Decoding the Biology of Bipolar Disorder: An Update on Recent Findings in Genetics, Imaging, and Immunology

Bipolar disorder is one of the most common major psychiatric conditions. It is highly recurrent and is associated with significant morbidity and mortality. Because of lack of understanding of its biological underpinning, both diagnosis and treatment of bipolar disorder can be challenging, leading to less than optimal outcome. In recent years, there has been extensive and active research exploring the biological basis of bipolar disorder. Although much work remains, new findings from recent studies are shedding light on important aspects of the pathogenesis of bipolar disorder, which will help clinicians to detect bipolar disorder early and ultimately will translate into novel and personalized treatment for bipolar disorder. This review summarizes recent discoveries in the genetics, imaging, and immunology of bipolar disorder. The research findings overall suggest that bipolar disorder is associated with many genes, each with small effects that cumulatively contribute to its pathogenesis. Despite strong genetic determinants, environment may also significantly affect the pathophysiology of bipolar disorder. Biologically and clinically, lithium responders may constitute a distinct subgroup of bipolar disorder. Imaging studies demonstrated that bipolar disorder has subtle structural and functional changes that may serve as mood state as well as illness trait markers for bipolar disorder. Finally, an altered inflammatory profile and brain-derived neurotrophic factor appears to be implicated in bipolar disorder.