Cognitive change after subthalamic deep brain stimulation for Parkinson’s disease – a systematic meta-regressive analysis

Parkinson’s disease is a progressive neurodegenerative disorder characterised by motor dysfunction and cognitive disruption among other non-motor symptoms. No cure for Parkinson’s disease exists. Deep Brain Stimulation of the Subthalamic Nucleus (DBS STN) has been utilised for control of motor symptoms. However, cognitive deficits are commonly reported after implantation, and few exhaustive analyses exist to quantify and explain them. Our systematic review, meta-analyses, and metaregressions examine within-subjects change across thirteen cognitive domains, from 70 studies and 3000 participants at baseline measurements. Improvement was not observed in any domain, but substantial decline at 12 months was observed for phonemic and categorical fluency, which appeared to stabilise 24 to 36 months. Meta-regression suggests that few study characteristics are predictive of longitudinal outcomes, and we propose that further research into specific surgical or placement effects is necessary to mitigate short-term cognitive change after DBS STN in Parkinson’s disease. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement All authors are staff supported by their respective institutions and organisations and have acted on this review through in-kind support. DRS is a current investigator with the NHMRC Medical Research Future Fund (APP1200214). MB is supported by a NHMRC Senior Principal Research Fellowship (APP1156072). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes No additional data available as all data are from published works.