Biomarkers for mood disorders: A scoping review of research from India

Mood disorders pose significant diagnostic and therapeutic challenges. While biomarkers can improve diagnostic accuracy and personalize treatment, their geographic validation remains limited.

This scoping review synthesizes evidence from biomarker studies on depressive disorder (MDD) and bipolar disorder (BD) in India to map methodological trends and identify research gaps.

Studies conducted in India evaluating biomarkers in individuals with MDD or BD diagnosed via ICD-10 or DSM-IV/DSM-5 criteria were eligible. A systematic literature search was executed across PubMed and Scopus for studies published between January 2000 and December 2024. Screening was done in Covidence. Data charting was done independently by three reviewers. Newcastle-Ottawa Scale and AXIS tools were used for quality assessment.

Fifty-six studies were included. In MDD, elevated levels of interleukin-6 and cortisol were consistently reported. Inflammatory markers decreased, while brain-derived neurotrophic factor levels increased following treatment. C-reactive protein, neutrophil-to-lymphocyte ratio, malondialdehyde, and cortisol levels were associated with depression severity. Neuroimaging and electroencephalography studies demonstrated fronto-limbic circuit involvement in both MDD and BD. In BD, cognitive studies consistently reported impairments in executive function, learning, and memory. Additional novel findings included abnormalities in retinal arteriolar tortuosity and eye movement.

Biomarker findings from Indian studies largely align with evidence reported in Western Population. Methodological differences and clinical heterogeneity limit interpretation and comparability of findings. Future research should emphasize standardized methodologies, larger multicentric cohorts, and multimodal biomarker approaches as combining biological markers may offer greater diagnostic, predictive, and prognostic utility than individual biomarkers.