Meg Seymour, PhD
Transcranial magnetic stimulation (TMS) is a treatment developed for depression in which a device placed over the scalp uses magnetic fields in order to stimulate brain cells. The goal of TMS is to help activate regions of the brain where activity is decreased due to depression. If treatment with TMS is covered by a health insurance plan, it is usually only covered for people who have tried at least one antidepressant medication and not seen improvement in their symptoms. Treatment with TMS is costly, both financially and in terms of time. Because of this, it is important to know if TMS is even effective, as well as safe. This article will briefly describe the research that has been done on TMS.
How is TMS Studied?
It is difficult to study whether depression treatments work, because depression tends to get better or worse over time due to factors unrelated to treatment. Depression tends to ebb and flow, and patients often seek help when depression gets worse. Even without treatment, many depressed patients start to feel better over time. Because of this, studies that compare depression treatments over a period of 6-8 weeks often find improvement not only for those receiving the treatment, but also for patients in the placebo group (where patients receive “sugar pills” that have no active ingredients). To know if a treatment really works, it is important to compare those receiving the treatment to those receiving a placebo.
The most effective type of study is a randomized controlled clinical trial. This means that patients are randomly assigned to receive either the treatment or a placebo, and in the most effective studies, the patient and researcher do not know which one they are receiving. In studies for new medications, some patients are given a placebo pill, and for studying a procedure such as TMS, some patients are in what is called a “sham” group. A sham treatment for TMS means that a patient sits under the TMS device, but, unknown to the patient, no magnetic fields are actually generated.
Many studies on TMS are done by doctors who use TMS devices, so they are motivated to find evidence that the treatment works. It is important to look at studies where the researchers have no ties to companies that make TMS devices, and where patients and researchers do not know whether they are receiving actual TMS or a sham treatment.
Does TMS Work?
TMS has been shown to be a safe treatment,1 however the evidence does not suggest that it helps reduce depression. For example, a 2017 study compared patients treated with 20 sessions of TMS with those treated with 20 sham treatments. The study found that while patients showed improvement over time, there was no statistically significant difference in how much those in the TMS treatment group improved compared to those who received the sham treatment.2
Some studies have found that those receiving TMS reported better improvement in their depression than those receiving the sham treatment.3,4 However, in these studies, the researchers did different things with those in the treatment group and the sham group, so that the patients suspected whether they received the treatment or the sham. For example, some researchers pointed the device perpendicular to the heads of the patients in the sham group instead of directly against it, making it rather obvious to the patients whether they were or were not actually getting the treatment. This knowledge could explain why those in that sham group did not do as well as most depressed patients in either sham treatment or in placebo groups for antidepressant drug studies.
In 2020, another study looked at more than 100 adolescent patients with treatment resistant depression who were randomly assigned to receive either TMS or a sham treatment. Each patient received 30 treatments over the course of 6 weeks. Both groups of patients showed improvement in their depression, but there was no difference in symptom relief between the two groups. This means that depressed adolescents receiving TMS treatment did not benefit more than those receiving a sham treatment.5
For more detailed information about the research and the history of TMS treatments, read our report.
The Bottom Line
Although TMS is a safe treatment, it is not effective for treating depression. Treatment with TMS is expensive, and although the costs vary, treatment can cost hundreds of dollars a session, with each patient’s sessions typically taking place 5 days a week for 4 to 6 weeks. This adds up to thousands of dollars, and is financially expensive and a large time commitment. But the bottom line is: it doesn’t work.
All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.
The National Center for Health Research is a nonprofit, nonpartisan research, education and advocacy organization that analyzes and explains the latest medical research and speaks out on policies and programs. We do not accept funding from pharmaceutical companies or medical device manufacturers. Find out how you can support us here.
- McClintock SM, Reti IM, Carpenter L, et al. Consensus Recommendations for the Clinical Application of Repetitive Transcranial Magnetic Stimulation (rTMS) in the Treatment of Depression. Journal of Clinical Psychiatry, 2018. 79(1) :16cs10905.
- Carpenter LL, Aaronson ST, Clarke GN, et al. rTMS with a Two-coil Array: Safety and Efficacy for Treatment Resistant Major Depressive Disorder. Brain Stimulation. 2017. 10(5):926-933.
- Blumberger DM, Maller JJ, Thomson L, et al. Unilateral and Bilateral MRI-Targeted Repetitive Transcranial Magnetic Stimulation for Treatment-Resistant Depression: A Randomized Controlled Study. Journal of Psychiatry & Neuroscience. 2016;41(4):E58-66.
- Theleritis C, Sakkas P, Paparrigopoulos T, et al. Two Versus One High-Frequency Repetitive Transcranial Magnetic Stimulation Session per Day for Treatment-Resistant Depression: A Randomized Sham-Controlled Trial. Journal of ECT. 2017. 33(3):190-197.
- Croarkin PE, Elmaadawi AZ, Aaronson ST, Schrodt GR, Holbert RC, Verdoliva S, Heart KL, Demitrack MA, Strawn JR. Left prefrontal transcranial magnetic stimulation for treatment-resistant depression in adolescents: a double-blind, randomized, sham-controlled trial. Neuropsychopharmacology. 2020:1-9.