January 2nd, 2012
04:04 PM ET
A new study is advancing the possibility that mentally ill patients who do not respond to conventional therapies may benefit from battery-powered electrodes surgically implanted in their brains.
The procedure, called Deep Brain Stimulation (DBS), uses a pacemaker-like device to deliver small, steady electrical charges to specific brain circuits that control our moods.
While DBS has been approved by the FDA since 1997 to treat the symptoms of movement disorders - essential tremor, Parkinson's disease and dystonia– its use in mental illness is experimental. Only a few scientists have tested DBS on just several dozen psychiatric patients suffering from treatment-resistant depression and obsessive-compulsive disorder.
The most recent study, published Monday in the online edition of Archives of General Psychiatry, includes not only 10 patients with major depressive disorder, but also 7 patients with bipolar II disorder, who typically have frequent, severe depressive episodes and are at a high risk of suicide.
All patients had tried conventional treatments, including psychotherapy, psychiatric medications, and electroconvulsive therapy. But nothing they tried brought any meaningful relief.
Their lives were typically burdened with deep feelings of detachment - like “being in a muck,” says Dr. Helen Mayberg, the Emory University neurologist who led the new study. “You can’t move; you can’t connect. You feel like you’ve done something wrong and you want to be dead.”
The principle measure for the level of illness in the experimental subjects was the Hamilton Depression Rating Scale, a widely-used questionnaire that asks patients about 17 different symptoms. Only patients whose Hamilton scores were 20 or above, which indicates severe depression, were eligible for the study.
A 50% drop in the Hamilton score after the DBS surgery was counted as a “response.” Patients whose Hamilton scores dropped below 8 were considered to be in “remission,” experiencing the normal ups and downs of healthy people.
After 24 weeks, 41% of the patients had a positive response to the stimulation and 18% were in remission. After two years of stimulation, the response rate was up to 92% and 58% of the patients were in remission. The increasing rate of improvement is consistent with data from earlier experiments showing that the impact of the electrical stimulation seems to accumulate over time.
Dr. Paul Holtzheimer, a psychiatrist who recently moved from Emory to Dartmouth Medical School, and Emory neurosurgeon Dr. Robert Gross, are also co-authors of the study.
The target of their DBS surgery is the white matter just below a pea-size brain structure known as Area 25. Earlier experiments by Mayberg had identified Area 25 as a junction box for the brain circuits linked to our moods. She calls it “a ringleader”. Using powerful imaging technology, Mayberg found that Area 25 seems to be overactive in depressed patients. She theorized that a small electrical current might make this area active.
Mayberg and a neurosurgeon at Toronto Western Hospital tested the theory in a groundbreaking experiment using Deep Brain Stimulation on six severely depressed patients, which was published in 2005.
Mayberg, who holds a patent with another scientist on the DBS procedure for depression, has licensed her intellectual property to St. Jude Medical, Inc. which also pays her and others on her team consulting fees.
The new study adds additional support to Mayberg’s original findings that DBS appears to be safe and effective.
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