The International Journal of Neuropsychopharmacology

Research Article

Durability of antidepressant response to vagus nerve stimulation (VNSTM)

Harold A. Sackeima1a2 c1, Stephen K. Brannana3, A. John Rusha4, Mark S. Georgea5, Lauren B. Marangella6a7 and John Allena3

a1 Department of Biological Psychiatry, New York State Psychiatric Institute, New York, NY, USA

a2 Departments of Psychiatry and Radiology, Columbia University, New York, NY, USA

a3 Cyberonics, Inc., Houston, TX

a4 Department of Psychiatry, University of Texas, Southwestern Medical Center, Dallas, TX, USA

a5 Departments of Psychiatry and Radiology, Medical University of South Carolina, Charleston, SC, USA

a6 Department of Psychiatry, Baylor College of Medicine, Houston, TX

a7 South Central Mental Illness Research Educational and Clinical Center, Houston, TX


This study characterized the durability of improvement in patients who responded early or late while receiving vagus nerve stimulation (VNS). In both a pilot and pivotal study, patients were identified who had at least a 50% reduction in symptom scores 3 months (early responders) or 12 months (late responders) after starting VNS. Probabilities were determined for maintenance of response at 12-month and 24-month time-points. Consistency of improvement throughout the 24-month study period was evaluated, testing for change in serial depression ratings. In the pilot study, 30.5%, 23.7% and 45.8% were early responders, later responders, and non-responders, respectively. These rates were 14.6%, 19.5%, and 65.9% in the pivotal trial. The potential confound of alterations in antidepressant treatment was examined in the pivotal trial. In the pilot study, 72.2% and 61.1% of early responders (n=18) were responders at 12 and 24 months, respectively; 78.8% of late responders (n=14) were responders at 24 months. In the pivotal trial, of early responders (n=30), 63.3% and 76.7% maintained response at 12 and 24 months, respectively; of late responders (n=40), 65.0% maintained response at 24 months. Early and late responders had fewer changes in medication than non-responders across the pivotal study period. In both studies, analyses of serial depression ratings showed stable improvement in early and late responders. These samples had exceptional levels of chronicity and treatment resistance. Yet patients who showed substantial clinical benefit maintained the improvement at remarkably high rates. This durability of benefit was not attributable to alterations in other treatments.

(Received May 12 2006)

(Reviewed July 01 2006)

(Revised September 25 2006)

(Accepted October 13 2006)

(Online publication February 09 2007)