ADHD numbers up, baffling scientists

The number of children diagnosed with attention-deficit/hyperactivity disorder (ADHD) has reached more than 10 percent, a significant increase during the past 20 years, according to a new study.

The rise was most pronounced in minority groups. The rate of diagnosis doubled in girls, although it was still much lower than in boys.

But the researchers say they found no evidence confirming frequent complaints that the condition is overdiagnosed or misdiagnosed.

The United States has significantly more instances of ADHD than other developed countries, which researchers said has led some to think Americans are overdiagnosing children. Wei Bao, the study’s lead author, said in an interview that a review of studies around the world doesn’t support that.

“I don’t think overdiagnosis is the main issue,” he said.

Nonetheless, those doubts persist. Stephen Hinshaw, who co-authored a 2014 book called “The ADHD Explosion: Myths, Medication, Money, and Today’s Push for Performance,” compared ADHD to depression. He said in an interview that neither condition has unequivocal biological markers, which makes it hard to determine whether a person has the condition. Symptoms of ADHD can include inattention, fidgety behavior and impulsivity.

“It’s probably not a true epidemic of ADHD,” said Hinshaw, a professor of psychology at the University of California at Berkeley and a professor of psychiatry at the University of California at San Francisco. “It might be an epidemic of diagnosing it.”

In interpreting their results, the study’s authors tied the higher numbers to better understanding of the condition by doctors and the public, new standards for diagnosis and an increase in access to health insurance through the ACA.

Because of the ACA, “some low-income families have improved access to services and referrals,” said Bao, an assistant professor of epidemiology at the University of Iowa College of Public Health.