Protocol for mixed methods study exploring the gut-brain health among South Indian population.

INTRODUCTIONDepressive disorders are a major cause of disability worldwide and are frequently accompanied by somatic manifestations, particularly gastrointestinal (GI) symptoms. Emerging evidence implicates the gut–brain axis in the pathophysiology of depression, yet domain-wise characterisation of GI symptoms across stratified depression severity remains underexplored in the Indian context. Variations in diet, microbiota composition and cultural patterns of somatisation further necessitate region-specific evidence. This study aims to perform domain-wise analysis of GI symptoms across varying levels of depression severity among adult psychiatric outpatients.

METHODS/DESIGNThis hospital-based mixed-method study will be conducted in the psychiatry outpatient department of a tertiary care centre in South India. Approximately 300 adults (18–60 years) with newly diagnosed depression and Hamilton Depression Rating Scale-17 (HAMD-17) score ≥8 will be recruited. GI symptoms will be assessed using the GI Symptom Rating Scale (GSRS) across five domains: reflux, abdominal pain, indigestion, diarrhoea and constipation. Sociodemographic and clinical variables including body mass index, lifestyle factors, dietary habits and sleep duration will be recorded. Primary analysis will assess the correlation between total GSRS and HAMD-17 scores, while secondary analyses will compare domain-wise GI symptoms across depression severity groups and identify independent predictors using multivariable regression. A qualitative subsample will undergo semi-structured interviews to explore perceived gut–brain interactions. Statistical analysis will be performed using SPSS and R, with p<0.05 considered significant.

ETHICS AND DISSEMINATIONThis study has been approved by the Institutional Ethics Committee (IEC) of KLE College of Pharmacy, Bengaluru. Study results will be disseminated through national and international meetings and peer-reviewed publications (IEC reference number: KLECOPBLR/2025-26).