Brain Stimulator Takes Time to Fight Depression, But Benefit Lasts

(Ivanhoe Newswire) -- A brain implant can help fight depression in patients for whom other treatments are ineffective, but the therapy can take as long as a year to show benefit, reveals new research from Washington University School of Medicine in St. Louis.

In a small study, researchers followed 24 patients who were implanted with vagus nerve stimulators (VNS) after other treatments proved ineffective in battling their severe depression.

Brain scans revealed changes in brain activity three months in to implant therapy and continued to evolve over 21. "The effects come after a significant period of treatment time," reports lead investigator Charles Conway, M.D. "In psychiatry, we're used to seeing results after six to 12 weeks."

Scientists also observed parallels between the brain changes and mood improvements in the patients. The brain scans revealed changes similar to those induced by electroconvulsive therapy (ECT), a controversial depression treatment from which benefits are often short-lived.

"The existing evidence suggests that about 70 percent of patients who get better from vagal nerve stimulation at one year stay better at two years," reports Conway. "That is unheard of in a depressed population this severe and suggests that the brain changes induced by this treatment appear to be long-lasting."

The vagus nerve stimulator was approved for use in patients with severe treatment resistant depression by the Food and Drug Administration last year. The implant emits tiny electrical pulses to stimulate the brain, but experts do not fully understand how it helps.

"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."

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SOURCE: Annual Meeting of the Biological American Psychiatrists, Toronto, May 18-20, 2006, and American Psychiatrists Association, May 20-25, 2006