The very latest research on the controversial treatment Electroconvulsive Therapy (ECT) has found that when administered to rats, it stimulates new brain nerve cell growth, rather than causes brain damage as had been widely believed by campaigners against ECT. The study by a Danish team of psychiatrists led by Dr Torsten Madsen could also explain why ECT had been associated with some memory loss in around a third of patients, as the nerve cell growth occurred in the part of the brain where neuroscientists believe memory is located. If new nerves grow there, this probably disrupts memory storage in the old cells, which would have to move aside to make way for the new nerve cells.

The research is part of a spate of new studies which for the first time are suggesting a mechanism by which ECT might work - a problem which has dogged the treatment from its inception. Another new study by a group of psychiatrists from Johannesburg has just found that blood flow in the brain is improved following ECT.

Given the latest research suggests that serious chronic depression eventually produces actual brain damage in the form of loss of nerve cells, the ability of ECT to stimulate new nerve cell growth could even lead to a resurgence in its use.

Convulsive therapy was introduced to the field of psychiatry in the 1930s arising from the observation that schizophrenic patients appeared to be never epileptic, while no epileptic patients ever seemed to get schizophrenia, which consequently led psychiatrists to chemically induce convulsions in schizophrenic patients. In fact this initial observation was ironically enough, actually completely wrong - schizophrenia and epilepsy are not mutually exclusive.

But in 1938, Cerletti, a professor of psychiatry in Rome, introduced electric currents to induce seizures in psychotic patients. The first electroconvulsive therapy (ECT) treatment was given to a 39-year-old man with catatonic schizophrenia who had been found wandering the streets and could only speak "an incomprehensible gibberish". A low dosage of electricity was administered, which resulted in a seizure and caused the patient to burst into song. The patient received a total of 11 electrical applications, responded well, and one year later was working regularly in his old job.

It is now well over 60 years since Cerletti first administered electric shocks to the brains of mentally disturbed patients, yet it might surprise most people to hear that still in Britain around 10,000 patients are treated with ECT each year.

Perhaps one of the reasons why ECT is such an emotive issue is because of the persisting images of its barbaric administration, a legacy left by its early administrators. Early ECT was administered while the patient was fully conscious, and it was not uncommon for patients to experience fractured bones, lost teeth, and numerous other unpleasant effects.

One graphic report of witnessing ECT in 1963 - the same era when Ken Kesey as an orderly in a psychiatric hospital produced the anti-ECT bestseller One Flew Over the Cuckoo's Nest - had about two dozen patients, lying on their backs and strapped to treatment tables, lined up from one end of the room to the other. The doctor proceeded to work her way along the ward of patients administering ECT as those still awaiting treatment watched and waited. This procedure, however, is no longer practised and ECT suites have been designed to protect patients from witnessing others receiving ECT.

In addition the introduction of muscle relaxant drugs in the 1950s helped to reduce the incidence of fractures. At the same time the use of anaesthetic became common practice, meaning that patients were no longer conscious during treatment. These modifications in the administration of ECT meant that it could be administered with reasonable safety, few side effects, and a minimum of discomfort, leading one notable review to conclude that "today ECT is a relatively harmless treatment, not significantly more distasteful than having a tooth filled under local anaesthetic".

However critics of ECT claim that these changes are largely cosmetic and argue that the basic treatment hasn't changed, it still involves passing a large amount of electricity through people's brains.

In between these two extreme views on ECT is the opinion held by some that, although ECT may work, it is nevertheless a less than aesthetically pleasing and indelicate procedure. Perhaps we are doing the right thing, but in a very crude way, just as if one were trying to right a watch with a hammer.

Now the National Institute of Clinical Excellence (NICE) has just reviewed whether ECT should continue to be available on the NHS, and concluded its use should be markedly restricted from previous practice. NICE recommends that ECT be restricted to the rapid and short term relief of severe mood disorders after all other treatment options have failed and suicide is a risk. The Royal College of Psychiatrists appealed against the decision saying it was too restrictive, but the appeal was rejected because of the uncertainty about long term adverse effects and in particular a recent review of patients' views.

That unique review was produced by the Service User Research Enterprise (SURE), based at the Institute of Psychiatry in London, and was a report by patients of patients' experiences of receiving ECT. It concluded that psychiatric research tended to underestimate side-effects perhaps because these were subtle, and also patients might under-report them to their own doctors who had given them the ECT.

In particular the report found memory loss was a significant side-effect in around a third of those who had received ECT. Set against this report is the most recent review of the effectiveness of ECT just published in The Lancet from Professor John Geddes of the University of Oxford, which concluded that ECT is an effective short-term treatment for depression, and is probably more effective than drug therapy.

Some psychiatrists defend ECT from the charge that it causes memory loss, by pointing out that such effects could be associated with the depressive illness itself. But now this argument seems to be threatened by the latest Danish research which finds that new brain cell growth in the memory area of the brain could be a direct benefit of ECT and explain why it cures depression, but also accounts for a negative effect on memory.

It now seems that the very reason why ECT works is linked to its most worrying side-effect. However the key to the continued use of ECT is that it treats depression quickly when this might be urgently required in an actively suicidal patient.

One of the most common reasons given by psychiatrists for administering ECT is indeed that by merit of its speed of effect it prevents suicide. One study on the effects of ECT on suicide rates found suicides to be lower in ECT treated patients than in patients given psychotherapy alone.

One example is the case of a middle aged woman with severe depression in the 1970s which is cited as support for this claim. Following a suicide attempt, the patient was sectioned and placed in a psychiatric hospital. As the patient had previously received ECT, which had cleared up a similarly severe depression, her psychiatrist requested that she receive ECT as treatment for her present illness. Despite the patient's own request, ECT was denied. Within a week, the patient had absconded, jumped off a bridge, and succeeded in taking her own life. The problem is that it can never be totally proven that the patient took her own life because she had been prevented from receiving ECT. It may well have been the case that her depression was so severe that she felt she could continue with life no longer, and had ECT been administered, she may still have committed suicide.

Some objectors to the claim that ECT can prevent suicide suggest that there is anecdotal evidence that the confusion and memory loss associated with ECT may even facilitate suicide in some patients. To support this claim, critics document the fate of Ernest Hemingway who shot himself only days after being released from hospital following more than 20 doses of ECT. Before his death Hemingway complained to his biographer, "What is the sense of ruining my head and erasing my memory, which is my capital, and putting me out of business?'

This would seem to be an example of that all too often doctors assessment of a medical treatment - "it was a brilliant cure, but we lost the patient".

Dr Raj Persaud is author of the best-selling book From The Edge Of The Couch - Bizarre Psychiatric Cases And What They Teach Us About Ourselves published by Bantam Press, £12.99