Does Baseline Physiological Arousal Influence Inhibitory Control in Adults with Autism Spectrum Disorder?

Background:  

Cardiac autonomic functioning (a.k.a. physiological arousal) is increasingly acknowledge to be related to problems that people with autism spectrum disorder (ASD) encounter in daily life. Baseline physiological arousal has been suggested to modulate inhibitory control in typically developing (TD) individuals: when confronted with a stressor, low baseline arousal would lead to more prepotent response inhibition difficulties than high baseline arousal. Recent meta-analysis showed that people with ASD have prepotent response inhibition difficulties (effect size: 0.55). However, a significant amount of heterogeneity between the studies was observed, suggesting there are unknown factors that influence inhibitory control in people with ASD. Baseline physiological arousal could be one of these factors.

Objectives:

We aim to examine the influence of baseline physiological arousal on prepotent response inhibition.

Methods:

Inhibitory control was measured with an emotional stop signal task (ESST) including neutral and negative pictures with stop signal reaction time (SSRT) as outcome measure. Participants were 32 male adults with ASD and 30 TD adults (age 18-45). Physiological arousal, at baseline and during the ESST, was indicated by heart rate variability (HRV). Data collection is expected to end in November 2015, with both groups containing 40 participants. Final results can be presented in May 2016.

Results:

Preliminary group comparisons revealed that the ASD group had significantly lower baseline HRV than the TD group. Both groups had similar SSRTs on the ESST. Using a median split on baseline HRV, both the ASD and TD group consisted of a significantly different low and high baseline HRV subgroup. The low ASD subgroup had significantly lower baseline HRV compared to the other three subgroups. The high ASD and high TD subgroup had similar baseline HRV. Mixed ANOVA analysis showed no interaction effect of baseline HRV on ESST, but indicated that all groups performed worse on the negative condition. Exploratory group comparisons revealed that the low ASD subgroup had significantly higher SSRTs compared to the high ASD subgroup.

Conclusions:

These preliminary findings suggest that adults with ASD are more aroused at baseline compared to TD adults but have similar prepotent response inhibition abilities. Both groups showed more prepotent response inhibition difficulties when confronted with a stressor. So far, results suggest no influence of baseline HRV on prepotent response inhibition. Exploratory analysis suggest a low baseline HRV subgroup within the ASD population that seem to have more prepotent response inhibition difficulties than adults with ASD with higher baseline HRV.