More than one in 10 US kids have ADHD as diagnosis rates surge

Attention deficit hyperactivity disorder (ADHD) is not due to bad parenting or too much sugar in the diet but heredity, a new study has found. Children with ADHD find it difficult to focus and can be disruptive and uncontrollable both at home and at school. (AFP)

More than 10 percent of U.S. children have been diagnosed with attention deficit hyperactivity disorder (ADHD), reflecting a surge in recent years particularly among girls and minority groups, a new study finds.

Spikes in diagnoses among girls, Hispanics and older kids may be the result of better screening and monitoring among previously under diagnosed groups, experts say.

Roughly 5.8 million children aged five to 17 years are now diagnosed with ADHD, which is characterized by social and behavioral problems as well as challenges in school, according to the analysis of cases reported by parents from 2003 to 2011.

Diagnosis rates jumped 43 percent overall during the study period, from 8.4 percent of children in 2003 to 12 percent by 2011.

Over that time, diagnosis among girls jumped 55 percent from 4.7 percent in 2003 to 7.3 percent in 2011, though prevalence remained higher among boys.

"The sharper increase among girls was a surprise primarily because ADHD is typically diagnosed among boys," said study co-author Sean Cleary, a public health researcher at George Washington University in Washington, D.C.

"One possibility to explain the increasing trend among females is a greater recognition of ADHD symptoms observed (e.g. withdrawn, internalizing) that are traditionally overlooked because they are not typically considered a sign of this condition," Cleary added by email.

To assess shifts in diagnosis patterns over time, Cleary and co-author Kevin Collins of Mathematic Policy Research analyzed data on more than 190,000 children from U.S. surveys conducted in 2003, 2007 and 2011.

As part of the surveys, parents reported whether their child had been diagnosed with ADHD.

Boys accounted for the majority of cases, and diagnosis for them rose 40 percent during the study period to 16.5 percent by 2011.

Age also played a role in diagnosis rate gains, with the a 33 percent increase among kids aged five to nine years old, a 47 percent climb for those 10 to 14 years, and a 52 percent surge for teens 15 to 17 years.

While white children still made up the majority of cases, diagnosis rates climbed much more for black and Hispanic youth, according to the results in the Journal of Clinical Psychiatry. In particular, diagnosis among Hispanic children spiked 83 percent over the study period. For blacks, diagnoses rose 58 percent.

Shortcomings of the study include low response rates and its reliance on data from telephone surveys that didn't include mobile numbers until 2011, the authors note.

Still, the rising diagnosis rates aren't surprising, and are consistent with trends U.S. clinicians have been seeing for years, said Quyen Epstein-Ngo, a psychology researcher at the University of Michigan in Ann Arbor who wasn't involved in the study.

It's possible that some of the increase in diagnosis is due to some children having avoided diagnosis in the past as a result of having less severe symptoms, more coping strategies or a stronger support system to help them deal with the demands of school, Epstein-Ngo said by email.

"It could be that the last several years have seen an increased ability, or willingness, to recognize that older adolescents who are still struggling could require more formal help and support," Epstein-Ngo said. "Alternatively, it could be that increased pressures on adolescents to perform and achieve are leading to a push for more ADHD assessments."

Some previous research has also raised concerns that children from certain minority groups may have been underdiagnosed in the past, noted Dr. Timothy Wilens, chief of child and adolescent psychiatry at Massachusetts General Hospital and Harvard Medical School in Boston.

The surge in diagnosis for some non-white students in the study "may reflect appropriately increased testing and evaluation of academic and interpersonal difficulties," Wilens, who wasn't involved in the study, said by email.

Even though the data point to rising ADHD diagnosis rates, Wilens cautioned, the study based on parents' responses to a single survey question doesn't help answer why children were diagnosed or what treatment they may have received.

"I do believe these data indicate that adolescents, girls, and certain racial ethnic groups are being monitored more stringently for behavioral and academic difficulties including ADHD and other problems," Wilens added.