Saliva, pupil size differences in autism show system in overdrive

July 13, 2012 By Karen Henry
Saliva, pupil size differences in autism show system in overdrive
Christa Anderson, left, University of Kansas assistant research professor, and Kathryn Unruh, 2012 KU honors graduate in behavioral neuroscience, use technologies such as eye-tracking, pupil measurement, salivary responses and neuroimaging to look for biomarkers of autism and investigate the autonomic nervous system as a possible nexus of the disorder.

(Medical Xpress) -- University of Kansas researchers have found larger resting pupil size and lower levels of a salivary enzyme associated with the neurotransmitter norepinephrine in children with autism spectrum disorder.

However, even though the levels of the enzyme, salivary alpha-amylase (sAA), were lower than those of typically developing in samples taken in the afternoon in the lab, samples taken at home throughout the day showed that sAA levels were higher in general across the day and much less variable for children with ASD.

“What this says is that the autonomic system of children with ASD is always on the same level,” said Christa Anderson, assistant research professor. “They are in overdrive.”

The sAA levels of typically developing children gradually rise and fall over the day, said Anderson, who co-directed the study with John Colombo, professor of psychology.

Norepinephrine (NE) has been found in the blood plasma levels of individuals with ASD, but some researchers have questioned whether these levels were just related to the stress from blood draws.

The KU study addressed this by collecting salivary measures by simply placing a highly absorbent sponge swab under the child’s tongue and confirmed that this method of collection did not stress the children by assessing their stress levels through cortisol, another hormone.

Collecting sAA levels has the potential for physicians to screen children for ASD much earlier, noninvasively and relatively inexpensively, said Anderson.

But Anderson and Colombo also see pupil size and sAA levels as biomarkers that could be the physiological signatures of a possible dysfunction in the autonomic nervous system.

“Many theories of autism propose that the disorder is due to deficits in higher-order brain areas,” said Colombo. “Our findings, however, suggest that the core deficits may lie in areas of the brain typically associated with more fundamental, vital functions.”

The study, published online in the May 29, 2012 Developmental Psychobiology, compared children between the ages of 20 and 72 months of age diagnosed with ASD to a group of typically developing children and a third group of children with Down syndrome.

Both findings address the Centers for Disease Control’s urgent public health priority goals for ASD: to find biological indicators that can both help screen children earlier and lead to better understanding of how the nervous system develops and functions in the disorder.

Colombo is the director and Anderson is research faculty member of the University of Kansas Life Span Institute, which focuses on neurodevelopmental and translational research across the life span.

Explore further: Study shows delays in siblings of children with autism spectrum disorders

Related Stories

Recommended for you

Adults with autism overcome childhood language challenges

March 1, 2017

Results of a small study of adults with autism at Johns Hopkins has added to evidence that their brains can learn to compensate for some language comprehension challenges that are a hallmark of the disorder in children.

Autism risk linked to herpes infection during pregnancy

February 22, 2017

Women actively infected with genital herpes during early pregnancy had twice the odds of giving birth to a child later diagnosed with autism spectrum disorder (ASD), according to a study by scientists at the Center for Infection ...

Researchers find autism biomarkers in infancy

February 15, 2017

By using magnetic resonance imaging (MRI) to study the brains of infants who have older siblings with autism, scientists were able to correctly identify 80 percent of the babies who would be subsequently diagnosed with autism ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.