Dear 18-Year-Old Brain

Dear 18-Year-Old Brain,

©CurvaBezier/Getty Images

©CurvaBezier/Getty Images

Thanks so much for managing my son for all these years. What a time you two are having together!

I remember when you learned where your toes were, how to count, and what hot and cold felt like. I'll never forget the day you solved a complex math problem that I could not. Believe it or not, it delighted me to realize your development was surpassing my own in that way.

A few weeks ago, we celebrated your 18th birthday. Congratulations! I am so proud of who you are and of all you've learned. You are a senior in high school, and so many blessed opportunities await you.

Funny thing, though: you sort of thought passing that 18-year-old mark means you're all grown up. In many ways, that's true. You can now vote, join the armed services, get married, buy firearms, sue in your own name, and serve on a jury. That's sort of a mixed bag, isn't it?

What you cannot do is consistently make wise behavioral decisions. Don't feel bad! You're learning and growing every day! There's nothing wrong with you, technically. At 18 years of age, you're just biologically incapable of withstanding peer pressure in a truly adult way.

Neuroscience shows that you will mature more completely in about seven years. After age 25, your prefrontal cortex will catch up with the rest of your development. Again, don't feel bad, Brain. It's the way we all grow.

One book that taught me about all this is Welcome to Your Child's Brain by two neuroscientists, Sandra Aamodt and Sam Wang. In a 2011 interview on NPR, Dr. Aamodt highlighted some key concepts:

The changes that happen between 18 and 25 are a continuation of the process that starts around puberty, and 18 year olds are about halfway through that process. Their prefrontal cortex is not yet fully developed. That’s the part of the brain that helps you to inhibit impulses and to plan and organize your behavior to reach a goal.
— Sandra Aamodt, neuroscientist and co-author of the book Welcome to Your Child's Brain

It's an established, verifiable fact that the "adult brain" is still cooking until age 25. Car rental companies have seen this research. You see, 18-Year-Old Brain, that's why rental companies don't really trust their cars to people under age 25. 

Why am I writing this letter to you now, though? Why am I telling you stories about neuroscience?

Because you are going to a New Year's Eve party tomorrow.

When I asked if the parents would be home all night, your good-natured eye roll worried me--is it possible to dislocate eyeballs, I wondered? When I asked if there would be any illegal substances available at the party, you smiled patiently, if a bit condescendingly. It seems you really did imagine all those questions would disappear at the stroke of midnight on your 18th birthday.

Well, here's a little more research to explain why I won't stop asking these questions for a few years:

A 20 year old is 50 percent more likely to do something risky if two friends are watching than if he’s alone.
— Sandra Aamodt, neuroscientist and co-author of the book Welcome to Your Child's Brain

A 20 year old! You have 2 more years to go before you work your way UP to a 50/50 chance to make a healthy choice at a party!

You are an impressive organ, Brain in my Son. Research shows that individual brains develop at different rates, and I'm guessing you are ahead of your peers in many ways. You show great discipline in your school work, and you are genuinely cheerful and helpful at home. You are a good example to your younger siblings' brains. Thank you.

Nonetheless, even brains that develop slightly ahead of schedule can't miraculously skip years of growth. At 11 months old, for example, you walked slightly earlier than many babies. But it's not like you were a human marvel, taking steps within hours of birth. No, development takes time. A lot will happen between the ages of 18 and 25. Just think! Seven more years of conversations about healthy choices and brain development and all the rest. Thanks be to God.

I love you!