Is Deep Brain Stimulation Associated With Detrimental Effects on Cognitive Functions in Patients of Parkinson's Disease? A Systematic Review.

Deep brain stimulation (DBS) is a rapidly evolving procedure with its application in multiple fields of neurology, but it is most prominent in Parkinson's disease (PD). Through electrode implantation in different areas of the brain, it brings a favorable change to the motor symptoms to the magnitude that none of the medications have been able to, but the effect on cognition of the patients is still unknown. We did a comprehensive search through PubMed and Cochrane databases and conducted a systematic review by following the PRISMA guidelines. Inclusion criteria were studies conducted only in PD patients, after the year 2008. The studies published in languages other than English were excluded. Thirteen studies, including randomized and non-randomized controlled trials, observational studies, and meta-analysis, were analyzed in detail. The results showed a declining trend in verbal fluency and attention domains of cognition, while other functions remained unchanged. The decline was significant but not enough to impact the quality index in patients. DBS is associated with worse performance in verbal fluency and attention, and there is a further need for studies focusing on these domains with long-term follow-up. The overall cognitive profile was not affected significantly.