Exercise as good as drugs for blues

JUST an hour of exercise a week is as effective as antidepressants at beating the blues, new research says.

More than a million Australians a year develop the mental illness. Depression, anxiety and substance abuse is estimated to cost the economy nearly $13 billion in health care costs, forgone tax revenue, and welfare benefits.

A review of 49 studies involving 266,939 individuals followed for seven years, published yesterday in The American Journal of Psychiatry, found physical activity can protect against the emergence of depression, regardless of age.

Separate Australian research found 12 per cent of depression cases could be prevented by just an hour’s activity a week. The more exercise, the greater the effect.

People who did no exercise had a 44 per cent greater risk of depression than those who exercised one to two hours a week, according to work by the Black Dog Institute’s Associate Professor Sam Harvey.

However, nearly one in three Australians don’t meet the recommended 150 minutes of physical activity per week, and 15 per cent don’t exercise at all.

Experts hypothesise that exercise prevents depression by releasing in the body a neuroprotective protein called brain-derived neurotrophic factor. It also activates the cannabinoid system — the same pathway activated by marijuana — leading to a natural high, said Black Dog’s clinical director, Associate Professor Josephine Anderson.

Dr Joseph Firth, from Western Sydney University, said randomised controlled trials had shown exercise has the same effect as antidepressants, and also increased the effect of the medication.

Personal trainer Michelle Bridges, who promotes the work of the Black Dog Institute, said her own experience was that exercise was important for mood.

“When I’m not training as regularly as I should, I feel my mood drop. I can see it in myself, and the people around me see it. When you train you release a whole bunch of happy chemicals that change your perception of your problems,” Bridges said.

“You have a different set of eyes … it’s like taking a pressure cooker and pushing the release valve,” she said.

While the mother of a twoyear-old aims to train seven days a week, she said that most weeks she only managed four to five sessions.

But she tries to seize whatever opportunity for exercise presents itself.

“I knock out lunges while I’m putting the washing on the line, or do push ups against the kitchen bench,” Bridges said.

She recently tried surfing, and was “absolutely terrible, but that didn’t stop me trying”.