Development of Respiratory Sinus Arrhythmia in Young Infants With Autism Spectrum Disorder, Preterm Birth, and...

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.