Why repetitive transcranial magnetic stimulation should be available for treatment resistant depression

Antidepressant medications are the most commonly used treatment for major depression. Thirty to 40% of people will fail the first course of antidepressant medication and the success rate falls with each further medication trial. Treatment resistant depression (TRD) is defined as depression that has not remitted after at least two trials with antidepressants from different pharmacologic classes with adequate dose, duration, and compliance. TRD is associated with substantial disability, increased morbidity and mortality, and reduced quality of life.

The options for TRD include a further antidepressant switch, augmentation with lithium, an atypical antipsychotic or other agents, and non-pharmacological treatments such as cognitive behavioural therapy and mindfulness. Response rates are low for all of these interventions in this patient population. Electroconvulsive therapy (ECT) is more effective than repetitive Transcranial Magnetic Stimulation (rTMS) (Slotema et al., 2010) (particularly for those with severe depression), but has the disadvantages of the risk of cognitive side effects, and being unacceptable to some patients.

rTMS has been extensively evaluated in TRD. Large multi-centre trials (e.g. George et al., 2010) and a recent meta-analytic study (Slotema et al., 2010), demonstrate that rTMS has an effect size of 0.55, compared to sham rTMS, in patients with depression. This is similar to that of antidepressant medications. rTMS can be effective when antidepressant medications have failed (Demitrack and Thase, 2009) and does not have any of the side effects, such as obesity and sexual dysfunction, associated with antidepressants. rTMS has an excellent safety profile. Common side effects are minor (scalp pain during stimulation, headache) and the main serious risk is that of seizure induction, which is rare. Post-market surveillance on rTMS shows very low levels of serious toxicity in 14,000 patients worldwide since 2008. Treatment protocols vary, but a typical course of treatment might involve 18-30 treatments (each lasting about 30 minutes) over 4-6 weeks. This is a substantial time commitment, but there is no anaesthetic needed and patients do not require a recovery period after treatment. The acute rTMS treatment course should generally be followed by ongoing therapy (e.g. medications and/psychological treatments) to prevent relapse. If relapse does occur then further courses of treatment, or maintenance rTMS treatment, are sometimes needed. rTMS has been shown to be cost effective, compared to switching of antidepressant medication, in patients with TRD (Simpson et al., 2009). Successful treatment of depression is associated with resumption of work and reduction in medical costs with resulting social and economic benefits.

rTMS has been utilised as a treatment for depression since the mid-1990s. However, there is currently no public reimbursement and the costs are not covered by private health insurance. There are a handful of rTMS services in Australia, supported by various funding arrangements. Local experience shows good acceptance of rTMS by both patients and referring psychiatrists.

Wider availability of rTMS would add a safe, effective treatment option for those patients with TRD who fail to respond to multiple antidepressants, including many who are unwilling to undergo or who are unsuitable for ECT. Unlike new drugs, rTMS is not being promoted widely by a manufacturer, so there is no impetus to greater availability, other than the efforts of clinicians and patients. If rTMS is to become part of our therapeutic repertoire, then as a profession we will need to find effective ways to achieve acceptance by both Medicare and the private health funds. This requires active engagement by the Royal Australian and New Zealand College of Psychiatrists in the task of promoting rTMS as a safe and effective treatment, and investment by the profession in developing the resources and expertise required to participate in the bureaucratic processes required for funding approval. Given the growing pipeline of new brain stimulation treatments, this investment should not be seen to be short term and solely focussed on rTMS but a critical part of expanding the psychiatric treatment armamentarium.