Adolescence is a time of dramatic changes in brain structure and function. The malleability of the adolescent brain explains why this period is such a crucial time of growth: Young people are testing limits, enjoying novel experiences and social interactions, and becoming independent. At the same time, the specific ways in which the teenage brain remains immature, particularly the less developed circuits of the prefrontal cortex relative to other brain areas, contribute to the propensity of adolescents to engage in impulsive behaviors and to take risks (Somerville et al., 2010). This is crucial for healthy development; but inevitably, for many teens, it also includes a variety of unsafe behaviors like experimenting with addictive substances including tobacco, alcohol, marijuana, and other drugs. The fact that key brain areas have not sufficiently matured may make the teen brain more susceptible to being altered by those substances in both the short- and long-term, maybe even permanently.
