Move over Prozac; here comes transcranial magnetic stimulation (TMS). In just five years, this new therapy could be a first line treatment for some types of depression.

At least that's the prediction of Dr. Gary Hasey, director of the TMS laboratory at St. Joseph's Healthcare and associate professor in the department of psychiatry and behavioural neurosciences at McMaster University in Hamilton.

TMS uses magnets to stimulate the frontal cortex region of the brain (located above the left temple) to increase brain activity. MRI scans show that many depressed people have below-average activity levels in this region of the brain.

TMS involves passing an electric current through a hand-held magnetic coil, creating a magnetic field measuring anywhere from 3,000 to 8,000 amps (an energy filed comparable to that of an MRI scanner). This magnetic field is directed at the dorso-lateral prefrontal cortex area of the conscious patient's brain.

Although still experimental, the procedure looks promising. In an as-yet-unpublished study of about 50 depressed people who had failed trials with several antidepressants, 27 per cent of those who also underwent TMs showed a "full response" to the treatment, meaning their symptoms had decreased by more than half. Zero per cent of those in the placebo group, who received "fake" TMS treatments (they were subjected to the same procedure but the magnetic field wasn't turned on), had a full response.

Health Canada has approved the TMS technology for treatment of drug-resistant depression. But Hasey thinks it's too early to make TMS widely available. "There are still several bugs to work out," he says.