Opinion
EDITORIAL
Enhancing Our Understanding of Teen-Driver Crashes Dennis R. Durbin, MD, MSCE; Jessica Mirman, PhD; Allison Curry, PhD, MPH
While progress has been made in reducing the number of teens killed in motor vehicle crashes, crashes continue to be the leading cause of death for teens in the United States.1 The high crash rate for teens is owing in large part to their lack of driving experience.2,3 Related article page 517 Continued identification of speand Patient Page page 592 cific characteristics of teens that lead to elevated crash risk can inform interventions for high-risk subgroups. This month’s issue of JAMA Pediatrics includes a study by Ouimet et al4 that examined the association between cortisol reactivity and subsequent occurrence of crash and near-crash (CNC) events among newly licensed teens. As part of the Naturalistic Teen Driving Study, salivary cortisol reactivity in response to a stress-inducing task was assessed at baseline in a sample of 42 healthy, typically developing 16-year-old participants, after which they drove instrumented vehicles for 18 months. Ouimet et al4 found that teens with lower cortisol reactivity in response to the stressor had higher CNC rates during the first 18 months of licensure. In addition, those with lower cortisol reactivity had a slower decrease in CNC rates over time. The authors posited that the associations observed in their study could be owing to individual differences in optimal physiological arousal and/ or to the manner by which teens process emotional information. The extent to which the authors believe these are competing, complementary, or interactive processes remains unclear. Most compelling, and supported by other literature, is the idea of a normative emotional learning pathway, whereby individual differences in hypothalamic-pituitary-adrenal (HPA) axis reactivity affect the sensitivity of drivers to stimuli in the driving environment, which subsequently affects learning.5 For example, as teens gain independent driving experience, they are exposed to a variety of emotionally evocative stimuli—such as near misses with unexpected hazards—which enables them to better anticipate, avoid, and react more effectively in the future. In this hypothesized pathway, the emotional response (as indicated by greater cortisol reactivity) to stressors and challenges experienced during the learning-to-drive process promotes effective learning of necessary skills. The findings by Ouimet et al4 would suggest that, although all teens gain experience over time and this experience is associated with decreasing CNCs, individual variation in cortisol reactivity—specifically a weaker emotional reactivity in response to hazards—might attenuate the association between experience and lower crash risk. Further support for the emotional learning hypothesis among teen drivers is provided by prior experimental research. In a small convenience sample of experienced and novice drivers, Kinnear et al6 found that the magnitude of skin conductance response, a physiological measure of autonomic arousal, to simulated driving hazards increased as a function of real-world driving experience.
Implications for Researchers The most immediate implication of the findings of the Ouimet et al4 study is for continued research 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 owing to preexisting conditions or history of risky behaviors. For example, variation in function of the HPA axis has been implicated in clinical samples of youth as a potential factor in the development of antisocial disorders, as well as a variety of internalizing and externalizing disorders.7-9 Although the current study benefited from strong data collection methods, generalizations are difficult to make owing to the small and likely nonrepresentative sample of healthy, typically developing teens; very few actual crash events; and limited characterization of the near crashes. It remains unclear what proportion of novice teen-driver crashes might be explained by individual differences in HPA regulation. Previous research has suggested that most crashes involving teen drivers are due to inexperience and not overt risk taking on the part of teens,2,3 lending additional support to an emotional learning pathway. Further research is needed to explicate the mechanisms by which individual differences in the HPA system covary by developmental factors, driving experience, and other individual difference variables (eg, attention-deficit/ hyperactivity disorder and conduct disorder) to affect driving behaviors and outcomes.
Implications for Health Care Providers Health care providers may already sense that certain teens in their practice are at high risk for unsafe driving. Quantifying this concern in the form of a diagnostic test may be desirable to some practitioners and to the public. However, caution is warranted because the premature development of such a test could lead to unintended harms such as pathologizing normative behavior or to biological reductionism—ie, embracing a solely biological explanation of phenomena that span several levels (eg, social, psychological, and biological),10 a common occurrence in the popular press.11 In sum, while the results of the Ouimet et al4 study 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. The clinician’s role is to provide anticipatory guidance to parents and teens12 and to recognize that these general recommendations might not be enough to protect teens at greater risk for crashing. There continues to be a lack of specific recommendations and evidence-based solutions for highrisk teens, a critical avenue for continued research.
