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Study Stokes Controversy Over Vagus Nerve Stimulation for Treatment Resistant Depression

More than a year after VNS was called “the latest moneymaking gimmick” by the Alliance for Human Research Protection, a new longitudinal study suggests benefits of up to 24 months for those with chronic, treatment resistant depression. Does it matter that one of the study’s lead authors is employed by the only company providing VNS devices?

More than a year ago, we commented on the controversy surrounding vagus nerve stimulation for treatment resistant depression. (See “Critics Alarmed at Growing Use of Vagus Nerve Stimulation for Depression”.) At the time, Linda Andre, of the nonprofit Alliance for Human Research Protection in New York, called VNS “the latest moneymaking gimmick” designed to rapidly expand the market for products made by Cyberonics — the only supplier of VNS equipment. While some patients swear by the device, critics have long pointed to the lack of clear scientific evidence that the $40,000 vagus nerve stimulation device alleviates depression at all, let alone particularly effectively.

Now, however, a press release from the Medical University of South Carolina has been making the rounds, announcing long term benefits of up to two years for those participants in a longitudinal study whose symptoms improved at all during treatment. (Readers whose scientific skepticism meter is set to ‘sensitive’ will probably notice that this is a subtly different question from the question of whether the device actually works; the study found that when patients made improvements while undergoing treatment, most continued those improvements for up to 24 months.)

Notably, the press release does not disclose that the study’s second lead author, Stephen K. Brannan, is an employee of Cyberonics.

Does it matter that one of the study’s leaders is paid by the company whose device is being tested?

Here’s the original press release:

Researchers at the Medical University of South Carolina (MUSC) have announced the results of a two-year study, which tested the long-term antidepressant response to VNS (Vagus Nerve Stimulation) Therapy(TM) in patients with treatment-resistant depression (TRD). The study, of which Mark S. George, M.D., MUSC Distinguished Professor of Psychiatry, Radiology and Neurosciences is a lead author, is expected to appear in the April 2007 issue of the International Journal of Neuropsychopharmacology. Results showed that, of the patients who responded to VNS Therapy, either early or later in treatment, the majority continued to experience significant clinical benefit for up to 24 months. VNS Therapy is the first and only treatment for TRD to demonstrate such long-term improvements.

Patients included in this study, led by Harold A. Sackeim, PhD, of Columbia University, experienced severe chronic depression which proved to be treatment-resistant. The study participants had a 50 percent improvement in their depressive symptoms at either three months or a year after being treated with VNS Therapy. Between 61 percent and 79 percent of these patients sustained this response for 24 months. The durability of response was not attributable to alterations in other treatments.

“These data showing durability of response with VNS Therapy are pretty remarkable under any circumstances, but particularly for the patient population studied here,” said George. “Patients with TRD don’t respond to medications, and even when they do, they often develop tolerance after 6 months, and the depression returns. These findings regarding long-term sustained effectiveness are very encouraging for psychiatrists and patients with treatment-resistant depression. This study analysis provides additional confirmation that, at least for some patients, the benefits of VNS Therapy for TRD are long-term and improve over time.”

Many people with major depression relapse frequently, often despite numerous other treatment trials. More than 40 percent of patients experience a recurrence after two years and more than 60 percent experience recurrence after five years. Eighty percent to 90 percent of those patients having experienced two or more episodes of depression will have additional episodes. Electroconvulsive therapy (ECT) is considered by many psychiatrists as the most effective acute intervention for TRD. However, the majority of TRD patients relapse during the first year following response to ECT. This study shows that VNS Therapy is an effective long-term treatment option for some of these patients.

The FDA approved VNS Therapy as an adjunctive long-term treatment of chronic or recurrent depression for patients 18 years of age or older who are experiencing a major depressive episode and have not had an adequate response to four or more adequate antidepressant treatments. VNS Therapy is also FDA-approved as an adjunctive therapy used to reduce the frequency of seizures in adults and adolescents over 12 years of age with partial onset seizures that are refractory to antiepileptic medications. In addition to treatment-resistant depression and pharmacoresistant epilepsy indications, VNS Therapy is at various stages of research as potential treatments for anxiety disorders, Alzheimer’s disease, bulimia, chronic headache/migraine and morbid obesity.

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