Nicholas Fabiano highlighted that while exercise is recognized as a first-line treatment in global guidelines, its implementation may be underappreciated and underutilized, partly because prescribing medication can be perceived as simpler than prescribing exercise. Exercise may also function effectively as part of a combined treatment approach, potentially following initial mood improvement from antidepressants to facilitate engagement in lifestyle habits.
Limitations and Future Research
This updated review incorporated 35 new trials into previous versions published in 2008 and 2013, with overall conclusions largely remaining consistent. A primary limitation is that most trials included in the review were small, typically with fewer than 100 participants, which restricts the ability to draw definitive conclusions.
The long-term effects of exercise interventions for depression remain undetermined due to the scarcity of studies that followed participants beyond the initial treatment period. Professor Clegg noted that larger, high-quality studies are still required to identify which specific types of exercise are most effective, for which individuals, and whether the benefits are sustained over time.