Well, no. They aren’t. But that’s not to say that they’re not responsible for at least some placebo effects, including as one study found, painkilling effects.
The whole thing’s a bit complicated, but here’s the gist: science has long known that cannabinoid receptors – chemicals in the brain whose only seeming purpose is to receive and utilize cannabinoids, basically what gets you high in pot – exist in the body. But in studying why the Placebo Effect works in some cases but not others, scientists have stumbled upon the theory that certain cannabinoid receptors are being utilized when the brain is fooling itself into believing a drug works or doesn’t.
Check it out here:
Body May Use Cannabinoids to Make Placebos Work | Wired Science | Wired.com.