Related Experiment Video
Updated: Sep 9, 2025
Measuring Cardiac Autonomic Nervous System ANS Activity in Toddlers - Resting and Developmental Challenges
Published on: February 25, 2016
Development of Respiratory Sinus Arrhythmia in Young Infants With Autism Spectrum Disorder, Preterm Birth, and
Jessica Bradshaw1,2, John E Richards1,2, Julia Yurkovic-Harding1,2
1Department of Psychology, University of South Carolina, Columbia, South Carolina, USA.
Insights
Respiratory sinus arrhythmia (RSA) development was studied in infants. Infants later diagnosed with autism spectrum disorder (ASD) showed elevated RSA from 9-24 months, unlike typically developing peers.
Area of Science:
- Autonomic nervous system development
- Pediatric neurodevelopment
- Cardiorespiratory interactions
Background:
- Respiratory sinus arrhythmia (RSA) reflects parasympathetic activity and adaptability.
- Lower resting RSA is associated with preterm birth and autism spectrum disorder (ASD).
- Early RSA development in preterm infants or those at high ASD risk is largely unknown.
Purpose of the Study:
- To examine the developmental trajectories of resting RSA and mean interbeat interval (IBI) from 1 to 24 months in infants at varying risk for ASD.
- To compare RSA and IBI development between infants born preterm (PT), those with elevated likelihood for ASD (EL), and those with low likelihood for ASD (LL).
Main Methods:
- Longitudinal study of 137 infants from 1 to 24 months.
- Tracking resting RSA and mean IBI.
- Classification of infants based on ASD likelihood (EL, LL) and developmental outcome (ASD, neurodivergent (ND), typically developing (TD)).
- Mixed-effects models used to analyze developmental trajectories and group differences.
Main Results:
- Both RSA and mean IBI increased across all groups from 1 to 24 months, with fastest growth in the first 6 months.
- Preterm infants showed initially lower RSA and IBI, but normalized when corrected for prematurity.
- Infants later diagnosed with ASD exhibited elevated RSA from 9 to 24 months, differentiating them from TD and ND infants.
Conclusions:
- Elevated resting RSA in infants later diagnosed with ASD may indicate altered social monitoring, attentional regulation, or stress responses.
- Findings contrast with lower RSA in older children with ASD, suggesting developmental shifts in autonomic function.
- RSA warrants further investigation as a potential early biomarker for ASD.
Abstract:
Respiratory sinus arrhythmia (RSA) is a key index of parasympathetic function and environmental adaptability. Lower resting RSA has been linked to preterm (PT) birth in infancy and autism spectrum disorder (ASD) in childhood, yet RSA across the first 2 years in young infants born PT or later diagnosed with ASD remains unknown. This study examined resting RSA and mean interbeat interval (IBI) development from 1 to 24 months in infants at varying ASD likelihoods, including infant siblings of children with ASD and those born PT. A longitudinal design tracked resting RSA and mean IBI in 137 infants from 1 to 24 months. Infants were classified as elevated likelihood for ASD (EL), low likelihood for ASD (LL), or PT and later classified by developmental outcome as ASD, neurodivergent (ND), or typically developing (TD). Mixed-effects models examined developmental trajectories and group differences. Results indicated that both RSA and mean IBI increased across all groups from 1 to 24 months, with the most rapid growth observed in the first 6 months. PT infants exhibited lower RSA and mean IBI initially, but aligned with LL infants when age was corrected for prematurity. Infants later diagnosed with ASD showed no early RSA differences, but exhibited elevated RSA from 9 to 24 months, distinguishing them from TD and ND infants. Elevated resting RSA in ASD from 9 to 24 months may reflect reduced social monitoring, increased attentional regulation, or decreased stress during a resting period free of structured tasks. These findings contrast with lower RSA in older children with ASD, highlighting developmental shifts in autonomic function and the need for further research into RSA as an early biomarker for ASD.
Related Concept Videos
01:19Autism Spectrum Disorder
These core symptoms manifest differently among individuals, ranging from mild to severe. The disorder's complexity extends beyond its clinical presentation, encompassing a diverse range of biological, cognitive, and sociocultural influences.
01:18Dysrhythmias IV: Characteristics of Bradyarrhythmias
01:16ECG Interpretation of Arrhythmias I: Sinus Arrhythmias
Types of Arrhythmias
Sinus Node Arrhythmias
Sinus Bradycardia: Originating from the sinoatrial (SA) node, sinus bradycardia involves slower impulses, resulting in a heart rate of less than 60 beats per minute (bpm). Causes include sleep, vagal stimulation, beta-blockers, hypothyroidism,...
01:29Dysrhythmias III: Characteristics of Dysrhythmias
01:29Disturbances in Heart Rhythm
Arrhythmias are categorized by their speed, rhythm, and origin. A slow heart...
01:28Mechanism of Cardiac Arrhythmias