Even if you’ve never used it, medical marijuana has a pretty distinctive look and aroma. The exception, according to a Valley researcher, is the marijuana that’s federally authorized for medical trials.

Dr. Sue Sisley is conducting the first-ever federally approved study on the effects of cannabis on veterans suffering from PTSD. The Scottsdale physician spent six years fighting for approval and finally got a shipment of clinical-grade marijuana for testing last year.

But when she opened the packaging, she wasn't too happy.

“I, of course, was disappointed,” she said.

Not only did the cannabis not look and smell like marijuana available at dispensaries, it was significantly less potent. Sisley had asked the federal government for a supply of marijuana with a THC content of 12 percent.

“This is a phenotype that’s readily available in every retail store in Arizona or Colorado. It’s a common phenotype,” she said.

What she got was ground-up cannabis with visible stems – an unnecessary part of the plant that’s usually discarded – and a THC content between 7 and 8 percent.

“Despite giving them almost two years, they weren't able to grow cannabis to spec in the way we’ve asked them. So ultimately just we gave up asking and took whatever they had available,” she said.

Speaking Tuesday via FaceTime from a conference out of state, Sisley said the problem is that all of the marijuana that is federally-approved for clinical research comes from a single farm at the University of Mississippi. With a contract from the National Institute on Drug Abuse, the university has been the sole legal distributor of cannabis for scientific purposes since 1968.

“Monopolies are a problem when it comes to science because monopolies cause entities to become lazy,” Sisley said.

The federal farm has relatively few varieties – approximately 185 according to a letter from the U.S. Department of Health and Human Services and Drug Enforcement Agency – and doesn’t do testing that many states consider standard. For example, the farm does not test for mold in its samples, Sisley said.

The marijuana available for testing also tops out at a potency of 13 percent THC, even though dispensaries widely offer marijuana between 20 and 30 percent.

“In an ideal world, scientists would have access to real-world cannabis -- what patients are actually using day-to-day,” she said. “It's tough to mimic the real world when you're forced to use study drug from only one place.”

Now that she’s seen the clinical crop up close, she worries about the impact on previous marijuana studies.

“A lot of the efficacy trials may show minimal effectiveness but not as robust as what patients are describing, and we wonder if that's partly because some of these studies are being sabotaged from the beginning by a study drug that isn't optimal,” she said. “It's time to end the monopoly and allow cannabis research to finally flourish in this country.”

Although far from ideal, Dr. Sisley said the marijuana is usable for the study and is actively recruiting veterans to participate.

If you'd like to participate in the study and are interested in seeing if you qualify, contact the Scottsdale Research Institute at Arizona@marijuanasites.org.