The purpose of this paper was to study whether exercise provides protection against new-onset depression and anxiety, to study the intensity and amount of exercise required to gain protection and to determine what mechanisms may underlie these associations. 33,908 adults having no symptoms of common mental disorder or limiting physical health conditions, were prospectively followed for 11 years. Validated measures of exercise, depression, anxiety, and a range of potential confounding and mediating factors were collected.
Undertaking regular leisure-time exercise was associated with reduced incidence of future depression but not anxiety. The majority of this protective effect occurred at low levels of exercise and was observed regardless of intensity. The social and physical health benefits of exercise explained a small proportion of the protective effect. Previously proposed biological mechanisms, such as alterations in parasympathetic vagal tone, did not appear to have a role in explaining the protection against depression. The authors concluded that regular leisure-time exercise of any intensity provides protection against future depression but not anxiety. Relatively modest changes in population levels of exercise may have important public mental health benefits and prevent a significant percentage of new cases of depression.
Harvey SB, Øverland S, Hatch SL, Wessely S, Mykletun A, Hotopf M: Exercise and the Prevention of Depression: Results of the HUNT Cohort Study. Amer. J. Psychiatry [Epub ahead of print, Oct. 3, 2017; doi: 10.1176/appi.ajp.2017.16111223.]