Current Research Reviews Archives

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Our Current Research Reviews ("CRR") is designed to summarize the most recent research on DBS to the general public in a comprehensive, yet simplified fashion. Due to copyright laws we are not allowed to put full articles on the website, but we want to provide the reader with understandable snippets of what is going on in the research world.  The CRR will be updated monthly to keep you informed of further insights into DBS therapy, including DBS advances, limitations, strengths, and weaknesses.  We try to monitor "hot topics" in research and provide such information to our readers.

The idea for our CRR is structured after the valuable service that Joe Bruman offered to the Parkinson's community. In 1994, when the Web was in its infancy, Joe began publishing an easy-to-read overview of published science and medical news on Parkinson's disease. He updated it monthly until his death in 2003. We acknowledge Joe's contribution, and our researchers are continuing his tradition for the DBS community. As Joe has eloquently stated on his site, "CRR items describe current work which may or may NOT prove to be important. Each one is just a piece of the big PD jigsaw puzzle. … CRR provides an inkling of where we are, what lies ahead."

A few other points are noteworthy:

  1. Should you desire a copy of the full article, the articles that we review are available most often for a fee (ranges from $15-50) online or through medical or public libraries (fees will vary).  The fees are set up by the journal in which it is published. or The Parkinson Alliance is not affiliated with these journals, and we do not receive any money from the purchase of any article.
  2. We provide a link to a website ( that will help the reader find the article online.  If you go to through the link on our website to search for an article in which you are interested, you should be brought directly to that article's information.  Usually on the upper left hand area of the screen there will be 1-2 buttons that will say something to the effect of "click here to read" or "full text pdf," and the name of the journal will be listed.  Click on one of those buttons and you should be redirected to the journals website (e.g. Neurology, Movement Disorders, etc). 
  3. Most of the journal websites are pretty self explanatory on how to order the journal and are upfront about their fees.  It may be possible to order the article through your local library, which will vary from library to library.  Some hospitals may also allow patients to make a copy of an article that is available in their medical libraries.  This will also vary per hospital, and you can find out about a hospital's resources by asking the hospital libraries directly.

The information contained in our CRR is for educational purposes only and is not intended as medical advice.

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Research Review Archives

Current Research Review — Jan/Feb 2017

Clinical interventions in aging

Tan ZG, Zhou Q, Huang T, Jiang Y. Clin. Efficacies of globus pallidus stimulation and subthalamic nucleus stimulation for advanced Parkinson. Clinical interventions in aging, 2016 Jun 21;11:777-86. doi: 10.2147/CIA.S105505. eCollection 2016.

Click here to read a longer version of this review.

Introduction:   Parkinson’s disease (PD) is a common neurological condition that is initially treated with levodopa to control the motor symptoms.  The medications are frequently effective but as the disease progresses the medications are frequently not as effective and can cause adverse motor side effects (e.g. freezing and dyskinesias) for People with Parkinson’s disease (PWP).  Additional therapies were created, deep brain stimulation (DBS), in the 1990’s and have consistently shown efficacy in controlling motor symptoms for PWP.  Much of the earlier research focused on the motor control and did not pay as close attention to the nonmotor symptoms which can also be very disabling.  Recent research has focused on neurocognitive outcomes and these authors conducted a meta-analysis to review such studies.  

Method:  After establishing multiple exclusion and inclusion criteria, a review of the literature was completed and ten randomized clinical trials (9 bilateral STN or Gpi, 1 unilateral) were analyzed.  The trials had evaluations at a variety of times including 6, 12, and 24 months postsurgery.


      Motor: The results were slightly mixed before 24 months but at the 24 month mark the DBS STN group had more motor improvement. Notably the score difference was only a few points which showed to be statistically significant but likely was not clinically noticeable.  

      Medications: Results showed that more medication was needed after DBS GPi.
      Mood: The results showed that the DBS STN group had statistically significant lower mean depression scores but only by a few points.  Notably both groups had clinically meaningful depression mean scores with variability within each group.
      Cognition: A variety of cognitive domains were evaluated including language (fluency and naming), processing speed, executive functioning, and a broad screening measure.  Most of the cognitive measures showed no difference between groups but the DBS STN group had lower scores on the fluency measures and one task of executive functioning.  Mean test scores were not provided so it was unclear to what level each group was experiencing cognitive changes in general.
      Quality of Life (QoL): QoL was measured by the PDQ-39 which is a self-report measure looking at multiple dimensions of QoL (scales: mobility, activities of daily living; ADLs, emotions, stigma, social support, cognitions, communication, body pain, and an overall score). The DBS GPi group had higher scores in all areas but stigma which still tended towards the GPi group.  

Conclusion:  The authors concluded that both groups had improvement in motor functioning after DBS regardless of the target site and the minimal findings between the two were clinically insignificant.  They suggested that the choice for surgical intervention may be better suggested by the medicinal needs and nonmotor symptoms present prior to surgery.  As an example, they noted that DBS STN may be a better option for a PWP that had more levodopa induced dyskinesias prior to surgery as they likely would have a lower dose of levodopa after DBS which may minimize that adverse event.  They note that it is important to monitor depression symptoms in all PWP undergoing DBS.  The neurocognitive findings also noted that the DBS STN had more cognitive challenges on three specific measures that may have been due to surgical effect as the challenges remained even when the DBS was off.  Interestingly the DBS GPi group had higher QoL in most areas but was based on limited data with some possible presurgical differences as well.   This meta-analysis is a great first approach in looking at the nonmotor symptoms of DBS treatment for PWP.  These findings continue to suggest that the best approach to choosing the appropriate target for DBS should be based on the individual PWP after evaluation by a multidisciplinary team.

(The full article was available free online at the time of this writing through the pubmed link below. Click on the button in the top right area of the screen. 

Click on either link and it should take you to the article and you can click on the PDF or HTML option to read or access the article.)

Click here for the PubMed Abstract