Last updated February 18, 2019 at 1:54 pm
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.
“We know depression is a leading cause of disability around the world, but we know much less about how to prevent this debilitating condition,” said lead author Dr Karmel Choi from Massachusetts General Hospital in the US. “We wanted to harness the advances of large-scale genomic studies to validate a promising prevention target for depression.”
The research relied on a technique called ‘Mendelian Randomisation’ which uses genetic variation as a kind of ‘natural experiment’.
Probing the link between exercise and depression
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.
According to Dr Joseph Firth from Western Sydney University, the study provides the “strongest evidence to date for using exercise as a potential strategy to reduce the risk of depression, across the population.”
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.
Fifteen minutes is all that’s needed
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.
The University of Sydney’s Professor Ian Hickie, who was part of the Psychiatric Genomics Consortium which contributed to the project offered some simple take-home advice:
‘Despite the fact you feel fatigued, tired or jetlagged, if you’re physically active, you’ll improve your mood,” he said. “And sometimes you’ll need other people to help you – go with a friend or family member.”
So what are you waiting for? Get moving!
You can read the full AusSMC Expert Reaction here
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