Frances Jensen ’78, M.D., is a distinguished professor and neuroscience researcher, but when her sons reached adolescence—morphing from cherubic little boys into “utterly mystifying creatures” with dyed hair and mood swings—she was as baffled as any parent. So she turned to the data. There, she found rational explanations for adolescents’ confounding behaviors—as well as startling facts about how sleep deprivation, stress, alcohol and cannabis affect the developing brain. When she realized how hungry other parents, and teens themselves, were for good information presented without judgment, Jensen turned her findings into an acclaimed book, The Teenage Brain: A Neuroscientist’s Survival Guide to Raising Adolescents and Young Adults (Harper, 2015). Jensen, who is chair of the neurology department at the Perelman School of Medicine at the University of Pennsylvania, wrote the book with Pulitzer Prize–winning journalist Amy Ellis Nutt ’77. Here, Jensen discusses the unique opportunities of this critical period of brain development.

Until recently, the teenage brain was a relatively neglected research area.

The teen brain was enshrouded by misinformation and myth—the biggest myth of all being that the adolescent brain is more or less equivalent to the adult brain, just with fewer experiences. We now know that’s completely wrong. Adolescence is a discrete moment in brain development. The brain is the last organ in the body to mature and takes until the mid-to-late 20s to complete the process. That means that even upon leaving college, your brain is not done.

The teen brain is more powerful than the adult brain.

Teens are primed for learning; they have more of the building blocks of learning and memory, and those building blocks are programmed to operate at higher capacity. But there’s a “use it or lose it” system at work; synapses that don’t get used are pruned. We once believed that a person’s IQ was fixed, but in fact only a third of teens’ IQs remain static during adolescence. A third of teens’ IQs actually increase in a statistically significant way, while another third actually lose IQ points during adolescence.

It’s also extremely uneven.

Teens have an overabundance of gray matter—the brain cells that are the building blocks of thought, perception, motion and bodily processes. But they have an undersupply of white matter, the connective wiring that helps information flow efficiently through the brain. The brain is “wired” from back to front; myelination (the process of adding a myelin sheath around a nerve so information can flow more quickly) begins in the limbic system, which is the most animal part of our brain. The frontal lobes, which are responsible for executive functioning, are literally the last to be myelinated. So there’s a striking imbalance through adolescence: Teens have split-second access to the most impulsive parts of their brain but not to the part that regulates judgment, insight, abstraction and self-awareness.

Teens have unique vulnerabilities.

In the same way a teen can learn faster than adults, teens can also become addicted to substances faster, more easily and in longer-lasting ways. Teens are also uniquely affected by stress. This is especially worrisome today, when teens have such easy access to stressful material. When today’s teens make a mistake [online], it never disappears. The stakes are high.

The right education matters.

In most high schools, only struggling learners have their learning styles addressed through testing. But why not everyone? Wouldn’t it be great to know at age 14 that you’re a particular kind of learner and that you need a specific approach to optimize your learning? By the time they choose colleges, kids must remember that they’ll be bringing to school a brain that’s still under construction. They will, quite literally, leave with a different brain than they started with. This is a time to be deliberate and thoughtful.

As frustrating as teens can be, we need to help them.

We’re the ones with access to our frontal lobes. We need to be present, to help them think about filtering stresses and achieving balance. We must remind them—again and again and again—of the facts about how their brains work. They might have sound reasoning when it comes to SAT questions, but they won’t have it for good judgment until they’re well into their 20s. Be patient and stay connected. They need you more than they can possibly know.

Ali Benjamin’s latest book is The Thing About Jellyfish (Little, Brown Books for Young Readers, 2015).

SAQ, Fall 2015