27674
The Respiratory Sinus Arrhythmia in Young, Low-Functioning Children with and without Autism Spectrum Disorder
Heart rate variability, and more specifically, respiratory sinus arrhythmia (RSA) is considered as a peripheral biomarker of social competence and emotion regulation. Earlier research has often found lowered RSA in individuals with ASD and it has been associated with various difficulties in social cognition, such as emotion recognition, social responsiveness and spontaneous use of eye gaze. There have, however, been also contradictory findings showing no ASD specific differences in RSA. It is assumed that the decreased RSA is not unique to ASD but shown to relate social difficulties in other neurodevelopmental disorders too. In addition, the earlier studies have mainly been done in school-aged, high-functioning children with ASD leaving open the question whether lowered RSA evokes early in autistic development and relates to social difficulties also in low-functioning children with ASD.
Objectives:
The main aim of the study was to investigate baseline RSA in young, low-functioning children with severe ASD. In order to study the effects of developmental level to RSA, we had an IQ-matched comparison group of developmental delay children (DD) without ASD. Age-matched typically developing children (TD) served as a normative control group. In addition, the connections between RSA and reciprocal social interaction, communication and restricted, repetitive, and stereotyped patterns of behaviour were studied in all the groups.
Methods:
The final sample consisted of 14 children with ASD, 17 TD children and 16 children with DD. Every group included 2 girls and the age ranged from 29 to 81 months. Heart rate was measured whilst the children looked at a neutral video about a person building with Lego bricks for 3 minutes. Data was carefully offline video analysed in order to reject artefacts. RSA was analysed in 0,24–1,04 Hz using a Matlab-based in-house program. The parents filled Social Communication Questionnaire (SCQ) as a measure of autistic behaviour.
Results:
The findings revealed significant difference in RSA between the groups (Kruskal-Wallis H = 6,324, p = .042). Paired comparison showed that the children with ASD had lower RSA than TD children and children with DD. There were no differences in RSA between TD and DD children. SCQ domains of reciprocal social interaction and communication were not associated to RSA in any of the groups. However, a trend of interaction between RSA and restricted, repetitive, and stereotyped behaviour (RRB) was found both in the ASD and DD groups. The higher RSA was connected to more RRB in children with ASD whereas in children with DD higher RSA was connected with less RRB.
Conclusions:
The findings of the study indicated that lowered RSA is detectable early in the autistic development and is not related to the developmental delay without ASD. Interestingly, the RSA connection to restricted, repetitive, and stereotyped behaviour seemed to be reversed in children with ASD and children with developmental delay. Restricted and repetitive behaviour as an aid for self-regulation in ASD deserves further clarification.