An investigation of the combined risks of adolescence, attention-deficit/hyperactivity disorder (ADHD), and driving while engaged in texting or cell phone conversation found that while distractions significantly impair the driving performance of all adolescents, the negative effects of texting are especially prominent in youngsters with ADHD.
The study was conducted in 61 adolescents aged 16 and 17 years—28 with ADHD and 33 controls. Each participant engaged in a 40-minute simulated drive. During the first 10 minutes, participants familiarized themselves with the simulator. The remaining 30 minutes were divided into 3 separate, 10-minute periods. During 1 of these periods the participant was not subject to any distraction while in the other 2, he or she received a phone call or text message that necessitated a response. During the course of each period, a car suddenly merged into the driver’s lane or a pedestrian unexpectedly crossed the street in front of the participant’s vehicle. Investigators examined participants’ braking, swerving, and related responses to these unanticipated events and sampled their driving speed and position in relation to adjacent road lanes and traffic (lateral position) during the entire drive.
Compared with controls, teenagers with ADHD showed more variability overall in speed and lateral position. Average speed or braking response time did not vary between the 2 groups, however. Cell phone distraction had large effects in both groups on average speed, speed variability, and variability in lateral position, although all participants showed less variability in lateral position during conversation than when they were not subject to distractions.
During texting—the most impairing distraction--both groups drove more slowly and evidenced more speed and lateral position variability than when they were not distracted. Lateral position variability was more pronounced in participants with ADHD. They were outside their lanes for 3.3% of the drive during texting compared with 2.0% of the time for controls. Investigators therefore concluded that texting incrementally increases driving risk for adolescents with ADHD, adding to their existing ADHD-related driving impairments (Narad M, et al. JAMA Pediatr. 2013;167:933-938).
COMMENTARY In an accompanying editorial, F. K. Winston and colleagues endorse the practice of graduated driver licensing, a program adopted by many states that restricts new drivers to low-risk driving situations, progressively allowing them exposure to higher-risk situations with increased driving experience (JAMA Pediatr. 2013;167:892-894). There is some evidence that this approach decreases teenaged fatalities in the first 6 months of driving. If becoming a safe driver is a developmental milestone, we must recognize that not every adolescent will meet that milestone at the same age. Parents of drivers in this study may recognize this, given that the drivers with ADHD had about 4 fewer months of driving experience than the controls. Maybe the parents of teenagers with ADHD dragged their feet in getting to the Department of Motor Vehicles, a delay that recognizes that not every child is ready to drive on his or her 16th birthday. —Michael Burke, MD