Pacemakers -- for Anxiety
Anxiety -- the Nerve
That suggests an intriguing theoretical reason why VNS might work well for people with anxiety, he says.
"Emotions are not brain events, but the brain's interpretation of bodily events," George says. "When you feel scared, it's really your brain sensing that your heart rate is going up."
So by stimulating the vagus nerve, George and others hope to influence the exchange of information between body and brain, and thereby relieve the symptoms of anxiety.
Whether this works remains to be seen. Today, the device implanted in Scott's chest activates every five minutes, stimulating her vagus nerve with a small electrical current for a period of five seconds. When it activates while she is talking, her voice suddenly becomes mildly hoarse.
"Some days I think it's helping, and some days I don't know," she says. "At first I was expecting something instantaneous, but it doesn't work that way. It can take months to see any results."
Reason for Hope
George says there is reason for hope.
For the last 10 years, VNS has been successful treating patients with epilepsy who do not respond to conventional therapy. Stimulating the vagus nerve appears to reduce the number of daily seizures such people experience by up to 40% -- and some patients become completely seizure-free, George says.
VNS was approved by the FDA for treatment-resistant epilepsy in 1997.
VNS has also shown promise in the treatment of depression. It is approved for this use in Europe and in Canada, but not in the U.S.
In a report published last year in the Journal of the Society of Biological Psychiatry, 30 people with depression, who were not helped by common medications, received VNS. Forty percent of the patients showed some improvement after the treatment, according to the study.
Remarkably, some patients appeared to have no depression at all after the treatment.
"What got me interested was the fact that 20% to 25% of patients were completely well after treatment," says George, a co-author of the study. "Among people with treatment-resistant depression, you rarely see complete remission. These were people who had failed on three or four medications, and two-thirds of the group had had electroconvulsive therapy [ECT, the so-called shock treatment]."