Cannabis is widely known to be a recreational drug illegal in some states and legal in others,

but what do you know about cannabis therapies often referred to as medical marijuana?

For well over a century compounds extracted from the marijuana plant,

and there are over 500 of them have been used as therapies for a variety of medical applications,

from treating anxiety to addressing pain.

So where are all the clinical trials and why are doctors still not able to prescribe medical cannabis?

Hello and welcome to USA Today's The Excerpt.

I'm Dana Taylor.

Today is Tuesday, April 7, 26.

Joining me to discuss this is Dr. Stacey Gruber, director of the marijuana

investigations for neuroscientific discovery at McLean Hospital and an associate professor of

psychiatry at Harvard Medical School. Dr. Gruber, thank you so much for being here.

Thanks for having me. When people hear the word cannabis today, they usually associate it with its recreational use, which involves THC, the psychoactive compound of marijuana.

But cannabinoid therapies have been around for well over a century. Briefly, Dr.

Gruber, what happened? So it's a great question, and I think you're exactly right. When people hear

the term cannabis or marijuana, they think one thing, right? Recreational use, it's a drug for

pleasure and fun. They forget that cannabis has an extremely storied past

here in this country.

It was legal.

And actually a prescription medication.

For example, it was part of our pharmacopoeia in 1850,

which meant that you didn't have an indication for use

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