A widely used test for diagnosing autism may miss children whose parents are not concerned that their child may have the condition, according to a new study1.

The tool, called the Autism Diagnostic Interview-Revised (ADI-R), is a 93-item questionnaire that caregivers fill out. It is often used with another test, called the Autism Diagnostic Observation Schedule (ADOS), that clinicians complete. Results on the two tests usually agree, but children who score high on the ADOS sometimes score low on the ADI-R.

The study provides a possible explanation for this mismatch: Some parents do not recognize autism features in their children, or do not consider them to be problematic.

“There’s huge variation in how much parents are aware of the social deficits associated with autism,” says senior investigator Catherine Lord, director of the Center for Autism and the Developing Brain at New York-Presbyterian Hospital. Lord is co-creator of the two tests.

The findings drive home the importance of using multiple tools when diagnosing autism, says Fred Volkmar, director of the Yale Child Study Center, who was not involved in the study. “And regardless of which instruments you use, you have to have good clinical judgment,” he says.