Plasma Phosphoethanolamine Levels as a Biomarker for Monitoring Major Depressive Disorder

Abstract This study is the first to identify a promising candidate monitoring biomarker for major depressive disorder (MDD), plasma phosphoethanolamine (PEA) concentrations. A naturalistic observational study in clinical psychiatry was conducted with Japanese subjects between 2011 and 2020. Out of the 576 patients, 295 had depressive disorders, 264 had psychiatric disorders other than depression, and 17 had physical disorders without psychiatric disorders. In 170 patients with MDD only, in whom remission was easily identified, plasma PEA levels were measured at two or more time points. These levels dropped significantly in depressive episodes, increased as remission approached and were significantly higher in remission. Psychiatric diagnosis alone explained 38% of the variance in plasma PEA concentrations. Receiver operating characteristic (ROC) curve analysis also showed sufficient discriminatory power to detect depression, with an area under the curve (AUC) of 0.84 (95% confidence interval (CI): 0.80-0.87). Further researches are needed.