Rates of ADHD (attention deficit hyperactivity disorder) have risen by 24% over the last ten years, researchers from the Kaiser Permanente Southern California Medical Group reported in JAMA Pediatrics.

The authors, who carried out a study of medical records at the Kaiser Permanente Southern California health plan, described the increase as “very significant”.

A study carried out by researchers from Northwestern Medicine reported in the March/April 2012 issue of Academic Peditrics that the ADHD diagnosis rate had risen 66% in ten years.

ADHD, which is estimated to affect between 4% and 12% of school-aged children in the USA, persists into the teenage years and adulthood in approximately 66% to 85% of cases.

Experts are not sure what the origins of ADHD are. They believe it is caused by a combination of genetic and environmental factors. One study, published in Mayo Clinic Proceedings found that multiple exposures to anesthesia at a young age was linked to a higher rates of ADHD.

In this latest study, Darios Getahun, M.D., Ph.D. and team set out to determine whether ADHD rates had increased since 2001 in southern California, and if so, by how much. They gathered and examined patient medical records from children who received care at KPSC (Kaiser Permanente Southern California) from January 2001 to the end of December 2010.

Of the 842,830 kids who had received care during that period, 4.9% (39,200) had received an ADHD diagnosis.

Dr. Getahun said:

“The findings suggest that the rate of ADHD diagnosis among children in the health plan notably has increased over time. We observed disproportionately high ADHD diagnosis rates among white children and notable increases among black girls.”

Below are some of the highlighted findings from the study:

  • 2.5% of children were diagnosed with ADHD in 2001
  • 3.1% of children received an ADHD diagnosis in 2010
  • From 2001 to 2010, there was a 24% increase in the percentage of children with confirmed ADHD
  • From 2001 to 2010 the ADHD rate increased from 4.7% to 5.6% in Caucasians, 2.6% to 4.1% in African-Americans, and 1.7% to 2.5% in Hispanics.
  • During the same period, ADHD rates for Asian/Pacific Islanders remained the same

ADHD is more common in boys than girls, the authors added. However, they found that the sex gap for African-American children is gradually closing.

Boys from high-income households have the highest ADHD rates.

A report published by the National Center for Health Statistics, part of the CDC (August 2011), found that the prevalence of kids diagnosed with ADHD rose from 7% to 9% of all children, an increase of 28% from 1998-2000 through 2007-2009.

Written by Christian Nordqvist