The present invention relates to a method of increasing blood brain barrier permeability in a subject. This method involves selecting a subject who would benefit from increased blood brain barrier permeability and subjecting the selected subject to a treatment. That treatment increases adenosine level and/or bioavailability, modulates adenosine receptors, and/or increases CD73 level and/or activity under conditions effective to increase blood brain barrier permeability in the subject. Methods of decreasing blood brain barrier permeability in a subject, treatment of a subject for a disorder or condition of the central nervous system, and screening compounds effective in increasing blood brain barrier permeability, as well as pharmaceutical agents are also disclosed.