BOSTON (Reuters) - Stimulating an area near the base of the brain may help people with otherwise untreatable obsessive-compulsive disorder, researchers reported on Wednesday.
But the pilot study of 16 volunteers showed a substantial rate of serious adverse effects, Dr. Luc Mallet of Pitie-Salpetriere Hospital in Paris and colleagues reported in the New England Journal of Medicine.
Obsessive-compulsive disorder, or OCD, is caused by unwanted thoughts that continually intrude into a patient's mind and prompt constant repetitions of the same actions or thoughts, such as an urge to wash the hands constantly.
About 2 percent of the population experiences OCD at some point in their lifetime.
Treatment with cognitive-behavioral therapy and antidepressants fails up to 40 percent of the time, the researchers said.
The Mallet team tried deep-brain stimulation in an area called the subthalamic nucleus because it integrates movement, cognition and the emotional components of behavior. All 16 volunteers had suffered from OCD for at least six years, and standard treatment had done little to help them.
Stimulating the same region of the brain has been a treatment for Parkinson's disease since 1997. It relieves some of the tremor seen in those patients.
The research team found that when electrodes were implanted and turned on, the volunteers scored an average of 19 points on a 40-point scale that measures the severity of symptoms. When their electrodes were kept off, they scored, on average, 28 points.
On a second scale, in which a higher ranking on a scale of one to 90 indicated more improvement, patients scored 56 when the electrodes were active and 43 when they were not.
Whenever the electrodes were turned off, the patients who had improved reverted to their old behaviors, the researchers said.
But 11 volunteers suffered at lease one serious side effect, including four cases that were related to the surgery. One suffered brain bleeding. Two, including a 17th volunteer in whom the treatment was not tested, developed infections that required electrode removal.
Among all the patients whose electrodes were activated, three became manic, two developed anxiety, another had involuntary movements and one developed an array of difficulties, including being unable to speak clearly or walk property.
"Therefore, the benefits of this surgical treatment for symptoms of OCD should be carefully weighed against the potential occurrence of such serious adverse events," the researchers wrote.
Editing by Maggie Fox and Eric Beech