Blood biomarkers and treatment response in major depression.

INTRODUCTION: Millions of people worldwide suffer from depression, but despite advances in pharmacological therapies, many patients do not experience symptomatic remission or treatment response, even after treatments with several medications. As such, there is an urgent need to identify biomarkers that can not only predict the treatment response but also allow a rational selection of optimal therapy for each patient. Areas covered: This review examines the recent findings, coming from different 'omic sciences,' in human blood-based biomarkers associated with antidepressant treatment response with particular attention on genetic/epigenetic and biochemical biomarkers. Specific emphasis will be placed on key molecules related to neuroplasticity and inflammation because of their involvement in the pathophysiology of depression and antidepressant response. Expert commentary: Biomarker identification is still an ongoing work. Indeed, to date, no biomarkers have sufficiently proven specificity, sensitivity, and reproducibility to be used in the clinical setting. However, 'omic' approaches hold great promise in identifying multiple features for predicting antidepressant response, making a personalized treatment strategy possible for each patient, and thereby assist with quick and efficacious responsiveness. It is thus necessary that future studies take an integrative approach that includes clinical assessment, environment influences, and molecular and biological biomarkers.