Enzymatic biomarkers of oxidative stress in patients with depressive disorders. A systematic review

Oxidative stress (OS) results from the imbalance between the production of reactive oxygen species and the body’s antioxidant mechanisms and is associated with various diseases, including depression. Antioxidants protect cells by neutralizing free radicals and include enzymatic components such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione S-transferase (GST). The concentration of these biomarkers can quantify OS. This research aimed to gather available information published in the last ten years about the concentration of enzymatic OS biomarkers in samples from patients with depressive disorders. Method: A systematic review was conducted following the PRISMA guidelines, including original scientific articles that evaluated enzymatic OS biomarkers in participants with depressive disorders, using the keywords and boolean operators “superoxide dismutase” OR “catalase” OR “glutathione” AND “depress*” in the databases PubMed, SAGE Journals, DOAJ, Scielo, Dialnet, and Redalyc. Results: The initial search showed 614 results, with only 28 articles meeting the selection criteria. It was observed that all evaluated oxidative stress enzymatic markers showed a significant increase or decrease in patients with depressive disorders, due to a wide variability in the depressive disorders studied, the type of biological sample analyzed, and the techniques used. Conclusion: There is evidence of the relationship between enzymatic OS biomarkers and depressive disorders, but additional studies are needed to clarify the nature of this relationship, particularly considering the different types of depressive disorders.