Reviewed in the United States on October 21, 2014
I was a little leery of this book from the opening pages. Dr. Jensen opens with a horror story - her teenage son came home with his hair dyed black. She just couldn't imagine how such a level-headed kid could do such a thing. And, worse, he wanted to get red streaks as well. So her solution was to spend a fortune taking him to her "color guy" to get it done right. I guess Dr. Jensen and I have different ideas on parenting. I made a vow early on never to sweat the small stuff, and I consider hair color well within that category - if that's the worst my kids do in their teenage years, I will count my blessings. Furthermore, if they're going to experiment with hair color, they can take responsibility and accept the consequences themselves. Green hair is not fatal.
But maybe the information on the teenage brain is better, and we can just agree to disagree about parenting. Dr. Jensen clearly knows her stuff as far as brain development, anatomy, physiology and chemistry go, but I found her information a bit weak, disorganized and failing to thoroughly connect the dots, and I found many of her illustrative stories distracting and a bit alarmist.
Dr. Jensen starts with an overview of brain structures relevant for cognitive and emotional functioning, including, among others, the brain stem, the amygdala, the hippocampus and the cerebral cortex, especially the frontal lobes. She shows how brain development is a process of both "pruning", in which excess neurons are selectively cut back based on environmental stimulation or lack thereof and "myelination" in which the neurons are coated with a fatty sheath with helps to send signals faster along neuronal pathways. The pruning allows for specialization of function within brain regions and allows neurons with to "fire" and "wire" together creating associations to learn new information and hone new skills. Myelination allows different brain regions to be more connected and integrated.
These developmental processes start from the back, more primitive parts of the brain and work forward toward the more advanced "executive" parts of the brain. The amygdala, for instance, is one of the most primitive parts of the brain which allows for recognition of and response to threats and stress. It is highly reactive to emotion, but until the frontal lobes are better developed and integrated, the child/teenager has little ability to process and manage that emotion and control impulses.
The processes of pruning and myelination are part of brain "plasticity", meaning that the brain has great potential to change. For a long time it has been thought that this period of great plasticity was limited to early childhood (up to about age five), which is why early childhood enrichment and learning have been considered so important. But science is now showing us that adolescence (beginning in the early teen years and continuing through young adulthood, approximately the early twenties) is another period of great plasticity. Which means that teens are capable of learning and changing nearly as much as young children. This means that adolescence is an exciting time of opportunity, growth and development. But it also means that the perils of the teen years are even more intense because negative experiences during these years are more likely to be encoded in the brain and lead to life-long emotional, relational, legal and general health problems.
Dr. Jensen spends a chapter discussing what this means for teens' ability to learn and the importance of sleep (along with a discussion about teens' diurnal cycles, indicating that teens' tend to be sleep deprived because they are biologically programmed to go to sleep and wake up later than adults, but are nonetheless required to function on adults' schedules and how this is potentially harmful for teen brain development). She then spends a chapter discussing risk-taking behavior in teens and how the reward centers in teens' brains are wired to respond much more excitedly to potential rewards (including and especially peer approval) than adults' brains - to the point that teens have difficulty evaluating risks if the pull of the reward is too strong.
Next Dr. Jensen spends a chapter each discussing potential harmful influences and obstacles frequently encountered in the teen years, including tobacco, alcohol, pot, stress, mental illness, digital overload and concussions, along with how those factors can affect teens' brains and why teens are so much more susceptible to their influence. I do have an issue with her chapter on stress because she seems to be saying that teens are under a lot more stress than adults. I think it's more that teens have fewer and less developed coping mechanisms than adults, so the stress they have seems greater ("drama"). But I'd say it's absurd to suggest that someone who has a home and food to eat is under more stress than the parents who are working to provide that home and food.
Finally Dr. Jensen wraps up with a look beyond adolescence into young adulthood and how continuing brain plasticity offers unique opportunities, yet continuing perils, for young people. She provides some advice on how to help the burgeoning adult in your life make a successful transition, which is pretty much just a developmental continuation of her advice for structuring your teens' life for maximal likelihood of success. Basically it boils down to don't be afraid to be involved in your child's life. Although the quality and intensity differ as children age, children continue to need supervision and guidance well into adulthood.
There is certainly a lot of good information in this book, but it's just not presented as effectively as it could be. Dr. Jensen is trying hard to present precise scientific information in generally understandable layman's terms, but she doesn't get either quite right. She is trying hard to be both scientific and folksy, but some of her jargon is not adequately explained (especially when a previously discussed brain structure or function comes up again in later chapters) and sometimes her folksy tone makes it difficult to accept her scientific viewpoint.
In addition, a lot of her presentation of studies relies on correlational studies without addressing the issue of causation. For instance, she'll talk about brain abnormalities found in teens who smoke, drink or use illegal drugs with the implication that the drugs caused the abnormality. But there also needs to be a discussion of the possibility that brain abnormalities may be likely to lead teens to such behavior - perhaps they are more prone to risk-taking or more responsive to rewards, or perhaps they are "self-medicating" to deal with the effects of their abnormalities.
Finally, Dr. Jensen seems to believe that teens need to be beaten over the head with alarmist messages about the dangers of the world. I agree that repetition is helpful for learning, but generally speaking, lack of information is not why kids get into the problems they do. Every kid by now knows that smoking causes lung cancer and that driving under the influence greatly increases the chance of serious collision. The problem, however, is that teens think that they are invincible. It can help to show them situations involving kids their own age, but such situations can also be traumatizing and paradoxically increase the likelihood of the behavior. Seeing a mangled car that was involved in a DUI accident, for instance, can lead to a variety of emotional responses including excitation. There are no easy answers, of course, but keeping the lines of communication open is vital. Beating kids over the head too much can lead them to tune out and shut down.
There have been a spate of books lately on brain development and what it means for raising children and adolescents. In my view, this is one of the weaker of those books. For a better view of the brain science side of the equation I recommend Laurence Steinberg's AGE OF OPPORTUNITY (although I part company with him too on a lot of his applications of what we've learned about teenage brain development). And although it's aimed more at parents of younger kids rather than teenagers, for the child-rearing angle I recommend Daniel Siegel and Tina Payne Bryson's NO DRAMA DISCIPLINE. The important take-away of that book is how children's and teen's brains are wired to respond to perceived stress and threats, including that posed by how we as parents interact with our kids when we get angry and punitive. And for a very thorough look at how stress affects all human systems, including the brain, I recommend Robert Zapolsky's WHY ZEBRAS DON'T GET ULCERS. The more we learn about brain development and functioning over the life course, the more we seem to realize that stress is one of the prime determinants in whether people thrive or fail. As parents, including parents of teens, the best gifts we can give our children are a safe and secure environment and the tools to manage and rebound from stress and trauma when they do occur.