Deep Brain Stimulation and Cognitive Outcomes Among Patients With Parkinson's Disease: A Historical Cohort Study

Objective: Deep brain stimulation (DBS) is an effective treatment for motor symptoms of Parkinson's disease; however, there is conflicting literature about the effect of DBS on cognitive function. The authors conducted a historical cohort study involving patients with Parkinson's disease who underwent DBS of the globus pallidus pars interna (GPi; N=12) or subthalamic nucleus (STN; N=17). Methods: The authors investigated differences in four neuropsychological test scores at 6 months post-DBS (follow-up) as compared with baseline (i.e., Boston Naming Test, WAIS Verbal Comprehension Index [WAIS-VCI], Working Memory Index [WAIS-WMI], and Processing Speed Index [WAIS-PSI]). Results: GPi DBS patients showed no difference between baseline and follow-up on any neuropsychological test. STN DBS patients had lower scores indicating decreased performance at follow-up as compared with baseline on WAIS-PSI (mean [SD], 91.47 [10.42] versus 81.65 [12.03]; p=0.03). There was a significant (p=0.008) difference between the change in baseline to follow-up scores on the WAIS-VCI for the STN DBS and GPi DBS groups (i.e., STN DBS patients scored lower at the 6-month follow-up compared with baseline, whereas GPi DBS patients scored higher). Conclusions: GPi may be a preferred target for DBS in patients with Parkinson's disease when considering cognitive outcomes.