A number of possible mechanisms have been explored, but there is still no safe, reliable and universally applicable method for delivering drugs across the blood-brain barrier (BBB) to treat central nervous system diseases. Now researchers have succeeded in tuning the effect of methamphetamine, a cause of BBB breakdown, enabling brain penetration of small molecules and therapeutic proteins, without damaging the epithelial cells that constitute the main physical element of the barrier.

This could be a make-or-break week for Biogen Inc., with the U.S. Centers for Medicare & Medicaid Services (CMS) expected to announce a draft coverage decision for the company’s Alzheimer’s drug, Aduhelm.