How medical is medical marijuana?

The, um, common effects of marijuana are well known. See: Cheech and Chong, Harold and Kumar Go to White Castle, the parking lot of any rock music festival. But the medicinal effects are less well understood. Yale psychiatry professor Deepak Cyril D’Souza says that’s a problem when it comes to states legalizing marijuana for specific medical conditions. “We need evidence,” he says—evidence as strong as that required for approving other medications.

D’Souza is the lead author of an editorial published in June in the Journal of the American Medical Association called “Medical Marijuana: Is the Cart Before the Horse?” In it, he discusses the findings of two JAMA studies that the research used to support marijuana use for several of the conditions sanctioned by states’ medical marijuana laws is of “very low quality.”

The studies that do exist, D’Souza says, are mostly too small to draw reliable conclusions, while others have focused solely on THC or CBD—just two of the more than 400 compounds found in cannabis. He knows it can be difficult to do the rigorous double-blind studies he believes are necessary. One problem is that states have hesitated to fund marijuana research. So has the federal government, which considers cannabis a Schedule 1 drug (a drug with, among other things, a high potential for abuse). Plus, D’Souza says, most study participants are able to figure out pretty quickly whether they’ve been given a placebo or the real thing—making double-blind studies more complicated.

D’Souza, who has studied cannabinoids for 20 years, argues without solid science, the term medical marijuana “gives a false impression that it’s being endorsed by physicians.” The bottom line: “We just need to do the research”—and states and the public need to be patient.