In October 2008, repetitive transcranial magnetic stimulation (rTMS)
was approved for use by the FDA as a treatment for major depression for patients who have not responded to at least one antidepressant medication. The treatment involves using a magnet instead of an electrical current to activate the brain. First developed in 1985, rTMS has been studied as a possible treatment for depression, psychosis and other disorders since the mid-1990′s.
Clinical trials studying the effectiveness of rTMS reveal mixed results. According to the NIMH website, when compared to a placebo or inactive (sham) treatment, some studies have found that rTMS is more effective in treating patients with major depression, but other studies have found no difference in response compared to inactive treatment.
Unlike ECT, in which electrical stimulation is more generalized, rTMS can be targeted to a specific site in the brain. Scientists believe that focusing on a specific spot in the brain reduces the chance for the type of side effects that are associated with ECT, but opinions vary as to what spot is best.
A typical rTMS session lasts 30 to 60 minutes and does not require anesthesia. An electromagnetic coil is held against the forehead near an area of the brain that is thought to be involved in mood regulation. Short electromagnetic pulses are then administered through the coil, and the magnetic pulse easily passes through the skull, causing small electrical currents to stimulate nerve cells in the targeted brain region. Because this type of pulse generally does not reach further than two inches into the brain, scientists can select which parts of the brain will be affected and which will not be.
The magnetic field is about the same strength as that of a magnetic resonance imaging (MRI) scan. Generally, the person will feel a slight knocking or tapping on the head as the pulses are administered. Not all scientists agree on the best way to position the magnet on the patient’s head or give the electromagnetic pulses. They also do not yet know if rTMS works best when given as a single treatment or combined with medication.
Sometimes a person may have discomfort at the site on the head where the magnet is placed. The muscles of the scalp, jaw or face may contract or tingle during the procedure, and mild headache or brief lightheadedness may result. It is also possible that the procedure could cause a seizure, although documented incidences of this are very uncommon. A recent large-scale study on the safety of rTMS found that most side effects, such as headaches or scalp discomfort, were mild or moderate, and no seizures occurred. Because the treatment is new, however, long-term side effects are unknown.