Adaptive versus conventional deep brain stimulation for bradykinesia in Parkinson's disease: a comparative effectiveness analysis.

BACKGROUND: Conventional deep brain stimulation (cDBS) is an established treatment for motor complications in Parkinson's disease, whereas adaptive deep brain stimulation (aDBS) adjusts stimulation in response to physiological or behavioral feedback. This review examines whether aDBS provides clinically meaningful advantages over cDBS for bradykinesia and akinesia, while also considering stimulation delivery, adverse effects, and non-motor outcomes. METHODS: A structured narrative review of relevant literature was conducted using PubMed/MEDLINE, Scopus, Web of Science, citation tracking, and focused searches. Evidence was grouped by comparison paradigm, adaptive control strategy, and outcome. RESULTS: The clinical evidence consists mainly of proof-of-concept investigations, brief crossover studies, feasibility studies, and small cohorts. Selected short-term comparisons generally did not detect a motor-outcome difference from cDBS, but most were underpowered for equivalence or non-inferiority. Several beta-guided paradigms reduced stimulation time or energy delivery, but this was not universal and cannot be assumed to indicate better symptom control, fewer adverse effects, or longer device life. No adequately powered large-scale randomized trial has demonstrated the clinical superiority of aDBS over optimized cDBS. Evidence concerning gait, speech, cognition, mood, and other neuropsychiatric outcomes remains limited. Interpretation is further restricted by differences in patient selection, stimulation targets, biomarkers, adaptive algorithms, medication states, outcome measures, follow-up, and timing after implantation. CONCLUSIONS: Adaptive DBS is technically feasible and offers a promising approach to individualized stimulation, but its comparative clinical value remains uncertain. Larger randomized trials with standardized outcomes and long-term follow-up are needed before superiority over conventional stimulation can be established.