Differential diagnosis of bipolar II disorder and major depressive disorder: Integrating multimodal approaches to overcome clinical challenges.

Clinically differentiating bipolar II disorder (BD-II) from major depressive disorder (MDD) remains a significant challenge in modern psychiatry. These two conditions share substantial clinical symptomatology, making accurate diagnosis difficult in routine clinical practice. Misdiagnosis may lead to inappropriate treatment strategies, increased psychological and physical burdens, reduced quality of life, and impaired social functioning. Genetic overlap may partially explain the clinical similarities between MDD and BD-II, and biomarkers along with neuroimaging techniques are receiving increasing attention as tools to aid in diagnosis. For example, electroencephalography has been shown to effectively distinguish between unipolar depression and bipolar depression; serum levels of glycogen synthase kinase-3 have also been investigated as a potential tool for differentiating between the two disorders. A comprehensive assessment integrating clinical characteristics, genetic basis research, and multimodal evaluations using neuroimaging and biomarkers through a multidisciplinary approach will help enhance clinicians' ability to distinguish between MDD and BD-II. By improving diagnostic accuracy, more personalized and effective treatment strategies can be developed, ultimately improving patients' health outcomes and quality of life.