Researchers from University College London (UCL) found no difference in the effects of THC and CBD on regular cannabis users of different ages.
The observational study examined 24 adolescent participants (16-17 years old) and 24 adult participants (26-29 years old), all of whom were already regular users of cannabis.
Over the course of three weeks, the participants inhaled three types of vaporised cannabis under close supervision in a clinical setting. The participants were given either a placebo, a strain of cannabis high in THC, (the main psychoactive component of cannabis) or a high-CBD and high-THC form of cannabis. There were administered in doses typical for recreational use.
The participants were asked to report on how each strain of cannabis affected them at regular intervals. They also completed verbal memory tests and tests which measured the psychoactive effects of THC, such as delusions, cognitive disorganisation or paranoia.
Adults and adolescents are equally vulnerable to the negative effects of cannabis
The researchers observed all the expected effects of THC and CBD in the participants’ responses. These included feeling high, feeling anxious, having mild transient psychotic-like experiences, and memory impairment. They found no evidence that the effects of THC or CBD differed between adults and adolescents.
“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. Adolescence is a key developmental stage of life when people are at an increased risk of developing mental health problems,” said psychology lecturer and lead author of the study Dr Will Lawn.
“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 THC than adults,” added Dr Lawn.
CBD does not dampen the psychoactive effects of THC
Concern over the impact of cannabis on young people has grown in recent years and some researchers have suggested that CBD may protect against some of the harmful aspects of cannabis use. A recent observational study by the same authors found that adolescents were more vulnerable to cannabis addiction than adults, but they were no more vulnerable to depression and anxiety.
Cannabis contains natural variations of CBD, which is non-intoxicating, as well as relative levels of psychoactive THC. The use of CBD products has grown rapidly as the popularity of over-the-counter wellness supplements has risen. This study has tested the effects of CBD by administering different levels of the component to participants. The researchers found that levels of CBD did not impact the subjective effects of cannabis use. The participants reported no difference in memory impairment or psychotic-like effects.
“Adding a moderate dose of vaporised CBD, about 25mg, to cannabis that is already high in THC does not alter the subjective experience, nor does it protect from effects such as paranoia or memory impairment. However, we have not investigated the long-term effects of low-dose CBD nor the therapeutic effects of high-dose pharmaceutical CBD here,” explained Dr Lawn.
