Melbourne, Australia: Doubling THC potency doesn’t necessarily lead to a corresponding increase in cannabis’ mood-altering effects, according to a review of 40 human studies published in the journal Neuroscience & Biobehavioral Reviews.
Researchers from Australia, Canada, the United Kingdom, and the United States systematically reviewed studies on the subjective effects of THC versus placebo in over 1,000 participants. They determined that the perceived effects of cannabis tended to plateau at higher doses.
Investigators reported: “[W]e found that increasing the dose of THC from 2.5 mg to 5 mg to 10 mg only slightly increased feelings of high (estimated to increase from 31.6 to 34.3 to 39.6 percentage points on a 100-point scale), rather than doubling the intensity of the experience at each dose category.”
Commenting on this finding in an accompanying editorial, researchers wrote, “This is common in pharmacology – the study of how drugs work – where bigger doses often bring smaller and smaller extra effects once a certain level is reached.”
The study’s authors concluded: “As THC dose increases, subjective feelings of high and tiredness increase in a non-linear manner, with a sharp increase up to approximately 14 mg and 20 mg respectively, followed by a plateau. These findings provide preliminary, quantitative evidence to inform public health guidance for cannabis consumers on the likely subjective effects of specific amounts of THC. … In legal recreational markets, it may be helpful to explain to consumers that doubling the quantity of THC consumed is unlikely to produce a doubling of the intensity of the subjective experiences during intoxication.”
The findings of a separate review paper published earlier this month in the journal Preventive Medicine concluded that consumers self-titrate their cannabis intake based upon the strength of the product they are consuming. “Consumers adjust their inhalation patterns to achieve a desired subjective effect,” that study’s authors determined. “For example, participants dose-dependently inhaled less cannabis as the amount of active cannabis increased.”
NORML has consistently pushed back against legislation imposing arbitrary THC potency limits on state-legal cannabis products, arguing that consumers distinguish between higher-potency and lower-potency cannabis products and moderate their consumption accordingly.
Full text of the study, “The subjective effects of delta-9-tetrahydrocannabinol: A systematic review and dose-response meta-regression,” appears in Neuroscience & Biobehavioral Reviews. Additional information is available from the NORML Fact Sheet, ‘THC Potency Concerns: Are Stronger Products More Problematic?‘