Cognitive outcome and reliable change indices two years following bilateral subthalamic nucleus deep brain stimulation☆
Introduction
Bilateral subthalamic nucleus deep brain stimulation (STN-DBS) is currently the treatment of choice for treatment resistant tremor and motor complications in patients treated with levodopa for Parkinson’s disease (PD) [1], [2]. This procedure has been successful in ameliorating dyskinesias, decreasing levodopa medications, and increasing “on” medication time and health-related quality of life (QOL) [3], [4].
However, less is known regarding the cognitive outcome following STN-DBS. Initial research suggested that STN-DBS did not lead to significant changes in short-term global cognitive skills when assessed with brief screening measures [5], [6], [7]. Conversely, studies utilizing more comprehensive neuropsychological batteries revealed short-term, mild impairments in verbal fluency, memory and executive function [8], [9], [10], [11], [12], [13]. Despite evidence of mild short-term cognitive impairments, long-term cognitive effects of STN-DBS have not been as thoroughly assessed. While some studies have not found cognitive changes following DBS [6] other investigations have documented declines in verbal fluency, verbal memory, information processing speed and executive function [10], [11], [12]. A meta-analysis on STN-DBS cognitive outcome research found that 41% of patients had evidence of cognitive impairments in verbal memory and fluency, executive functioning, attention, working memory, mental speed, and response inhibition an average of 13 months following surgery [13]. These studies suggest that the cognitive effects of STN-DBS remain underestimated and highlight the need to perform comprehensive neuropsychological evaluations to better capture the full effects of STN-DBS.
The purpose of the present study was to investigate the cognitive effects of bilateral simultaneous STN-DBS using a comprehensive neuropsychological assessment and a matched medically-managed PD control group two years following surgery. Moreover, we present reliable change indices (RCIs) to compare statistically reliable cognitive changes between the groups for each neuropsychological measure over time. Additionally, dementia caseness analyses using both DSM-IV-TR [14] and Emre [15] criteria were performed.
Section snippets
Participants
Nineteen PD patients who had bilateral simultaneous STN-DBS were compared to 18 non-surgical PD patients using comprehensive neuropsychological assessment at baseline and at a 2 year follow-up evaluation. The STN-DBS patients were consecutive patients who underwent STN-DBS for the treatment of PD from the Baylor College of Medicine Parkinson’s Disease and Movement Disorders Center (BCM-PDMDC). The non-surgical PD patients were a convenience sample of PD patients from the PDMDC who were
Subjects
Table 1 presents baseline demographic information for STN-DBS patients and PD controls. Groups were matched post-hoc on age, gender, baseline Hoehn and Yahr staging, duration of PD, and baseline MMSE scores. However, the STN-DBS group had significantly less education and higher baseline dopaminergic medication usage. Education correlated significantly (p < 0.05) with Digit Span, BVMT-R Total Recall, and BNT and thus was entered as a covariate. To control for changes in dopaminergic medications
Discussion
Using a comprehensive neuropsychological assessment, we examined the cognitive effects of bilateral simultaneous STN-DBS 2 years after surgery compared to a matched PD medically-managed group and present RCIs for each of the cognitive measures. These exploratory findings suggest that STN-DBS patients 2 years following surgery demonstrated impairments in nonverbal memory (BVMT-R-delay), oral information processing speed (SDMT), and language (VF & SF). These findings were further emphasized with
Author contributions
Amy E. Williams – execution of project including statistical analyses and writing of manuscript.
Gladys Marina Arzola – execution of project and manuscript.
Adriana M. Strutt – Patient assessment and review and critique of statistics and manuscript.
Richard Simpson – Surgical procedures and review and critique of manuscript.
Joseph Jankovic – Treating neurologist and review and critique of manuscript.
Michele K. York – execution of project and review and critique of statistics and manuscript.
Competing interest
Dr. Jankovic: Medtronic and St. Jude Medical.
Dr. Simpson: Medtronic and St. Jude Medical.
Acknowledgements
This material is the result of work funded by a NIH/NINDS K23 grant (PI: M.K. York) and supported with resources from the Department of Veterans Affairs, Michael E. DeBakey Veteran’s Affairs Hospital, Houston, Texas. The authors wish to thank the National Parkinson’s Foundation and the Parkinson’s disease patients who willingly gave of their time to participate in this research project.
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2021, NeuroscienceCitation Excerpt :Interestingly, while subthalamic nucleus (STN) DBS allows for a greater reduction in levodopa equivalent dose (LED), globus pallidus pars interna (GPi) DBS produces a more pronounced improvement in dyskinesia than STN DBS (Ryu et al., 2017; Liu et al., 2019). Cognitive and memory decline is observed more frequently in PD patients receiving STN DBS than those receiving GPi DBS or those that did not undergo surgery (Hariz et al., 2008; Williams et al., 2011; Cernera et al., 2019), possibly owing to the associative and limbic connectivity of the STN (Parent and Hazrati, 1995; Temel et al., 2005; Arnold Anteraper et al., 2018). A meta-analysis found the adverse effects of STN DBS on human cognition included mildly significant declines in executive function and in verbal learning and memory, with moderately significant declines in verbal fluency (Parsons et al., 2006).
Predicting Neurocognitive Change after Bilateral Deep Brain Stimulation of Subthalamic Nucleus for Parkinson's Disease
2021, World NeurosurgeryCitation Excerpt :We found significant deterioration in visuospatial function at 1 year after STN-DBS, which was further emphasized by RCIs indicating that approximately 40% of patients showed reliable impairment. Our findings are consistent with some studies that reported a decline in visuospatial function following DBS14,26,55,56; however, other studies reported no changes after surgery.16,17,57-59 Even studies that included a control group have either reported significant changes in visuospatial function in DBS patients57 or no significant decline.17,59,60
Conversion to MCI and dementia in Parkinson's disease: a systematic review and meta-analysis
2019, Parkinsonism and Related DisordersCitation Excerpt :Two studies [51,60] used the MoCA [70]. Criteria by Caviness and colleagues [71] were used for one study [65]. The Mini-Mental State Examination was used for a study administered by a neurologist without reference to MDS criteria [61].
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The review of this paper was entirely handled by an Associate Editor, R. L. Rodnitzkyi.
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Authors contributed an equal amount to the development and writing of the manuscript and share first authorship.