Why Our Young Adults Do the Things They Do

Brain health of younger adultsAbout a decade ago, Frances Jensen’s sweet-natured 15-year-old son returned home from a friend’s house with his hair dyed black and announced he was planning to add red streaks.

Jensen’s reaction was typical of countless parents who suddenly confront a stranger living in their house. “I was gobsmacked. Is this really my child?” she writes.

While many of us would just start ranting, Jensen, then a Harvard Medical School neurology professor and researcher, was inspired by the incident to start looking into why her son and other adolescents suddenly turn into “unfamiliar, unpredictable” people.  Her research eventually culminated in The Teenage Brain: A Neuroscientist’s Survival Guide to Raising Adolescents and Young Adults.

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While not exactly light beach reading, her book is worth diving into for the insights it offers about both our teenage children and grandchildren as well as our often puzzling 20-somethings.

Some key points from the book:

  • Until the last decade or so, little research was devoted to the teen and young adult brain. Instead scientists explored infant and child development believing — wrongly it turns out — that brain growth was complete by kindergarten. So we really didn’t need to go crazy with flash cards and Baby Einstein products in the crib. Now, thanks to advances in both basic science research and technology, the study of the brain has become “transformative,” Jensen says.
  • There are miles of wiring inside the brain that need to be insulated before adulthood. The insulation process starts in the back of the brain and does not fully finish until the early to mid-20s and sometimes later, especially for men. The last place to complete connections are the frontal lobes, which control reasoning, insight and impulses. Young people are not “firing on all cylinders,” Jensen says.
  • Because of the way their brains are wired, young adults are more susceptible to drug, alcohol and smoking addictions. Jensen explains that addiction is a form of learning and memory that occurs in the reward-seeking area of the brain. Just as young people can learn facts more quickly than adults, they can also get addicted “faster, harder, longer” than older people — and the impact can be more toxic, actually killing brain cells.


We spoke this week with Jensen, now chair of the neurology department at the University of Pennsylvania’s Perelman School of Medicine, about her findings and how they relate to young adults.

Q. You write that the brain is still immature even after college and often until the mid-20s, especially for young men.

A. Yes, I think the car rental companies realized that because they don’t let people under age 25 rent cars! While this is the perfect age to be acquiring skills, they really still don’t have impulse control and their emotional responses to situations are not mitigated by the reasoning we have as older adults.

Q. So what can parents do to help them through this period?

A. So many move home after college, and parents should consider it a gift rather than a nuisance. It’s your last chance to influence their behavior through role modeling by doing things like making your bed, paying your bills on time, not leaving dishes in the sink. They watch you and will learn to model that this is how an adult acts.

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Q. What about adult children who are struggling where to go next with their lives?

A. You can’t helicopter them, but as parents we know so much about them. We can help them develop the insights they need to make decisions by taking the conversation to a higher level. Don’t give them the pros and cons about a decision, for example, but model for them how to make such a list. Your role is as an adviser, not a problem solver.

Mary W. Quigley’s blog, Mothering21, tackles parenting of emerging adults and beyond.

Photo: Maxkabakov/iStock

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