A UC San Diego-led analysis of the ABCD study, involving 11,036 children aged 9 to 17, found that cannabis use during mid-to-late adolescence is associated with slower development in memory, attention, processing speed, and decision-making.

Following nearly 12,000 children for more than a decade, researchers observed associations between childhood cannabis use and poorer neurocognitive performance in late adolescence.

The study does not establish causation; researchers accounted for factors like family background, mental health, environment, and prior cognitive performance, but other influences could still be at play.

Findings raise greater concerns for high-risk groups, who may be more vulnerable to cognitive impacts from early cannabis use.

Researchers plan to continue tracking participants into young adulthood to understand long-term effects and how the timing and frequency of use influence brain development.

Lead author Natasha Wade, PhD, stresses that delaying cannabis use supports healthier brain development and warns families about potential impacts from cannabis products with mislabeled CBD/THC content.

Even modest cognitive effects could affect school performance and daily functioning during adolescence, a period of rapid brain development.

The findings are published in Neuropsychopharmacology on April 20, 2026, using the ABCD Study, the nation’s largest long-term brain development study.

The study implies that preventing early cannabis use could lead to better developmental outcomes for children and teens.

Biological tests (hair, urine, saliva) alongside self-reports were used to gauge cannabis exposure, spanning recent use to several months prior.

The negative effects appear gradual rather than immediate, indicating reduced developmental potential for users compared with non-users.

Dr. Darien Sutton notes that early cannabis initiation is linked to slower cognitive development rather than an acute impairment, framing the issue as developmental timing.