(HealthDay News) — Regular leisure-time exercise of any intensity is associated with reduced incidence of future depression, according to a study published online Oct. 3 in The American Journal of Psychiatry.
Samuel B. Harvey, Ph.D., from King’s College London, and colleagues prospectively followed a healthy cohort of 33,908 adults with no symptoms of common mental disorder or limiting physical health conditions for 11 years. Data were collected on validated measures of exercise, depression, anxiety, and a range of potential confounding and mediating factors.
The researchers found that there was a correlation between undertaking regular leisure-time exercise and reduced incidence of future depression but not anxiety. Most of this protective effect occurred at low levels of exercise and was seen irrespective of intensity. After adjustment for confounders, assuming that the relationship was causal, the population-attributable fraction suggested that 12 percent of future cases of depression could have been prevented if all participants engaged in at least one hour of physical activity per week. A small proportion of the protective effect was explained by social and physical health benefits of exercise. Protection against depression was not explained by previously proposed biological mechanisms, such as alterations in parasympathetic vagal tone.
“Relatively modest changes in population levels of exercise may have important public mental health benefits and prevent a substantial number of new cases of depressions,” the authors write.