The role of physiological arousal during the emergence of ASD symptomatology

: from infancy to pre-school

Abstract

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder marked by social interaction and communication difficulties. Although results are mixed, previous studies show indications for hyper-arousal during resting states and hypo-responsiveness to environmental stimuli in ASD. Moreover, associations between physiological responses to environmental stimuli and social, communication and executive function abilities have been reported. Because research on autonomic differences in early development is sparse, the central question of this thesis is: Do children with/at risk for ASD and typically developing (TD)/low risk children differ in physiological arousal and is physiological arousal associated with ASD symptomatology? This thesis incorporates two samples. The first sample included 2 to 4-year-old children with (N = 71) and without (N = 66) ASD. Comparison during both social and non-social paradigms show no group differences in heart rate (HR) or heart rate variability (HRV). However, children with ASD showed a larger HR increase from non-social to the social videos compared to TD children. HRV during the non-social videos correlated positively with language skills in the ASD group, especially those with lower cognitive skills. Larger HR deceleration to a social video was related to receptive language and longitudinally, decrease in HR from non-social to social related to communication and social skills in children with ASD. HR and HRV showed good test-retest reliability over ~4 weeks; however, measures of change in physiological arousal had poor reliability. The second sample included 28 infants at low and 93 infants at high familial risk for ASD. HR was measured during non-social and social (Happy and Sad) videos at 5, 10 and 14 months. Groups did not differ in HR or HR deceleration. With age, both groups showed an increase in HR deceleration to the Sad video. Cross-lagged models showed bidirectional relationships between physiological arousal and communication, social and regulation abilities. To conclude, HR and HRV are not diagnostic markers for ASD, however, there are associations between autonomic arousal and individual differences in development. Early difficulties in adapting physiological arousal to the environment can impact the development of social and communication skills.

Date of Award	1 Apr 2019
Original language	English
Awarding Institution	King's College London
Supervisor	Tony Charman (Supervisor)