Approximately 20% to 30% of patients with major depressive disorder do not respond to pharmacotherapy.1 For patients with treatment-resistant depression (TRD)—typically defined as an inadequate response to at least 1 antidepressant trial of adequate dose and duration—neurostimulation may be an effective treatment option.
Two forms of neurostimulation used to treat TRD are deep brain stimulation (DBS) and transcranial magnetic stimulation (TMS). In DBS, electrodes are placed within the patient’s cranium and affixed to specific target locations. These electrodes are electrically stimulated at various frequencies. Transcranial magnetic stimulation is a noninvasive treatment in which a magnetic field is produced over a patient’s cranium, stimulating brain tissue via electromagnetic induction.
Media portrayals of most alternative therapies are inacurate.2 In addition, the negative cognitive changes seen in depression mean patients are less likely to effectively compare the advantages and disadvantages of alternative treatment options. Therefore, both patients and clinicians require education on these treatment options and their adverse effects.
In this article, I compare DBS and TMS, and offer suggestions for educating patients about the potential adverse effects and therapeutic outcomes of each modality.
Deep brain stimulation
Deep brain stimulation is FDA-approved for treating Parkinson’s disease, essential tremor, dystonia, and obsessive-compulsive disorder (OCD).3 It has been used off-label for TRD, and some preliminary evidence suggests it is effective for this purpose. A review of 22 studies found that for patients with TRD, the rate of response to DBS (defined as >50% improvement on Hamilton Depression Rating Scale score) ranges from 40% to 70%.1 Additional research, including larger, randomized, sham-controlled trials, is needed.
A consensus on the optimal target location for DBS has not yet been reached. Studies have had varying degrees of symptom improvement targeting the subgenual cingulate gyrus, posterior gyrus rectus, nucleus accumbens, ventral capsule/ventral striatum, inferior thalamic peduncle, and lateral habenula.1
A worsening of depressive symptoms and increased risk of suicide have been reported in—but are not exclusive to—DBS. Patients treated with DBS may still meet the criteria for treatment resistance.
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