SAN DIEGO -- Exercise may have modest benefits as a treatment for patients suffering from anxiety or depression, researchers reported here.
In a review of meta-analyses and tens of thousands of patient data, exercise was shown to have a small effect on anxiety (Cohen's d=0.34) and a modest effect on depression (Cohen's d=0.56), according to Henning Budde, PhD, of the Medical School Hamburg in Germany, and colleagues.
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
"Exercise training induces similar processes, as they were observed, with medical treatment," Budde said during his presentation at the meeting of the Society for Neuroscience.
The interaction between exercise training and anxiety/depression is a known one, noted session moderator Hector Caruncho, PhD, of the University of Saskatchewan in Canada.
The problem, Caruncho cautioned, is not so much that patients aren't affected by an exercise intervention, but that depression makes getting out of bed to do the exercising a difficult task.
Previous research on the link between exercise and depression has been mixed. One study showed that exercise did not improve outcomes in anxiety and depression in the general population, but later research showed the opposite, with exercise being associated with moderate improvements in depression symptoms. This was true also in a population of multiple sclerosis patients who were supported through a motivational phone intervention.
Budde noted that with the publication of the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders, mixed anxiety depression is a new diagnostic category, and that comorbidity with the two disorders is high.
His group reviewed 39 meta-analyses of the effects of exercise on depression and anxiety, which included anxiety scores for 61,100 patients and depression scores for 81,141 patients.
Articles were published from 1990 to 2013 and reported effect sizes for the impact of exercise or physical activity on different measures of anxiety and depression.
The authors also conducted a t-test between anxiety and depression scores and found exercise had a significantly greater effect on depression scores versus anxiety scores (t=3.65, P<0.001).
Budde noted that exercise "causes physiological changes in monoamine levels, alters the levels of the stress hormone cortisol, and leads to upregulation" of the brain-derived neurotrophic factor, nerve growth factor, insulin-like growth factor, and vascular endothelial growth factor.
He added that exercise is also associated with effects on brain plasticity, including neurogenesis in limbic structures.
Antidepressants and exercise are both responsible for increases in dendritic arborizations and brain-derived neurotrophic factor expression, he said, which is contrasted by reductions in dendric arborization and reduction in brain-derived neurotrophic factor seen in severe stress.
The authors reported no conflicts of interest.
Society for Neuroscience