Every year, clinical depression afflicts more than 18 million Americans, many of whom don't respond to conventional antidepressants like Prozac and Zoloft. But a promising new type of therapy is gaining wider use. The technique, called "transcranial magnetic stimulation," uses pulses of magnetic energy to induce electric currents in specific brain regions. While no one knows exactly why it works, researchers say the treatment can alleviate depression.

Magnetic brain stimulation has been used experimentally for years. Mark George, a neurologist and psychiatrist at the Medical University of South Carolina in Charleston, SC, says that in a number of limited trials, the technique helped severely depressed patients-though modestly and for short periods. These early results have led to government approvals in Israel and Canada. But magnetic therapies have only recently entered large-scale human testing in the United States. A new study, launched in early 2004 and involving hundreds of patients at numerous centers, "should be pivotal" in gaining the U.S. Food and Drug Administration's approval for the therapy in one to two years, says George. "It would be surprising if the therapy didn't prove effective," he adds.