THURSDAY, Aug. 18, 2011 (HealthDay News) -- Over the last decade, an increasing number of American children have been diagnosed with attention-deficit hyperactivity disorder (ADHD), a new government survey reveals.
Researchers from the U.S. Centers for Disease Control and Prevention found that between 2007 and 2009, an average of 9 percent of children between the ages of 5 and 17 were diagnosed with the disorder. This compared with just under 7 percent between 1998 and 2000.
The survey also indicated that previously notable racial differences in ADHD incidence rates have narrowed considerably since the turn of the millennium, with prevalence now comparable among whites, blacks and some Hispanic groups.
"We don't have the data to say for certain what explains these patterns, but I would caution against concluding that what we have here is a real increase in the occurrence of this condition," stressed study author Dr. Lara J. Akinbami, a medical officer with the National Center for Health Statistics. The findings appear in an Aug. 18 report from the agency.
"In fact, it would be hard for me to argue that what we see here is a true change in prevalence," Akinbami added. "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. So, this is probably about better screening, rather than a real increase, and that means we may continue to see this pattern unfold."
According to the National Institutes of Health, ADHD is the most common behavioral disorder among children.
Children with ADHD are apt to have problems staying focused, and often suffer learning and behavioral problems as a result of a tendency to engage in hyperactive and/or impulsive behaviors.
The new survey was conducted by interviewers from the U.S. Census Bureau through face-to-face and telephone interviews involving a nationally representative group of parents. Basic family demographic information was collected, along with the ADHD status of each household's children.
Although rates rose among both boys and girls, a greater percentage of boys were diagnosed with ADHD overall, rising from roughly 10 percent in 1998-2000 to more than 12 percent between 2007 and 2009. Across the same time frame, the prevalence rate among girls rose from just below 4 percent to between 5 percent and 6 percent.
One group, however, appeared to buck the trend: Mexican children. This group consistently registered the lowest ADHD prevalence rate, both in 1998-2000 as well as a decade later in 2007-2009. Akinbami said the reason for this remains unclear, although she suggested that less access to health care and/or particular cultural proclivities might contribute to fewer diagnoses overall.
In addition to the principal findings, the authors were also able to track both financial and geographical trends.
For example, ADHD prevalence hit above-average levels among two groups: households where the family income was below the poverty line (10 percent) and households where income fell somewhere between the poverty line and double the poverty line (11 percent).
Location also seemed to play a role, as the current prevalence rate among those living in both the Midwest and the southern part of the country shared an above-average prevalence rate of 10 percent. This was a shift from 10 years earlier, when the South had a higher prevalence rate than all other regions.
"Even if we're not exactly clear on what accounts for the rise in ADHD, on a population level the increase of this condition really signals a challenge for the education system and the health care system," said Akinbami.
"Children of ADHD," she noted, "use a lot more health care dollars than their peers, because the condition itself requires a lot of monitoring. And they are also much more likely to have other chronic health care conditions, such as asthma or learning disabilities or conduct diagnoses like conduct disorder, which makes managing them for schools and physicians and parents much more difficult. So, it's clearly something for public policy experts to be concerned about."
Dr. Tanya Froehlich, a developmental and behavioral pediatric specialist at the Cincinnati Children's Hospital Medical Center, said discerning what is driving the higher numbers will be difficult.
"There's no way to tell just based on this data," she said. "But we know that there has been a great emphasis over the last 10 years on raising doctor awareness of ADHD and giving them better tools to diagnose."
"For instance," Froehlich noted, "in 2001 the American Academy of Pediatrics put out clinical practice guidelines on the assessment and treatment of children with ADHD. And a tool kit was also put out giving physicians actual measures to use to assess ADHD. All of this has really empowered physicians and parents. So given that, I would not really be surprised if that's why more and more kids have been diagnosed."
For more on ADHD, visit the U.S. National Institutes of Health.