Ms. Serpa, then 16, had gotten flustered trying to sort out a rapid string of directions from her father while preparing to back out of their driveway. “There was a lack of communication,” she said. “I stepped on the gas instead of the brake.”
On her second attempt to learn, Ms. Serpa recalled, she “totally freaked out” at a busy intersection.
It was four years before she tried driving again. She has made great progress, but so far has still fallen short of her goal: Two weeks ago she knocked over a cone while parallel parking and failed the road test for the fourth time.
Learning to drive is hard and scary for many teenagers, and driving is far and away the most dangerous thing teenagers do. But the challenges are significantly greater for young people who, like Ms. Serpa, have attention problems.
A number of cognitive conditions can affect driving, and instructors report a recent increase in the number of teenagers with Asperger syndrome seeking licenses.
But the largest group of challenged teenage drivers and the mostly closely studied, appears to be those with attention deficit hyperactivity disorder (ADHD, ADD).
A 2007 study, by Russell A. Barkley of the Medical University of South Carolina and Daniel J. Cox of the University of Virginia Health System, concluded that young drivers with ADHD are two to four times as likely as those without the condition to have an accident, meaning that they are at a higher risk of wrecking the car than an adult who is legally drunk.
Researchers say that many teenagers with attention or other learning problems can become good drivers, but not easily or quickly, and that some will be better off not driving till they are older or not at all.
The most obvious difficulty they face is inattention, the single leading cause of crashes among all drivers, said Bruce Simons-Morton, senior investigator at the National Institute for Child Health and Human Development in Bethesda, Md.
“When a driver takes his eyes off the road for two seconds or more, he’s doubled the risk of a crash,” he said.
Inexperienced drivers usually are distractible drivers. Dr. Simons-Morton cited a study on a closed course in which teenagers proved much more adept than adults at using cellphones while driving and missed more stop signs.
The situation isn’t helped by how “noisy” cars have become, with cellphones, iPods and Bluetooth devices, said Lissa Robins Kapust, a social worker and coordinator of a driving program at Beth Israel Deaconess Medical Center in Boston. “Driving is so busy on the inside and the outside of the car it’s the most complex thing we do.”
But ADHD involves more than distractibility (?). Its other major trait is impulsiveness, which is often linked to high levels of risk-taking, said Dr. Barkley.
“It’s a bad combination” for young drivers, he said. “They’re more prone to crashes because of inattention, but the reason their crashes are so much worse is because they’re so often speeding.” Many drivers with ADHD overestimate their skills behind the wheel, Dr. Barkley noted.