Large US Teen Study Links Cannabis Use to Slower Brain Development

A large, longitudinal study of 11,036 U.S. youths aged about 9–10 to 16–17 found that cannabis use during adolescence is linked to slower development across memory, attention, and processing speed, with THC exposure driving most of the effects and CBD exposure showing relatively normal scores. While causality can’t be proven, researchers controlled for family background, mental health, and other substances, suggesting that delaying cannabis use may help protect the developing brain. The findings come from the ABCD study and were published in Neuropsychopharmacology, with even small cognitive differences potentially affecting learning, standardized testing, and daily functioning.