Biomarkers of bipolar disorder in omics and neuroimaging

Bipolar disorder (BD) affects 1% of the global population. BD is a group of chronic psychiatric disorders characterized by recurrent manic or hypomanic episodes that may alternate with depressive episodes. Given the current diagnostic modalities, accurately diagnosing BD, particularly distinguishing it from unipolar depression (UD), is challenging. Biomarkers have emerged as potent instruments for establishing objective diagnostic criteria for BD, and their identification, which reflects the pathophysiological processes of BD, can facilitate the precise diagnosis of the disorder. In this review, the search terms "BD" and "diagnosis" or "biomarker" were used as the key search syntax. In total, 110 studies were included. This review systematically examines the research in the field and summarizes current studies on biomarkers of BD in omics and neuroimaging. We hope that this review will benefit research aimed at establishing objective diagnostic criteria for BD and developing novel therapeutic interventions.