Bursts of magnetic energy may ease severe depression and improve mood without inducing memory loss.
For many depression sufferers, antidepressants such as St. John's wort, Prozac, 5 HTP, Paxil, SAMe . . . have lessened and in many cases even eradicated the gloom of mild to moderate depression. But some severely depressed individuals have found lesser relief in these medications, leading some to believe that there is no escape from severe depression. Now an experimental treatment may help an estimated 20% to 30% of those individuals. Termed transcranial magnetic stimulation (TMS), this experimental therapy applies short bursts of magnetic energy to a patient's skull, stimulating regions of the brain that regulate moods. "This could be a potent new weapon in our therapeutic arsenal," says Dr. Sarah H. Lisanby, director of the Magnetic Brain Stimulation Laboratory at Columbia University / New York State Psychiatric Institute in New York.
Developed in 1985, transcranial magnetic stimulation was inspired by electroconvulsive therapy (ECT), in which people are given electric shocks to their brains to induce brief seizures and ease symptoms. Although electroconvulsive therapy can be effective for people suffering from severe and intractable depression, it can cause serious side effects, such as confusion and memory impairment. "We thought that by using a milder and more localized stimulation, we could relieve depression without the memory disturbance," says Dr. David H. Avery, a psychiatrist at the University of Washington School of Medicine in Seattle, who has studied transcranial magnetic stimulation. Since then, techniques have been refined, and new brain scanning tools, such as positron emission topography and magnetic resonance imaging, have enabled scientists to better identify the brain regions that govern our emotions. As a consequence, researchers can aim the magnetic beams with more precision, and they have a better understanding of how much stimulation is needed, says Lisanby. In a typical session, a doctor holds a powerful electromagnetic coil, which produces about the same amount of energy as an MRI machine, on the patient's forehead. The device creates a pulsating magnetic field that passes through the skull and seems to stimulate the electrical circuits in the brain.
Patients are awake during the procedure, which normally lasts for
about 45 minutes. They may feel a light tapping on their head with
each pulsation, and some experience mild scalp contractions or
headaches. But they don't experience side effects that would prevent
them from resuming normal activities immediately after treatment.
Unlike the magnets sold at health food stores for various purposes,
which aren't at all powerful, the stimulators create enough
electrical current to prompt nerve cells in the brain to fire. This
seems to energize brain areas by stimulating blood flow and spiking
levels of mood-enhancing brain chemicals, such as dopamine and
serotonin. "What is clear is that TMS triggers changes in brain
function," Avery says. Tests conducted in the last decade have
yielded encouraging results. A 2002 Columbia University analysis of
25 small studies indicated that, overall, TMS patients experienced a
28% reduction in symptoms compared with a 7% reduction in those who
received sham treatments.