Chronic teen cannabis use may negatively impact brain's reward system, increase risk of addiction cpikul@brown.edu June 4, 2026 PROVIDENCE, R.I. [Brown University] — A new study shows that among teens who use cannabis, the drug may interfere with the brain’s reward system at a time of crucial development, and higher-potency cannabis products have more pronounced effects. “Adolescence is a critical window for brain development,” said lead study author Sarah A. Thomas, an assistant professor of ps