The link between exercise and mental health has long been suspected, but now it’s confirmed that exercise can prevent depression.
An international study of the genetics of 300,000 people suggests that exercise helps prevent depression, confirming what many scientists suspected to be true.
The links between exercise and depression have been known for some time but what was not clear was whether exercise reduced the risk of depression, or if being depressed simply led people to exercise less. It was your classic chicken and egg scenario.
The research relied on a technique called ‘Mendelian Randomisation’ which uses genetic variation as a kind of ‘natural experiment’.
Professor Anthony Hannan from the Florey Institute of Neuroscience and Mental Health told the AusSMC this new study uses the power of modern genomics to ask a simple question: Does physical activity reduce depression, or does depression reduce physical activity?
The study found that higher physical activity as measured on a Fitbit-style device does appear to protect against the risk of depression.
“The average person who increases their levels of physical activity can reduce their risk of depression,” said Prof Hannan.
Mendelian Randomisation relies on the relatively random way genes are inherited to try and show cause and effect, rather than randomly assigning people a treatment in a clinical trial.
It can provide valuable insights, but according to Dr Nina McCarthy from the University of Western Australia, it is not immune to error or bias.
“I would caution though that this work should be seen as a piece of the jigsaw, and we should interpret findings from Mendelian Randomisation studies in the context of other sources of evidence,” she said.
Depression affects more than one million Australians every year, and the researchers say their rough calculations suggest that replacing sitting with 15 minutes of a heart-pumping activity like running, or with an hour of moderately vigorous activity, is enough to produce a step up in activity that was linked to a lower depression risk.
Lyndal is the Director of News and Partnerships at the Australian Science Media Centre. She spends her days turning complex science papers into tasty morsels to help news journalists cover science. Lyndal has an Honours Degree in Biotechnology from Flinders University and a Graduate Diploma in Science Communication from the Australian National University. She has spent the last 20 years communicating science in a range of settings including science museums, within the pharmaceutical industry and in media relations both here and in the UK. Lyndal regularly speaks about science on ABC Radio National and 2CC in Canberra. Lyndal was also a member of Inspiring Australia’s Science and the Media Expert working group for the Federal Department of Innovation, Industry, Science and Research.