Dr. Frances Jensen: Figuring Out What’s Going on in the Teen Brain

In 2015, Dr. Frances E. Jensen made the New York Times best-seller list with her book The Teenage Brain: A Neuroscientist’s Survival Guide to Raising Adolescents and Young Adults (Harper, 2015). Cowritten with Amy Ellis Nutt, the book gathers what we’ve discovered about adolescent brain functioning and, in the process, dispels some commonly held myths about the teen years. The book is accessible, even warm, while at the same time including rigorous scientific data that demonstrates the teenage brain isn’t, as Jensen herself had once thought, “an adult brain with fewer miles on it.” In fact, one of the traits of the teen brain is its plasticity: as Jensen says, “If the human brain is very much a puzzle, then the teenage brain is a puzzle awaiting completion.”

Jensen, a neuroscientist and Solo Mom of two boys, came to write the book out of frank curiosity. “[My kids] were developing very, you know, independently, and doing some very interesting things,” she said in a C-Span Q&A. When her auburn-haired son Andrew returned home from a friend’s, having dyed his hair jet black, she says she was a little taken aback.

As she shares in The Teenage Brain, Andrew then wanted to add red streaks to his new inky hair. Jensen, after taking a breath, wanted to know why. “[M]y sweet-natured firstborn son had suddenly become unfamiliar, unpredictable, and bent on being different,” she says. “As his mother and a neurologist, I thought I knew everything there was to know about what was going on inside my teenager’s head. Clearly I did not . . . So as a mother and a scientist, I decided I needed to—I had to—find out.”

The Teenage Brain is the groundbreaking result of her curiosity, and if it has helped parents of teens better understand what’s going on not only inside but outside their kids’ heads, it isn’t just for the parents. Jensen thinks it’s important for kids to understand what’s going on, too. “During the teenage years, our brains are both more powerful and more vulnerable than at any other time of our lives,” she said in a 2015 interview with the Association for Supervision and Curriculum Development. And kids need to know that. “[T]he teenage brain is highly impressionable and excitable because it has so many synapses, and synapses grow by being excited and turned on,” she says. The situation is a double-edged sword: “[G]ood experiences leave their mark much more quickly [on teens]—but so do bad experiences. The clinical research shows that binge drinking, substance abuse, and stress all tend to have a stronger effect on teenagers than on adults.”

To add to that, impulsivity and responsible decision making aren’t traditionally a hallmark of the teen years. The reason can be traced to brain development, Jensen explains. “We have a natural insulation . . . called myelin,” she told NPR in 2015. “It’s a fat, and it takes time. Cells have to build myelin, and they grow it around the outside of these tracks, and that takes years.” The insulation process starts in the back of the brain and moves toward the front. “And what’s in the front?” Jensen asks rhetorically. “Your prefrontal cortex and your frontal cortex. These are areas where we have insight, empathy, these executive functions such as impulse control, risk-taking behavior.”

Jensen hopes parents will read the book and gain an appreciation for the importance of staying connected to their kids, especially in an era of constant online and media exposure. “I guess what parents have to realize is that you need to sort of stay on top of your—of being connected to—your teenager,” she told C-Span. She elaborated in an interview with the Guardian: “Teenagers need to become independent, but we live in a very complex world, and no other teenage generation in history has had this much stimulation and exposure to the many potential stresses that arise from their being online. Because of this, parents do need to be vigilant and stay connected with them.”

And Jensen’s boys? They are now in their 20s. She’s graduated from being the Solo Mom of teens. Asked what it was like, raising her sons, Jensen’s response is immediate. “I loved every minute of it,” she told C-Span. “It was the journey of my life.”

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