Year: 2020
Type: dissertation
Study design: Observational Study
Abstract: Autism Spectrum Disorders (ASD) are a group of pervasive neurodevelopmental disorders characterised by qualitative impairments in social functioning. Studies over the last three decades have revealed relationships between autonomic dysregulation, indexed by decreased Heart Rate Variability (HRV), and cardiovascular risk in children and adults diagnosed with ASD. HRV is an objective marker that provides physiological insight into the Autonomic Nervous System (ANS). Decreases in HRV are purported to be a risk factor for cardiovascular morbidity, mortality, and poor mental health. The overarching objective of this thesis was to explore and compare resting-state HRV parameters between individuals diagnosed with ASD and neurotypical controls. This thesis focuses on empirical work examining the physiological measure of HRV as an index of cardiac autonomic function in adults and children diagnosed with ASD to better understand how HRV may contribute to poor physical, psychological, and social well-being. Chapter 1 of this thesis provides a detailed review of the extant literature surrounding HRV and autonomic functioning in adults and children diagnosis with ASD, compared to neurotypical controls, within which the subsequent empirical studies (Chapter 2 and 3) are couched. Chapter 2 presents an empirical study investigating differences in resting-state HRV parameters between adults diagnosed with ASD, relative to neurotypical adults. The main objective of Chapter 2 was to understand whether participants diagnosed with ASD demonstrate reductions in HRV in comparison to neurotypical individuals. It was proposed that there would be a reduction in HRV in the ASD group, and that this reduction would be particularly evident in HRV measures associated with predominantly parasympathetic activity. Furthermore, we hypothesised that reduced resting-state HRV would be associated with individuals taking psychotropic medication use. Finally, Chapter 2 investigated whether the presence of psychiatric comorbidities in the ASD group was also associated with reductions in HRV. Chapter 3 then examined the role of HRV in a younger cohort of children with ASD, relative to neurotypical children. The core objective of Chapter 3 was to identify whether HRV was reduced in children diagnosed with ASD, and the potential association between psychotropic medication use and HRV in children with ASD. It was hypothesized that children diagnosed with ASD would show decreased HRV compared to neurotypical children. Chapter 4 consolidates the results and present overall implications from the empirical studies presented within the thesis. The cumulative research presented in this thesis suggests that decreased HRV is associated with autonomic dysregulation in ASD. These findings provide additional evidence for the role of autonomic functioning in the pathogenesis of ASD. Moreover, the studies contribute to our understanding of the potential physiological mechanisms that may lead to cardiovascular risks in individuals with ASD. These studies provide support for our hypothesis that a reduction in HRV may contribute to dysregulation in autonomic cardiac control in ASD population.
Author: Rinku Thapa
Language: English
Subfield: Cardiology and Cardiovascular Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W3046383758