effect of deep brain stimulation on parkinson disease dementia: a systematic review and meta-analysis

Introduction: patients in the early stages of parkinson disease (pd) may have subtle cognitive deficits, while overt cognitive deficits are usually manifestations of late-stage pd. there is still a debate on the outcome of deep brain stimulation (dbs) on the cognitive function of pd patients. this study aimed to investigate the effect of subthalamic nucleus (stn)-dbs on the dementia of pd patients after surgery compared to medical therapy and other procedures. methods: we searched pubmed, scopus, cochrane library, and web of science database on october 2020, with keywords: “deep brain stimulation,” “parkinson disease,” “dementia,” and “memory.” reviews, abstracts, case presentations, and letters were excluded. results: in total, 491 studies were screened after removing the duplicates. the screening results yielded 81 articles to be screened for eligibility. finally, 6 studies were included in this meta-analysis for synthesis. overall, 800 patients were included in this meta-analysis, using the mattis dementia rating scale (mdrs) and descriptive data from the articles extracted to assess global dementia. conclusion: our results suggest that the stn-dbs group showed a larger cognitive decline than the patients receiving the best medical treatment (bmt). however, comparing stn-dbs with globus pallidus interna stimulation and pallidotomy could not demonstrate a significant statistical effect on the global dementia of patients. more long-term studies with larger sample sizes are needed to validate current findings.