The University of Pennsylvania Health System is testing a new way of treating chronic depression without using medication.

Close to 19 million Americans suffer with chronic depression and for many, medication and traditional therapy don't work.

The University of Pennsylvania is one of 16 medical centers across the country that is trying a therapy is called transcranial magnetic stimulation.

TMS is a noninvasive procedure. It focuses magnetic energy waves precisely on the part of the patient's brain scientists believe is responsible for mood.

"It's not like taking a drug or a medication, which goes to every part of the body and can give you side effects. This is a targeted treatment to help a part of the brain work better so the person no longer feels depressed," said Dr. John O'Reardon of the University of Pennsylvania Health System.

The magnet works like a mini magnetic resonance imaging scan and activates the prefrontal cortex of the brain. When the magnet hits the exact spot needed for treatment, the patient's thumb twitches. Each TMS session lasts 45 minutes. The patient is awake during the procedure and doesn't feel a thing.

"We think these neurons, these nerve cells, these circuits make new brain neurochemicals, things like serotonin or neuroepinephrine, and in that process they start doing their job again," O'Reardon said.

The procedure doesn't start working immediately. Doctors say it takes two sessions a week for two weeks before the patient starts feeling better.

If the clinical trials show that some of the patients in the trials can be helped by TMS, the Food and Drug Administration could eventually approve it.

TMS is already being used to treat depression in Canada and Israel. Earlier studies have already shown it has promise.

To find out more about the study and whether you may qualify to participate, click here to get to the University of Pennsylvania Web site.