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By Brenda L. Mooney
SAN FRANCISCO—For decades, a lot of the buzz in 
Parkinson’s disease research has centered on technologies 
such as deep brain stimulation (DBS). 
A recent review from the VA, which reported 10-year 
clinical outcomes of globus pallidus interna (GPi) vs. 
subthalamic nucleus (STN) deep brain stimulation 
(DBS) for Parkinson’s disease, shed some light on the 
benefits and limitations of that approach.
“Our findings confirm that DBS therapy, regardless 
of target, has a significant positive effect on some motor 
functions (notably tremor, rigidity, dyskinesia, and 
motor fluctuations) and has less of an impact on others 
(bradykinesia, axial signs) over 10 years,” wrote the 
researchers led by the San Francisco VA Healthcare 
System and the University of California San Francisco. 
“The initial advantage of STN over GPi in medication 
reduction was not seen in the long term. These study 
findings can help inform patients living with DBS or 
considering DBS therapy about what they can expect in 
the later stages of the disease, up to 10 years.”
The primary outcome of the study was the change 
in off-medication/on-stimulation Unified Parkinson’s 
Disease Rating Scale III score (UPDRS III) from baseline 
over time between the two targets at 2, 7 and 10 years. 
The VA treats about 110,000 veterans with Parkinson’s 
disease, and the study included 156 participants.
The researchers pointed out that many of the patients 
in the study were relatively advanced in their disease at 
the time of enrollment and did not experience a halt in 
disease progression, which is considered possible in some 
patients receiving DBS therapy, nor did the therapy “sub-
stantially influence many non-motor domains in the 
very long term. Patients continued to experience dete-
rioration and greater disability. ”
No differences were detected between the two 
targets because both cohorts were significantly worse on 
indicators of quality of life at 7 and 10 years, including a 
decline in cognition.
“Some have suggested that current DBS therapy may 
influence disease progression; however, this remains con-
troversial and unproven so far,” the authors explained. 
“The field of DBS since this study was conducted has 
New Solutions for an  
Old Problem: Extending 
Dopamine Effectiveness  
In Parkinson’s Disease
VA Study Highlighted Limitations of  
Deep Brain Stimulation
Deep brain stimulation works well for some 
Parkinson’s disease patients for some period 
of time, but the long-term benefits might not 
be as promising, according to a new VA study.  
That brings clinicians back to their problem of 
decades: How to extend dopamine benefits 
to avoid “off” episodes.  New pharmaceuticals 
might offer the answers.

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