Regular exercise of any intensity for as little as 1 hour per week can prevent depression in people of all ages and genders, according to findings by an international research team led by the Black Dog Institute in Randwick, Australia. The study monitored exercise levels and symptoms of anxiety and depression in 33,908 Norwegian adults for more than 11 years.
“We’ve known for some time that exercise plays a role in treating symptoms of depression, but this is the first time we’ve been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression,” said lead study author Samuel Harvey, PhD, associate professor at the Black Dog Institute and the University of New South Wales in Sydney.
The study’s purpose was to examine whether exercise provides protection against new-onset depression and anxiety and, if it does, to determine the intensity and amount of exercise required. Researchers also sought to understand underlying mechanisms for any association between mental health benefits and exercise.
Data analysis of population-based surveys of healthy participants showed a relationship between exercise and depression. People who at baseline reported doing no exercise had a 44% higher chance of developing depression compared with those who exercised 1–2 hours a week. Interestingly, the association did not hold true for those with anxiety.
“We are still trying to determine exactly why exercise can have this protective effect,” said Harvey. “But we believe it is from the combined impact of the various physical and social benefits of physical activity.”
“The study means that we can be much more confident about informing the public of the benefit of even a modest amount of physical exercise in helping to prevent clinical depression,” said Josephine Anderson, associate professor and clinical director at the Black Dog Institute. “One hour a week of physical exercise is likely to be doable.”
This study was published in the American Journal of Psychiatry (2017; doi:10.1176/appi.ajp.2017.16111223).