context: Researchers are working on new approaches to treatment-resistant depression. They offer hope to people who haven't been able to relieve their depression with traditional methods. Currently, some of these approaches are available for people with depression only through research studies. Here are some of the newest advances for tackling treatment-resistant depression. Transcranial Magnetic Stimulation ( TMS, or r TMS) sends bursts of energy -- from electromagnets -- to specific areas of the brain. This treatment is thought to affect nerve cell communication in the brain that may play a role in depression. The procedure is fairly simple and can be done in a doctor's office. It was approved by the FDA as a standard (nonexperimental) treatment for depression in October, 2008. The TMS device itself has two parts: an insulated wire coil (that can look like a paddle) and a box that supplies the power. During the procedure, the doctor or a technician will place the "paddle" against your scalp. The specific area of your scalp depends on what part of the brain your doctor is trying to affect. When switched on, the wire coil creates a magnetic field that can painlessly penetrate your brain. This magnetic field excites the targeted brain areas. Sessions often last about 30 minutes. You might be treated 5 days a week for 4 to 6 weeks. While more research needs to be done, TMS seems to have few risks and side effects, and it doesn't require hospitalization. Some people feel muscle contractions in the scalp. Rarely, TMS causes headaches or dizziness. But no evidence suggests that it affects the memory, like electroconvulsive therapy ( ECT) sometimes can. However, TMS is a different treatment than ECT and has not been shown to have comparable efficacy to ECT. TMS could cause a seizure, but experts say that's very unlikely with a risk of about 1 in a thousand people. Magnetic Seizure Therapy ( MST) is an experimental procedure that uses strong magnetic fields to trigger a controlled seizure in the brain. The effects are similar to those of ECT. For reasons that doctors don't entirely understand, these seizures can relieve the symptoms of depression rapidly. MST requires a stay in the hospital. During the procedure, you would need to be under general anesthesia. Doctors hope that because the stimulation can be more accurately targeted than ECT, it may have less of an effect on memory. Deep Brain Stimulation ( DBT) is an invasive surgical procedure in which electrodes implanted in specific brain areas deliver a targeted electric current to relieve the symptoms of depression. It is already used as a treatment for Parkinson's disease. The electrodes that are surgically implanted in certain regions of the brain are powered by a battery pack implanted in the chest or abdomen. While there has so far been only very limited research on this approach for treatment-resistant depression, the limited results have been promising. A randomized controlled trial of DBS in 25 patients with treatment-resistant major depression, published in JAMA Psychiatry in 2016, reported a 40% positive response rate. Vagus Nerve Stimulation ( VNS) is a surgical procedure in which a pacemaker-like device delivers electrical impulses to the vagus nerve, which connects to areas of the brain believed to be involved in regulating mood. For reasons that doctors don't completely understand, these electrical impulses transmitted via the vagus nerve to the brain can relieve the symptoms of depression. The impulses may affect the way nerve cell circuits transmit signals in areas of the brain that affect mood. However, it usually takes several months before you feel the effects. While these new treatments are exciting, most are still experimental. Doctors aren't sure yet how well they work long term or what the effects will be. But if you're interested in trying one, talk to your doctor about signing up for a clinical trial.