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Deep Brain Stimulation More Effective than Best Medical Therapy Even in Older Parkinson’s Patients

For release: Wednesday, January 7, 2009

Deep brain stimulation (DBS) was more effective than best medical therapy (BMT) in improving “on” time-- periods of unimpeded motor function--and quality of life in a large comparison study of more than 200 advanced Parkinson’s disease (PD) patients.  Patients in the DBS group, even those over 70 years old, gained as much as four and a half hours of on time compared to the BMT group, who gained none.

The study results appear in the January 7, 2009 issue of The Journal of the American Medical Association (JAMA).*   The multi-center clinical trial was jointly funded by the Department of Veterans Affairs (VA) and the National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health.

“This is the first large randomized, controlled clinical trial to compare the benefits and risks of DBS and BMT in a very wide age range of Parkinson’s patients.  More than one-quarter of the patients in the study were over 70,” said Claudia Moy, Ph.D., a program director at NINDS. “Every age group fared better in the DBS group.”

The typical Parkinson’s patient is over age 50 and has other medical conditions.  PD is a type of motor system disorder which results in tremor, rigidity, slowness of movement, and impaired balance and coordination.  Medications used to control these symptoms often stop working after a number of years.

In DBS, electrodes are implanted in the brain and connected to a small electrical device called a pulse generator that can be externally controlled.  DBS, the surgical intervention of choice for PD when motor complications are not managed well by medications, entered clinical use in the late 1990s. While it has been a highly successful treatment for PD, there are inherent risks associated with the surgery.  In this study, there were more adverse events in the surgically treated patients.  One patient died due to bleeding in the brain after implantation of the electrode.

A total of 255 PD patients with a mean age of 62 were randomized to DBS or BMT at seven VA and six university hospitals.  BMT patients were managed actively by movement disorder neurologists who applied state-of-the-art strategies, including adjusting current medications, and provided non-pharmacologic approaches such as physical, occupational, and speech therapy.

After six months, the researchers measured the change in “on” time when the patient had good motor function and system control. Patients were also assessed on motor function, quality of life, and cognitive functions.

DBS patients reported an average increase of 4.6 hours of "on" time a day, compared to no change in “on” time in the BMT group.  Seventy-one percent of the DBS group experienced improved motor functioning compared to 32 percent in the BMT group. And there were significant improvements in quality of life experienced by DBS patients.  However, the DBS group showed slightly reduced performance on some cognitive tests compared to patients receiving BMT.  BDS patients were more likely to suffer from confusion during the first three months, but not in the final three months of the trial.

The authors caution that the benefits need to be weighed against the risk of complications related to DBS surgery. “As with many effective therapies, there may be a price to pay in terms of increased risk of adverse events,” said Dr. Moy.   The total number of adverse events was 3.8 times higher in the DBS than the BMT group. The most frequent adverse events in both groups were gait disturbance, falls, motor dysfunction, balance disorder, depression, and dyskinesia and dystonia, which cause involuntary movements. There were more falls in the DBS group, often resulting in injuries (fractures, dislocations, head trauma) requiring surgery and other interventions.  It is not clear whether DBS increases fall risk directly or patients are at higher risk of falling due to their improved overall function and greater activity level.

Many of the adverse events experienced by the DBS group were related to the surgical procedure itself and occurred during the first three months after surgery. The majority of these resolved by the six-month follow-up.  Only falls and dystonia were significantly greater among individuals who received DBS than BMT in the later three months.

Medtronic Neuromodulation, the manufacturer of the DBS device, also provided financial support for the trial. 

NINDS is the nation's primary supporter of biomedical research on the brain and nervous system. Information from the NINDS about Parkinson’s disease is available at   The NIH — The Nation's Medical Research Agency — includes 27 Institutes and Centers and is the primary Federal agency for conducting and supporting basic, clinical, and translational medical research. It investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit

* Weaver F, et al “Best Medical Therapy versus Bilateral Deep Brain Stimulation for Patients with Advanced Parkinson’s Disease: A Randomized Controlled Trial.” The Journal of the American Medical Association, January 7, 2009.

Last Modified January 7, 2009