Drugs and alcohol disrupt the brain's communication system and cause incorrect messaging by fooling the brain's pleasure center. Teen brains are actively growing and have more receptors, meaning drugs stay in the brain longer than in adults. Any substance use teaches teen brains to form addictions faster than adult brains. Studies show teens who used marijuana before age 16 performed worse on IQ tests and had affected brain regions responsible for decision making. Drugs and alcohol affect teens more severely and for longer than adults, increasing risks of negative effects and addiction.