Teens who use cannabis may see slower growth in memory, attention, language, and processing speed, according to a new study from the University of California San Diego.
The Research
Researchers analyzed data from 11,036 children in the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term investigation of youth brain development in the U.S. The study, published in Neuropsychopharmacology, followed participants from ages 9-10 through ages 16-17, tracking cognitive performance and substance use with both self-reports and biological tests (hair, urine, saliva).
The team found that teens who used cannabis showed slower improvement across several cognitive domains compared to nonusers. Initially, some users performed as well as or better than peers, but their gains leveled off after they started using, while nonusers continued to improve.
Importantly, within a smaller subgroup, teens with evidence of THC exposure (the primary psychoactive compound) experienced greater memory decline over time. No such pattern was seen for CBD exposure, though the number of CBD users was limited.
Lead author Natasha Wade, PhD, noted, “These results point to THC as a likely driver of the changes we're seeing.” The researchers adjusted for many factors including family background, mental health, and other substance use.
Why It Matters
Adolescence is a critical period for brain development. Even modest cognitive differences can impact school performance, daily functioning, and future learning. The findings highlight the potential risks of cannabis use during this window, especially as products become more widely available and often contain varying levels of THC.
What You Can Do
If you're a teen or a parent, consider delaying cannabis use to support healthy brain development. If you're curious about your own cognitive strengths, taking a validated IQ test can give you a baseline. For those who do use cannabis, staying aware of its potential effects on memory and thinking is essential.
Source: ScienceDaily Mind & Brain
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