In a webinar last week hosted by federal Substances and Mental Health Services Administration, (SAMHSA), a cannabis expert slammed the myth that legalizing the drug would increase youth usage. He touched upon the issues of the roadside testing of marijuana impairment and of the possibility of testing positive after consuming CBD.
Ryan Vandry was an experimental psychology professor and lecturer at Johns Hopkins University’s Behavioral Pharmacology Research Unit. His public presentation, titled “Behavioral Pharmacology of Cannabis – Trends in Use, Novel Products, and Impact,” focused on continuing education for medical professionals. Titled “Behavioral Pharmacology of Cannabis – Trends in Use, Novel Products, and Impact,” it focused primarily on how variables like dosage, product formulation, mode of administration and chemical components such as terpenes can influence the drug’s effects.
Vandry noted that marijuana was the most popular illicit drug used in the United States. While the self-reported usage by adults is up as more and more states have legalized marijuana in recent years he said, it has remained or even fallen for youth.
The use of cannabis by youths is one area of great concern in light of legalization, he says, but surprisingly this group has remained relatively steady. [for] “both past year and daily use.”
Vandry pointed to California data dating back to 1996 when California ended its prohibition of medical marijuana. He said that “there has been really no change” in cannabis usage rates among 8th, 10th, or 12th-grade students. In fact, consumption rates have decreased in recent years.
The researcher repeatedly emphasized the need for policymakers and health experts to differentiate between different kinds of cannabis, focusing less on delta-9 THC levels—which currently distinguish hemp from marijuana at the federal level—and more on a given product’s physical and cognitive impacts.
Vandry noted that “there is a disconnect between what we know about these products, and the development of retail cannabis product.” The cannabis industry drives diversity by competition. Scientifically, it’s hard to keep up with all the new products.
Generally, Vandry called for a differentiation between THC and similar cannabinoids, including delta-8 THC, which is usually derived from legal hemp, and other products that are dominant in CBD, according to the behavioral and health impacts. THC and similar cannabinoids—including delta-8 THC, which is usually derived from legal hemp—exhibit characteristics typical of drugs of abuse, Vandry said, such as substance use disorders, withdrawal and impairment.
He continued by saying that CBD is “a different animal” and that there was “no indication” in the research of impaired or problematic use when CBD was administered with very low amounts of THC. CBG “looks similar to CBD because it does not produce THC like effects,” said the researcher, citing his own research.
But Vandry pointed to the current legal distinction between delta-8 THC and delta-9 THC—which both cause psychoactive effects—as an example of where regulations lag behind cannabis science. While delta-8 is metabolized more quickly in the body and is often described as less potent, a study he was involved in “showed…that if you just take double the dose of delta-8, you can get the exact same effects as delta-9,” he said.
The researcher explained that these chemicals are regulated in two different ways by the federal government. Delta-9 THC has been classified as a Schedule I substance, while delta-8 THC derived from hemp would not be scheduled.
A second area in which current policies fail is the evaluation of marijuana-related impairment. Vandry, along with his co-workers, examined the three field sobriety testing methods used by law enforcers and concluded that those who showed signs of impairment in psychomotor abilities and were given THC still passed these screening tests.
Vandry reported that subjects who received a THC dose of 25 milligrams, which caused impairment in some cases, tested well below the per se THC limits. This was especially true when THC was administered orally.
In spite of the fact that the pharmacodynamics are similar, “the blood and blood THC levels following oral consumption is very low,” explained he. In an experiment, 25 mg THC was given to people and they registered only two nanograms THC for every milliliter blood.
Even when their THC or blood alcohol levels are not above the per se limit, people who combine alcohol with marijuana show significant impairment.
Vandry explained that this is a problem of public safety, which we should resolve.
Other tests may result in false positives if they are not accurate.
As an example, CBD products often contain very low amounts of THC. Vandry stated that, in his research, people taking similar products often tested positive for the drug metabolite found in urine tests used to detect marijuana usage.
In many cases, he explained, a positive test was obtained “after an acute dose” and “in most cases, following chronic dosage for at least two weeks.” Positive tests usually stop after the user has stopped using THC, but in some cases they continue to test positive a week or more later.
Terpenes—often pointed to by cannabis connoisseurs as responsible for modulating the experience of a particular strain or product—are a complicated matter that scientists are still sorting out, Vandry said. He noted, for example that renowned cannabis researcher Ethan Russo pushed the “entourage hypothesis,” which states that different chemicals in marijuana modulate overall experience.
Vandry said that “much of the marketing and advertising of cannabis companies today will claim specific terpenes have therapeutic effects or benefits above and beyond marijuana itself.” Vandry said sometimes the claims are supported by data, and at other times they’re not.
