Cardiac autonomic regulation as a proxy of early neurodevelopment: A systematic review.

Background: Cardiac autonomic regulation and early neurodevelopment are linked, but research has focused largely on specific domains, such as attention and memory, neglecting broad neurodevelopmental outcomes. The use of diverse study populations and methodologies further hinders interpretation, highlighting the need for more consistent, integrative research in this area. Therefore, the aim of this study was to clarify how cardiac autonomic regulation (as quantified by heart rate indices) is associated with global neurodevelopment in infancy through a systematic literature review.

Method: A systematic literature search was carried out in the Scopus, PubMed, Web of Science, and ProQuest databases for studies published between January 1980 and December 2022. The search terms were a combination of words that included elements from three categories: 1) cardiac vagal regulation, 2) neurodevelopment indicators, and 3) population (neonate/infant).

Results: Five studies involving 933 infants (48 % of whom were girls) and baseline evaluations from birth to 26 weeks of age were included. The findings were mixed: while some studies identified positive associations between parasympathetic activity and neurodevelopmental outcomes, others reported nonsignificant or inconsistent associations. The variability in study designs, measurement methods, and population characteristics likely contributed to these discrepancies. However, respiratory sinus arrhythmia (RSA) was the most commonly used indicator, and the highest percentage of studies reported significant associations between neurodevelopment and autonomous functioning (RSA = 83 %, heart rate variability = 69 %), particularly when controlling for factors such as age and birthweight.

Conclusions: Although autonomic regulation during the first years of life appears to be associated with neurodevelopment, the evidence is not entirely consistent across all heart rate indices or developmental domains. Further research is needed to better understand these relationships, particularly in light of the methodological differences and potential confounding factors. Recognizing individual differences in autonomic nervous system regulation could provide valuable insights into neurodevelopmental trajectories.