About 10 percent of U.S. children have diagnosed attention-deficit/hyperactivity disorder, a new study found.

Researchers from the University of Iowa found 10.2 percent of children between the ages of 4 and 17 had diagnosed ADHD in the 2015-2016 survey, up from 6.1 percent in 1997 and 1998.

ADHD was already considered one of the most common conditions among children, and the spike shows just how many young people are being diagnosed with it. Teachers and parents are more aware of the disorder, which can stifle kids' ability to concentrate and sit still in school.

"With the continuous increase of this condition, it is very common now. This is really, really common compared to other conditions," said Dr. Wei Bao, an assistant professor of epidemiology at the University of Iowa and one of the authors of the paper published Friday in JAMA Network Open.

To determine the prevalence of ADHD, researchers reviewed data on 186,457 children collected in the National Health Interview Survey, an in-person interview that the Centers for Disease Control and Prevention conducts annually.

However, the high number might not be entirely reflective of how many kids actually have ADHD, said Dr. Scott Benson, a psychiatrist at the Creekside Psychiatric Center in Pensacola, Florida.

Many children, especially those living in poverty or dealing with challenges at home, may struggle to focus. That's natural given the stressors they're dealing with, but it may cause some doctors to question whether the child has ADHD.

Inattention, hyperactivity and impulsivity are symptoms of ADHD, according to the American Psychiatric Association.

"We know one of the common errors is misdiagnosis," said Benson, who was not involved with the study. "So at first blush, it just looks like the kid's not paying attention. The second time, you realize the child is struggling with deep anxiety so he's not going to respond to ADHD treatment."

When kids are correctly diagnosed with ADHD, though, he said treatment works. Doctors can prescribe medications, such as Adderall and Vyvanse. So it is important for parents to take their children to the doctor when they suspect something and for doctors to carefully and accurately examine them.