BackgroundDeep brain stimulation (DBS) is an established therapy for advanced Parkinson’s disease (PD). However, its impact on neuropsychological outcomes remains controversial and lacks systematic integration. This study aims to systematically evaluate the effects of DBS on cognitive and neuropsychiatric symptoms in PD patients through a meta-analysis of randomized controlled trials (RCTs).MethodsA systematic search was conducted in databases including PubMed, Embase, the Cochrane Library, and Web of Science for RCTs comparing DBS with best medical treatment (BMT). Cognitive outcome measures included Verbal Fluency test, the Stroop Color and Word Test, the Wisconsin Card Sorting Test (WCST), and the Mattis Dementia Rating Scale (MDRS). Neuropsychiatric outcome measures encompassed Part I of the Unified Parkinson’s Disease Rating Scale (UPDRS-I), the Beck Depression Inventory-II (BDI-II), the Montgomery-Asberg Depression Rating Scale (MADRS), as well as the Brief Anxiety Scale (BAS) and Beck Anxiety Inventory (BAI). Risk of bias was assessed using the Cochrane RoB 2 tool, and effect sizes were pooled using RevMan 5.4 software.ResultsA total of 10 randomized controlled trials involving 1,274 patients were included. Meta-analysis results indicated that, compared to BMT, patients undergoing DBS showed a more significant decline in performance on Verbal Fluency test and the Stroop Color-Word Interference Test. No statistically significant differences were observed between the two groups regarding overall cognitive function, cognitive flexibility, depressive symptoms, anxiety symptoms, or overall neuropsychiatric symptoms. Sensitivity analysis suggested that the effect of DBS on anxiety symptoms may vary across studies, indicating a potential beneficial role of DBS in this domain.ConclusionDBS treatment did not lead to widespread cognitive or neuropsychiatric decline in patients with PD based on group-level analyses. However, within the assessed cognitive domains, mild, specific negative effects were observed on higher-order executive functions. Clinical decision-making should incorporate individualized neuropsychological assessment and monitoring to balance the benefits of motor symptom improvement with potential cognitive risks.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/recorddashboard, this meta-analysis has been registered on the PROSPERO platform (Registration number: CRD420251273115).