Protein Biomarkers in Major Depressive Disorder: An Update

Major depressive disorder (MDD) is common. Despite numerous available treatments, many individuals fail to improve clinically. Diagnosis of MDD continues to be commonly accomplished via behavioral rather than biological methods. Biomarkers may provide objective diagnosis of MDD, and could include measurements of genes, proteins, and patterns of brain activity. Proteomic analysis and validation of biomarkers is less explored than other areas of biomarker research in MDD. Mass spectrometry (MS) is a comprehensive, unbiased means of proteomic analysis, which can be complemented by directed protein measurements, such as Western Blotting. Prior studies have focused on MS analysis of several human biomaterials in MDD, including human post-mortem brain, cerebrospinal fluid (CSF), blood components, and urine. Further studies utilizing MS and proteomic analysis in MDD may help solidify and establish biomarkers for use in diagnosis, identification of new treatment targets, and understanding of the disorder. A biomarker or a biomarker signature that facilitates a convenient and inexpensive predictive test for depression treatment response is highly desirable.