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JAMA Pediatrics June 2014 Volume 168, Number 6
Copyright 2014 American Medical Association. All rights reserved.
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511
Opinion Editorial
Implications for Families These findings provide initial support from neurobiological data, complementary to existing behavioral and epidemiologic data, for current recommendations to reduce teen driver crash risk. (1) Families should ensure that there is sufficient quantity, quality, and diversity of practice during the learner period to ensure that teens are capable of recognizing potential sources of crash risk under the wide range of conditions they are likely to face as independent drivers, including more challenging situations such as driving at night and in inclement weather. As just noted, cortisol reactivity may serve as a biomarker for the emotional learning pathway such that low cortisol reactivity is associated with diminished attention to potential threats in the driving environment—in other words, a lack of defensive driving. While it may seem intuitive for parents to protect their teen during the learner phase by limiting their exposure to riskier situations, this may undermine the potential benefits of learning that can result from the teen’s supervised exposure to emo-
tional stimuli. (2) Families ought to familiarize themselves with their state’s graduated driver license provisions and follow or extend them as necessary. And (3) families should use the structure of the graduated driver license law to guide the learningto-drive process but not treat it as a conveyer belt. Some teens might need more time in any given phase and may require additional supports for safety. For example, as Ouimet et al4 suggested, for teens demonstrating concerning behaviors during the learner or intermediate phase of driving, families may want to use in-vehicle monitoring tools to supervise and provide feedback on their teen’s driving. Finally, families and health care providers should recognize driving as a health behavior because motor vehicle crashes are currently the leading cause of death for adolescents. Health care providers need to be prepared to support families in the learning-to-drive process, highlighting the need for providers to have competency in this area and evidence-based resources available to them.
ARTICLE INFORMATION
REFERENCES
Author Affiliations: Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania (Durbin, Mirman, Curry); Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (Durbin); Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (Durbin, Curry).
1. Centers for Disease Control and Prevention National Center for Injury Prevention and Control. Injury prevention and control: data and statistics (WISQARS). http://www.cdc.gov/injury/wisqars/. Accessed May 27, 2013.
Corresponding Author: Dennis R. Durbin, MD, MSCE, Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, 3535 Market St, Ste 1150, Philadelphia, PA 19104 ([email protected]). Published Online: April 7, 2014. doi:10.1001/jamapediatrics.2013.5402. Conflict of Interest Disclosures: None reported. Additional Contributions: We thank Dustin Albert, PhD, Center for Child and Family Policy, Duke University (Durham, NC), and Nancy Kassam-Adams, PhD, Department of Pediatrics, The Children’s Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania (Philadelphia), for their review and comments on a draft of this editorial. They did not receive compensation for their contributions.
2. Curry AE, Hafetz J, Kallan MJ, Winston FK, Durbin DR. Prevalence of teen driver errors leading to serious motor vehicle crashes. Accid Anal Prev. 2011;43(4):1285-1290. 3. McKnight AJ, McKnight AS. Young novice drivers: careless or clueless? Accid Anal Prev. 2003;35(6):921-925. 4. Ouimet MC, Brown TG, Guo F, et al. Higher crash and near-crash rates in teenaged drivers with lower cortisol response: an 18-month longitudinal, naturalistic study [published online April 7, 2014]. JAMA Pediatr. doi:10.1001/jamapediatrics.2013.5387. 5. Damasio AR. The somatic marker hypothesis and the possible functions of the prefrontal cortex. Philos Trans R Soc Lond B Biol Sci. 1996;351(1346): 1413-1420. 6. Kinnear N, Kelly S, Stradling S, Thomson JA. Do We Really Drive as We Feel? Behavioural Research in Road Safety. London, England: Department for Transport; 2007:124-135.
