[Integration of basic and clinical researches to develop the biomarker of ‍depression].

Because of absence of the objective biomarker for major depressive disorder (MDD) or depressive state, psychiatrists depend on subjective examinations in order to properly diagnose their patients. We recently identified the candidates of the objective biomarker of depressive state of late-onset MDD by profiling gene expressions in white blood cells of patients and model mice. We also investigated whether gene expression profiling of white blood cells was useful to elucidate the biological alterations in the brain. Furthermore, we newly developed transgenic mice which will be useful for elucidating the neurological mechanisms of emotional abnormalities in psychiatric disorder. In this review, I introduce our recent research to help for understanding of translational approaches to develop the biomarker of depression.