Individuals who had a concussion take longer to regain complex reaction times, including reaction times for driving situations, according to a preliminary study released today that will be presented at the American Academy of Neurology's Sports Concussion Virtual Conference from July 31 to August 1, 2020. The preliminary results could have implications for how quickly experts recommend the resumption of driving after a concussion.
The drivers who had concussions had slower complex reaction times than those who did not have concussions by an average of 0.06 seconds. When reacting to a change in stoplight color, those with concussions took 0.24 seconds longer to react, or the equivalent of 15.6 feet in stopping distance, compared with those without concussions. During the driving simulation, involving a child running in front of a car, it took those with concussions 0.06 seconds longer to react, or the equivalent of 3.3 feet in stopping distance, compared with those without concussions.
Slower reaction time is a strong predictor of crash risk, and these additional split seconds and feet needed to change the vehicle's movement could be critical for avoiding an accident. Interestingly, only the computerized complex and Stroop reaction times moderately related to the driving stoplight reaction time, and no other relationships were observed, suggesting reaction-time measures are not a perfect replacement for measuring real-life driving reaction times.
The computerized test consisted of 4 measures of reaction time including simple, complex, and Stroop reaction time.
Participants included 28 college students with valid drivers' licenses mean age 20 years, including 14 with sports-related concussion and 14 without. All participants were matched by age, sex, and driving experience. Participants completed both a simulated driving reaction time test and a computerized neurocognitive test within 48 hours of their concussion symptoms resolving, which occurred an average of 16 days after the injury.
The driving reaction time test consisted of two simulated driving scenarios. The first scenario involved a stoplight reaction time simulation in which the stoplight changed from green to yellow and participants had to rapidly choose to brake or accelerate. The second scenario involved a child running in front of a vehicle and participants needed to brake or swerve to avoid collision.
Chen Zhao, MD; Jonathan G. Hakun, PhD; Krishnankutty Sathian, MBBS, PhD; and Nikolaos Scarmeas, MD, MS, PhD
Barbara C. Jobst, MD
Tzu-Ying Chuang, MD, PhD, and Dhanashri Miskin, MD