Bipolar Disorder might be caused by a physical overgrowth of the brain's 'plumbing' system.
April 14, 2026
Original Paper
Dysregulation of Hippo Signaling Pathway as a Convergent Mechanism Underlying Choroid Plexus Defects in Bipolar Disorder
bioRxiv · 10.64898/2026.04.10.717745
The Takeaway
Research traditionally focused on brain chemicals, but this study links the disorder to an enlarged choroid plexus. This structure controls brain fluid, suggesting the illness is a structural developmental defect rather than just a mood imbalance.
From the abstract
Bipolar disorder (BD) is a prevalent and highly heritable psychiatric condition. Developmental mechanisms are implicated but the specific molecular origins remain unclear. The choroid plexus (ChP), which regulates cerebrospinal fluid (CSF) and brain homeostasis, has been implicated in BD, but its role is poorly understood. Here, we identify aberrant expansion of ChP in human cortical (hCOs) and ChP organoids (hChPOs) derived from, and in vivo structural magnetic resonance imaging (sMRI) scans of