In addition to psychoactivity – the other important differences lie in their affects on the mind and body of users.
Though they both work by interacting with the endocannabinoid system of the body they differ in how effectively they bind to receptors and that is how they each exert different influence on the person.
CBD does not bind nearly as strongly to the CB1 receptors in the CNS (central nervous system – basically your brain for the purposes of this article). THC on the other hand binds strongly to the CB1 receptros in the brain making the user high. In fact the CBD molecule can compete with THC molecules at the receptor and effectively reduce the high feeling.
Another way in which they differ is where we find the most of each. Cannabis has higher levels of THC while hemp has higher levels of CBD. Legally speaking with Farm Bill legalized derivatives of hemp with less that 0.3% THC by dry weight. So while CBD is federally legal if derived from hemp that meets this standard – psychoactive, is legal all across the country regardless of whether or not marijuana is legal in a certain state.
In fact the body produces an endogenous chemical called anandamide whose similar structure to THC explains the similar activity of the molecules at the receptor level. CBD though chemically similar has a significant change in the way it attaches to these same receptors and has subsequently different effect. Anandamide is very interesting as it is the drug that causes the runners high. It’s not just endorphins – it’s cannabinoids which also explains why runners are somewhat addicted to running.
Why does THC get you high while CBD doesn’t?
Due to the different chemical structures the interaction with the cannabinoid receptors of the endocannabinoid system result in different activation of the receptors which are known as CB1 (in the brain) and CB2 (in the periphery).
The effect of THC on CB1 receptors in the central nervous system and brain causes psychoactive effects due to the strength of the binding of THC and the ensuing pathways it activates. CBD on the other hand does not bind as tighty to the CB1 receptors. In fact if very high, taking CBD can reduce the effects of THC intoxication as the CBD at higher doses can compete with the THC molecules and by binding albeit weakly – can reduce the effects of psychoactivity induced by THC.
THC on the other hand does not bind as well to CB2 receptors where CBD has a stronger effect – thus having effects on the inflammatory, immune and pain pathways without causing psychoactive symptoms.
That said CBD may interact with as many as 60 receptors in the body so the story is much more complex than this article can explain and all the more so as research remains limited.
Summary
CBD and THC are chemically similar exogenous plant derived cannabinoids that have different effects due to their different affinity for various receptors including those in the endocannabinoid system. The most recognizable difference is that CBD does not get you high whereas THC does and that CBD is not federally legal if derived from hemp plants with low THC levels.
However there are many other differences and potential benefits and drawbacks for each based on the condition being addressed. Further research into these and other cannabinoids is ongoing.