Predictors of cognitive and psychosocial outcome after STN DBS in Parkinson Disease.
Smeding HM, Speelman JD, Huizenga HM, Schuurman PR, Schmand B. Predictors of cognitive and psychosocial outcome after STN DBS in Parkinson Disease. , 2009 May 21. [Epub ahead of print]
The purpose of this article was to look at the effects of DBS STN on cognition, mood, and quality of life in people with Parkinson’s disease (PWP) as well as to evaluate any predictive factors for such changes. The researchers tested two groups, one that had PD without DBS and another that had PD and underwent DBS STN surgery. Each group was tested at baseline and then 12 months later. No significant differences were found at baseline testing between the two groups on cognitive testing. Twelve months after surgery, the DBS STN group showed improvement in their motor scores as well as a reduction in usage of levodopa. In regard to the cognitive testing the DBS group showed decline, as compared to the control group, in the areas of verbal fluency (naming items as fast as one can that are from a category or that start with a letter; this finding is common), immediate and delayed memory, a Stroop task (a difficult task requiring naming the color of ink that a word is printed in, while ignoring the word itself), reading speed, and visuospatial reasoning. Regarding the mood and behavior questionnaires, they found that the DBS STN group had more improvement in their quality of life as compared to the control group regardless of whether or not they experienced change in cognitive functioning. It is notable that although there was a decline noted in scores on research measures, not all of the PWP that experienced change were able to detect a difference in their everyday lives. As the findings of cognitive decline after DBS STN has been mixed, the authors suggest replication of this study, and continued attention is needed to this area.
The researchers also wanted to examine possible predictors of cognitive decline and quality of life in PWP. They found that those PWP who had impaired attention, advanced age, and did not respond well to levodopa at baseline were more likely to experience cognitive decline after DBS STN. They also found that how the PWP responded to levodopa prior to surgery was the best predictor of improvement in quality of life after surgery.
The authors concluded that DBS STN is an efficacious treatment for improved motor symptoms of PD as well as quality of life in the PWP. However, the treatment has been found to have adverse effects that PWP need to know about before undergoing such treatment. They discuss that physicians should also pay attention to premorbid factors before surgical intervention that may help predict who is more likely to have such adverse cognitive events after the surgery.