Noninvasive Neuromodulation for Cognitive Dysfunction in Parkinson’s Disease: A Scoping Review

Background/Objectives: Parkinson’s disease with mild cognitive impairment (PD-MCI) represents a critical early-intervention window before progression to dementia. However, non-pharmacological cognitive treatment options are poorly characterized. This scoping review maps noninvasive neuromodulation interventions evaluated for cognitive outcomes in PD-MCI and in broader PD populations. Methods: Following JBI scoping review methodology and PRISMA-ScR guidelines, PubMed, Scopus and Google Scholar were searched for empirical studies published between May 2006 and September 2026 that applied noninvasive neuromodulation in adults with PD-MCI or broader PD populations and reported cognitive outcomes. Studies were classified as direct PD-MCI evidence (diagnosis confirmed using Movement Disorder Society Task Force criteria) or adjacent PD cognitive evidence. Results: Eleven studies across five modalities were included: tDCS (n = 6), iTBS (n = 2), TPS (n = 1), tcVNS (n = 1), and taVNS (n = 1). Only four studies (two tDCS and two iTBS) enrolled participants with confirmed PD-MCI; the remaining seven enrolled broader PD populations. Favorable findings came mainly from small samples, and protocols, outcome measures, and populations were heterogeneous. Conclusions: Evidence specific to PD-MCI is limited and mixed. Several studies pairing stimulation with cognitive training reported favorable outcomes, but this pattern was inconsistent and does not establish superiority over stimulation alone. No VNS trial enrolled participants with confirmed PD-MCI or used cognition as a primary endpoint.