A two-year study evaluating the efficacy of vagus nerve stimulation for long-term antidepressant benefit has determined the intervention is effective. Results showed that of the patients who responded to VNS Therapy, the majority continued to experience significant clinical benefit for up to 24 months.
The finding is salient as the patient population studied consisted of individuals experiencing severe chronic depression classified as treatment-resistant.
The 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.
The study, of which Mark S. George, M.D., is a lead author, is expected to appear in the April 2007 issue of the International Journal of Neuropsychopharmacology.
Patients included in this study, led by Harold A. Sackeim, PhD, of Columbia University, experienced severe chronic depression which proved to be treatment-resistant. “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.