CHARLESTON, SOUTH CAROLINA -- New long-term findings demonstrate that patients with difficult to treat chronic or recurrent depression continue to respond to vagus nerve stimulation (VNS) therapy for up to two years.
Results from the 60-patient long-term study, led by Mark George, MD, distinguished professor, departments of Psychiatry, Radiology and Neurology at the Medical University of South Carolina, indicate that extended treatment with VNS is associated with the elimination or reduction of depressive symptoms and an improved ability to perform daily functions.
The study, conducted to determine whether the promising results seen in an acute phase (three month) pilot study were sustained after one to two years of treatment with VNS, used remission and response rates as the primary indicators of success. Response means that a patient's depression symptoms were cut in half; remission means that a patient has become virtually symptom-free. The study found that depressed patients with VNS improved over time in terms of remission and response and also improved in their ability to function:
- 27% of patients were in remission after one year, increasing from 15% at the end of the acute study;
- 45% of patients responded to treatment after one year, increasing from 31% at the end of the acute study; and
- 54% of patients responded to treatment after two years, increasing from 46% at the one-year mark.
"There is a need for a more effective and tolerable long-term treatment because 20 to 30 percent of Americans with depression do not respond satisfactorily to currently available treatments," stated George. "The results from this long-term study suggest that VNS could be an effective long-term therapy to help people with chronic and recurrent depression maintain a better quality of life and higher level of day-to-day functioning."
Depression is a mental illness of global proportions, affecting approximately 340 million people worldwide and more than 18 million American adults. Furthermore, major depression is a leading cause of disability. The illness is characterized by sad moods, loss of interest or pleasure, feelings of guilt or low self-esteem, disturbed sleep and appetite, low energy level and the decreased ability to concentrate. These problems many times become chronic or recurrent and prevent those affected from performing everyday tasks and family and occupational responsibilities.
"Depression is a chronic, disabling lifelong illness that requires a well-tolerated treatment that provides both acute symptom relief and continued benefits," stated Harold Sackeim, Ph.D., professor, department of Psychiatry and Radiology, Columbia College of Physicians and Surgeons and New York State Psychiatric Institute. "Studies of VNS for depression thus far indicate that this therapy may be an option for patients who have not had a positive long-term response to commonly available treatments."
VNS stimulates the limbic system, a group of related brain structures that affect mood, motivation, sleep, appetite, alertness and other factors commonly altered by depression. VNS is delivered to the left cervical vagus nerve by a stopwatch-sized generator - the NeuroCybernetic Prosthesis (NCPâ) System - implanted just under the skin in the left chest area. VNS delivers pre-programmed, mild, intermittent electrical pulses to the left vagus nerve 24 hours a day. The implantation procedure takes approximately one hour and usually requires no overnight hospitalization.
VNS is safe and does not cause the side effects normally associated with depression medications, such as weight gain, loss of sexual function, cognitive impairment and insomnia.
Side effects associated with VNS typically occur only when stimulation is on. They include voice alteration, shortness of breath, neck discomfort and coughing, all of which are reported less frequently over time.
VNS with the Cyberonics NCP System was recently approved for sale in the European Union and in Canada as a treatment of depression in patients with treatment-resistant or treatment-intolerant major depressive episodes including unipolar depression and bipolar disorder (manic depression). VNS with the Cyberonics NCP System was approved by the FDA in 1997 for use as an adjunctive therapy in reducing the frequency of seizures in adults and adolescents over 12 years of age with medically refractory partial onset seizures. In addition, the NCP System is currently approved for epilepsy in all the member countries of the European Union, Canada, Australia and other markets.
The first patient with depression to be treated with VNS was implanted at MUSC in July 1998, and MUSC researchers have continued to pioneer VNS as a treatment for neuropsychiatric disorders, including depression. MUSC researchers have also been combining VNS with real-time functional brain imaging. The Medical University of South Carolina's mission is to preserve and optimize human life in South Carolina and beyond through education, research and health care. Located on the Charleston peninsula, the university educates students from across the state and beyond. It provides primary care services for the local community and serves as a referral center for specialized care for patients from across the state, the nation and the world.
Ellen Bank, Medical University of South Carolina, 843-792-2626
Samantha Narcisse, Porter Novelli, 212-601-8276