Based on dozens of studies covering hundreds of thousands of
participants, Chinese researchers found that sedentary behavior was
linked to a 25 percent higher likelihood of being depressed compared
to people who were not sedentary.
The research has limitations, Long Zhai, of Qingdau University
Medical College in Shangong, and his coauthors write, but it
suggests that physical activity would be a good prescription for
preventing depression.
“Although it was a thorough investigation of a relatively new
research area, a number of unanswered questions still remain,” said
Megan Teychenne from the Centre for Physical Activity and Nutrition
Research at Deakin University in Melbourne, Australia.
Among these is “whether sedentary behavior increases the risk of
depression; or whether it is that those with depression are just
more likely to engage in sedentary behaviors such as computer use or
television viewing,” said Teychenne, who wasn’t involved in the
study.
For their report, published in the British Journal of Sports
Medicine, Zhai and colleagues combined and re-analyzed the findings
for a total of 193,166 participants from 24 previously published
observational studies that looked at levels of sedentary behavior
and risk of depression.
Two of the studies were conducted in Australia, four in Asia, seven
in the Americas and 11 in Europe.
Across continents, the researchers found that people with the most
sedentary behavior were 25 percent more likely to be depressed
overall compared to those who were the least sedentary.
The study team also saw differences depending on people’s preferred
type of inactivity. Those whose most frequent sedentary behavior was
watching TV were 13 percent more likely to be depressed, while those
who spent their sedentary time using the computer or Internet, had a
22 percent higher depression risk.
The analysis didn’t look at the reasons behind the links. And, the
study team points out, most of the included studies accounted for
other factors, like illnesses, that might explain the sedentary
behavior, the depression, or both, but those studies may not have
taken every possible factor into account.
The research team also notes that they cannot rule out the
possibility that depression leads to sedentary behaviors rather than
the other way around.
Nonetheless, that the two go hand in hand is enough to suggest that
more activity might be the antidote, they conclude.
Teychenne also said that even though the study results are
inconclusive regarding the connection between sedentary behavior and
mental health, researchers do know that being sedentary is linked to
other poor health outcomes like cardiovascular disease and type 2
diabetes.
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“Therefore, the message we really need to get out to the public is
‘Move more and sit less,’” she said.
“I think it's certainly an important study, and it shows that there
are links but it does point out some issues that we need to think
about," Jennifer Brunet told Reuters Health.
Brunet is a researcher with the School of Human Kinetics at the
University of Ottawa in Ontario Canada, who was not involved with
the study.
She added that she doesn’t think all sedentary behavior is a bad
thing, and it could provide some escape from the stress of a hard
day.
“Sometimes people read; people go on the Internet, and
unfortunately, the measures that were used in the reviewed studies
didn't always differentiate what we can call healthier sedentary
behaviors versus unhealthy sedentary behaviors,” Brunet pointed out.
Still, she said, there's clear evidence that physical activity is
good for the management of depression symptoms as well as clinical
levels of depression.
There’s not enough good evidence to suggest that any one specific
form of physical activity is best, she added, but research indicates
that moderate exercise is most effective.
“I often tell people to pick activities that are enjoyable, and
that’s the key to it,” she said. “We don’t want to pressure people
to do physical activity, we want them to choose it and one way of
choosing it is if they feel it’s an enjoyable activity.”
SOURCE: http://bit.ly/WT2xy8 BMJ
Sports Medicine, online September 2, 2014.
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