Scientists have produced evidence that goes against the grain of conventional cannabis wisdom – adding a 650mg dose of CBD to a brownie containing 20mg of the psychoactive cannabinoid THC increases the effects of THC on the user, including the unwanted effects.
It is widely believed by cannabis users that CBD mitigates the more unwelcome effects of THC, such as paranoia, memory problems, feelings sedated, as well as an increased heart rate.
However, previous clinical research in this area has produced mixed results; some studies indicate that CBD enhances the effects of THC, some suggest the opposite, and others conclude that CBD has no impact on how the body reacts to THC and the effects experienced by the user.
To develop the available body of data on this subject, scientists chose to administer edibles to participants, as opposed to smoking or vaping. This had the additional benefit of allowing researchers a more precise degree of accuracy in dosing the cannabinoids.
The double-blind, randomised, controlled trial took place between January 2021 and March 2022 at the Johns Hopkins Behavioral Pharmacology Research Unit in the USA. Participants attended three 14-hour long sessions in which they were given brownies containing a specific dose of THC and CBD, or they were given a placebo brownie containing no cannabis.
Additionally, participants were given a ‘cocktail’ of frequently used pharmacological drugs such as caffeine and four others such as blood pressure medicine. This drug cocktail was given to enable scientists to better understand how cannabis interacts with them.
Participants were assessed on aspects such as their own opinion and analysis of what effect taking the brownie had on them, their cognitive and psychomotor performance, as well as their vital signs. Using the data collected, scientists found that brownies containing THC together with a high dose of CBD produced more intense adverse effects than those containing no CBD.
Researchers recorded the method of dosing and assessing participants, “At the beginning of each session, participants arrived at approximately 7:30 am and consumed a standard low-fat breakfast, and an intravenous catheter was placed into a forearm vein for serial blood collection. Next, a baseline blood sample (10 mL) was collected, and baseline assessments were completed, which included the following: vital signs (heart rate [HR] and blood pressure), cognitive and psychomotor performance, and subjective drug effects. Following baseline assessments, participants consumed a brownie (approximately 1 hour after breakfast), followed by administration of the CYP cocktail approximately 30 minutes later. Participants completed PD assessments and provided blood and urine samples at timed intervals for 12 hours post-CYP cocktail administration as described in the Outcome Measures section. After 12 hours, participants were discharged home, then returned to the laboratory the next morning for a short visit for blood collections and PD assessments approximately 24 hours after CYP cocktail administration.”
In their conclusion, researchers noted that “the present study evaluated the association of high dose Δ9-THC when ingested alone and in combination with high dose CBD in healthy adults who were infrequent cannabis users. Overall, ingestion of Δ9-THC + CBD produced more pronounced effects, greater impairment of cognitive and psychomotor function, and increases in HR relative to both Δ9-THC and placebo.”