The Potential of Vagus Nerve Stimulation

Vagal nerve stimulation (VNS) continues to be a viable solution for hard-to-treat depression. 

Scott Aaronson, MD, chief science officer, Institute for Advanced Diagnostics and Therapeutics at Sheppard Pratt, has been studying VNS for two decades.   

“The VNS device works when other treatments don’t,” he says. “I am so glad to add something that can help these people whom psychiatry hasn’t yet been able to help.” 

The VNS device is implanted beneath the skin of the upper chest, usually during an outpatient procedure, Dr. Aaronson says. Leads from the device are attached to the vagus nerve, which runs from the brain through the neck and into the abdomen. The device sends regular, mild electrical pulses through the vagus nerve to the brain, which can ease symptoms of  depression. 

The VNS device uses battery power, typically lasting seven to nine years, says Dr. Aaronson. He says some patients from clinical trials who had been lost to follow-up returned when their VNS device battery ran out, asking to be reimplanted with a new device. “Talk about voting with your feet,” Dr. Aaronson says. “They are getting better enough that they recognize they feel worse without it.” 

Dr. Aaronson has seen patients on VNS become productively employed or find enjoyment for the first time in years. He says the treatment can have a cumulative response. “Remarkably, this is one of the few treatments where your response actually continues to grow over time,” he says. 

Dr. Aaronson recently served as the principal investigator at the Sheppard Pratt study site for a one-year VNS study—the largest VNS study to date. In this study, about 1,000 people with treatment-resistant depression have been implanted with a VNS device. The study is enrolling patients with depression who have documented failures of at least four different treatment interventions, such as medications, electroconvulsive therapy, and psychotherapy. Of the approximately 1,000 patients enrolled, 500 have unipolar depression, and 500 have bipolar depression. The unipolar arm has completed enrollment, and the bipolar arm is still  enrolling. 

While this Medicare-funded randomized controlled clinical trial did not separate on the primary outcome measure for people living with unipolar depression, it did separate on some key secondary measures. Detailed findings are expected by the end of 2024. Results from the bipolar population arm of the study are expected in 2025. 

While most studies on depression treatments focus on acute outcomes, such as at the six- and twelve-week marks, this study will continue well beyond a year, when participants are moved to open-label treatment, Dr. Aaronson says. Participants will then be followed for an additional five years. “We’re getting all kinds of information about the long-term care of folks with very difficult-to-treat depressions,” he says.