In a press release, Bidwell, lead author and assistant professor in the Institute of Cognitive Science, stated, “Surprisingly, we found that potency did not track with intoxication level.” Additionally, in his view, “While we saw striking differences in blood levels between the two groups, they were similarly impaired.”
Bidwell and her colleagues were surprised by the results. They suspect several factors are at play. For starters, humans have a finite number of CB1 cannabinoid receptors, which are the primary target of THC molecules in the human body. At some point, THC saturates the body’s CB1 receptors. This means that adding more THC couldn’t create more significant intoxication because there is simply nowhere else to bind.
A second theory, explained in the press release on CU Boulder Today, speaks to THC tolerance. Regular exposure to potent concentrates could increase tolerance to THC. Also, Bidwell suspects, “There may be genetic or biological differences that make some people metabolize THC more quickly.”
Medically speaking, if higher levels of THC don’t lead to increased benefits, what are the implications for medical cannabis? Do patients need access to higher and higher concentrations? Bidwell told Marijuana Moment that her research, “raises 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.” This idea is an often repeated in dosing protocols discussed within medical circles – that it’s possible to achieve maximum relief of symptoms without the high.
Implications for Cannabis Policy on Roadside Impairment Tests
If concentrates don’t dramatically increase impairment, this has serious implications for cannabis policy, especially roadside tests for intoxication. With alcohol, the more you consume, the greater the intoxication. Cannabis consumption (measured by exposure to THC) doesn’t seem to work this way.
Currently, there are several roadside devices in use within North America. Often, these devices do not claim to test for impairment. As a 2019 article for the National Post reported, “Instead, they’re roadside screening devices that indicate whether someone has recently used cannabis. If the test shows recent use, the driver is [further tested to] form the basis for criminal charges.”
Importantly, Bidwell’s study seems to confirm that even plasma concentrations cannot confirm levels of intoxication. Intoxication may have more to do with the individual than the amount of cannabis they’ve consumed. If saliva, breathalyzers, and blood tests can’t demonstrate a level of impairment, cannabis policy may need to change. It must move towards a field sobriety test using physical and mental exercises – like they do in California.