As an example, Vandry and Russo’s collaboration on this experiment involved giving the D-limonene terpene in combination with pure THC doses inhalation of 30mg.
“As we added doses of limonene to it, we got dose-orderly reductions in subjective ratings of anxiety and paranoia and the subjective feeling that their heart was racing,” he said, “but the overall magnitude of the drug effect was unchanged, cognitive impairment was unchanged… It seems here that limonene has a very specific non-cannabinoid mechanism by which it can attenuate the anxiety or panic-inducing effects of high doses of THC.”
In contrast, the same testing found little evidence to support the claims of alpha pinene. This terpene is sometimes promoted by the cannabis industry as having the ability to ease anxiety, improve breathing and combat the THC’s memory impairing effects.
Vandry explained that there was no effect. “In contrast to the D-limonene study, we really saw no significant effect of alpha-pinene addition to delta-9 THC…on subjective drug effects, memory [effects] “Any cardiovascular effect or any other type.”
Other topics covered in the webinar included schizophrenia and psychosis, the difference between cannabis effects on men and women subjects and the need for increased research and quality control surrounding cannabis.
Vandry wasn’t convinced by the claims that there is a link between cannabis and schizophrenia. She noted that even though the U.S. rate of schizophrenia increased over the last year in some cases, it has not changed.
He said that “there is undoubtedly a correlation between heavy use of cannabis and early onset psychosis and the severity of psychosis” but “the causality to someone who otherwise would not develop psychosis still remains questionable.”
Vandry has also stated that marijuana use disorder, or cannabis addiction, is a serious public health problem, with similar rates of abstinence to nicotine and alcohol. Further, some research suggests that “females react differently” to this drug.
“They metabolize the drug differently, they progress more rapidly from first use to problematic use and are more treatment-resistant,” he explained, adding that female users also “tend to have greater withdrawal symptoms than men.”
The marijuana product’s THC content was also a cautionary note. He said that the overall dosage, and not its potency is important.
Self-titration, as explained by the researcher, is the concept of people adjusting their usage behavior depending on the potency. “If someone is given five percent and thirty percent flowers, their regular frequent daily user will be smoking much more of five percent just to achieve the same amount.”
It’s not about the concentration but the dosage that’s important, he explained.
The effects can vary depending on your diet as well, especially if you are taking cannabis orally. Vandry explained that “cannabinoids are more readily absorbed when taken along with high-fat meals than they would be if taken alone. This is contrary to the way most medicines work.”
Cannabinoids may also react with alcohol and caffeine.
Vandry stated that the gaps between scientific and policy understandings underscored a call for greater investment in product testing, research and data collection.
“We have to figure out the abuse liability of these different products. We also need to develop regulations which are product and dose specific, formulation and route particular,” said he. We need to improve quality control for retail products, and understand these minor cannabinoids.
Vandry said, “I have already stated this, but I’d like to see cannabis regulated not in general, but for THC dominant cannabis, CBD dominant cannabis, and other products. The current policy is really missing the point. You can find delta-8 at one end and delta-9 at the other.
A recent deep dive on the chemical composition of cannabis examined what gave products their distinct flavors and smells. It looked at how genetic makeup, cultivating methods, and post-harvest processes affected them.
According to the report, “the goal of this project is to enhance quality control in products, support breeding programs and provide guidance for future research on cannabis sensory science.”
Researchers continue to discover new things about cannabis despite a boom in research after prohibition. Researchers earlier this year, for example, announced that they successfully identified a new cannabinoid—cannabielsoxa—produced by the marijuana plant as well as a number of other compounds “reported for the first time from the flowers of C. Sativa.”
Other research in 2023, published by the American Chemical Society, identified “previously undiscovered cannabis compounds” that challenged conventional wisdom of what really gives cannabis varieties their unique olfactory profiles.
As for other recent cannabis research, scientists reported in May that they identified 33 “significant markers” in the cannabis genome that “significantly influence cannabinoid production”—a finding they say promises to drive the development of new plant varieties with specific cannabinoid profiles.
The paper cited a set of “massive genes” on one plant’s chromosome, which involved 60 Megabases (Mb), and were associated with cannabis strains that are THC dominant.
In the article it was stated that “the results provide valuable advice for Cannabis Breeding programs that use precise genetic markers for selection and refinement of promising Cannabis varieties.”
The research on marijuana is exploding in the last few years due to the fact that more and more states have made it legal for both medical and adult purposes. However, the Trump Administration’s priorities are not known.
For example, under the new administration, “marijuana” is also now one of nearly two dozen “controversial or high-profile topics” that staff and researchers at the National Cancer Institute (NCI) are required to clear with higher-ups before writing about.