Assessing how quickly the brain responds to sights and sounds could offer a more precise and earlier method to diagnose autism, new research suggests.

In a study of 43 kids with autism ages 6 to 17, researchers found a correlation between the severity of a child’s symptoms and how quickly they process different stimuli.

For the research, the children were asked to press a button as soon as they heard a tone, saw a visual image or were presented with both the tone and image. Meanwhile, the kids’ brain activity was measured using an electroencephalogram, or EEG.

Children who took the longest to respond when presented with an auditory prompt had the most pronounced autism symptoms, according to findings published online this week in the Journal of Autism and Developmental Disorders.

Autism severity was also associated with the kids’ lag times when they were prompted by both visual and sound cues, though there was no correlation between autism and the children’s response times to an image alone, researchers said.

“This is a first step toward developing a biomarker of autism severity — an objective way to assess someone’s place on the ASD spectrum,” said Sophie Molholm of the Albert Einstein College of Medicine of Yeshiva University who led the study.

What’s more, Molholm said that EEGs may prove useful after a child is diagnosed with autism by offering a measure to determine whether or not therapies are effective.

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