Adolescence is a time of great development. The brain is young, malleable and eager to experience new things. The teenage years are also the most crucial window for learning. Drug addiction, however, is a learned disease, and younger brains are the most susceptible. It takes about 25 years for a brain to fully develop. Although the brain reaches 90% of its adult size by age six, the brain undergoes major, dynamic changes throughout adolescence. There are four ways that the adolescent brain differs from the adult brain. The first one is the dopamine levels wherein there is more dopamine activity in the brain’s reward center in the early adolescence than at any other point in their life. Teens, therefore, go out of their way to seek rewarding experiences, such as experimenting with new drugs. Second is the hyper-rational thinking that is the part of the brain which is in charge of decision-making that is still not fully developed in adolescence. The next one is pruning which is like brain conditioning. The choices teens make now can affect their brains for life! And the last one is myelination where the brain’s white matter called myelin; enables nerve signals to quickly communicate with different parts of the brain.