Quantification of Anxiety Levels in Children with Autism Based on
Changes in Physiological Signals
Michele Pla1,3, Azadeh Kushki1, Tom Chau1,2, Evdokia Anagnostou1,2
1Bloorview Research Institute; 2 University of Toronto; 2 Universidad Iberoamericana
Objective: The objective of this study is to develop a method to non-invasively quantify anxiety levels in children with autism spectrum disorders by characterizing changes in physiological signals.
Target Population: High-functioning children with autism spectrum disorders
Introduction: Autism spectrum disorders are neurodevelopmental disorders defined by deficits in social interaction and communication and by unusual restricted, repetitive behaviours. While not a core clinical feature, anxiety disorders are highly associated with ASD. Several studies have reported that children with ASDs exhibited a higher degree of anxiety than typically developing children. Anxiety may be considered a possible consequence or even cause of the core features of ASD. In particular, it is suggested that obsessions, routines, and repetitive behaviours, may be partially driven by anxiety. Behaviours such as echolalia, rocking, and repetitive questioning tend to increase when children are anxious, suggesting that this may work as self-calming strategies. The interruption of these behaviours may increase anxiety levels. The high prevalence of anxiety in children with ASD and its profound impact on social and emotional development strongly motivate development of effective assessment and intervention techniques. However, assessment of anxiety in children with ASD is challenging as due to deficits in verbal communication and non-verbal communication. A promising direction for assessment of anxiety in children with ASD is the use of physiological measures that correlate with affective states. These measures are controlled by the autonomic nervous system (ANS) and include heart rate, skin conductance, skin temperature, and respiration. Physiological measures are especially well-suited for anxiety detection in children with ASD as they do not require verbal expression or emotional awareness, and reflect behavior not related to core deficits of ASD. The objective of this study is to examine the efficacy of these signals as a means for assessment of anxiety in children with ASD.
Methods: The study follows an ABA design that consists in a relaxation period (A), exposure to a stressor (B), and relaxation (A). For the baseline/relaxation periods, participants watch a short movie. The stressor consists of the Color Stroop Test (naming the colour in which a word is printed while the word actually names a different colour). This test has been widely used in studies of anxiety and is known to elicit physiological responses to anxiety and has been successfully used with children with ASD. Prior to the baseline and after the study concludes, a behavioural measure will be administered to assess changes in self-reported anxiety levels. Physiological measurement is performed throughout the study using Thought Technologies FlexComp. Thermal imaging of the face will also be recorded to look into changes in facial skin temperature associated to an increased blood flow due to anxiety.
Results and Conclusions: Data collection for this study is still in progress. Preliminary results indicate significant changes in the physiological signals in response to the Stroop test. The outcome of this study may ultimately lead to objective and non-invasive tools for measurement of anxiety in children with ASD.