Exploring the impact of multiple session a-tDCS of right sensory cortex on sensitivity of urge to cough

Objective: To explore the effects of multiple anodal transcranial direct current stimulation (a-tDCS) sessions on the right primary somatosensory cortex (rS1) in modulating the sensitivity of the urge to cough. Study Design: A double-blind, randomized, sham-controlled trial. Participants: Adults aged 18-60 years experiencing heightened sensitivity to the urge to cough. Exclusion criteria: individuals with neurological disorders, skin conditions affecting electrode placement, or contraindications to tDCS. Sample Size: Based on preliminary data and power analysis to detect a significant difference with an alpha of 0.05 and power of 0.8. Intervention: Experimental Group: Daily sessions of a-tDCS targeting the rS1 (2 mA for 20 minutes) for a total of 5 consecutive days. Control Group: Sham stimulation with the same parameters but with the current turned off after 30 seconds. Outcome Measures: Primary Outcome: Change in cough reflex sensitivity measured by capsaicin cough challenge test, pre- and post-intervention. Secondary Outcomes: Subjective urge-to-cough intensity ratings on a visual analogue scale (VAS) and cough-related quality of life (CQLQ) scores. Procedure: Baseline assessment including cough reflex sensitivity test, VAS for urge to cough, and CQLQ. Randomization of participants into experimental or control group. Administration of a-tDCS or sham stimulation according to group assignment. Daily post-session assessments of subjective urge-to-cough intensity. Final assessment of cough reflex sensitivity, VAS, and CQLQ after the last session. Data Analysis: Comparison of pre- and post-intervention changes in cough reflex sensitivity, VAS scores, and CQLQ between the experimental and control groups using ANCOVA, adjusting for baseline values. Intention-to-treat analysis to handle missing data. Ethics: The study will be conducted in accordance with ethical guidelines, with approval from the Institutional Review Board. Informed consent will be obtained from all participants. Expected Outcomes: This study aims to determine if repeated sessions of a-tDCS can modulate the sensitivity of the urge to cough, potentially offering a novel therapeutic approach for managing conditions characterized by heightened cough sensitivity.