AQP4 and schizophrenia: A decrease in Kw may predominantly reflect impaired water transport across the neurovascular unit, which can signify early microscopic changes in the blood–brain barrier and is related to the function of aquaporin-4 (AQP-4) [17].These studies contribute to our understanding of the alterations in blood–brain barrier permeability in schizophrenia patients and lay the foundation for further investigations into its role in the pathogenesis.