Over the past decade, state-legal weed businesses have worked to create extremely high-potency cannabis extracts, with THC levels reaching as high as 90 percent in some cases. But according to a new study published in the JAMA Psychiatry journal, these products probably won't get you any higher than regular old-fashioned bud.
Researchers from the University of Colorado, Boulder, set out to discover whether there is a relationship between THC blood levels and cannabis intoxication. Using the institution's CannaVans — mobile laboratories housed in cargo vans — researchers recruited 55 cannabis flower users and 66 concentrate users from the Colorado area.
Lead author Cinnamon Bidwell, assistant professor at the Institute of Cognitive Science, and her team used two CannaVans to drive to each subject's residence to conduct the experiment. “We cannot bring legal market cannabis into a university lab, but we can bring the mobile lab to the people,” said Bidwell in a statement. Federal law prohibits most researchers from administering cannabis to study subjects, so each subject was asked to buy their own weed and use it inside their own homes.
For the trial, flower users were asked to purchase bud with a THC content between 16 and 24 percent. Concentrate users were assigned extracts containing either 70 or 90 percent THC. Before the subjects got high, researchers drew their blood and administered a number of tests to assess the subjects' mood, subjective intoxication level, cognitive function, and balance. Subjects were then asked to get high in the comfort of their home, and then took the tests again immediately afterwards. One hour later, the tests were repeated a third time.
As expected, concentrate users had much higher THC levels in their blood than flower users. Minutes after getting high, concentrate users showed THC levels as high as 1,016 micrograms per milliliter, compared to 455 ug/ml for flower users. But contrary to expectations, concentrate users were not significantly more stoned than flower users.
"Surprisingly, we found that potency did not track with intoxication levels," Bidwell explained. "While we saw striking differences in blood levels between the two groups, they were similarly impaired." Bidwell said that these findings raise “a lot of questions about how quickly the body builds up tolerance to cannabis and whether people might be able to achieve desired results at lower doses.”
Both subject groups self-reported similar levels of feeling intoxicated, and achieved similar results on the cognitive and balance tests. Immediately after getting high, each group performed around 11 percent worse during the balance test, and each group also did worse on memory tests, compared to when they were sober. But one hour after getting high, the subjects' balance, memory, and cognitive functions had almost completely returned to normal.
"People in the high concentration group were much less compromised than we thought they were going to be," said coauthor Kent Hutchison, professor of psychology and neuroscience at CU Boulder, in a statement. "If we gave people that high a concentration of alcohol it would have been a different story."
Researchers believe that tolerance may explain the findings of the study. Regular concentrate users probably develop a high tolerance to THC over time, which may limit the intoxicating effect of the concentrates. The scientists point out that all subjects in the test are experienced weed users, and that a first-time pot user may have a much more serious reaction to dabbing a high-THC extract. The study authors also theorize that “cannabinoid receptors may become saturated with THC at higher levels, beyond which there is a diminishing effect of additional THC."
The study raises some interesting implications for cannabis users. For one, the findings suggest that health officials’ concern that “weed is stronger than it was in the 1960s” may not be relevant. Even in recent times, cops are warning about “super high potency” weed, but the study shows that users of these high-potency products are not more likely to be impaired than users of standard-grade weed.
The findings also raise doubts about using THC blood levels to test drivers' levels of intoxication. The present study shows that one hour after getting stoned, a concentrate user shows few signs of cognitive or motor impairment, even though they still have extremely high THC blood levels. Another recent study has also found that subjects still test positive for THC one day after smoking weed, but their driving skills are not impaired in any way.