How doctors consider depression treatment

What an interesting reaction to my column on depression, of December 17th. It certainly sparked a response on the letters page from medical colleagues.

Given that the piece was primarily for patients - and was triggered by an upset caller to The Irish Times, who felt a fraud for needing long-term antidepressant therapy - the strong response from some doctors was unexpected, especially as the column advocated an end to any dogmatic or absolutist approach to the treatment of depression.

The debate about whether to treat depression with psychotherapy, medication or both is an established one. So how do doctors decide what to recommend to their patients?

In an effort to decide the optimum treatment for any medical condition, doctors rely on what is called evidence-based medicine. Essentially, this means looking for research evidence, based on the gold standard of medical research: the randomised double-blind controlled trial.

Such studies compare new treatments with old, with neither the doctor nor the patients aware of who is receiving which treatment. In addition, the decision about who gets what treatment is random.

One of the bibles of evidence-based medicine is a biannual publication called Clinical Evidence. The latest edition is just to hand; what does it have to say about treating depression?

"Systematic reviews have found that antidepressant drugs versus placebo [dummy pill] are effective in the acute treatment of all grades of depressive disorder."

"One systematic review of mixed quality trials has found that St John's wort is an effective treatment for mild to moderate depression."

"One large trial has found that interpersonal therapy, compared with placebo or no treatment, improves the symptoms of mild to moderate depression."

"Of the interventions examined, prescription antidepressant drugs are the only treatment for which there is good evidence of effectiveness in severe depressive disorders."

On the face of it, it seems reasonable to offer a choice of medication, psychotherapy or both to patients with mild to moderate depression.

For the patient who is severely ill with the disease, however, a doctor would appear to risk failing in his duty of care were he not to recommend antidepressant-drug therapy.

Equally, there is an obligation to outline to a patient the benefits and side effects of all treatments, while ultimately allowing him to choose.

Once a person has made a choice, however, I believe a doctor is obliged to do everything in his power to encourage compliance with the treatment. This means encouraging the patient, helping to identify his fears, his hopes, his reasons for lapses, all the while offering support.

I have found it very important to emphasise the positive aspects of drug treatment in those patients who have themselves chosen this form of therapy for depression.

Not least of my concerns is that my patient should have some analogous concept of how the treatment might work. The analogy of the car running out of petrol and requiring a top-up to continue sits very well with the concept of boosting the level of neurotransmitters in the brain with antidepressant "fuel".

Equally, for the patient who fears dependence and - like our caller - feels marginalised by the need to take tablets, the analogy of depression being like asthma or diabetes is an effective one.

I have found such analogies equally helpful in explaining the possible benefits of cognitive behavioural therapy.

I make no apology for using these analogies. They may not sit well with those who require absolute proof in the form of blood tests for depression. In my experience, such absolutism does more to marginalise patients than it does to help them recover.

There is a huge need to demystify medicine and science without devaluing them. The use of analogies in explaining disease and treatment is extremely helpful in this regard and is well received by patients; it is also an accepted part of the training of general practitioners.

Blaise Pascal wrote in the 1600s about reason. "There are two excesses: to exclude reason and to admit nothing but reason. The supreme achievement of reason is to realise that there is a limit to reason."

E-mail Dr Muiris Houston, Medical Correspondent, at mhouston@irish-times.ie or leave a message at 01-6707711 ext 8511. He regrets he cannot reply to individual medical problems