Early-diagnosis of major depressive disorder: From biomarkers to point-of-care testing

Major depressive disorder, or depression, is one of the most common mental illnesses worldwide. This prevalent mental disorder can trigger numerous concurrent problems, including extreme suicidal tendencies in serious cases, yet the current clinical diagnosis of depression awaits finer advances. The current clinical diagnosis of depression by psychological tests and clinical interviews sometimes leads to misdiagnosis and mistreatment. Therefore, screening high-quality depression biomarkers and the development of accurate and convenient early diagnosis methods become crucial. This review summarizes a variety of potential biomarkers for the diagnosis of depression, focuses on the advantages and disadvantages of each biomarker in the early diagnosis, and discusses the feasibility of applying these biomarkers for diagnosis of depression. Meanwhile, disposable devices and wearable devices for detecting these biomarkers are introduced and analyzed, and future perspectives for early diagnosis of depression especially in a point-of-care scenario are proposed.