The Influence of Noise on Autonomic Arousal and Cognitive Performance in Autism Spectrum Disorder

Background: As many as 95% of individuals with autism spectrum disorder (ASD) experience sensory dysfunction, and the ubiquitous nature of sensory stimuli can present significant challenges to everyday functioning. Although previously unexplored, it is particularly important to understand how sensory stimuli impede an individual’s ability to learn and perform cognitive tasks, especially given the overwhelming sensory nature of many education and workplace environments. Additionally, overwhelming sensory input activates the autonomic nervous system’s stress response, which may be a key mechanism in the relationship between dysregulated sensory processing and difficulties in cognitive performance.

Objectives: To model the impact of sensory reactivity on cognitive functioning, we investigated the relationship between noise (a pervasive and challenging sensory stimulus) and performance by experimentally manipulating noise levels and task difficulty during measures of working memory. We concurrently collected sympathetic and parasympathetic responses during these tasks to explore the role of autonomic arousal in this relationship.

Methods: Participants included 22 adolescents with ASD (mean age=14.5, range=12-17 yrs) and 18 typically developing (TD) controls (mean age=15.1, range=12-17 yrs). Diagnoses were confirmed using the ADOS and ADI-R in the ASD group and ruled out using the ADOS and SRS in the TD group. Groups were matched on age and Wechsler Verbal Comprehension Index. Participants completed a series of visually presented number span tasks in a 2 x 2 experimental manipulation of noise levels (quiet vs. 75dB gated white noise) and task difficulty (forward span vs. backward span). Electrocardiography, respiratory sinus arrhythmia, and electrodermal activity were collected continuously throughout baseline, cognitive conditions, and recovery periods.

Results: Analyses of cognitive performance data revealed a significant noise (quiet vs. noise) x difficulty level (forward vs. backward) interaction, F=7.25, p=.01, with both groups doing better with the addition of noise in the forward condition, and the ASD group doing marginally worse with the addition of noise in the backward condition. Analyses of heart rate data revealed a significant group x noise x difficulty level interaction, F=7.42, p=.01, with both groups showing increased heart rate with the addition of noise in the forward condition, but only the ASD group showing continued increases in heart rate with the addition of noise in the backward condition, t= -2.10, p<.05. Correlations between the performance and autonomic data revealed an adaptive effect of increased arousal in the forward condition for both groups, r= -.48, p=.004. However, for individuals with ASD, there was a detrimental relationship between increased arousal and performance in the backward condition, r=.60, p=.05.

Conclusions: This study is one of the first to investigate specific adaptive consequences of sensory processing dysfunction in ASD. Findings indicate that simultaneously processing background noise while performing demanding cognitive tasks has both performance and physiological consequences. Importantly, the strongest group differences were in autonomic reactivity, highlighting the importance of monitoring functioning and well-being through multiple methods. These results underscore the importance of minimizing sensory demands in learning contexts for individuals with ASD and suggest that self-regulation interventions may be particularly helpful in minimizing autonomic effects of dysregulated sensory processing.