Are dangerous teens’ brains too mature?

Why do many teens do dangerous things—speeding, having unprotected sex, drinking and driving? One theory is that areas of the brain involving behavioral control are slower to develop in these adolescents than in teens who behave more cautiously. However, a new study indicates that teens who engage in dangerous behaviors exhibit increased —not decreased—white matter maturity.

Gregory Berns and colleagues used an imaging method called diffusion tensor imaging (DTI) to explore the development of white matter tracts in the brains of 91 teens between the ages of 12 and 18.They also asked the teens to complete the Adolescent Risk Questionnaire, which measures levels of dangerous activity.

After adjusting for age, the researchers detected significant evidence of increased myelination and/or density of fibers—both evidence of greater brain maturity—in the teens who took more risks. “The direction of correlation,” they say, “suggests that rather than having immature cortices, adolescents who engage in dangerous activities have frontal white matter tracts that are more adult in form than their more conservative peers.” The researchers conclude that “precocious development of these tracts may predispose some adolescents to engage in behaviors that society considers too adult in nature for their chronological age.”