Treating depression with drugs may not be new, but many doctors feel that patients expect to receive a packet of pills for their depression or anxiety as a matter of course.

Both GPs and the public have taken it on trust that SSRIs — a new generation of antidepressants hailed as just as good as older drugs, but without side-effects such as dry mouth, blurred vision and constipation — are going to be effective.

We have taken it on trust that a person who takes an SSRI, such as Prozac, and gets better has done so because of the drug. Patients who do not respond after four to six weeks of treatment either have their dose increased or are switched to an alternative SSRI with the expectation that they will not have to endure side-effects. But it seems that this absence of side-effects may mirror a similar lack of benefits for most patients.

This crucial finding has only come to light because a meta-analysis — combining the results of several smaller studies and analysing them as a whole — published today includes unpublished clinical trials. This research has seldom seen the light of day because of “publication bias” — if a drug company sponsors a trial that shows that their drug is no better than current medication or placebo — then the results are far less likely to appear in literature.

“Defeat depression” was a campaign in the 1990s that became a turning point for the uptake in SSRIs. It was backed by the Royal College of Psychiatrists and was designed to raise awareness among GPs and the public.

It aimed to encourage patients to admit to symptoms that might indicate an underlying depressive illness, even when they were presenting mainly with physical symptoms.

GPs were instructed to take such symptoms seriously, but many doctors felt that the campaign’s hidden agenda was to encourage more frequent SSRI prescribing. In 2008 there may be more suitable treatments available, such as cognitive behavioural therapy (CBT), where the focus is on “talking rather than taking”. However, the funding has not been forthcoming for CBT — the waiting lists are unacceptably long — and as a result many patients receive a prescription for an antidepressant. This is often simply to tide them over until they are seen in an appropriate setting. The irony is that patients then sometimes find it hard to stop their SSRIs, which in any case should not be stopped suddenly because this can induce withdrawal symptoms.

In the same way that I would order a panel of blood tests or scans to get to the bottom of a physical symptom, I often ask patients to complete a standardised mental health questionnaire (the hospital anxiety and depression scale, or HAD for short) before advising which course of action is most likely to help them.

The HAD scale is valuable in that it differentiates between patients whose symptoms primarily reflect anxiety, who in the main do not need drug treatment, and those whose symptoms are mainly depressive. It also quantifies the severity of the patient’s symptoms. Those whose scores indicate only a mild or moderately severe depression are usually best advised to avoid prescription drugs, though they might wish to try an over-the-counter product such as St John’s wort (hypericum).

Those whose symptoms suggest a moderately severe depression might be encouraged to undergo a course of CBT in an effort to relieve their symptoms. It is essential that GPs take patients who present with symptoms of anxiety and depression seriously but this does not necessarily require the prescription of an antidepressant drug. As today’s evidence underlines, such a prescription may, for some patients, not be worth the paper it’s written on.

Dr Martyn Lobley is a GP in southeast London

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