Looking at more than 3,000 teenaged boys who had been in car accidents, a group of Canadian researchers found those who had been diagnosed with various forms of ADHD were more than a third likelier to be involved in a car accident than teenaged boys without ADHD.
“If teenagers with ADHD brought their risk down to that of normal teens without ADHD, that might have prevented about 1 in every 20 crashes we observed in our study,” Dr. Donald Redelmeier at the University of Toronto told Reuters Health.
The key element here is probably “distraction,” Redelmeier said in an interview. People with ADHD often struggle to maintain focus and one lapse can have a major impact behind the wheel, he said. “A couple moments of inattention can really change your life forever.”
Reporting in the journal PLoS Medicine, he and his colleagues also found that teens with ADHD were more likely to get injured in accidents even if they were pedestrians. Here, too, distraction probably plays a role, Redelmeier said, perhaps if teens step into oncoming traffic without paying attention.
Other distractions - such as talking on the phone and texting - have been shown to increase the risk of accidents.
To investigate whether internal distractions from a hyperactive brain also had an effect, the researchers reviewed medical records on 3421 teenaged boys hospitalized following car accidents (whether or not the teens were at fault), and compared their health history to 3812 boys admitted to have their appendix removed, serving as controls.
The team found that 22 percent of the teens in accidents had been diagnosed with a form of ADHD, versus only 17 percent of controls. Boys with ADHD were 37 percent more likely to be in an accident, relative to boys without the diagnosis.
The same trend was equally present in teenaged girls. Teenaged boys are already more likely than any other group to have accidents and having ADHD is not as risky as, for instance, drinking alcohol while driving, Redelmeier noted.
But with an estimated 10 million vehicles involved in crashes in 2008 in the U.S., even a small impact on accident risk involves many people, he noted. Although many of the included teens were presumably being treated for their ADHD, the treatment itself is probably not at fault, Redelmeier noted -- other research that tested driving ability in a simulated condition has found that people with ADHD taking medication were better behind the wheel, not worse, he said.
The most important steps teenagers (particularly those with ADHD) can take to stay safe behind the wheel include avoiding speeding as well as alcohol, minimizing distractions, using a seatbelt, keeping a safe distance from other cars and obeying doctor’s orders, Redelmeier said. Of course, parents can’t prevent their teenagers with ADHD from driving, but it makes sense to take extra precautions in this group, the researcher suggested.
For instance, some licensing authorities require drivers to indicate whether they have conditions that may impair their performance, such as epilepsy and diabetes. “All we’re suggesting is they add one more medical condition onto that already existing list of conditions,” Redelmeier said.
SOURCE: PLoS Medicine, online November 15, 2010.
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