Unlike previous studies, the current study enrolled 251 patients who had just started having mild fluctuations and were still responding fairly well to drugs.
After being randomly selected to be in one of two groups, one receiving medication alone and the other receiving medication plus deep brain stimulation, the researchers found that those who received the combination therapy actually did better.
Patients in the deep brain stimulation group experienced an improvement of 26 percent in their quality of life.
This, said Deuschl, was "the most impressive finding," although mobility was also improved in the combination group.
Participants receiving deep brain stimulation did have a higher rate of suicide (two in this group versus one in the medication-only group), though the researchers speculated that the people in the study may have started out with higher risk for suicide.
In any event, patients undergoing deep brain stimulation would need to be closely monitored for psychiatric symptoms, the study authors added.
An accompanying editorial called the study "one of the most rigorously conducted trials of neurostimulation," yet also pointed out some limitations.
For one thing, patients in the study were younger, healthier and less likely to be demented than most patients with Parkinson's disease.
And deep brain stimulation alleviated only some symptoms of the disease.
The procedure is widely available in the United States, said Singer, but is only approved -- and Medicare only covers it -- for more advanced patients.
Still, the findings suggest that "instead of waiting for patients to have very marked fluctuations, peaks and very deep valleys, [we] move in when the peaks and valleys are not that steep," Singer said.
"The data suggest that patients can safely, and with significantly better outcome, receive neurostimulation," said Deuschl. "We expect that the international guidelin
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