7. Hawes DJ, Brennan J, Dadds MR. Cortisol, callous-unemotional traits, and pathways to antisocial behavior. Curr Opin Psychiatry. 2009;22(4):357-362. 8. Lopez-Duran NL, Olson SL, Hajal NJ, Felt BT, Vazquez DM. Hypothalamic pituitary adrenal axis functioning in reactive and proactive aggression in children. J Abnorm Child Psychol. 2009;37(2): 169-182. 9. McBurnett K, Lahey BB, Frick PJ, et al. Anxiety, inhibition, and conduct disorder in children, II: relation to salivary cortisol. J Am Acad Child Adolesc Psychiatry. 1991;30(2):192-196. 10. Cohen CI. The biomedicalization of psychiatry: a critical overview. Community Ment Health J. 1993;29(6):509-521. 11. Beck DM. The appeal of the brain in the popular press. Perspect Psychol Sci. 2010;5(6):762-766. doi:10.1177/1745691610388779. 12. Weiss JC; Committee on Injury, Violence, and Poison Prevention, American Academy of Pediatrics; Committee on Adolescence, American Academy of Pediatrics. The teen driver. Pediatrics. 2006;118(6):2570-2581.
More Work Needed to Protect Children but Promising Trend Data on Exposure to Violence John R. Lutzker, PhD; Katelyn Guastaferro, MPH; Daniel J. Whitaker, PhD
Finkelhor and colleagues1 continue their leadership in providing trend data on maltreatment of children. Their previous work has shown that within child maltreatment there has been a 20-year decline in emotional child abuse and sexual abuse but not child neglect.2 Their current study, based on 3 large representative samples of national random digit dialing surveys, finds encouraging data on exposure to 512
violence among children defined more broadly, with 27 significant declines in child maltreatment rates from 2003 to 2011 in children and youth aged 2 to 17 years.1 These findings from self-report data mirror trends seen in Federal Bureau of Investigation statistics, other crime data, and adult surveys. Some of the most dramatic declines reported by Finkelhor et al were in rates of bullying, assault victimization, vandalism,
JAMA Pediatrics June 2014 Volume 168, Number 6
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archpedi.jamanetwork.com/ by a Simon Fraser University User on 06/04/2015
jamapediatrics.com
EDITORIAL
Enhancing Our Understanding of Teen-Driver Crashes Dennis R. Durbin, MD, MSCE; Jessica Mirman, PhD; Allison Curry, PhD, MPH
While progress has been made in reducing the number of teens killed in motor vehicle crashes, crashes continue to be the leading cause of death for teens in the United States.1 The high crash rate for teens is owing in large part to their lack of driving experience.2,3 Related article page 517 Continued identification of speand Patient Page page 592 cific characteristics of teens that lead to elevated crash risk can inform interventions for high-risk subgroups. This month’s issue of JAMA Pediatrics includes a study by Ouimet et al4 that examined the association between cortisol reactivity and subsequent occurrence of crash and near-crash (CNC) events among newly licensed teens. As part of the Naturalistic Teen Driving Study, salivary cortisol reactivity in response to a stress-inducing task was assessed at baseline in a sample of 42 healthy, typically developing 16-year-old participants, after which they drove instrumented vehicles for 18 months. Ouimet et al4 found that teens with lower cortisol reactivity in response to the stressor had higher CNC rates during the first 18 months of licensure. In addition, those with lower cortisol reactivity had a slower decrease in CNC rates over time. The authors posited that the associations observed in their study could be owing to individual differences in optimal physiological arousal and/ or to the manner by which teens process emotional information. The extent to which the authors believe these are competing, complementary, or interactive processes remains unclear. Most compelling, and supported by other literature, is the idea of a normative emotional learning pathway, whereby individual differences in hypothalamic-pituitary-adrenal (HPA) axis reactivity affect the sensitivity of drivers to stimuli in the driving environment, which subsequently affects learning.5 For example, as teens gain independent driving experience, they are exposed to a variety of emotionally evocative stimuli—such as near misses with unexpected hazards—which enables them to better anticipate, avoid, and react more effectively in the future. In this hypothesized pathway, the emotional response (as indicated by greater cortisol reactivity) to stressors and challenges experienced during the learning-to-drive process promotes effective learning of necessary skills. The findings by Ouimet et al4 would suggest that, although all teens gain experience over time and this experience is associated with decreasing CNCs, individual variation in cortisol reactivity—specifically a weaker emotional reactivity in response to hazards—might attenuate the association between experience and lower crash risk. Further support for the emotional learning hypothesis among teen drivers is provided by prior experimental research. In a small convenience sample of experienced and novice drivers, Kinnear et al6 found that the magnitude of skin conductance response, a physiological measure of autonomic arousal, to simulated driving hazards increased as a function of real-world driving experience.
