The potential for metabolomics in the study and treatment of major depressive disorder and related conditions.

INTRODUCTION: Major depressive disorder (MDD) is a common mental disease, associated with a debilitating condition and high prevalence. Although the underlying mechanism of MDD remains to be elucidated, several factors, including social, biological, and psychological factors, have been associated with disease pathogenesis. Metabolomics can provide new insights into the prognosis, treatment response, and related biomarkers associated with MDD at the metabolic level. AREAS COVERED: In this review, we investigated the metabolic changes identified in different bio-samples from animal models of depression and MDD patients. Moreover, we summarized the metabolites associated with antidepressant treatment responses. Keywords used for the literature searches were 'depression' [MeSH] and 'metabolomics' [MeSH], in PubMed. EXPERT OPINION: Metabolomic evidence in humans has indicated that amino acid metabolism, energy metabolism, and lipid metabolism are the primary metabolic alterations that are observed in the etiology of MDD, and animal models serve as an important theoretical reference in this field. Metabolomics has shed new light on the pathogenic mechanisms and treatment responses during MDD; however, study results are not always consistent. The application of metabolomic results to clinical practice will require the integration of different biological samples and other omics studies, as well as the clinical validation of study findings.