Prevention of postoperative delirium with transcranial alternating current stimulation: study protocol for a randomised controlled trial.

INTRODUCTION: Postoperative delirium (POD), a common and serious neurological complication in elderly patients following non-cardiac surgery, is associated with increased risk of complications, cognitive decline, prolonged hospital stay, and higher mortality. Current prevention strategies are limited and unsatisfactory. As a non-invasive neuromodulation technique that modulates cortical oscillations and may improve age-related cognitive impairment, transcranial alternating current stimulation (tACS) emerges as a promising intervention for POD. METHODS AND ANALYSIS: This two-stage, randomized, double-blind, sham-controlled trial will enroll elderly patients aged ≥65 years undergoing non-cardiac surgery. In Stage 1, In Stage 1, 268 patients will be randomized to physiologically matched θ-tACS, α-tACS, γ-tACS (all 2 mA) or sham stimulation to identify the optimal frequency-plus-montage tACS protocol for POD prevention. In Stage 2, another 268 patients will receive optimal-frequency-plus-montage tACS at 1 mA, 1.5 mA, 2 mA or sham stimulation to determine the optimal intensity. Primary outcome is POD incidence (3D-CAM). Secondary outcomes include pain, cognition, sleep, anxiety and depression. Electroencephalography and blood biomarkers will be assessed. Data will be analyzed using SPSS 26.0. This study aims to develop an optimal tACS protocol for POD prevention in elderly surgical patients. ETHICS AND DISSEMINATION: This study was approved by the Ethics Committee of Shifang people's hospital (202634). The results of the trial will be presented at national and international meetings relevant to the topic area and submitted to international peer-reviewed journals. CLINICAL TRIAL REGISTRATION: https://www.chictr.org.cn/showproj.html?proj=317411, identifier ChiCTR2600123512.