Implications for Researchers The most immediate implication of the findings of the Ouimet et al4 study is for continued research 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 owing to preexisting conditions or history of risky behaviors. For example, variation in function of the HPA axis has been implicated in clinical samples of youth as a potential factor in the development of antisocial disorders, as well as a variety of internalizing and externalizing disorders.7-9 Although the current study benefited from strong data collection methods, generalizations are difficult to make owing to the small and likely nonrepresentative sample of healthy, typically developing teens; very few actual crash events; and limited characterization of the near crashes. It remains unclear what proportion of novice teen-driver crashes might be explained by individual differences in HPA regulation. Previous research has suggested that most crashes involving teen drivers are due to inexperience and not overt risk taking on the part of teens,2,3 lending additional support to an emotional learning pathway. Further research is needed to explicate the mechanisms by which individual differences in the HPA system covary by developmental factors, driving experience, and other individual difference variables (eg, attention-deficit/ hyperactivity disorder and conduct disorder) to affect driving behaviors and outcomes.
Implications for Health Care Providers Health care providers may already sense that certain teens in their practice are at high risk for unsafe driving. Quantifying this concern in the form of a diagnostic test may be desirable to some practitioners and to the public. However, caution is warranted because the premature development of such a test could lead to unintended harms such as pathologizing normative behavior or to biological reductionism—ie, embracing a solely biological explanation of phenomena that span several levels (eg, social, psychological, and biological),10 a common occurrence in the popular press.11 In sum, while the results of the Ouimet et al4 study 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. The clinician’s role is to provide anticipatory guidance to parents and teens12 and to recognize that these general recommendations might not be enough to protect teens at greater risk for crashing. There continues to be a lack of specific recommendations and evidence-based solutions for highrisk teens, a critical avenue for continued research.
jamapediatrics.com
JAMA Pediatrics June 2014 Volume 168, Number 6
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archpedi.jamanetwork.com/ by a Simon Fraser University User on 06/04/2015
511
Opinion Editorial
Implications for Families These findings provide initial support from neurobiological data, complementary to existing behavioral and epidemiologic data, for current recommendations to reduce teen driver crash risk. (1) Families should ensure that there is sufficient quantity, quality, and diversity of practice during the learner period to ensure that teens are capable of recognizing potential sources of crash risk under the wide range of conditions they are likely to face as independent drivers, including more challenging situations such as driving at night and in inclement weather. As just noted, cortisol reactivity may serve as a biomarker for the emotional learning pathway such that low cortisol reactivity is associated with diminished attention to potential threats in the driving environment—in other words, a lack of defensive driving. While it may seem intuitive for parents to protect their teen during the learner phase by limiting their exposure to riskier situations, this may undermine the potential benefits of learning that can result from the teen’s supervised exposure to emo-
tional stimuli. (2) Families ought to familiarize themselves with their state’s graduated driver license provisions and follow or extend them as necessary. And (3) families should use the structure of the graduated driver license law to guide the learningto-drive process but not treat it as a conveyer belt. Some teens might need more time in any given phase and may require additional supports for safety. For example, as Ouimet et al4 suggested, for teens demonstrating concerning behaviors during the learner or intermediate phase of driving, families may want to use in-vehicle monitoring tools to supervise and provide feedback on their teen’s driving. Finally, families and health care providers should recognize driving as a health behavior because motor vehicle crashes are currently the leading cause of death for adolescents. Health care providers need to be prepared to support families in the learning-to-drive process, highlighting the need for providers to have competency in this area and evidence-based resources available to them.
ARTICLE INFORMATION
REFERENCES
Author Affiliations: Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania (Durbin, Mirman, Curry); Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (Durbin); Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia (Durbin, Curry).
