Suzana Herculano-Houzel

Adolescence is a brain thing


Pick a book about the brain at random and you’ll probably read that most of the brain’s transformations take place during the first three years of life – or, with good grace, the first ten. After that… chaos: with the brain supposedly ready, adolescence would be that phase of life where everything would be fine if only hormones didn’t get in the way.

Fortunately for teenagers and those who live with them, this can no longer be considered true. Far from being ready, the adolescent brain goes through a second long period of remodeling and learning, the end result of which is what every parent hopes for their child: they become independent, responsible and socially well-integrated.

The brain transformations of adolescence begin in the hypothalamus which, by controlling the production of sex hormones and becoming sensitive to them, allows the brain to discover sex. This is followed by changes in the reward system, which suffers a huge drop and no longer finds pleasure in what used to be pleasurable. The result is a set of diagnostic marks of adolescence: boredom, loss of interest in childhood games, impatience, a preference for novelty and a taste for risk. The whole thing is great, because it makes us abandon the pleasures of childhood and want to leave home in search of new horizons. Otherwise, who would give up their home, food and clean clothes?

The only downside is that the changes needed in the cerebral cortex to deal with the new adolescent impulses in an adult way take around ten years. Attention, language, memory and abstract reasoning are all processes that are rapidly improved and put to the test with the sudden interest in politics, philosophy and religion. On the other hand, the ability to put oneself in other people’s shoes and to anticipate the consequences of one’s own actions, the basis for good decisions and life in society, only comes at the end of adolescence, thanks to changes in the brain and a lot of experience. Time alone is not enough: becoming independent and responsible requires learning to make good decisions, and that can only be learned by… by making decisions.

Teenagers, therefore, do what they can with the brain they have – and it’s a good thing. Our duty is to help them by offering information, alternatives and the right to make mistakes from time to time. I’m hoping to continue thinking like this when my children become teenagers…

Originally published in Folha de São Paulo on April 2007

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