While the research findings echo those of nationwide studies, the new study is stronger than some other studies, says researcher Darios Getahun, MD, PhD, a scientist at Kaiser Permanente Southern California, a large health plan.
"We relied on the clinical diagnosis of ADHD [by doctors] and medication prescriptions rather than teacher or parent report," he says.
From 2001 to 2010, the rate of new cases of doctor-diagnosed ADHD rose from 2.5% to 3.1%, an increase of 24%.
"It's an increase that warrants attention," he says. Growing awareness of the condition is one reason for the rise, he speculates.
The study is published online in JAMA Pediatrics.
ADHD is one of the most common childhood neurobehavioral disorders, according to the CDC.
Children with ADHD have trouble paying attention or act impulsively, or both.
While the American Psychiatric Association estimates that 3% to 7% of school-aged children have ADHD, other studies have found higher rates.
ADHD Rising: Study Details
The Kaiser researchers looked at the health records of 842,830 children in the health plan. They ranged from 5 to 11 years old.
Of those, nearly 5%, or 39,200, had an ADHD diagnosis.
When they looked at the rates of a new diagnosis, they found the 24% rise, from 2.5% in 2001 to 3.1% in 2010.
White and African-American children were both more likely to be diagnosed than were Hispanics or Asian-Pacific Islanders.
Typically, more boys than girls are diagnosed with ADHD. In the new study, they found an overall boy-to-girl ratio of 3 to 1, similar to other research.
However, they also found a 90% rise in ADHD in African-American girls.
Growing awareness and cultural norms may help explain the findings, Getahun says.
He says parents, teachers, and doctors are all more aware of the condition.
As for Asian children being less likely to have a diagnosis, Getahun says that could be partly due to the reluctance of some Asian parents to seek out mental health care.