Science Says Your Brain Isn't Fully Developed Until You're This Age

While the age at which you legally become an adult is 18, your brain isn't fully developed yet. According to Insider, the prefrontal cortex is the part of the brain that helps with impulse control and that's still not completely done growing even when 18-year-olds are graduating high school and heading off to college, the military, working full-time, or backpacking across Europe. 

The Society for Neuroscience claims that the white matter in your brain doesn't peak until you are about 40 years of age. White matter is found deeper in the brain, while the gray matter is on the outside. White matter is made up of nerve fibers covered by myelin that serves to protect those neurons (via MedlinePlus). Maturity is connected to the prefrontal cortex, located at the front part of the frontal lobe. The prefrontal cortex is responsible for cognitive abilities and control, decision making, planning, problem-solving, and impulse control. 

So, when is your brain fully developed?

While you might legally become an adult at 18-years-old, neuroscientists have identified a different age as to when your brain becomes fully developed. An article published in BBC News points to independence as one of the major markers of a mature mind, which plays on the legal aspects of leaving your parent's guidance and financial support. Some say it's intelligence that determines whether or not we have become fully developed. Developmental neuroscientists, however, are focusing on impulse control and rationality when it comes to brain development.

There are clear differences between a teen's brain and an adult's brain. According to the University of Rochester Medical Center, good judgement and rationality are things that teens haven't yet mastered because their brains aren't fully developed yet. Adults think with their prefrontal cortexes, the rational part of the brain that adults use while thinking about long-term consequences and good judgement. On the other hand, teens think with their amygdala, the emotional part of the brain. The American Psychological Association adds that teens use gut reactions and fear when making decisions with the amygdala parts of their brains. 

The University of Rochester Medical Center and American Psychological Association agree that the brain isn't fully developed until age 25, and that seems to be the consensus for many developmental neuroscientists.