Major U.S. Study Links Teen Cannabis Use to Slower Cognitive Gains

Overview

• The UC San Diego–led analysis, published Monday in Neuropsychopharmacology, tracked 11,036 youths in the national ABCD Study from ages 9–10 to 16–17.
• Teens who began using cannabis showed slower improvement in memory, attention, language and processing speed, a shift researchers say can hinder schoolwork and daily tasks.
• Exposure measurement combined self-reports with hair, urine and saliva tests to reduce missed or misreported use.
• A subgroup with toxicology evidence of THC showed worsening memory over time, unlike peers with evidence of CBD exposure.
• The authors report associations rather than proof of causation, describe the differences as modest after adjusting for many confounders, and plan continued follow-up into young adulthood.