Psychiatric diseases are clearly different from other physical diseases in that the pathophysiology of the diseases is still unknown. Therefore, except for dementia and epilepsy, there are no objective biomarkers for diagnosis. A set of examinations is performed to rule out physical diseases, but there is no diagnostic evaluation tool for depression that corresponds to, for example, blood pressure, blood glucose, x-rays, or echocardiography.　The reasons for the poor understanding of the pathophysiology of psychiatric disorders include the difficulty in sampling the human brain and CNS, and there are no pure animal models for depression or bipolar disorder because the human and animal brains are very different. Another barrier regarding drug treatment is that high-molecular-weight drugs cannot reach the central nervous system due to the blood-brain barrier.
In this lecture, from the standpoint of being involved in several clinical trials as a medical expert, I would like to introduce some of the mood disorder-related drugs currently under clinical trial in Japan, despite the above limitations. I would like to prospect to solve the issue of psychiatric disorders described above from genomics and PGx and new technologies that are expected to overcome the barriers of psychiatry.