Children with autism may be over-diagnosed with ADHD: Study

PHILADELPHIA, Oct. 28 (UPI) -- Many children with autism spectrum disorder may have been mistakenly diagnosed with attention-deficit hyperactivity disorder, researchers suggest in a study.

Scientists at the Children's Hospital of Philadelphia say a screening tool used to diagnose ADHD may be less accurate when a child has autism. The research team included one of the psychologists responsible for developing the mechanism, known as the ADHD Rating Scale Fourth Edition.

In the study, published in the Journal of Autism and Developmental Disorders, the authors conclude the screening method should be refined to provide a more accurate diagnosis.

"One of our best current screening measures for ADHD may be over-diagnosing ADHD in children with autism," lead researcher Benjamin Yerys said in press release. "This is important because medications that work for ADHD may be less effective for a child on the autism spectrum."

The authors add that the overlap between the disorders often makes diagnosis a challenge, noting an estimated 30 percent or more children with autism also have ADHD.

In the study, researchers analyzed 386 autistic children between the ages of 7 and 17 who had no intellectual disability. The subjects were tested for ADHD using the scale developed in the 1990s. Investigators found some of the questions on the ADHD scale were high for children with autism instead of being high just for the subset of children who had ADHD symptoms.

Yerys says many of those questions need rewording, and is calling for clinicians to combine the ratings with a follow-up interview with parents until the current system is updated.

"One underlying problem may be in how we ask these questions," he concluded. "Until we're able to develop and validate a new rating scale that takes symptoms of autism into account, parents who are concerned should seek out clinicians who are conducting evaluations for ADHD and are also taking into account the possibility of autism."