Zapping Out Depression

By:
Randy Dotinga

If a pacemaker can keep a heart in working order by zapping it with electric shocks, why not do the same thing for malfunctioning brains?

This is the idea behind electroshock, or electroconvulsive therapy (ECT), whereby electric currents are shot through a patient's brain to provoke epileptic seizures. Electroshock therapy has been used for decades to treat major depression and other mental illnesses. While it often conjures frightening images of broken bones and memory loss, ECT has made great strides since it was first introduced 70 years ago. Although effective in treating depression, it is still fairly controversial in the medical world.

Medical advancements in ECT now give patients the option of having a device that administers the shocks implanted into their body. The treatment is called vagus nerve stimulation therapy (VNS). The generator, placed just below the skin in the chest area, continually stimulates the brain via the vagus nerve. One of the longest nerves in the brain, the vagus travels from the brain stem through organs in the neck, thorax and abdomen.

The idea of vagus nerve stimulation therapy, approved for use in depression in 2005 by the U.S. Government Food and Drug Administration, is to readjust the brain's chemistry with mild intermittent pulses of electricity.

The signals travel along the vagus nerve and stimulate the limbic system, an area that affects mood, motivation, sleep, appetite, alertness and other factors altered by depression. What happens in the brain isn't quite clear, but the brief electric pulses appear to change the levels of neurotransmitters, the chemicals that work together to give us emotions.

Vagus nerve stimulation therapy, which can cost $15,000-$25,000, isn't for most depression sufferers. Instead, it's designed for people who just can't shake the condition no matter what they do. "It's a huge deal for people with depression to know that there's something new out there to consider when medications fail," said Dr. Sarah Lisanby, director of the Columbia Brain Stimulation Service at Columbia University.

You'll need to have tried at least three or four antidepressant drugs before your doctor will let you undergo the treatment. Some patients also try electroconvulsive therapy beforehand. This seems to work best as a short-term treatment.

Typically, doctors insert the vagus nerve stimulator under the skin of the upper chest, said Dr. Mounir Soliman, clinical service chief of the University of California at San Diego's Department of Psychiatry. The pulse is intermittent, but continues 24 hours a day: "It goes for about 30 seconds, after that, it's off for five minutes," he said. Patients aren't supposed to feel pain or shock or any other type of external sensation. Some side effects, such as change in voice, shortness of breath, cough, or tickling in the throat, can occur during stimulation, but tend to go away with time.

Vagus nerve therapy isn't a solo treatment; patients don't rely on it by itself. "You have to use it in conjunction with medications. Assuming you have a patient who's responding partially to one medication, you'll add [VNS] to the current medication to achieve some sort of response," Soliman said.

Unfortunately, vagus nerve therapy isn't a guaranteed cure. In fact, only about one in three patients actually sees major relief, according to studies. And it may take months to a year before patients feel better. Still, when nothing else works, any relief for depression is a good thing.

While VNS is a fairly new treatment for depression, doctors are well-educated on the possible risks because they've used vagus nerve stimulation therapy in the past to treat epileptic seizures. It was during those treatments that they noticed it helps to alleviate depression, too.

So what's next for VNS? Researchers hope to pinpoint exactly how vagus nerve therapy works and what doses are most effective. The introduction of the treatment "is a major development, but it's not the end of the story," said Lisanby.

SOURCES: Interviews with Sarah Lisanby, M.D., assistant professor, Columbia University College of Physicians and Surgeons and director, Columbia Brain Stimulation Service; Mounir Soliman, M.D., clinical service chief, Department of Psychiatry, University of California at San Diego; Web site, U.S. Food and Drug Administration, Washington, D.C., VNS Therapy System - P970003s050