Post-traumatic stress disorder (PTSD), generalized anxiety disorder (GAD), and depression are psychiatric disorders that interfere with daily-life activities. In Canada, the prevalence of PTSD is approximately 12%, 2.6% for GAD and 8% for depression. These mental disorders result from brain dysregulation, such as neurological over-arousal (e.g. anxiety), neurological under-arousal (e.g. depression) or instable-arousal (e.g. PTSD), in that patients have problems in intentionally controlling neural functioning. Patients with mental health disorders usually require pharmacological and/or psychological interventions such as cognitive-behavioral therapy, however approximately two-thirds of patients with major depressive disorder do not have adequate responses to conventional treatments.
A potential alternative to pharmacological and psychological interventions are brain stimulation techniques such as transcranial magnetic stimulation (TMS). TMS is a non-invasive technique, whereby a small coil placed over a patient’s scalp. The electric current circulating through the coil produces a magnetic field which can then pass through the scalp and bone and induce changes in nerve cell activity in the cortex. The effect of the magnetic stimulation is dependent on location, intensity and frequency of the magnetic pulses. Its repetitive form is referred to as repetitive TMS (rTMS), and has been used for diagnostic and therapeutic purposes in a variety of neuropsychiatric disorders. Two emergent forms of TMS include theta-burst magnetic stimulation (TBS) and EEG-based synchronized TMS (sTMS). TBS involves the use of a triple-pulse burst in either a continuous or intermittent form and is thought to induce longer-lasting effects, while it is the intent of sTMS to identify the most optimal stimulation protocol for an individual patient in real-time.
TMS was initially used to investigate nerve conduction. It can be used as a tool for brain mapping, as a probe for neuronal networks, and as a modulator of brain function. Clinically, brain stimulation has been found to improve symptoms of depression, however due to the multifactorial nature of the intervention, the overall effectiveness of TMS for the treatment of depression remains unclear. Even less well known is the efficacy and effectiveness of TMS for the treatment of PTSD and GAD.
The purpose of this report is to review the clinical effectiveness of TMS for treating PTSD, GAD and depression, and to summarize the guidelines that are associated with the use of TMS for these conditions.
Copyright © 2014 Canadian Agency for Drugs and Technologies in Health.