FRIDAY, May 26 (HealthDay News) -- Vagal nerve stimulation, a new type of therapy for treatment-resistant depression, can take between three and 12 months before its benefits are first felt by patients, researchers find.
A vagal nerve stimulator is implanted in the chest with wires that run under the skin to the vagal nerve in the neck. The device emits electrical pulses to stimulate the brain. The therapy was approved in 2005 by the U.S. Food and Drug Administration to treat severe treatment-resistant depression. It's also used to treat epilepsy.
In this study, researchers used PET brain scans to monitor patients who received vagal nerve stimulation. Eight patients took part in the study for the three and six month scans, six patients at 12 months, and four patients at 24 months.
The PET scans detected significant changes in brain activity starting three months after the procedure began, and the brain activity changes continued to evolve over the next 21 months. The changes detected by the brain scans "roughly paralleled improvement in mood," the study said.
This long delay before a treatment begins to be effective is something psychiatrists aren't use to, noted lead investigator Dr. Charles Conway, an assistant professor of psychiatry at Saint Louis University School of Medicine in Missouri, said in a prepared statement.
"This is very different from the delays we see with existing treatments for depression, including pharmacotherapy and electroconvulsive therapy. The biggest changes in the brain that we're noting occur between 12 and 24 months after patients begin receiving vagal nerve stimulation. In psychiatry, we're used to seeing results after six to 12 weeks," Conway said in a prepared statement.
The findings are preliminary and need to be replicated, he noted.
"But (the findings) suggest that, in this type of therapy, the brain takes a relatively long time to change, perhaps as long as a year or more. In this sense, vagal-nerve stimulation may represent a paradigm shift in the way we view depression treatment. Patients may have to be instructed to 'be patient' with the expectations that the antidepressant effects will be slow to come," Conway said.
The U.S. National Institute of Mental Health has more about depression.
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