may help ease symptoms of depression, according to a fresh look at past
who analysed data from previous studies found people who exercised experienced
a "moderate" reduction in their depressive symptoms compared to those
who did other activities, such as using relaxation techniques, or received no
review provides some additional evidence that there may be some benefit (to
exercise)," Dr Gillian Mead, the study's senior author from the University
of Edinburgh in Scotland, told Reuters Health.
review from the Cochrane Collaboration, an international organisation that
evaluates medical research, found similar results, but more studies looking at
the link between exercise and depression have since been published.
become aware of some new trials in the area and – in general – the Cochrane
review should be kept updated if there is new evidence that may lead to
changes," Mead said. About 1 in 10 Americans reports being depressed,
according to the US Centres for Disease Control and Prevention.
popular treatments for depression include anti-depressant medications and
psychotherapy. Mead and her fellow researchers write in The Cochrane Library,
however, that many people prefer alternative treatments, and some doctors
recommend exercise as a potential option.
Single measurement for comparison
For the new
review, they searched databases for all medical trials conducted through March
2013 that compared exercise among adults with depression to other activities or
no treatment. Overall, the researchers were able to combine data from 35 trials
that included 711 people who were randomly assigned to an exercise program and
642 who were randomized to comparison groups. Because the studies used various
scales to assess depression, they converted the results into a single
measurement to compare people in exercise and non-exercise groups.
measurement, a difference between groups of 0.2 represents a small effect, 0.5
a moderate effect and 0.8 a large effect. Mead's team found a 0.62-point difference
in depressive symptoms favouring people who exercised.
In one of the included trials from 2007, for
instance, researchers found 45% of people who took part in supervised exercise
no longer met the criteria for depression after four months, compared to 31%
taking an inert placebo pill.
In another trial from 2002, 55% of older
people experienced a significant decline in depression symptoms after 10 weeks
of exercise, compared to 33% who attended informational talks during that time.
difference between groups, however, was greatly diminished when the review
authors only analysed data from the six trials that were considered high
quality. Still, exercise appeared to reduce depressive symptoms as much as
psychotherapy or antidepressant medications. But Mead cautioned that those
findings are only based on data from a small number of trials. "One has to
be careful saying it was as effective as other therapies," she said.
More information needed
that it's still unknown how exercise affects depression."There are lots of
ideas about potential mechanisms, but I don't think there is enough evidence in
the literature that one mechanism applies more than another," Mead said.
researchers were also unable to say which type of exercise is best, but Mead
said previous reviews have recommended people choose an activity that they'll
stick with over the long run.
people are prescribed exercise or they choose exercise, the big challenge is to
make the exercise real," Dr Madhukar Trivedi, who has studied the effect
of exercise on depression but wasn't involved with the new research, told
the recommendation from the treating clinician is that you should be exercising
with some frequency and intensity... it's important that the patient follow
that regimen week after week," Trivedi, a professor of psychiatry at the
UT South-western Medical Centre in Dallas, said.
Lucas, who was also not involved with the new review but has studied the topic
before, said studies tend to show a dose-response relationship between exercise
dose is very important. If you're walking at a very slow pace, this has no
effect," Lucas, a visiting scientist at the Harvard School of Public
Health in Boston, told Reuters Health.