Exosome for Early Diagnosis of Bipolar Affective Disorder

Objectives: Bipolar disorder (BD) is a chronic and recurrent mental illness characterized by depressive episodes and manic or hypomanic episodes, leading to severe functional impairment and cognitive damage. Unfortunately, it is difficult to accurately distinguish between major depressive disorder (MDD) and BD in the early stages, resulting in misdiagnosis and mistreatment. According to statistics, only 20% of BD patients with initial depressive symptoms receive a correct diagnosis within the first year of onset, with an average delay of 5-10 years from onset to final diagnosis. BD patients are often treated with antidepressant medication systematically due to being diagnosed with MDD, affecting the disease course and clinical outcomes. The current study aims to explore the role of peripheral exosomes as biomarker to distinguish BD from MDD in early stage. Methods: The study includes two stages: the first stage is a case-control study, comparing the concentrations of peripheral blood exosome metabolites (microRNA and related proteins) among three groups (BD patients, MDD patients, and healthy controls, n=30 per group) to identify target microRNA and proteins with statistically significant differences. The "latent class analysis (LCA)" on target microRNA and protein will be performed on all samples to observe whether it can effectively distinguish bipolar disorder, depressive episode, and healthy participants. Then, based on the LCA analysis results, "receiver operating characteristic (ROC)" analysis will be conducted to further determine the optimal concentration cut-off value for each indicator and ultimately determine the target biomarkers. The second stage is a clinical validation study in which subjects, who come from an on-going trial and initiated with a depressive episode and were followed up for five years at least, are divided into two groups (MDD group and BD group, n=20 respectively) based on whether they have hypomanic/manic episodes currently or previo