Autism spectrum disorder (ASD) can be diagnosed in children as young as 24 months, although the median diagnosis age is older than four years. According to a new study, children with ASD and attention-deficit/hyperactivity disorder (ADHD) who are first diagnosed with only ADHD are likely to have their diagnosis of ASD delayed until after age six. The findings, from the National Survey of Children’s Health, indicate that screening for ASD should be administered to young children, even if they have already been diagnosed with ADHD.
The researchers analyzed data from 1,496 children with ASD. Of the study population, 42.9 percent also had an ADHD diagnosis. Among those diagnosed with both ADHD and ASD, 44.5 percent received an ADHD diagnosis before an ASD diagnosis.
The data demonstrate a consistent delay in the diagnosis of ASD when a child is first diagnosed with ADHD. Even when accounting for age and ASD severity, being diagnosed with ADHD first delayed a diagnosis of ASD by 2.9 years, compared to children with just an ASD diagnosis.
Around half of the children with ADHD and ASD were diagnosed with ADHD first, which considerably delays children’s ability to receive interventions for ASD. Four out of five children diagnosed with ADHD first were not diagnosed with ASD until after age six.
“We recommend adherence to American Academy of Pediatrics guidelines for universal screening for ASD at 18 and 24 months of age. However, the majority of children with initial ADHD diagnosis in our population-based community sample received their ASD diagnosis when they were older than 6 years, well beyond the age when signs and symptoms of ASD should clearly be notable and when behavioral therapies appear to be most effective,” stated Amir Midonvik, MD, of Boston Children’s Hospital and Harvard Medical School.
This research is published in the journal Pediatrics.