Did you know there are 400 miles of blood vessels in the human brain? Did you know there is also a complex blood–brain barrier which protects us, but also can block drug and innovative gene therapies. Rust and colleagues discuss both sides of the 'wall' that protects our brain in the journal Brain. Key Points: - What is the blood-brain barrier (BBB)? - The authors remind us that it is a vascular structure. - The barrier is designed to protect us from toxins and pathogens circulating in the blood. - Unfortunately, the barrier can also block drugs and therapies designed to treat disorders of the brain. My take: The brain is a hungry organ. The brain's blood vessels spans 400 miles. Experts think that every one of your ~86 billion neurons has its own capillary w/in 25 µm. There is a complex vascular barrier designed to exchange ions, molecules and cells. It is important for us to remember that the barrier is actually different across our brain regions. As we age, the barrier changes. If we hit our head, the barrier changes. If we get a degenerative disease like Parkinson's or Alzheimer's, the barrier changes. We are entering an era of nanomedicine and of uncaging drugs designed to slip by this barrier. Gene and other therapies will depend on beating the barrier. Focused ultrasound and other techniques have been under development for improving delivery of treatments. So for those designing the next generation of brain therapies remember – ad augusta per angusta – to glory through narrow spaces. academic.oup.com/brain/advan… #parkinson @Brain1878