Study Finds No Cognitive Impairment From Infrequent Teen Cannabis Use

As research into the effects of cannabis continues to evolve, a recent Portuguese investigation sheds light on an important yet understudied area – occasional cannabis use during adolescence. The study, published in Psychopharmacology, explored whether infrequent teen marijuana consumption impacted cognitive functioning and brain activity.

Leveraging data from the large-scale IMAGEN longitudinal study, researchers analysed participants initially around 14 years old who reported low-to-moderate cannabis use over time. Stringent criteria excluded those with significant substance use history to isolate the effects of light marijuana consumption.

Through comprehensive cognitive assessments, brain scans, and psychological evaluations at multiple timepoints, the investigation yielded insightful findings.

While adolescents with higher conduct issues and stronger peer influence were more likely to initiate cannabis use by 19, neither baseline brain activity nor cognitive performance predicted future use. Crucially, at ages 19 and 22, the infrequent cannabis users exhibited no significant impairments in cognitive functioning or anomalies in reward processing compared to non-users.

“We did not find evidence of cognitive impairment in light cannabis users, neither before nor after use onset,” the researchers stated. “These effects appear minor and may not be clinically significant.”

However, persistent light use was associated with higher self-reported conduct problems and hyperactivity/inattention symptoms by age 22, though no deficits in objective cognitive measures emerged.

The study’s lead author emphasized that while reassuring for occasional adolescent use, the findings may not extend to heavy users or those with cannabis use disorder. Larger sample sizes could also yield more robust conclusions.

Nonetheless, the research offers valuable insights into a prevalent yet overlooked pattern of teen substance use. As cannabis legalization expands, understanding the nuanced impacts, especially during crucial developmental stages, takes on heightened importance.

“Our study allowed examining potential pre-existing risk factors and consequences of light cannabis use in a developmental sample,” the authors concluded. “We found no cognitive impairments, but identified conduct issues as a risk factor for persistent use.”

As cannabis policies evolve, such targeted investigations will inform public health efforts and harm reduction strategies tailored to adolescents.


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