Abstract
Objectives
To address three questions; (a) does exercise provide protection against new onset depression and anxiety, (b) if so, what intensity and amount of exercise is required to gain protection and (c) what mechanisms underlie any association?
Method
A ‘healthy’ cohort of 33 908 adults, selected on the basis of 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.
Results
Undertaking regular leisure time exercise was associated with a 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. After adjustment for confounders, the population attributable fraction suggests that, assuming the relationship is causal, 12% of future cases of depression could have been prevented if all participants had engaged in at least one hour of physical activity each week. 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.
Conclusions
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 substantial number of new cases of depression.
To address three questions; (a) does exercise provide protection against new onset depression and anxiety, (b) if so, what intensity and amount of exercise is required to gain protection and (c) what mechanisms underlie any association?
Method
A ‘healthy’ cohort of 33 908 adults, selected on the basis of 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.
Results
Undertaking regular leisure time exercise was associated with a 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. After adjustment for confounders, the population attributable fraction suggests that, assuming the relationship is causal, 12% of future cases of depression could have been prevented if all participants had engaged in at least one hour of physical activity each week. 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.
Conclusions
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 substantial number of new cases of depression.
| Original language | English |
|---|---|
| Journal | The American Journal of Psychiatry |
| Publication status | Accepted/In press - 12 Jun 2017 |
