Car crashes are one of the leading causes of injury death in the U.S., and they’re caused by a number of different reasons. But the distractions that texting while driving brings could be one of the most fatal. With teens, the distractions become worse when they’re added to their lack of experience and impulsiveness. A new study finds what many already knew: Teens driving and texting are at a higher risk of getting into an accident. But it also found that those who are diagnosed with attention deficit hyperactivity disorder (ADHD) are at an even higher risk.

“Texting is especially dangerous because it involves visual, manual, and cognitive distractions,” study author Dr. Jeffery N. Epstein, director of the Center for ADHD at Cincinnati Children’s Hospital, said in a press release. “Those are the very kinds of distractions that lead to car accidents.”

Read More: Text-To-Voice No Safer Than Manually Texting While Driving, Study Says

More than nine people are killed and 1,060 people are injured each day from distracted driving. Since 2009, the rates of sent or received text messages has risen almost 50 percent to 196 billion in 2011. According to Additute Magazine, drivers with ADHD are four times more at risk of getting in an accident or being ticketed for speeding or running a stop sign.

Although they take medications to improve focus, impulsivity, and attention, they’re less likely to be medicated during the weekends or at night, which also happens to be when they do the most driving, according to the researchers. Because of this, those who participated in the study were asked not to take their medication.

Texting Distracts All Drivers

The researchers studied 61 drivers between the ages of 16 and 17 years old. Almost half of them had been diagnosed with ADHD. For 40 minutes all of the participants drove in a simulator, where the researchers measured speed and lane position. For half of the time, all of the teens drove with no distractions. Then in ten-minute intervals, the teens drove while texting and driving, and then while talking on the phone and driving.

Read More: Texting And Driving: Almost Half Of American Teens Distracted Behind The Wheel

The researchers found that drivers found that using a hands-free device to speak on the phone had no negative impact on either groups, in fact, it improved their skill. The researchers said it reflected previous research that had shown conversing with someone during a boring task can improve visual attention.

Texting, however, resulted in the opposite. Participants with ADHD drifted out of their lanes about 1.8 percent of the time when they were undistracted. Those who didn’t have the disorder drifted 0.7 percent of the time. Both groups went out of their lanes while texting for a longer period of time. Those with ADHD spent 3.3 percent of their time outside of the lane, while those without it spent about two percent of their time outside of their lanes, the LA Times reported. In other words, drivers without ADHD drove with the same amount of distraction as someone with ADHD when they sent text messages.

“That’s a heck of a lot of time for a kid or any driver to be out of their lane when they’re driving,” Dr. Epstein told HealthDay.

Read More: Teens Who Text While Driving Are More Likely to Drive Drunk And Take Other Big Health Risks

“All these kids need to stop texting behind the wheel,” he continued. “The impact of texting is just so big that for these kids to be texting behind the wheel just poses such a danger to themselves as well as other driver that there just needs to be not only a policy stopping texting behind the wheel but also enforcement.”

Almost half of all American teens text while driving.

Is There a Solution To Texting and Driving?

Developing a way to enforce a no-texting-while-driving policy may not be so difficult. Similar to the idea of an in-car Breathalyzer that allows someone who has had a DUI to start a car only if they’re not drunk, phone apps or in-car devices may also be able to shut a phone off if it senses the car is moving, Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven and Alexandra Cohen Children’s Medical Center of New York, told HealthDay.

Read More: On Texting And Driving: You’ll Never Want To Text And Drive Again After Watching This Documentary

He also suggested eye tracking systems that can sound an alarm or vibrate the driver’s seat when it senses the driver’s attention drifting off the road for more than a couple of seconds.

“Those are the sorts of things that would be interesting if they work out,” he told HealthDay.