Atypical Arousal Regulation in Children With Autism but Not With Attention-Deficit/Hyperactivity Disorder as Indicated by Pupillometric Measures of Locus Coeruleus Activity.

Researchers studied how children with autism regulate their alertness and attention during tasks by measuring pupil size changes. They found that autistic children had slower reaction times when tasks seemed less important, and their pupils showed they had trouble adjusting their alertness level based on how useful the task was. This suggests autistic children may struggle to match their energy and attention to what a situation requires.

This study examined arousal regulation in 31 children with autism spectrum disorder (ASD), 28 with ADHD, and 31 typically developing controls using pupillometry to measure locus coeruleus-norepinephrine system activity during a visuospatial reaction-time task. The research found that children with ASD showed slower reaction times specifically during low-utility task conditions compared to controls. Pupil measurements revealed that increased ASD symptoms were associated with higher baseline pupil size during low-utility conditions, suggesting increased tonic arousal. Children with ASD also showed smaller changes in pupil responses between different task conditions, indicating reduced ability to adapt arousal levels based on task demands.

This atypical arousal regulation may contribute to performance difficulties in autism.

Results suggest arousal regulation difficulties may contribute to performance challenges in autism, particularly for tasks perceived as less important. Pupil measurements could potentially serve as objective markers of arousal dysregulation. Interventions targeting arousal regulation and task engagement strategies may be beneficial for autistic children.

Study involved relatively small sample sizes with uneven gender distribution (mostly males). The research was limited to visuospatial tasks, so generalizability to other cognitive domains is unclear. The study design and methodology details are not fully specified in the abstract.

Atypical arousal regulation may explain slower mean reaction time (MRT) in autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder compared with typical development. The locus coeruleus-norepinephrine system (LC-NE) underlies arousal regulation and adapts its activity to the utility of a task. LC-NE tonic and phasic activity are indexed by baseline pupil size (BPS) and stimulus-evoked pupillary response (SEPR). The study assessed pupillometry in ASD (n = 31, 3 female/28 male), attention-deficit/hyperactivity disorder (n = 28, 3 female/25 male), and typically developing control subjects (n = 31, 16 female/15 male) during a visuospatial reaction-time task that manipulates arousal by conditions with low and high task utility.

We estimated linear mixed models of BPS, SEPR, and MRT in a per-trial analysis to investigate arousal regulation of task performance. Slower MRT occurred in the ASD group compared with the typically developing control group during low-utility conditions while controlling for dimensional ASD and attention-deficit/hyperactivity disorder symptoms. In low-utility conditions, BPS and SEPR were inversely related and both were associated with faster MRT. Increased ASD symptoms across groups were associated with higher BPS during low-utility conditions.

Changes in BPS and SEPR between task-utility conditions were smaller in the ASD group. Slower visuospatial task performance in ASD is specific to low task utility. Arousal was associated with task performance and showed altered activity in ASD. Increased BPS during low-utility conditions suggested increased LC-NE tonic activity as an ASD symptom marker in children.

Smaller changes in BPS and SEPR in ASD indicated attenuated LC-NE activity adaptation in response to high-utility conditions. Slower performance and atypical arousal regulation are probably associated with attenuated LC-NE activity adaptation.