Insights into the blood–brain barrier in mental health disorders: from experimental models to clinical findings

The blood-brain barrier (BBB) is recognized as a protective interface that maintains neural homeostasis. Specifically, it blocks the entrance of potentially harmful agents and controls the molecular traffic between the circulatory system and the central nervous system. Emerging evidence from preclinical models and clinical studies indicates that alterations in the BBB's permeability and transport processes contribute to the pathophysiology of several mental illnesses, including depression, anxiety, bipolar disorder, and schizophrenia. Specifically, we examine whether BBB disruption contributes to the onset and progression of psychiatric conditions, whether psychiatric pathology itself promotes barrier dysfunction, or whether these processes interact in a self-perpetuating cycle. By providing a translational perspective that bridges experimental models and clinical observations, this review provides a comprehensive and dynamic perspective on its role in mental health. Understanding these mechanisms may open new avenues for therapeutic strategies focused on preserving or restoring barrier integrity as a means of preventing or mitigating psychiatric disorders.