Does CBD protect against adverse effects of THC?

Can higher CBD levels reduce the harmful effects of cannabis use? That is the question that researchers from King’s College London tried to answer in a psychopharmacological study of forty-six healthy participants, who had little or no experience with cannabis use. The group received various cannabis preparations with 10 mg THC and a varying CBD content (0, 10, 20 and 30 mg) via a vaporizer, in a double-blind and randomised study. The cannabis used for the study originated from Bedrocan and was produced in accordance with Good Manufacturing Practice.

Fifteen minutes after cannabis inhalation, participants completed a series of tasks measuring mental abilities and reported how “pleasant” they experienced the cannabis. They also went on a 15-minute ‘hospital walk’, with the task of buying a £2 item of their choice from a cashier in the hospital shop. They had to ask for a receipt. They were observed from a distance by the research team. After any intoxicating effects had subsided, psychological questionnaires and a semi-structured clinical interview were administered.

No evidence

The researchers found no evidence that CBD reduces the acute adverse effects of THC. In terms of cognition, the adverse effects of THC mainly refer to effects on attention and memory. In terms of mental health, this mostly relates to the emergence of psychotic symptoms.   Also, there was no evidence that it changed the subjective or pleasurable effects of THC. This was the case for all CBD:THC dose ratios used in the study.

Interesting data

Bedrocan’s Chief Scientific Officer Mikael Kowal about the outcome: “This is interesting data which is somewhat contradictory to previous research on the interactions between THC and CBD, in which CBD has been shown to reduce some of the negative effects of THC. It is difficult to say which factors contributed to these different results, however there is a possibility that the differences are related to the use of specific cannabis varieties. Specifically, the current study used Bedrocan® and added various amounts of Bedrolite® to the THC-rich variety, in order to achieve the desirable amounts of CBD. Possibly, using a cannabis variety that already contains both THC and CBD (like Bediol®) would yield different results. This is only speculation, but in such a case it may be possible that other compounds in cannabis, aside of CBD, contribute to modulating the effects of THC.“