DALLAS – Aug. 31, 2005 – Vagus nerve stimulation (VNS)therapy, a treatment recently approved by the Food and DrugAdministration for treatment-resistant depression, produced a positiveresponse in more than 25 percent of patients in a national, yearlongstudy led by UT Southwestern Medical Center psychiatrists.
Sixteen percent to 20 percent of the study group experienced total remission.
Resultsof the study, led by Dr. A. John Rush, vice chairman for research inpsychiatry at UT Southwestern, appear in the September issue ofBiological Psychiatry. Findings from two additional related studiesalso are included in the issue.
VNS therapy, which the FDAapproved for treatment of epileptic seizures in 1997 and for depressionin July, has been studied in clinical trials for treatment-resistantdepression since 1998. VNS therapy includes surgical implantation of asmall battery-operated pulse generator – similar to a pacemaker – in apatient's left upper chest. Thin, flexible wires from the device aretunneled into the neck and send mild, intermittent pulses to the neck'sleft vagus nerve. The vagus nerve in turn delivers these pulses aboutevery five minutes to the areas of the brain involved in the regulationof mood, motivation, sleep, appetite and other symptoms relevant todepression.
Karmen McGuffee, who had the vagus nerve stimulatorimplanted in 1999 after suffering from severe depression for more than15 years, said the device has restored her life. A participant in oneof the first clinical trials at UT Southwestern, she had taken morethan 10 types of antidepressant drugs before the surgery, with littlesuccess.
"It was like having the color come back into my world,"said Mrs. McGuffee, 35. "Before VNS therapy, I could barely functionand only then with a lot of help. At the time, I had nothing to lose.
"NowI feel brighter and lighter. I'm not constantly worried, and I lookforward to everyday activities. Things that other people take forgranted, such as managing a house, a family and a job all are nowpossible."
VNS therapy is only indicated for people who have notbeen helped by other depression treatments, said Dr. Rush. "If you havetreatment-resistant depression and need long-term treatment, VNS is anoption that should be considered. While it's not going to get everybodyinto remission, it's doing pretty well in very difficult-to-treatpatients," he said.
Two of the three studies in the currentjournal compared patients with major depressive disorder or bipolardisorder, all of whom were implanted with the vagus nerve stimulator.In the first trial, which included 235 people and only lasted for 10weeks, patients implanted with the stimulator received either activeVNS therapy or no therapy, meaning the device was not activated. Therewas little change in either group.
Dr. Rush's second multicentertrial, which included 205 of the same patients, provided active VNStherapy for a full year to all participants, measuring their symptomsof depression at regular intervals using several standard ratingscales. One rating scale showed a 27.2 percent reduction in symptomsamong participants and a 15.8 percent remission rate at year's end –suggesting that long-term treatment with VNS offers a greater benefitthan its short-term application. A second rating scale showed reductionin symptoms by 28.2 percent and a 20.3 percent remission rate.
"Thisis a very good response, given the type of highly resistant depressioninvolved," Dr. Rush said. "Participants in the trials were some of themost treatment-resistant depressed patients ever studied, with at leasthalf having been hospitalized for the disease at least once."
Thestudies also showed VNS to be well-tolerated, with few serious adversereactions, he said. Possible side effects, however, can include aslight voice alteration or temporary hoarseness, cough, tickling in thethroat or shortness of breath during exertion – symptoms which mayoccur intermittently when the stimulation is on.
The third study,of which Dr. Rush was a co-author, compared two groups of people withsimilar degrees of severe depression. One group was implanted with thevagus nerve stimulator as well as given other types of treatments fordepression, including medication and cognitive therapy. The secondgroup did not receive the device, but was treated for depression.Results showed a 27 percent reduction in depressive symptoms in the VNSgroup, compared to a 13 percent reduction in the second group.
Dr.Mustafa Husain, professor of psychiatry and internal medicine at UTSouthwestern, said VNS offers "new hope" for severely depressedindividuals.
"VNS treatment can be very useful in combinationwith antidepressants for a particular group of patients who arechronically depressed," he said. "It can provide new hope for a betterlife to those who are not responding to antidepressant medications."
Dr.Husain and Dr. Rush were involved in all three studies, which includedresearchers from more than 20 sites around the country. The studieswere supported in part by Cyberonics Inc., manufacturer of VNS Therapy.
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