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Original Investigation
June 2014

Higher Crash and Near-Crash Rates in Teenaged Drivers With Lower Cortisol Response: An 18-Month Longitudinal, Naturalistic Study

Author Affiliations
  • 1Faculty of Medicine and Health Sciences, University of Sherbrooke, Longueuil, Quebec, Canada
  • 2Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
  • 3Douglas Hospital Research Centre, McGill University, Montreal, Quebec, Canada
  • 4Virginia Tech Transportation Institute, Blacksburg, Virginia
  • 5Department of Statistics, Virginia Tech, Blacksburg, Virginia
JAMA Pediatr. 2014;168(6):517-522. doi:10.1001/jamapediatrics.2013.5387

Importance  Road traffic crashes are one of the leading causes of injury and death among teenagers worldwide. Better understanding of the individual pathways to driving risk may lead to better-targeted intervention in this vulnerable group.

Objective  To examine the relationship between cortisol, a neurobiological marker of stress regulation linked to risky behavior, and driving risk.

Design, Setting, and Participants  The Naturalistic Teenage Driving Study was designed to continuously monitor the driving behavior of teenagers by instrumenting vehicles with kinematic sensors, cameras, and a global positioning system. During 2006-2008, a community sample of 42 newly licensed 16-year-old volunteer participants in the United States was recruited and driving behavior monitored. It was hypothesized in teenagers that higher cortisol response to stress is associated with (1) lower crash and near-crash (CNC) rates during their first 18 months of licensure and (2) faster reduction in CNC rates over time.

Main Outcomes and Measures  Participants’ cortisol response during a stress-inducing task was assessed at baseline, followed by measurement of their involvement in CNCs and driving exposure during their first 18 months of licensure. Mixed-effect Poisson longitudinal regression models were used to examine the association between baseline cortisol response and CNC rates during the follow-up period.

Results  Participants with a higher baseline cortisol response had lower CNC rates during the follow-up period (exponential of the regression coefficient, 0.93; 95% CI, 0.88-0.98) and faster decrease in CNC rates over time (exponential of the regression coefficient, 0.98; 95%, CI, 0.96-0.99).

Conclusions and Relevance  Cortisol is a neurobiological marker associated with teenaged-driving risk. As in other problem-behavior fields, identification of an objective marker of teenaged-driving risk promises the development of more personalized intervention approaches.