1. Centers for Disease Control and Prevention National Center for Injury Prevention and Control. Injury prevention and control: data and statistics (WISQARS). http://www.cdc.gov/injury/wisqars/. Accessed May 27, 2013.
Corresponding Author: Dennis R. Durbin, MD, MSCE, Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, 3535 Market St, Ste 1150, Philadelphia, PA 19104 ([email protected]). Published Online: April 7, 2014. doi:10.1001/jamapediatrics.2013.5402. Conflict of Interest Disclosures: None reported. Additional Contributions: We thank Dustin Albert, PhD, Center for Child and Family Policy, Duke University (Durham, NC), and Nancy Kassam-Adams, PhD, Department of Pediatrics, The Children’s Hospital of Philadelphia and Perelman School of Medicine at the University of Pennsylvania (Philadelphia), for their review and comments on a draft of this editorial. They did not receive compensation for their contributions.
2. Curry AE, Hafetz J, Kallan MJ, Winston FK, Durbin DR. Prevalence of teen driver errors leading to serious motor vehicle crashes. Accid Anal Prev. 2011;43(4):1285-1290. 3. McKnight AJ, McKnight AS. Young novice drivers: careless or clueless? Accid Anal Prev. 2003;35(6):921-925. 4. Ouimet MC, Brown TG, Guo F, et al. Higher crash and near-crash rates in teenaged drivers with lower cortisol response: an 18-month longitudinal, naturalistic study [published online April 7, 2014]. JAMA Pediatr. doi:10.1001/jamapediatrics.2013.5387. 5. Damasio AR. The somatic marker hypothesis and the possible functions of the prefrontal cortex. Philos Trans R Soc Lond B Biol Sci. 1996;351(1346): 1413-1420. 6. Kinnear N, Kelly S, Stradling S, Thomson JA. Do We Really Drive as We Feel? Behavioural Research in Road Safety. London, England: Department for Transport; 2007:124-135.
7. Hawes DJ, Brennan J, Dadds MR. Cortisol, callous-unemotional traits, and pathways to antisocial behavior. Curr Opin Psychiatry. 2009;22(4):357-362. 8. Lopez-Duran NL, Olson SL, Hajal NJ, Felt BT, Vazquez DM. Hypothalamic pituitary adrenal axis functioning in reactive and proactive aggression in children. J Abnorm Child Psychol. 2009;37(2): 169-182. 9. McBurnett K, Lahey BB, Frick PJ, et al. Anxiety, inhibition, and conduct disorder in children, II: relation to salivary cortisol. J Am Acad Child Adolesc Psychiatry. 1991;30(2):192-196. 10. Cohen CI. The biomedicalization of psychiatry: a critical overview. Community Ment Health J. 1993;29(6):509-521. 11. Beck DM. The appeal of the brain in the popular press. Perspect Psychol Sci. 2010;5(6):762-766. doi:10.1177/1745691610388779. 12. Weiss JC; Committee on Injury, Violence, and Poison Prevention, American Academy of Pediatrics; Committee on Adolescence, American Academy of Pediatrics. The teen driver. Pediatrics. 2006;118(6):2570-2581.
More Work Needed to Protect Children but Promising Trend Data on Exposure to Violence John R. Lutzker, PhD; Katelyn Guastaferro, MPH; Daniel J. Whitaker, PhD
Finkelhor and colleagues1 continue their leadership in providing trend data on maltreatment of children. Their previous work has shown that within child maltreatment there has been a 20-year decline in emotional child abuse and sexual abuse but not child neglect.2 Their current study, based on 3 large representative samples of national random digit dialing surveys, finds encouraging data on exposure to 512
violence among children defined more broadly, with 27 significant declines in child maltreatment rates from 2003 to 2011 in children and youth aged 2 to 17 years.1 These findings from self-report data mirror trends seen in Federal Bureau of Investigation statistics, other crime data, and adult surveys. Some of the most dramatic declines reported by Finkelhor et al were in rates of bullying, assault victimization, vandalism,
JAMA Pediatrics June 2014 Volume 168, Number 6
Copyright 2014 American Medical Association. All rights reserved.
Downloaded From: http://archpedi.jamanetwork.com/ by a Simon Fraser University User on 06/04/2015
jamapediatrics.com
