ADHD and texting both significantly impair driving performance among teenagers, according to a study published online today in JAMA Pediatrics.

Researchers from Cincinnati Children's Hospital Medical Center used a driving simulator to test the driving performance of 16- and 17-year-old drivers; approximately half of the study's 61 participants had been diagnosed with ADHD, the other half had not. During the 40-minute driving simulation, researchers measured the speed and lane position of the young drivers as they texted and talked on the phone.

Texting significantly affected drivers' speed and lane position for all study participants and further increased the risk for drivers with ADHD, according to researchers.

"Texting is especially dangerous because it involves visual, manual and cognitive distractions," said senior author Jeffery N. Epstein, PhD, director of the Center for Attention Deficit/Hyperactivity Disorder at Cincinnati Children's. "Those are the very kinds of distractions that lead to car accidents."

The study found that even when no distractions were present, drivers with ADHD demonstrated significantly more variability in speed and lane position than did teens without ADHD. Researchers report texting added to existing ADHD driving impairments, essentially doubling the amount of time kids with and without ADHD strayed from their lane.

The Cincinnati Children's study is believed to be the first to investigate the effects of texting on the driving performance of adolescent drivers with ADHD.

"Teens as a group are already at increased risk of distracted driving accidents. Now we know that an ADHD diagnosis and texting while driving increase those risks," added Dr. Epstein. "Our results demonstrate the need for increased education and enforcement of regulations against texting while driving for this age group."

Attention-Deficit/Hyperactivity Disorder is a behavior disorder, usually first diagnosed in childhood, which is characterized by persistent problems with inattention and/or impulsivity and hyperactivity.