Neuromodulation Therapies II: Repetitive Transcranial Magnetic Stimulation and Deep Brain Stimulation

Neuromodulation (or neurostimulation) therapies are of particular importance in geriatric psychiatry, as older adults are often unable to tolerate adequate pharmacotherapy of depressive disorders. Among neurostimulation treatments, electroconvulsive therapy (ECT) remains the principal and usually most definitive alternative to medications. However, newer treatments such as repetitive transcranial magnetic stimulation (rTMS) and deep brain stimulation (DBS) are emerging. rTMS involves stimulation of the brain using a magnetic coil applied to the scalp surface and is administered without anesthetic or loss of consciousness. It is very well-tolerated by most patients and has a high degree of acceptability. Its efficacy for treating depressive disorders is more modest than that of ECT, and early evidence suggested that it was less effective in older patients. However, more recent rTMS treatment protocols involving longer treatment courses and higher intensity of treatment parameters are showing promise in treating depressive disorders in older adults, with response rates of 30–60% and remission rates of 10–30%. rTMS is a useful addition to the armamentarium of treatments in geriatric psychiatry; its place in treatment algorithms will evolve with emerging research and increased availability for routine clinical use. Its uses for other indications (e.g., for anxiety disorders), or to improve cognition in major neurocognitive disorder, are also being explored in current research. DBS via direct bilateral stimulation of Brodmann area Cg25 with implanted electrodes showed some promise in open trials, but subsequent randomized controlled trials failed to demonstrate its efficacy; it remains an investigational treatment.