MONDAY, July 25 (HealthDay News) -- Parents of children with attention-deficit/hyperactivity disorder have one more worry to add to their list: Kids younger than 10 years old with ADHD may be unable to cross the street safely on their own.

New research found that while children with ADHD may look as if they are capable of crossing the street solo -- they do stop and look both ways before crossing -- they aren't always good at judging how much time they need to safely cross.

"In our study, the outcome of crossing the street was much worse for kids with ADHD than for their peers without ADHD," said the study's lead author, Despina Stavrinos, an assistant professor in the department of medicine at the University of Alabama at Birmingham. "Kids with ADHD left much less time to spare to cross, and there were several close calls," she said.

Results of the study, published online July 25, will appear in the August print issue of Pediatrics.

Unintentional injury is the leading cause of pediatric deaths, according to background information in the study. And, pedestrian injuries are a major cause of unintentional injury. About one in six pedestrian fatalities occurs in children between the ages of 7 and 10, according to the study.

In general, children with ADHD are more prone to injuries, Stavrinos said. And, the researchers wondered how ADHD might affect someone's ability to cross the street, because the task requires processing a lot of information quickly.

To answer that question, the researchers recruited 78 children between the ages of 7 and 10. Half of them had ADHD. The others were age- and gender-matched to the children who had ADHD to serve as a control group. All of the children with ADHD were asked to forgo their medications for 24 hours prior to the test.

The researchers had the children complete 10 simulated street crossings using a virtual street environment at the University of Alabama at Birmingham's Youth Safety Laboratory. The simulator shows a typical street scene with vehicles approaching from either side.

Before completing the virtual street crossings, the children had to walk a 25-foot distance four times, so the researchers could assess their walking speed. This information was then programmed into a virtual avatar that was used in the simulations.

While in the simulations, children stood on a wooden block that simulated the curb. When they thought it was safe to cross, they stepped down from the curb. At that point, the virtual avatars took over.

Although kids with ADHD looked as if they were displaying correct street-crossing behaviors by looking left and right before stepping into the road, they left themselves shorter gaps to cross than the control group did, and often had less time to spare when they got to the other side. And, several kids with ADHD had close calls with vehicles.

"This study reinforces the notion that kids with ADHD are more at risk in certain situations," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at the Steven and Alexandra Cohen Children's Medical Center of New York in New Hyde Park, N.Y.

Plus, this study may actually underestimate the extent of the problem. "If you've got kids in a distraction-free setting, and they're still showing more risk-related behavior, it may be an underestimate," he said.

The researchers believe the reason that children with ADHD might be less adept at street-crossing is a deficit in executive functioning. Executive functions are tasks the brain controls, such as timing, inhibition, planning, and execution of planning.

Stavrinos said that parents may get a false sense of security from seeing that their child looks left and right before crossing, but they need to spend more time making sure the child leaves enough time to cross safely. She said this might entail standing with your child at the curb and asking when he or she thinks it's safe to cross.

"Parents of children with ADHD may need to be more mindful and concerned that their children are indeed making good decisions with regard to street-crossing behaviors. When they're on medications that reduce their impulsivity, it may reduce the risk, but further studies need to look at ways to ensure safety," said Adesman.

Stavrinos also noted that medications for many children with ADHD may be wearing off at the end of the school day, just as they may need to cross the street.

More information

To learn more about attention-deficit/hyperactivity disorder, visit the U.S. National Institute of Mental Health.