Cannabis use in adolescents is not without risk for cognitive development and this is the main harmful effect documented in the literature. By raising awareness again of the risk of cannabis use in adolescence, a period when the brain is still in full development, this team from the CHU Sainte-Justine and the University of Montreal, goes further in understanding the risks , by showing that beyond the role of cognition in vulnerability to substance use, there are indeed and “in the other direction” simultaneous and lasting effects of cannabis use in adolescents.
Beyond the acute intoxicating effects, alcohol and cannabis abuse have been linked to impaired learning, memory, attention, and decision-making, as well as poorer school results. “Although numerous studies have already revealed differences in cognitive performance between groups of young users and non-users, the causal and lasting effects of the consumption of psychoactive substances on cognitive development have yet to be established,” explains Jean. -François G. Morin, co-author of the study.
The study presented here is unique in that it follows a large sample of high school students using measures of cognition and substance use. Using this data-intensive approach, the research has indeed been able to clarify the complex nature of the relationship between cognition and cannabis in adolescence.
To understand the relationship, the research team followed 3,826 adolescents over a period of 4 years and looked at the link between annual changes in substance use and cognitive development in many cognitive domains, such as memory recall, reasoning, inhibition and working memory. The analysis confirms that:
- vulnerability to cannabis (and alcohol use) in adolescence is associated with generally lower performance in all cognitive domains. This suggests the existence of 'a cognitive predisposition to cannabis use;
- however, in the other direction, an increase in cannabis use (but not alcohol use) appears to lead to simultaneous and delayed additional effects on cognitive functions, in particular on reasoning, memory recall , working memory and inhibitory control;
- In particular, the effect of cannabis use on a measure of inhibitory control, a risk factor for other addictive or addictive behaviors, could explain why early cannabis use is a risk factor for other addictions;
- Finally, some of the effects are even more pronounced when use begins earlier in adolescence.
These conclusions, which clarify the bilateral and reciprocal relationship between cannabis and cognition in adolescence, are essential in the current context of increasing legalization of cannabis. They must remind and raise awareness among parents, educators and health professionals, as well as young users, of the harmful effects of cannabis on the developing brain and encourage greater investment in drug addiction prevention programs.
It will be a question of carrying out additional analyzes with this cohort or others, on the same relationship to the period of transition to adulthood and in other contexts of legalization.
The researchers also want to determine whether these effects on brain development are related to other difficulties such as poor school performance, neuroanatomical damage and to what extent they predict the risk of future addiction or mental health disorders.
.jpg)
