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Neural marker may detect autism in nonverbal adults

Researchers have identified a possible nonverbal, neural marker of autism, according to study results published in Current Biology.

“Autism is hard to screen for in children, when the first signs are present. A trained clinician may be able to detect autism at 18 months or even younger; yet, the average age of a diagnosis of autism in the U.S. is about 4 years old,” Caroline Robertson, PhD, assistant professor of psychological and brain sciences at Dartmouth College, said in a press release. “We need objective, noninvasive screening tools that don’t depend on assessing a child’s behavior.”

In their study, Robertson and colleagues used brain imaging to measure the slower rate of binocular rivalry in 18 adults with autism and 19 age- and IQ-matched controls. To obtain neural data, researchers measured brain signals using an electroencephalography (EEG) electrode that was placed on each participant’s head over the visual region of the brain. Participants then looked at images of red checkerboards in the left eye and green checkerboards in the right eye that flickered back and forth at different rates, according to the press release.

“One of the big goals of the field is to develop objective neural markers of autism that can work with nonverbal individuals,” Robertson said in the release. “This neural marker is just that.”

According to the paper, people with autism had a slower rate of binocular rivalry compared with controls, meaning they were slower to switch from one image to the next. This demonstrated reduced neural activity in response to visual signals in the brain. The investigators also reported that the neural marker was independent of intelligence and offered an objective way to detect autism with 87% accuracy.

These findings provide robust evidence implicating the visual cortex in the neurobiology of autism, according to the researchers.

"This visual test may be a nonverbal marker of autism in adults. Our next steps are to learn whether this test could potentially be used to detect autism in pre-verbal children and nonverbal adults and develop it into a screening tool for the condition,” Robertson said. “In the meantime, this result gives us new insight into the brain in autism, showing that visual regions of the brain are affected.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.