The lifetime prevalence of major depressive disorder (MDD) is nearly 20%, and up to half of individuals diagnosed with the disorder do not respond to first-line treatment. A case of MDD is considered treatment-resistant once the patient has been taking an antidepressant for at least 6 weeks with no improvement in symptoms. Treatment-resistant depression (TRD) is associated with increased depressive symptoms and more severe educational, occupational, and social functioning, and patients with TRD “are at greater risk of hospitalization for their psychiatric illness, are more likely to abuse drugs and alcohol, and at increased risk of attempting suicide,” according to the National Alliance on Mental Illness (NAMI).
One alternate, non-invasive approach is transcranial magnetic stimulation (TMS), which was approved in 2008 by the FDA as a treatment option for MDD patients who do not respond to treatment with at least 1 antidepressant medication. Unlike electroconvulsive therapy (ECT), which uses generalized electrical stimulation, TMS targets specific sites in the brain to stimulate nerve cells in those areas. Experts believe the specific approach of TMS may reduce the chance of side effects that can result from ECT.