GPs should offer exercise on prescription to all patients with depression, says a report.
Exercise can help treat mild depression
The Mental Health Foundation said there was mounting evidence that a supervised exercise programme could treat mild to moderate depression as well as drugs.
Its report said there were growing concerns about the side effects of anti-depressants - and their over-use.
However, it said GPs are still turning to anti-depressants as their first line of treatment.
The cost of antidepressant prescriptions in England has risen by more than 2,000% over the last 12 years.
71% of GPs believe anti-depressants are quite effective
57% say they are over-prescribed
55% prescribe antidepressants as their first treatment response for mild or moderate depression
But only 35% believe drugs are the most effective intervention for these conditions
42% feel most patients given antidepressants would be as likely to get better if they were unknowingly prescribed a placebo
60% would prescribe antidepressants less frequently if other treatment options were more available to them
Clinical guidelines promote the use of exercise for the treatment of depression.
They also state that anti-depressants should not be used as a first-line treatment for mild depression, and that all but one of the newer SSRI drugs should not be given to under 18s.
But the MFH report - Up and Running? - found only 5% of GPs use exercise as one of their three most common treatment responses.
Many of the GPs surveyed for the report did not believe exercise was an effective treatment.
And the report said most common alternative approaches - psychotherapy and counselling - are often in short supply, with patients being asked to join long waiting lists.
As a result, the report found 78% of GPs had prescribed an anti-depressant in the last three years despite believing that an alternative treatment might have been more appropriate.
However, the survey also found GP attitudes may be changing. Recently qualified GPs are less likely than those who qualified 10 years ago to turn to anti-depressants as their first treatment response
Dr Andrew McCulloch, MHF chief executive, said: "Patients with mild or moderate depression asking their GPs for help are currently being denied an effective treatment option - exercise referral.
"Society needs to be educated about the benefits of exercise in treating mild or moderate depression, and GPs need to be made aware that exercise referral is available."
Will to change
Paul Bates, head of Mental Health And Disability Services, at South Tyneside Primary Care Trust, said: "For GPs, the cost of changing their practice is psychological, not financial."
The MHF is calling for the government to invest £20m in developing and promoting exercise referral as a treatment for mild or moderate depression across the UK.
It is estimated that there are now 1,300 exercise referral schemes across the UK.
But only 42% of GPs surveyed said they had access to such a scheme.
And only 15% of GPs who said they did have access used them frequently for patients with mild or moderate depression.
A British Medical Association spokesperson said: "GPs would certainly not be opposed to the idea of incorporating exercise into the treatment for depression.
"Unfortunately in many parts of the country schemes enabling them to make these referrals do not exist.
"Primary Care Organisations would need to commission such services and this would be one of many demands on available funding for NHS treatments."