The percentage of children diagnosed with attention deficit hyperactivity disorder (ADHD) rose across the board for kids, according to a government study from the Centers for Disease Control and Prevention (CDC) and reported by Health Day News.

ADHD, the most common behavioral disorder among children, decreases focus and learning ability, and it’s linked ot behavioral problems, hyperactivity and impulsive behavior.

For the survey, representatives from the U.S. Census Bureau conducted face-to-face and telephone interviews with a nationally representative group of parents. Researchers collected basic family demographics, such as geographic location and socioeconomic status, as well as the ADHD status of each child in the household.

Scientists found that between 2007 and 2009, an average of 9 percent of children ages 5 to 17 were diagnosed with ADHD versus just less than 7 percent between 1998 and 2000. What’s more, among non-Hispanic black youth, ADHD prevalence almost doubled, jumping from 5.1 percent to 9.5 percent. For non-Hispanic white kids, ADHD rose from 8.2 percent to 10.6 percent. (Interestingly, Mexican children had the lowest ADHD frequency stats during the two 10-year study periods.)

In addition, children in poverty-stricken households also experienced an increase in ADHD, as did kids living in the Midwest or South. And scientists found that although ADHD frequency increased for both sexes, more boys than girls were diagnosed with the disorder during the study period.

What’s causing the spike? Researchers aren’t sure. But some believe the numbers may not reflect an increase in ADHD prevalence.

“Instead, I would say that most probably what we found has a lot to do with better access to health care among a broader group of children, and doctors who have become more and more familiar with this condition and now have better tools to screen for it,” said Lara J. Akinbami, MD, a medical officer with the National Center for Health Statistics. “So this is probably about better screening, rather than a real increase, and that means we may continue to see this pattern unfold.”

What’s most important, Akinbami added, is that the findings signal a “challenge for the education system and the health care system.”

Want to help your little one stay more focused? Shutting off the TV might help. Click here to read more.