Foundations
The brain's chemical messengers and the barrier that guards it — the basis of every CNS drug.
The Brain's Chemical Messengers: Excitatory vs Inhibitory
Your brain is a storm of eighty billion neurons, every one constantly shouting 'go!' or whispering 'stop.' Health is the balance between those two forces — and nearly every drug that touches the mind works by tipping it. Tip too far toward 'go' and you get a seizure; too far toward 'stop' and you get coma. Learn the handful of chemicals that run this balance, and the whole of brain pharmacology opens up.
The Blood–Brain Barrier: How Drugs Reach the Brain
A patient with Parkinson's disease is missing dopamine in the brain — so why can't we just give them dopamine? Because the brain is guarded by the most selective wall in the body, and dopamine can't get past it. The clever workaround — smuggling in a disguised precursor that becomes dopamine only after it's inside — is one of pharmacology's most elegant tricks, and it's built entirely on understanding the blood–brain barrier.
