When is an adolescent an adult?

Much of our research has examined the extended period of adolescence. Adolescence is a period of enhanced learning and adaptiveness to the many social, physical and cognitive demands of this development phase as they move from dependence to relative independence from their parents and caregivers. It is a time when youth form a sense of who they are and hope to be. While there are continued changes in brain and behavior over the lifespan, there are especially significant changes during the prolonged period of adolescence that extends into the twenties. The basic parts of the brain are intact when we are born, but the connections between brain regions is what is changing with age and experience. Relevant connections are strengthened and less relevant ones are weakened resulting in faster and more efficient communication among brain regions. One of the last regions to develop is the prefrontal cortex. This region and its connections with other brain regions has been implicated in self control and decision making and shows continued significant development into the 20s. In contrast emotion related brain regions and their connections show peak changes by the mid to late teen years. While simple, self-paced, non arousing cognitive tasks may show adultlike patterns of performance by the early to mid-teens, tasks that require strategic behaviors and decision-making under emotionally charged and demanding conditions show steady improvements in self regulation and decision making well into the twenties. These latter abilities are the very ones that require connections among both cognitive and emotional networks of the brain that are still developing into young adulthood. These findings have important implications for when adolescents can and cannot make decisions that are relevant to legal responsibility (e.g., terms of voting rights and culpability).