850. Exercise and the Prevention of Depression: Results of the HUNT Cohort Study
Commentary by Rona Macniven, GlobalPAnet Executive, The University of Sydney, Australia
Being physically active has both physical and mental health benefits but the direct relationships between physical activity and mental health are less clear than relationships with physical health. There is a large burden of mental health conditions such as anxiety and depression in modern society therefore preventative efforts are important. The Health Study of (HUNT) examined whether physical activity provides protection against new-onset depression and anxiety, the intensity and amount of exercise required to gain protection and the mechanisms that explain any association.
The study took place in northern Norway over a period of 11 years where a “healthy” cohort of 33,908 adults, with no symptoms of common mental disorder or limiting physical health conditions completed two questionnaires 1984-86 (HUNT 1) and 1995-97 (HUNT 2). In HUNT 1, participants completed the 12-item Anxiety and Depression Symptom Index and provided information on their physical activity frequency and duration using a validated measure. In HUNT 2 they completed the Hospital Anxiety and Depression Scale. Information on a range of potential related variables such as socioeconomic and lifestyle factors and were also collected.
Relationships were found between physical activity and the risk of developing depressions but not anxiety. This relationship was evident among participants who had exercised for at least an hour a week which is a low level in relation to national and international physical activity recommendations, typically of at least 30 minutes a day. This relationship with depression was apparent regardless of the intensity of physical activity. In statistical models that accounted for the other potential related variables, it was established that 12% of future cases of depression could have been prevented with participation in at least an hour of physical activity each week. Other results suggest that relationships with mental health are complex; known social and physical health benefits of physical activity explained only a small proportion of this protective effect and biological mechanisms did not elucidate further explanations either.
In summary, this study indicates that the benefits of physical activity in preventing depression could be achieved at relatively low frequency and intensities in comparison to well established health risk factors such as heart disease. Other findings from other study populations will be required to confirm these findings but the message from the HUNT study is that encouraging inactive people to initiate some physical activity could have important benefits at the population level. The HUNT study is ongoing and we can anticipate that future results will build on these finding to generate further new knowledge of the complex relationships between physical activity and mental health.
Source: The American Journal of Psychiatry Ahead of Print. Access to this article may depend on your Institutional rights. Access the full article here.