Your Teenager’s Brain Exposed

10 Scientific explanations for adolescent impulsivity, moodiness and general alien-like behavior


First, let’s be clear: these are explanations, not excuses. No one’s condoning your son’s tendency to drive 20 miles over the speed limit or your daughter’s ability to shapeshift from angel to imp in 10 seconds flat. But if nothing else, understanding the physical developments (or lack thereof) behind that “thick skull of theirs” may help you realize that your teen’s crazy behavior isn’t necessarily due to bad parenting.

So until they mature into responsible and congenial adults, you’ll have to work hard to open the door to understanding, communication and compromise. Even if it’s only to hear it slam when you enforce curfew.

  1. When reading facial expressions to determine the emotions of another person, teenagers use the amygdala, the part of the brain that guides “gut” reactions. Adults, however, tend to rely on the part of the brain that controls reason and planning, called the frontal cortex. While the amygdala is about reactions, the frontal cortex is about rational thought. This may explain why adolescents tend to take more risks and act more impulsively than adults.
  2. The gray matter (neurons) of the brain continues to thicken through childhood, peaking at around 11 for girls and 12 for boys. Around puberty, the excess connections are thinned or pruned, leaving only the essential (and most-used) connections. You can see why engaging in activities like piano or chess at a young age (or any age, for that matter!) would help your teen later; with neural connections it’s use it or lose it!
  3. Don’t worry that you’re “babying” a teen who needs a little extra help getting organized or planning his next science project. The frontal lobe – which controls strategizing, planning and organizing, among other things – is still developing. No one’s going to blame you for that little nudge or note on the calendar.
  4. The frontal lobe, sometimes referred to as the “CEO” because of its executive functions, also controls decision-making. You can see where this is going. Granted, everyone makes bad choices from time to time. But teenagers are known as repeat offenders in this realm, particularly with the adolescent cocktail of drugs, alcohol and hormones.
  5. It’s not your imagination: girls’ brains mature earlier than boys’. In addition, girls have larger basal ganglia, part of the frontal lobe. It’s now believed that the size of these ganglia may help protect girls from common childhood disorders, such as autism, dyslexia, ADHD, Tourette’s and learning disabilities in general – all of which are more common in boys.
  6. Yes, your athletic son may have more girls calling him at 11 p.m. than the teen who sits in his basement playing video games. But it might not be because of his great physique. It’s believed that physical activity most influences the cerebellum, the part of the brain that we use for higher thought, including social skills. So the more athletic, the more social. The more social, the more dating prospects!
  7. While the brain’s plasticity may cause you to want to enroll your child in violin lessons, Japanese and math club, don’t overlook the importance of love. As Jay Giedd, M.D. explained it in an interview with PBS: “The brain is largely wired for social interaction and for bonding with caretakers. And sometimes it’s even disappointing to people that, with all the science and all the advances the best advice we can give is things that our grandmother could have told us generations ago: to spend loving, quality time with our children.”
  8. Teenagers don’t have as much myelin (that fatty coating around nerves that’s often referred to as “white matter”) as adults. In fact, this “nerve insulation” doesn’t complete until the mid-20s, which means there are fewer connections to the part of the brain insight (that darn frontal lobe again!). And without insight, your teen may frequently come across as selfish and unable to recognize how their actions affect others. Yes, it’s rude. But it’s also partially due to normal development.
  9. Our internal body clocks – called Circadian rhythms – change at puberty. That’s why teens usually fall asleep later than kids and adults, and have a harder time waking up early. It’s a brain thing – not an act of defiance against your imposed bedtime.

10. The best brain news might be that your teen’s brain is “plastic,” that is, always capable of change. In fact, numerous studies have shown that our brains can be trained (to increase attention, strengthen memory, raise IQ, etc.) well into our 80s. Teenagers who undergo intense one-on-one brain training can strengthen the neural connections, making them faster, smarter thinkers and learners – in school, athletics, extracurricular activities –  and on the road.

So there you have it – a rundown on your teen’s ever-changing brain. It’s not always pretty, easy or predictable, but it’s also not permanent. Remind yourself that it’s a normal phase of development and it won’t last forever. And while you can’t lock them in their rooms until they’re 18, you can tighten the door’s hinges! 




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