Welcome to Quantum Magazine's podcast.

Each episode, we bring you stories about developments in science and mathematics.

I'm Susan Vallett.

If you've ever been drunk, high, or even drowsy from allergy medication you've experienced what

happens when some molecules defeat the defense system called the blood brain

barrier and make it into the brain this barrier is an amazing multi-tiered

system of protection that's's next. Quantum Magazine is an editorially independent online publication supported by the

Simon's Foundation to enhance public understanding of science.

Hundreds of miles of capillaries wind through the brain.

The blood-brain barrier is embedded in the walls of those capillaries, keeping most molecules

in the blood from ever-reaching sensitive neurons.

Basically, the skull protects the brain from external physical threats, and the blood-brain barrier protects

it from chemical and pathogenic ones. The barrier is a fantastic feat of evolution, but it's very

much a nuisance for drug developers who've spent decades trying to selectively overcome it to

deliver therapeutics to the brain. Biomedical researchers want to understand the

barrier better because its failures seem to be the key to some diseases and because manipulating

the barrier could help improve the treatment of certain conditions. Elizabeth Ray is a research

biologist at the University of Washington Medicine Memory and Brain Wellness Center.

I think we're definitely still facing challenges and getting substrates and therapeutics across the

blood-brain barrier, but I think we've learned a lot over the last decade.

Like the rest of the body, the brain needs circulating blood to deliver essential

nutrients and oxygen and to carry away waste. But blood chemistry constantly fluctuates, and brain

...