The role of the blood brain barrier in neurodegenerative disorders and their treatment.

Neurodegenerative disorders represent a major medical challenge that is set to increase substantially in the decades ahead with the massive increase in the number of people in the world aged 65 or more. Neuroprotective therapeutics have the potential to play a key role in helping manage this growing global burden of long-term neurological care. However, neuropharmaceutical research is associated with significant challenges including: (1) the complexity of the brain (the cause of the majority of neurodegenerative disorders remains unknown); (2) the liability of central nervous system (CNS) drugs to cause CNS side effects (which limits their use); and (3) the requirement of neuropharmaceuticals to cross the blood-brain barrier (BBB). The BBB itself also plays a key role in most (if not all) neurodegenerative disorders since BBB dysfunction inevitably leads to inflammatory change including the movement of immune cells and immune mediators into the brain, which then contribute to the process of neurodegeneration. This review focuses on the role of the BBB in both neurodegenerative disorders and neuropharmaceutical research.