The Medical University of South Carolina (MUSC) on Monday stated that the results of a new functional MRI (fMRI) study examining the effects of VNS Vagus Nerve Stimulation) Therapy for patients with treatment-resistant depression (TRD) show that VNS Therapy modulates areas of the brain that control mood.
The researchers, who were led by Ziad Nahas, M.D., associate professor, MUSC Department of Psychiatry, and appears in the August 2007 issue of the journal Neuropsychopharmacology, additionally identified variables, including length of use, strength of stimulation, and level of depression, to better understand the impact of VNS Therapy.
The study demonstrated that VNS Therapy modifies activity of the medial prefrontal cortex, which is the same area of the brain targeted by many antidepressant medications and electroconvulsive therapy (ECT). A critical time for such effective modulation occurs after about 30 weeks of treatment.
The modulation could underscore the Therapy’s unique mechanism of action as a long-term treatment for chronic or recurrent depression. It directly corresponds with the timeframe within which patients tend to experience a decrease in symptoms of depression.
Further analysis of the data shows forth that modulation of the brain is a dynamic process which, over time, leads to improved responsiveness with continued use.
Recent neurological and psychological studies have demonstrated that the human brain is a dynamic, ever-morphing biological entity. When someone changes her mind, she is literally changing the structure of her brain.
“These data provide further insight into VNS therapy’s distinct mechanism of action and support its previously demonstrated long-term, sustained efficacy. We are encouraged to see the unique benefit VNS therapy may bring to patients with one of the most difficult-to-treat forms of depression and are excited to continue neurostimulation research at MUSC,” says Nahas.
VNS therapy was originally approved by the FDA for treatment of epileptic seizures in 1997. It was later approved for the treatment of depression in July of 2005. The therapy had been studied in clinical trials for treatment-resistant depression since 1998.
VNS therapy comprises the surgical implantation of a small, battery-operated pulse generator, something like a pacemaker, into a patient’s left upper chest. Thin, flexible wires from the generator get tunneled into the neck and shoot mild, intermittent pulses into the neck’s left vagus nerve, which in turn delivers these pulses approximately every five minutes to the areas of the brain involved in the management and balancing of mood, motivation, sleep, appetite, and other personality traits and behaviors affected by depression.
Patients have witnessed to having their lives literally restored to them through use of the VNS pulse generator, including patients otherwise resistant to psychiatric drugs or “talking cures” used to treat clinical depression. In studies, 16-20% of patients using VNS have experienced total remission of all symptoms of depression.
Medical University of South Carolina (PR Newswire), “New Study Supports Efficacy of Vagus Nerve Stimulation for Treatment-Resistant Depression”