Attending my former high school’s annual music concert recently, I watched as teenagers between the ages of 13 and 18 played their wind instruments, all of them conforming to the tempo set by the conductor’s baton. Each student was dressed in accordance with the black-and-white dress code – yet within that code, their outfit choices could not have been more different. I started thinking about how teenagers are conformists as well as nonconformists, and how perceptions of young people can be very much on the mark, or utterly mistaken.

These musings were undoubtedly influenced by a book I was reading at the time: “Inventing Ourselves,” written by Sarah-Jane Blakemore, a professor of cognitive neuroscience at University College London and recipient of the 2015 Klaus J. Jacobs Research Prize. The book focuses on Blakemore’s research on adolescent brain development and discusses the relevant literature.

Throughout history, teenagers and their sometimes erratic behavior have been criticized by their elders. Early in her book, Blakemore points out that even in ancient Greece, philosophers like Aristotle and Socrates spoke of youth much as many parents and other adults do today. Socrates, for example, observed, “The children now love luxury. They have bad manners, contempt for authority; they show disrespect for elders and love chatter in place of exercise.” Similarly, Aristotle once noted that young people are “lacking in sexual self-restraint, fickle in their desires, passionate and impulsive.”

What changes during adolescence, as children are gradually approaching adulthood? When it comes to the brain – basically everything! “Adolescents’ brains are physically different from younger children’s brains and from adult brains,” Blakemore writes. This has to do with differences in the rate at which various areas of the brain mature. Structural magnetic resonance imaging (MRI) has shown that significant changes take place in the prefrontal cortex– the brain area that is responsible for decision-making, planning, executive functioning, and the inhibition of inappropriate or risk-taking behavior during adolescence and early adulthood.

This may explain why teenagers tend to do risky things that we, as adults, consider “stupid.” When an individual takes a risk, the brain’s positive reward system, the limbic system, is activated. In teens, the limbic system is already quite mature and very sensitive to the reward that risk-taking promises. However, the development of the prefrontal cortex lags behind.

According to Laurence Steinberg, this “developmental mismatch” between the maturity and functioning of these two brain systems explains why teens take more risks: The prefrontal cortex, which keeps us from making impulsive decision and inhibits risk-taking, is not yet fully mature in adolescence, but the limbic system, which provides a thrill, is.

Blakemore recounts a personal experience: Late one night, she saw a teenage girl walking along the street, so she stopped and offered her a lift. As Blakemore was driving her home, the girl told her that she had been at a party with friends, and despite having no money with her, and although her phone battery had died, she was having so much fun that she decided to stay at the party even though that meant missing her bus. If Blakemore hadn’t given her a ride, she would have ended up walking the eight miles back to her home late at night.

“There is no such thing as an average adolescent brain, and teenage brains are not broken.”

Blakemore refers to that risky situation as a “hot context,” explaining that “when in a so-called hot context, teens are more likely to make risky decisions because they tend to conform socially with their friends’ behavior and their emotions are running high.”

When teenagers take risks, their brain’s reward center undergoes more activation than that of an adult. This effect is not unique to humans, but can also be observed in animals. For instance, adolescent mice take more risks than adult mice, and when given access to alcohol, teenage mice drink more when they are with their peers.

It is only within the last 25 years that brain researchers have been able to look inside the living human brain to examine its structure and observe brain activity across the lifespan. This is largely thanks to the development of such brain-imaging techniques as MRI. We now have a comprehensive understanding of how the human brain develops. Some brain regions continue to mature through childhood and adolescence and even into the 20s and 30s.

So, have we succeeded in unlocking the secrets of “the teenage brain”? Unfortunately, no. As Blakemore points out at the end of the book, there are always interindividual differences when it comes to brain development; the when and how may differ from one individual to another, and they depend at least in part on personal experience.

“This should be on the must-read list for anyone interested in translating research findings concerning brain development into policy and practice.”

The bottom line is that there is no such thing as an average adolescent brain, and teenage brains are not “broken.”We should recognize and embrace the fact that teenagers’ brains are undergoing dramatic and very important changes.

Combining the personal and the scientific, Blakemore’s book is as informative as it is readable. It is essential reading for anyone who wants to know more about how adolescents are wired. Indeed, “Inventing Ourselves” should be on the must-read list for anyone interested in translating research findings concerning brain development into policy and practice.


Inventing Ourselves: The Secret Life of the Teenage Brain, by Sarah-Jayne Blakemore, Doubleday, March 2018

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