In the largest study ever conducted with patients experiencing chronic and severe depression, researchers led by Dr. Scott Aaronson, Director of Clinical Research at Sheppard Pratt Health System have found that an implantable vagus nerve stimulation device (VNS Therapy) paired with antidepressant treatment (which could include medications, psychotherapy, or electroconvulsive therapy (ECT)) proves effective in reducing symptoms among patients with treatment-resistant depression. The study, now available online in the American Journal of Psychiatry, is the cumulative result of ten years of research following nearly 800 patients.
Prior to the study enrollment, patients had received, on average, more than eight unsuccessful treatments for depression. Depression is considered treatment-resistant after two or more unsuccessful interventions. The researchers looked at two groups—one group that was given proven anti-depressant treatments, including medications, psychotherapy, and ECT, and one group that was given both anti-depressant treatments and VNS Therapy. Over five years' time, researchers found that the VNS group reported better response rates earlier in treatment. In addition, the VNS group experienced reduced rates of mortality and suicidality. Across all patients enrolled in the study, the likelihood of response to treatment over the 5-year study period was 67.9% among VNS patients, compared to 40.9% of patients receiving treatment as usual. Importantly, response rates were sustained longer in the patient group receiving the addition of VNS Therapy.
The device used in the study is similar to a pacemaker, and works by sending regular, mild pulses of electrical energy to stimulate the vagus nerve, which connects to areas in the brain regulating mood. Researchers believe that findings from this study should lead to the increased availability of this treatment option for patients severely impaired by depression symptoms.
"We are very encouraged by the results of this unprecedented study, and hope that VNS becomes more readily available as a viable option for patients who have been through countless interventions for severe, chronic depression," said Dr. Scott Aaronson, lead researcher for the study.
Researchers noted that patients with a range of medical and treatment histories saw promising success rates using VNS. VNS proved effective for individuals whether their primary diagnosis was unipolar or bipolar depression, and also proved effective whether or not they had responded to ECT in the past. ECT is commonly used for treatment-resistant depression, but can cause some adverse side effects such as confusion or headaches.
"The positive long-term outcomes we see among both ECT responders and non-responders are remarkable. Going forward, VNS may prove to be a less disruptive alternative for patients who now rely on ECT. Additionally, for patients who haven't found ECT effective, VNS may prove to be a new, life-changing treatment option," Aaronson said.