Transcranial magnetic stimulation (TMS) is an experimental antidepression treatment that proved to be more effective than sham therapy in a large scale. A sham therapy, also called placebo therapy, is an inactive treatment or procedure that is intended to mimic as closely as possible a therapy in a clinical trial.

Though the experiment has not been approved by the FDA for antidepression treatment, an advisory panel for the agency found TMS to be safe. However, panel members also expressed doubts about the research showing the treatment to be effective.

TMS is a noninvasive procedure that requires no anesthesia and administered in an outpatient setting. This antidepression treatment sessions last from 30 to 45 minutes with patients reclining in a special chair while a specially placed coil device creates a magnetic field from outside of the body. This allows magnetic field to induce an electric current to regions of the brain thought to regulate mood.

Three hundred one patients with major depression who had failed to respond to antidepressant drugs participated in the experiment and half of them received TMS, which was given five times a week in 35-minute sessions for four to six weeks. The other half received the sham therapy, but neither the patients nor those administering the therapy knew which treatment was being given.

According to research report appearing in the December issue of the Biological Psychiatry journal, response and remission rates among patients who got active TMS were roughly twice those of patients who got the sham therapy.

While researcher John P. O'Reardon, MD, concedes that response and remission rates were relatively low for both treatment groups, this is because the study included only patients who had proven resistant to previous treatments.

Between 14% and 17% of patients on the active treatment had achieved a remission after six weeks, compared with 5% to 8% of patients in the sham treatment group.

?In a less-resistant population we would expect to see higher responses,? said O'Reardon.

Although TMS treatments are typically given five times a week, patients usually need a minimum of 10 sessions and as many as 30 to see improvement. Its major advantage is the fact that it is safe, however, the disadvantage is the time-intensity of the treatment.

When the FDA advisory panel met in January of this year to consider TMS, officials with the agency questioned the research showing TMS to be a useful antidepression treatment for major depression. However, there are those who are quite convinced with the studies, such as Mayo Clinic professor of Psychiatry and Pharmacology Elliott Richelson, MD, who may not be involved with the studies but said that since the studies involved patients who had not responded to other treatments, ?I think the responses they got were good.?

There are still very few centers around the country that offer TMS as antidepression treatment but the approval of FDA could change the trend and the treatment could potentially benefit a wide range of patients, not just those with major depression who have failed other therapies.