The results of a fascinating clinical trial challenge popular assumptions regarding "safer" strains of cannabis. The research found higher levels of cannabidiol (CBD) do not negate any potential adverse effects from smoking cannabis.
Tetrahydrocannabinol (THC) is the primary psychoactive compound in cannabis. It is responsible for what most people consider the "high" garnered when imbibing the plant. CBD, another cannabinoid present in the plant, has been widely linked to a number of beneficial health outcomes. It doesn't negatively influence cognitive performance like THC, and it has been found to hold anti-psychotic properties.
Several naturalistic studies of cannabis users have found those who smoke varieties with high CBD content show lower risk of cognitive impairments and psychotic symptoms compared to high THC users. The anti-psychotic properties of CBD have led some to suggest breeding strains of cannabis with higher CBD levels could offset some of the negative effects of THC.
Psychotic-like symptoms increased after inhaling cannabis, and 24 out of 46 participants (52.2%) experienced a clinically significant (increase of 3 or more on the PANSS scale) increase of symptoms on at least one visit. CBD had no impact. pic.twitter.com/E4sJ59SIwh
— Amir Englund (@AmirEnglund) November 16, 2022
So a team of researchers from King's College London set out to clinically test that idea. A cohort of 46 healthy volunteers were recruited to participate in four experimental sessions. Each session they inhaled cannabis vapor containing 10 mg of THC, and either 0 mg, 10 mg, 20 mg, or 30 mg of CBD.
Following a dose, each participant engaged in a series of different tests to measure everything from memory impairment to motor performance. Across every single task the researchers found CBD levels had no impact on participant performance.
Inhaling cannabis increased subjective ratings of “feel high”, “drug effects pleasurable”, “anxiety”, “want more drug” and others. CBD had no impact. pic.twitter.com/IAKin2QBaj
— Amir Englund (@AmirEnglund) November 16, 2022
“None of the CBD levels studied protected our volunteers from the acute negative effects of cannabis, such as anxiety, psychotic symptoms, and worse cognitive performance," said lead author Amir Englund. "It also did not change the quality of the intoxication in any way. The only effect of CBD we saw was that as the concentration of CBD increased, the more the participants coughed."
The researchers are cautious to note their findings only really apply to considerations over the ratio of CBD to THC in cannabis. So it is important to stress CBD by itself still does hold promising anti-psychotic effects, and there is the possibility that consuming CBD separately in the hours before ingesting THC could reduce the acute adverse effects of THC.
Nevertheless, the findings offer a robust counterpoint to the idea that a "safer" strain of cannabis could be developed by making sure it contains high levels of CBD. Englund suggests the only way to really minimize any adverse effects from cannabis is to consume a plant with low THC levels.
“THC and CBD are both produced from the same compound in the cannabis plant, so a variety which produces higher of amounts of CBD will naturally be lower in THC," said Englund. "It may still be safer for users to choose cannabis with higher CBD:THC ratios, but that’s because the same amount of cannabis will contain less THC than a lower CBD:THC variety. Overall, our advice to people wanting to avoid the negative effects of THC is to use less of it.”
The new study was published in Neuropsychopharmacology.
Source: King's College London
