Irritable bowel syndrome (IBS) is a common disorder of gut-brain interaction involving recurrent abdominal pain and altered bowel habits. Conventional treatments are often unsatisfactory. This trial hypothesizes that a single low dose of esketamine, which has rapid antidepressant effects, may alleviate IBS symptoms. The study is a single-centre, randomized, double-blind, placebo-controlled trial enrolling 92 patients per group across three severity levels. The primary outcome is the IBS Severity Scoring System measured at baseline and up to six weeks after colonoscopy. Secondary outcomes include quality of life, stool form, anxiety, depression, and somatic symptoms. The protocol is approved and registered.
Nitrous oxide inhalation produced time-dependent increases in brain entropy, particularly in the frontal lobe, among patients with treatment-resistant depression. These entropy changes, measured via multivariate multiscale entropy analysis of resting-state EEG, correlated with symptom severity and treatment efficacy, suggesting frontal region temporal-spatial brain entropy may serve as a biomarker for treatment-resistant depression and its treatment outcomes.