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. “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.”