SLPCase-ControlAutism research : official journal of the International Society for Autism Research2022

Measures of tonic and phasic activity of the locus coeruleus-norepinephrine system in children with autism spectrum disorder: An event-related potential and pupillometry study.

Yesol Kim, Girija Kadlaskar, Rebecca McNally Keehn and 1 others

PMID 36164264

WHAT IT FOUND

Children with autism showed larger resting pupil size and weaker pupil responses to targets, suggesting a nervous system stuck in high-alert mode that filters out less important sights poorly.

These measures correlated more with ADHD symptoms than with autism traits.

Key findings

01Children with ASD had significantly larger resting pupil diameter than typically developing peers, indicating higher baseline arousal.

02Children with ASD showed reduced pupil dilation to target stimuli but increased dilation to standard (repeated) stimuli, suggesting difficulty filtering redundant information.

03Pupil and brainwave measures correlated more strongly with ADHD symptoms (inattention and hyperactivity) than with autism-specific behavioral scores.

STILL TO COME

How it was doneWhat they foundWhat it means for SLPs

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What it does not show

The study is cross-sectional, so it cannot determine if these physiological differences cause symptoms or result from them. Children with ASD had significantly less usable data for eye-tracking and brainwave measurements due to movement and artifacts, which could introduce bias, although the authors state data loss was not correlated with the results. The measures of pupil size and brainwaves are indirect proxies for brain chemistry (norepinephrine) and may be influenced by other systems. The sample size is relatively small, and correlations were not corrected for multiple comparisons, making the symptom associations exploratory.

The easy way to misread this

Do not interpret these physiological differences as specific markers for autism. The study found that pupil and brainwave measures correlated more strongly with ADHD symptoms (inattention and hyperactivity) than with autism-specific behavioral scores, suggesting these arousal patterns may be common across both conditions.

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