In an editorial published today in JAMA Pediatrics, I commend the work being done by my teen driver safety colleagues at Virginia Tech as part of the Naturalistic Teen Driving Study. The study by Ouimet et al.¹ examines the association between cortisol reactivity and crashes and near-crashes among newly-licensed teens. “Cortisol reactivity” is a hormonal response to stress that can be measured. After examining the salivary cortisol reactivity in response to a stress-inducing task in a sample of 42 16-year-olds over an 18-month period, they found that teens with lower cortisol reactivity in response to stressful situations had higher crash and near-crash rates than those with higher cortisol reactivity.
Their study supports other research on normal emotional responses that lead to learning. This pathway may explain individual differences among teens in their sensitivity to stimuli in the driving environment that contributes to their learning. Other research shows that some hormonal response helps with optimal adaptation to environmental challenges, but too much stress can lead to cognitive deficits rather than learning. According to this theory, how teens emotionally respond (as indicated by greater cortisol reactivity) to challenges experienced during the learning-to-drive process may promote effective learning of necessary skills.
While these findings do present an interesting new line of research, they do not suggest that we are close to developing a clinically useful biomarker-based diagnostic test nor a pharmaceutical therapy to reduce the risk for teen driver crashes. Continued research is needed to better characterize the relationship between cortisol reactivity in response to stressors and crash risk in the general population of healthy teens and among those teens who might be at higher crash risk due to preexisting conditions, such as Attention Deficit/Hyperactivity Disorder (ADHD).
What physicians can do is guide families during the learning-to-drive process by encouraging them to offer 65-plus hours of supervised practice and to follow Graduated Driver Licensing provisions. Most important, physicians can help parents determine if their teens are ready to drive.
¹ Ouimet MC, Brown TC, Guo F, Klauer SG, Simons-Morton BG, Fang Y, Lee SE, Gianoulakis C, and Dingus TA. Higher Crash and Near-Crash Rates in Teenaged Drivers With Lower Cortisol Response: An 18-Month Longitudinal, Naturalistic Study. JAMA Pediatrics.2014 April 7 (online first).