An international team including researchers from The Black Dog Institute, UNSW Sydney, and Western Sydney University’s NICM Health Research Institute have found physical activity can protect against the emergence of depression, regardless of age and geographical region.

The researchers from Brazil, Belgium, Australia, USA, UK, and Sweden pooled data from 49 unique cohort studies of people free from mental illness that examined if physical activity was associated with a decreased risk of developing depression.

In total, 266,939 individuals were included, with a gender distribution of 47% males, and on average the individuals were followed up after 7.4 years.

Once the data were extracted, the researchers found that compared with people with low levels of physical activity, those with high levels had lower odds of developing depression.

Furthermore, physical activity had a protective effect against the emergence of depression in youths, in adults, and in the elderly and across geographical regions (in Europe, North America, and Oceania).

The findings coincide with the Black Dog Institute’s Exercise Your Mood week, from 30 April to 6 May, which encourages everyday Australians to improve their mental health through physical activity. In a recent study by The Black Dog Institute and UNSW, researchers found that 12% of cases of depression could have been prevented if participants had undertaken just 1 hour of physical activity each week.

Coauthor Dr. Simon Rosenbaum, senior research fellow at UNSW Sydney and the Black Dog Institute said the key challenge ahead is “ensuring that this overwhelming evidence is translated into meaningful policy change that creates environments and opportunities to help everyone, including vulnerable members of our society, engage in physical activity.”

Lead author, Dr. Felipe Barreto Schuch, from Universidade La Salle (Brazil), said: “This is the first global meta-analysis to establish that engaging in physical activity is beneficial for protecting the general population from developing depression.”

“The evidence is clear that people who are more active have a lesser risk of developing depression. We have looked at whether these effects happen at different age groups and across different continents and the results are clear. Regardless your age or where you live, physical activity can reduce the risk of having depression later in life.”

Coauthor Dr. Brendon Stubbs, postdoctoral research physiotherapist, Institute of Psychiatry, Psychology, & Neuroscience, King's College London and Head of Physiotherapy, South London and Maudsley NHS Foundation Trust, said: “Our robust analysis of over a quarter of a million people found consistent evidence that people who are more active are less likely to develop depression in the future.”

“We found that higher levels of physical activity were protective from future depression in children, adults, and older adults, across every continent and after taking into account other important factors, such as BMI, smoking, and physical health conditions.

“Given the multitude of other health benefits of physical activity, our data add to the pressing calls to prioritize physical activity across the lifespan.”

Coauthor Dr. Joseph Firth, research fellow at NICM Health Research Institute at Western Sydney University, said: “The compelling evidence presented here provides an even stronger case for engaging all people in regular physical activity; through schools, workplaces, leisure programs, and elsewhere, in order to reduce the risk of depression across the lifespan.”

Further studies are warranted to evaluate the minimum physical activity levels required and the effects of different types of activity and ‘dosages’ on subsequent risk for depression.

The findings are published in The American Journal of Psychiatry.