The Difference Between Teenage Brains And Adult Brains

By Debra Kelly on Friday, July 25, 2014
“Janie’s a pretty typical teenager—angry, insecure, confused. I wish I could tell her that’s all going to pass, but I don’t want to lie to her.” —Lester Burnham, American Beauty (1999)

In A Nutshell

Teenagers can look like adults, dress like adults, and even act like adults at times; sometimes, it might be hard to tell the teenagers from adults (and other times it isn’t hard at all). But it’s also crucial to remember that their brains are wired completely differently. It’s long been known that at the end of the day, teenagers just don’t think like adults, and that’s because the different sections of their brains aren’t connected the way they will be once they’ve matured a little more. Most specifically, teenagers lack many of the nerve connections that tie the frontal lobe to the rest of the brain, limiting their ability to think ahead.

The Whole Bushel

For years, parents have wondered just what weird thought processes make their teenage children do the irrational, stupid things that they’re known for. Crime rates go up in the late teen years, and so do the number of accidents and mortality rates. And neurological studies have shown that they just can’t help it.

It all has to do with the way the brain matures, a concept that’s been given the pretty logical name of neuromaturation. The brain is made up of white matter and grey matter. The grey matter stores all the information, and the white matter forms the connections between the different parts of the brain. Our grey matter matures when we’re between 11 and 12 years old, but the white matter hasn’t completely developed until we’re in our early twenties.

That means that the brains of teenagers literally aren’t physically fully connected. In an adult brain, there are a number of neural connections that allow the different parts of the brain to all work together. In the teenage brain, these connections aren’t fully formed yet, and it, unsurprisingly, impacts the brain’s ability to process information in a way that looks at the entire picture. It’s been found that the last part of the brain to finish developing its connections is the frontal lobe, which is also the part of the brain that governs attention span, impulses, and motivation.

Teenage brains are also more receptive to the benefits gained from certain interactions with their environment. There’s a helpful, practical reason for this, in that it can help encourage learning and exploring new experiences. But it can also lead to problems, in that the physical brain chemistry that’s milling around in teenage brains makes them much more likely to become addicted to things much more quickly than an adult, and those addictions can hold on through adulthood. The brain chemistry of an adult, on the other hand, fluctuates much less, makes pleasurable sensations return to an emotional baseline much quicker, and also makes forming habits—good or bad—take longer in adults.

Another difference between adult and teenage brains is the way that they respond to the emotions of others. In a test administered by researchers at the McLean Hospital in Massachusetts, it was discovered that when teenagers were asked to interact with images of other people and interpret the emotions on different faces, they were not only using a different part of their brain to process the information, but the conclusions they drew were very different than adult conclusions. For example, facial expressions that adults recognize as fear are interpreted as anger in teenagers, suggesting that teenagers’ inability to relate to adults isn’t just a matter of being stubborn, but may be a difference in the way they’re viewing the entire interaction.

The gradual change that parents see come over their teens that signals their maturation into adults is a physical maturation of their brains. Adult brains have a thick coating (essentially white fat) called myelin stretched over and protecting the nerves in the brain. It also makes connections faster, and the physical development of the myelin is making a teen’s behavior become gradually less like some bizarre, alien creature and more like an intelligent, responsible adult.

Show Me The Proof

PBS Frontline: Interview: Deborah Yurgelun-Todd
NPR: The Teen Brain: It’s Just Not Grown Up Yet Why Teenage Brains Are Different From Everyone Else’s