New research suggests that a commonly-used screening tool for attention deficit hyperactivity disorder may be faulty when used with children who have autism, potentially causing kids to receive inappropriate treatments.

Researchers analyzed results from the ADHD Rating Scale Fourth Edition for 386 kids ages 7 to 17 with autism. They found that children on the spectrum raised red flags on some questions whether or not the kids actually had ADHD.

“One of our best current screening measures for ADHD may be over-diagnosing ADHD in children with autism,” said Benjamin Yerys, a researcher at the Center for Autism Research at Children’s Hospital of Philadelphia who led the study published online this month in the Journal of Autism and Developmental Disorders.

“This is important because medications that work for ADHD may be less effective for a child on the autism spectrum,” Yerys said.

The ADHD screening tool relies on parents and teachers rating kids on 18 different factors designed to assess their level of inattention, hyperactivity and impulsivity. Results from the test are often used to determine possible eligibility for school services and other treatments.

However, Yerys said that the way the screening poses certain questions may be problematic. For example, one question parents and teachers are asked is “Does the child respond when spoken to directly?” While a “no” to this question could mean that a child has difficulty paying attention — a hallmark of ADHD — it also could mean that the child does not understand how to properly respond in social situations, a symptom of autism.

About 11 percent of all U.S. children have ADHD, according to the Centers for Disease Control and Prevention. But among children with autism, that number jumps significantly with past research finding that nearly 1 in 3 kids on the spectrum have ADHD too.

Researchers said the ADHD screening tool should be modified to minimize the potential for wrongly flagging kids on the spectrum.

“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,” Yerys said.