Nerve Stimulation Enhances Cognitive Function

The study, led by Harold A. Sackeim, Ph.D., of the New York State Psychiatric Institute, was published in the January 2001 issue of Neuropsychiatry, Neuropsychology, and Behavioral Neurology.

In a study of VNS as a depression treatment, researchers performed a battery of neuropsychological tests on 27 patients with treatment-resistant depression before and after ten weeks of VNS therapy. The 13 tests evaluated skills such as motor speed, psychomotor function, language, attention, memory, and executive function. The results showed no evidence of deterioration in any of these skills after treatment with VNS, and there were marked improvements in many cases.

VNS therapy is delivered by an implantable medical device similar to a cardiac pacemaker. A stopwatch generator is surgically implanted in the left chest and a nerve stimulation electrode is attached to the vagus nerve in the neck in a one-to-two hour procedure. Using an external programmer, the doctor can set or reset the stimulation parameters of the device. The system delivers preprogrammed intermittent electric pulses to the vagus nerve 24 hours a day. In another study, VNS was found to have a positive influence on the quality of life of epilepsy patients, although study results showed no clear cognitive changes. VNS was developed by Cyberonics, Inc. (Houston, TX, USA).

"Our data suggest that VNS can produce a mildly improved sense of physical, emotional, and social well-being, and these improvements are not necessarily tied to relief from seizures,” said Carl B. Dodrill, Ph.D., neuropsychologist, University of Washington Regional Epilepsy Center.



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