A reader asks, “Do you know if all components of cannabis cross the blood-brain barrier? Some obviously do.”
The simple answer is yes. The neutral cannabinoids are all small molecules that are highly lipophilic and cross the blood-brain barrier. The acid forms are also lipophilic and presumably would also cross the blood-brain barrier. But to our knowledge, no one has radio-labelled them to find out.
The Blood-Brain Barrier (BBB) is semi-permeable; it keeps hormones and neureotransmitters that are not lipid soluble from reaching the brain.