There have been enough popular science "brain" books published by now that even before looking at this one, we can expect several features, given the current state of neuroscience. First, it will be speculative and vague; neuroscience can give some promising hypotheses about how to explain behavior, in conjunction with some broad generalizations about the sociological conditions of the people they are discussing, in this case teens. Second, it will tell us very little new about how to intervene to change the behavior and mental states of concern, because there is not much new knowledge about how to do that. The neuroscience, when it explains anything, mainly just reiterates what we already knew. Third, much of the advice and information it will give turns out not to be neuroscience at all, but from social psychology, other areas of cognitive psychology, or rough and ready ideas from theories of psychotherapy. Fourth, they tend to minimize other forms of insight that focuses more on social explanation. In short, when these books are done well, they often provide some useful advice, but most of the neuroscience is largely irrelevant, and is just a way to make the ideas seem more convincing. When they are done badly, they are no more useful than a book of new-age spirituality.
The Teenage Brain is engagingly written, with plenty of anecdotes about the author's own children when they were teenagers. It covers many areas of concern to parents including sleep, drugs, alcohol, stress, mental illness, cell phones, sports and concussion (probably the chapter that makes the most use of brain science in ways to helpfully guide parental decisions), and criminal behavior. Oddly, there's not much about sexual behavior. It goes into the differences between teenagers and adults with a fair amount of detail, and gives a fairly broad picture, taking into a variety of perspectives. It tends to be reductive and simplistic, but it would be tiresome for a book to constantly acknowledging qualifications and uncertainties about its claims. It has some interesting information about the findings of modern neuroscience that help its claims. Jensen does refer quite a lot to evolutionary explanations of why teenagers are as they are, which borrows rather too much from the reader's willingness to go along with speculation, given the vastly evidentially unsupported state of evolutionary psychology when it attempts to give any detailed explanations.
Many of Jensen's anecdotes are about how parents complain to her that their teens don't think things through, don't pay attention, make rash decisions, make unwise decisions, or sleep a lot. Her response is effectively to say "it is because of their brains." Presumably, she has found that parents are given some comfort by this kind of response, or are less inclined to get frustrated when they accept this sort of explanation. It's puzzling why it would be just as good to reply "that's just the way teens are" without any reference to the brain. Jensen does spend time talking about how to change the behavior of teens, rather than simply accepting that there is nothing to be done. Fortunately, she does not recommend any brain surgery; her suggestions are all about sensible parenting.
© 2015 Christian Perring
Christian Perring, Professor of Philosophy, Dowling College, New York