Voluntary Exercise Does Not Relieve Anxiety/Depression
It what appears to reverse the accepted relationship between exercise and the relief of anxiety or depressive symptoms, researchers from the Netherlands have found no evidence that symptom relief comes about as a result of voluntary exercise.
Marlene H. M. De Moor, of VU University Amsterdam, the Netherlands and colleagues, were interested in the fact that all research to date on the association between exercise and symptom relief had derived from very specific clinical populations. The research team wanted to know whether the apparently simple relationship of increased exercise leading to decreased symptoms would generalize to the wider population, or whether some additional factors might have to be taken into consideration.
Using 5,952 twins, identified via the Netherlands Twin Register, along with 1,357 additional siblings and 1,249 parents, an evaluation was undertaken using survey techniques to assess symptoms of anxiety or depression and leisure-time exercise. All participants were aged 18-50.
Following analysis of data, the research team concluded that associations between anxiety, depression and exercise were small, "and were best explained by common genetic factors with opposite effects on exercise behavior and symptoms of anxiety and depression." De Moor went on to say, "in genetically identical twin pairs, the twin who exercised more did not display fewer anxious and depressive symptoms than the co-twin who exercised less."
The more one of the twins exercised, the fewer symptoms were seen in the other. The likely explanation for these findings points to exercise and mood being associated through some common genetic factor. Although these genes are as yet unknown, the authors suggest that potential areas for investigation are genes controlling neurological pathways processing dopamine, norepinephrine, opioids or serotonin.
Although exercise via prescription is more popular now, the authors stress that additional trials are needed before therapy using exercise can be properly legitimized. The authors also state that exercise can remain beneficial. "Only voluntary leisure-time exercise is influenced by genetic factors, whereas the other type of exercise is environment driven. The absence of causal effects of voluntary exercise on symptoms of anxiety and depression does not imply that manipulation of exercise cannot be used to change such symptoms."
De Moor, M.H.M., Boomsma, D.I., Stubbe, J.H., Willemsen, G., de Gus, E.J.C (2008) Testing Causality in the Association Between Regular Exercise and Symptoms of Anxiety and Depression. Archives of General Psychiatry. 65 (8) 897-905