Scientists at the University of California, San Diego (UC San Diego) have found that initiating marijuana use in adolescence hinders the development of thinking and memory skills. The study, published in the journal Neuropsychopharmacology, is based on data from more than 11,000 participants. It represents the longest-running and largest-scale study to date regarding the brain development of American youth.
Study Results
The researchers monitored 11,036 children from the ages of 9–10 up to 16–17. To ensure maximum accuracy, they utilized biological tests (hair, urine, and saliva samples) alongside self-assessment questionnaires. According to the results, the development process slowed down in adolescent cannabis users across various skills, including memory, attention, language proficiency, and information processing speed.
Interestingly, at a younger age, these children often showed better or identical results compared to their peers; however, as they grew older and began using cannabis, their progress stalled, while others continued to develop.
The study also specifically determined the impact of individual cannabis components. It was revealed that THC (tetrahydrocannabinol — the primary psychoactive ingredient) is directly linked to the deterioration of memory over time. Regarding CBD (cannabidiol), no such negative trend was observed in this group. However, scientists warn that the composition of cannabis products is complex; some products labeled as containing only CBD may still contain traces of THC.
Why Is It Important to Abstain from Cannabis Use?
Scientists note that the study does not prove a direct cause-and-effect relationship, as environmental factors and personality traits also play a significant role in this process. Nevertheless, when analyzing the data, researchers accounted for factors such as family environment, mental health, and the use of other substances. The final picture remained unchanged.
Abstaining from cannabis use promotes healthy brain development. As these products become more accessible, it is increasingly important for families and adolescents to understand how they affect a brain that is still in the process of developing.
