That study was funded by the device's manufacturer, Neuronetics, a company based in Malvern, Pa. It found that up to 17 percent of patients treated with the device for six weeks became symptom-free, about twice as many as those treated with a sham rTMS machine.
Subsequent studies have shown a range of results, with about a third of patients reporting complete relief. One 2010 study of 199 "moderately treatment resistent" patients funded by the National Institute of Mental Health found that rTMS was four times as likely to get patients symptom-free as was a sham procedure. Patients in that study were treated five times a week for three to five weeks. One key measure — known as the "number needed to treat" — found that one patient became symptom-free for every 12 who were treated. Five percent of the patients in the sham group became symptom-free.
Supporters such as those at TMS NeuroHealth say they are seeing better results than that among their patients, who can continue taking antidepressants along with their treatment. Curtis, for example, still takes a daily antidepressant four months after completing her treatment, but she has been able to sharply reduce the dosage.
Curtis said she noticed no change in her depression at the very start of her rTMS treatment, but she began feeling better after about two weeks of treatment. "I'm not up and down anymore," she said.
For patients who don't respond to prescription drugs and talk therapy, the other major option is electroconvulsive therapy, or ECT, in which an electrical current is sent through the brain to deliberately cause a seizure. The procedure, which is more widely used than rTMS, requires two to three treatments a week for three to four weeks and is effective for many patients. But it requires anesthesia and sometimes causes memory loss or confusion; rTMS does not require anesthesia, and its side effects are generally mild. A few small studies have looked at its effects on cognitive function and found either no effect or slight improvement, according to the AHRQ analysis. The costs of ECT — typically about $3,300 for four weeks of thrice-weekly treatments, according to AHRQ data — are covered by most private insurers as well as by Medicare and Medicaid. The cost is higher, however, if a patient must be admitted to the hospital.