Higher crash and near-crash rates in teenaged drivers with lower cortisol response: an 18-month longitudinal, naturalistic study.
OBJECTIVE
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.


METHODS
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.


METHODS
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
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.
Faculty of Medicine and Health Sciences, University of Sherbrooke, Longueuil, Quebec, Canada2Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
Marie Claude
MC
Ouimet
Douglas Hospital Research Centre, McGill University, Montreal, Quebec, Canada.
Thomas G
TG
Brown
Virginia Tech Transportation Institute, Blacksburg, Virginia5Department of Statistics, Virginia Tech, Blacksburg, Virginia.
Feng
F
Guo
Virginia Tech Transportation Institute, Blacksburg, Virginia.
Sheila G
SG
Klauer
Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.
Bruce G
BG
Simons-Morton
Department of Statistics, Virginia Tech, Blacksburg, Virginia.
Youjia
Y
Fang
Virginia Tech Transportation Institute, Blacksburg, Virginia.
Suzanne E
SE
Lee
Douglas Hospital Research Centre, McGill University, Montreal, Quebec, Canada.
Christina
C
Gianoulakis
Virginia Tech Transportation Institute, Blacksburg, Virginia.
Thomas A
TA
Dingus
D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D001334:Automobile Driving; D015415:Biomarkers / Q000097:blood*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D012044:Regression Analysis; D012309:Risk-Taking; D013315:Stress, Psychological / Q000097:blood; D014481:United States
D015415:Biomarkers; D006854:Hydrocortisone