negative regulation of vascular permeability regulation of blood-brain barrier permeability negative regulation of blood-brain barrier permeability Any process that decreases blood-brain barrier permeability, the quality of the blood-brain barrier that allows for a controlled passage of substances (e.g. macromolecules, small molecules, ions) into and out of the brain. downregulation of BBB permeability down-regulation of blood-brain barrier permeability 2016-10-26T13:18:25Z biological_process inhibition of maintenance of permeability of BBB als inhibition of maintenance of permeability of blood-brain barrier downregulation of blood/brain barrier permeability down-regulation of blood/brain barrier permeability downregulation of blood-brain barrier permeability negative regulation of blood/brain barrier permeability negative regulation of BBB permeability down-regulation of BBB permeability GO:1905604