Stress Weakens the Blood-Brain Barrier-Study
Stress can dramatically increase the ability of chemicals to pass through the blood-brain barrier , the complex system of blood vessels that protects the brain from toxins circulating in the bloodstream.
During the Gulf War, to protect themselves from chemical and biological weapons, Israeli soldiers took a drug called pyridostigmine. Nearly one-quarter of them complained of headaches, nausea, and dizziness – symptoms which occur only if the drug reaches the brain. Pyridostigmine molecules generally can't get into the brain, so why had the side-effects increased during combat?
An Israeli biochemist and physician wondered whether the stress of war might somehow have increased the permeability of the blood-brain barrier. The two researchers took a group of mice and stressed some by dunking them in water. They then injected the rodents with a dye and measured its intensity in the autopsied brains. They found that the dye had passed much more readily into the brains of the stressed animals.
The fact that stress can dramatically increase the ability of chemicals to pass through the blood-brain barrier has enormous implications, since many drugs are developed under the assumption that they will not enter the brain.24