Underlying biological mechanisms of emotion dysregulation in Bipolar Disorder

Buse Beril Durdurak ^1* Isabel Morales Muñoz ¹ Angharad N de Cates ^1,2,3 Chantelle E Wiseman ¹ Matthew R Broome ^1,4 Steven Marwaha ^1,5

• ¹ University of Birmingham, Birmingham, United Kingdom
• ² University of Oxford, Oxford, England, United Kingdom
• ³ Coventry and Warwickshire Partnership NHS Trust, Coventry, United Kingdom
• ⁴ Birmingham Women's NHS Foundation Trust, Birmingham, United Kingdom
• ⁵ Birmingham and Solihull Mental Health NHS Foundation Trust, Birmingham, United Kingdom

Difficulties with emotion regulation (ER) are a key feature of Bipolar Disorder (BD) contributing to poor psychosocial and functional outcomes. Abnormalities within emotion processing and regulation thus provide key targets for treatment strategies and have implications for treatment response. Although biological mechanisms and ER are typically studied independently, emergent findings in BD research suggest that there are important ties between biological mechanisms and the disturbances in ER observed in BD. Therefore, in this narrative review, we provide an overview of the literature on biological mechanisms underlying emotional dysregulation in BD including genetic and epigenetic mechanisms, neuroimaging findings, inflammation, hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neuroplasticity and brainderived neurotrophic factor (BDNF), and circadian rhythm disturbances. Finally, we discuss the clinical relevance of the findings and provide future directions for research. The continued exploration of underlying biological mechanisms in ED in BD may not only elucidate fundamental neurobiological mechanisms but also foster advancements in current treatment strategies and the development of novel targeted treatments.