Study: Cannabis Affects Adults & Teens Equally, CBD Does Not Mitigate THC's Immediate Effects

Does marijuana impact adolescents differently than it does adults? Can CBD reduce some of the effects of THC? A new experimental study published in Addiction and led by UCL and King's College London scientists offers some answers.

According to the research summary, the short-term effects of vaporized cannabis are the same on both adolescents and adults, and cannabidiol or CBD does not mitigate “the acute harms caused by delta-9-tetrahydrocannabinol.”

Study Details

Researchers assessed how regular marijuana users of various ages respond to inhaled marijuana with different levels of CBD. In the study, 24 adolescents (16-17 years old) and 24 adults (28-29 years old) took part, all of whom are regular weed consumers, writes Medical Xpress.

Participants inhaled three types of vaporized marijuana under medical supervision. On separate weeks, they were given either a placebo or a high THC cannabis strain, or a high CBD and high THC version (same amount of THC but with high concentrations of CBD). Doses were arranged to match that of a typical recreational use session.

After consumption, the participants were assessed in verbal memory, and for psychotic-like effects, such as delusion or paranoia. In addition to the test, they were also required to self-report how the substance was affecting them.

The findings: Both the THC and THC+CBD strains caused expected effects like feeling high, anxious, mild transient psychotic-like experiences and memory impairment. What’s more, adolescents reacted the same as adults.

"Immediately following consumption, cannabis can elicit psychotic-like effects, and impair verbal memory, and adolescents in our study who regularly smoke cannabis were just as vulnerable to this as the adults were,” said Dr. Will Lawn, the lead author of the study and psychology lecturer. “Adolescence is a key developmental stage of life when people are at an increased risk of developing mental health problems. Regularly producing transient psychotic-like effects and memory impairments through cannabis use is likely to augment the risk of psychological distress, especially in those who are vulnerable to these harms. However, critically, our results also indicate that 16- to 17-year-old cannabis users were not more sensitive to the acute harmful effects of cannabis than adults."

Previous Study’s Opposing Results

This study's findings are contrary to previous research. According to a study published in the Journal of Psychopharmacology in May 2022, CBD can minimize some of the negative effects THC has on the brain.

"Cannabis is a very popular recreational drug, and is also starting to be used medically for some purposes, but we still don’t know a great deal about how different cannabinoids affect the brain," study author Matt Wall, a senior imaging scientist at Invicro, told PsyPost at the time. The researchers revealed that THC and CBD have opposing effects.

In short, the researchers concluded that consuming a marijuana strain with both THC and CBD should decrease striatum connectivity, but to a lesser extent than a THC-only strain.

The findings suggest that “different types of cannabis have different effects on the brain,” Wall told the outlet. “High-strength, relatively pure-THC cannabis can severely affect some brain networks, but when THC is combined with cannabidiol (CBD) in a more ‘balanced’ way, these effects may be reduced somewhat, making a balanced strain of cannabis potentially safer to use. CBD by itself seems to have quite minimal effects on the brain networks we looked at, which means it’s probably safe for use as a potential therapy.”

Long-Term Effect Yet To Be Studied 

The new study, however, claims that CBD can’t protect from effects like paranoia and memory impairment and that it does not change the subjective experience. The authors did note that the study only examined the short-term effect and that long-term effects are yet to be researched.

While this study concluded that “adolescents are neither more resilient nor more vulnerable to the immediate effects of cannabis,” another study by the same authors revealed last year that adolescents are more vulnerable to cannabis addiction than adults. 

Photo: Benzinga edit with images by BAZA Production and Ground Picture on Shutterstock