MAGNETISM JUST MIGHT STICK AS TREATMENT FOR DEPRESSION.

Byline: >BY BETSY MASON

A potential new treatment for depression involving magnetic pulses applied to the brain is getting a closer look from neuroscientists at University of California, Berkeley.

Known as Transcranial Magnetic Stimulation or TMS, the magnetic therapy has shown promise in clinical trials, but scientists have little understanding of how it alters brain function.

Now, Ralph Freeman and a team of graduate students led by Elena Allen at Berkeley have taken a big step toward demystifying TMS.

They discovered that how the brain stimulation affects neurons depends on what the brain is doing at the time.

Their findings could help psychiatrists better understand how to apply TMS.

"We have to know how it works before we can know how to use it," said psychiatrist Sarah Lisanby, director of the brain stimulation division at Columbia University in New York.

In a TMS treatment, a paddle containing a coil with electric currents pulsing through it is placed on a patient's scalp. The currents create a magnetic field in the underlying area of the brain, which changes the electrical signals sent by neurons.

To figure out what exactly TMS does to neurons, Freeman's team tested it on the brains of anesthetized cats, in the area that processes what the eyes see.

Using a surgically implanted probe to measure the activity of neurons, they found that after a few seconds of TMS, the neurons fired more rapidly for a minute and then slowed down for several minutes.

But when the same pulses were applied while the cats were exposed to black and white bars flashing across a computer, which can be registered by the brain even under anesthesia, the TMS had a different effect. Instead of boosting brain activity, it slowed neuron firing for several minutes.

Though Freeman may be just scratching the surface of the magnetic effect, his study, which appeared in the Sept. 28 issue of Science, is an important step toward understanding TMS.

Though the Food and Drug Administration has not yet approved it for use on people, the agency is reviewing a TMS treatment device.

Psychiatrist Bret Schneider, a consulting assistant professor at Stanford University, has had success in his private practice using TMS to treat patients with depression that haven't been helped by drugs.

"It seems to effectively treat the depression in one-third to two-thirds of the patients who have failed to get better with anything else," he said.

About one-third of the patients Schneider treated with TMS for 45 minutes a day, five days a week for two to six weeks went into remission for several months. Another third didn't get complete relief, but saw some improvement from the treatment. A third weren't helped by the treatments. Some people felt stinging on their scalp for the first few treatments, and others experienced headaches. But only one out of several dozen patients wasn't able to stick with the therapy.

It's not clear yet if returning for another round of treatments will help stave off depression for longer, or if medications can help prolong the remission. But the magnetic stimulation offers much-needed hope for people who have tried several different types of antidepressants as well as psychotherapy to no avail, Schneider said.

"It's a tremendous relief. Patients have a hard time describing how wonderful it is."

Scientists hope that a better understanding of TMS could lead to treatments for schizophrenia and other psychiatric disorders.

Mason writes for the Contra Costa Times.