Investigating Autonomic Nervous System Dysregulation in ASD
There is emerging literature to suggest that autism spectrum disorder (ASD) may be associated with dysfunction of the autonomic nervous system (ANS), although the nature of the dysfunction and its relation to ASD symptomatology are not well understood.
To investigate differences in ANS response to tasks eliciting core and co-morbid deficits of ASD between typically-developing children and those with ASD.
A sample of typically-developing children (n=34, age: 12.5 +/-2.9 years, full-scale IQ: 112.6 +/- 14.2, 19 male), and those with a diagnosis of ASD (n=40, age: 12.0 +/- 2.9 years, full-scale IQ: 112.6 +/- 14.2, 33 male) completed five tasks to elicit behaviours associated with core deficits and co-morbidities of ASD: 1) Stroop test (performance anxiety), 2) public speaking task (social anxiety), 3) rapid visual information processing (RVP) test (attention), 4) stop-signal task (inhibition), and 5) the Reading the Mind in the Eyes test (theory of mind), as well as a physical activity task (treadmill walking). Each task was preceded by a baseline interval in which the participant watched a 5-minute animated movie clip. Throughout the experimental session, electrocardiogram (ECG) was measured and used to extract heart rate. Repeated measures multiple regression analysis was performed to examine the effect of group and group x task interaction on heart rate while controlling for age, gender, and full-scale IQ.
Multiple regression analysis showed a significant group x task interaction for heart rate (p=0.001). Posthoc analyses revealed that the heart rate increase in response to anxiety was significantly smaller in the ASD group compared to the typically-developing sample (Stroop task p=0.02, public speaking p=0.0004). No significant differences were found for other tasks. While heart rate was generally higher in the ASD group, these differences did not reach statistical significance.
Our results suggest an atypical pattern of ANS function in ASD that is specific to the anxiety response. These results are consistent with ANS hyper-arousal in ASD.