Scientists working with the John Hopkins University have published a study showing how a terpene called d-limonene found abundantly in cannabis, and in many citrus fruits, affects the experience of users when it is vapourised together with the well-known psychoactive cannabinoid THC.
Researchers working on the study, which will be published in the journal Drug and Alcohol Dependence next month, used a small cohort of 20 adults. They were instructed to vape a placebo, d-limonene, THC, or a combination of d-linonene and THC. Their experiences were recorded and each category was analysed and then compared to each other to determine the level of influence D-limonene has on THC.
The results showed that when taken alone d-limonene produced the same effect as the placebo, THC produced the expected ‘high’ effect on the user which researchers recorded as having “subjective, cognitive, and physiological effects”.
However, when D-limonene was vaped by participants at the same time as THC previously recorded sensations of anxiety fell. Significantly, anxiety fell at the same rate as the dose of d-limonene was increased.
“Ratings of anxiety-like subjective effects qualitatively decreased as d-limonene dose increased and concurrent administration of 30 mg THC+15 mg d-limonene significantly reduced ratings of “anxious/nervous” and “paranoid” compared with 30 mg THC alone.” the author of the study wrote.
There are many different elements to the cannabis plant, with the most well-known probably being cannabinoids and terpenes. Cannabinoids are mainly found in the cannabis plant although they are present in small quantities in other plants, and even in humans (as phytocannabinoids), these include THC and CBD. Terpenes are aromatic compounds found in cannabis and across the whole plant kingdom. Terpenes such as limonene and pinene help make things like oranges and pine trees smell as they do.
As well as cannabinoids and terpenes, the cannabis plant contains flavoids, minerals and other compounds. Previous research on how these elements interact with each other has primarily been focused on the relationship between CBD and THC. Results from the recent study investigating the link between D-limonene and THC open up the possibility of extending cannabis as a medication to those previously excluded due to other health issues.
Although the results are encouraging and could be used eventually to help open cannabis medicine up to more patients, caution must be taken when interpreting the data due to the small size of the study and the lack of existing data to test against.
“D-limonene selectively attenuated THC-induced anxiogenic effects, suggesting this terpenoid could increase the therapeutic index of THC. Future research should determine whether this effect extends to oral dose formulations and evaluate the interactions between other cannabis terpenoids or cannabinoids and THC.” the study concluded.
