Developmental Antecedents of Cardiac Autonomic Balance in Infancy

• In Event: 3-217 - Promoting the development of children’s autonomic regulation: The role of parents and the parent-child relationship

Integrative Statement

Cardiac autonomic balance (CAB; relative influences of sympathetic and parasympathetic nervous systems on the heart at rest) has been called the “final common pathway” linking health and mental health in adulthood (Thayer & Brosschot, 2005). Sympathetic and parasympathetic functioning that determine CAB stabilize by age five, after which low-sympathetic/high-parasympathetic CAB supports regulation and health (Alkon et al., 2011). Parasympathetic determinants of CAB are thought to develop most rapidly in the first six months of life, when feeding is often used to soothe. Neuromuscular regulation induced by nutritive sucking may exercise the system, laying physiological groundwork for the low-sympathetic/high-parasympathetic CAB that facilitates social regulation (Quigley & Moore, 2018). However, most longitudinal studies of parasympathetic functioning begin at 3-5mos, precluding investigation of earlier development and relations with childhood CAB.
Therefore, we examined (1) relations between parasympathetic tone across 2wks to 4.5yrs and age-five CAB; and (2) feeding practices that predicted periods of parasympathetic change associated with age-five CAB. We expected (1) age-five CAB to be related to parasympathetic change from 2wks-4mos and 4mos-6mos, when parasympathetic determinants of CAB are thought to develop most rapidly; and (2) feeding practices to predict 2wk-4mo and 4mo-6mo parasympathetic change, when feeding may soothe by exercising the parasympathetic system.
Method: Children (N = 150; 52% female; 91.8% White) and their mothers attended laboratory visits at child age 2wks, 4mos, 6mos, 12mos, 4.5yrs, and 5.5yrs, during which child respiratory sinus arrhythmia (RSA; parasympathetic tone) was collected. Child pre-ejection period (PEP; sympathetic tone) was measured at 4.5yrs and 5.5yrs. CAB was computed from 5.5yr RSA and PEP as zRSA-(-zPEP) (Berntson et al., 2008). Mothers reported on feeding practices (type, frequency) at each visit.
Results: A general linear model showed relations between age-five CAB and RSA across 2wks-4.5yrs, F(4, 31) = 5.06, p < .01, η2 = .40. Within-subjects contrasts showed higher age-five CAB (more-parasympathetic) to be predicted by 2wks-4mos RSA increases, F(1, 34) = 9.01, p < .01, and 4mos-6mos RSA decreases, F(1, 34) = 11.12, p < .01 (Fig. 1).
Two linear regressions examined predictors of 2wk-4mo and 4mo-6mo RSA change scores (Table 1). Nonsignificant covariates (infant age, sex) were trimmed. 2wks-4mos RSA increases, F(3, 133) = 49.60, p < .001, R2 = .53, were predicted by more-frequent feedings at 2wks, ß = -.17, p < .05, and lower 2wk RSA, ß = -.69, p < .001. 4mos-6mos RSA decreases, F(4, 123) = 10.01, p < .001, R2 = .25, were predicted by breastfeeding at 4mos, ß = -.19, p < .05, and greater 2wk-4mo RSA increases, ß = -.47, p < .001.
Conclusions: Parasympathetic increases from 2wks-4mos and decreases from 4mos-6mos were linked with health-promoting, low-sympathetic/high-parasympathetic CAB at age five. Frequent feeding in the first postnatal weeks may promote 2wk-4mo parasympathetic growth, initiating a developmental cascade by bolstering regulatory capacity. Although breastfeeding-associated RSA decreases from 4mos-6mos were unexpected, these may support acquisition of social regulatory skills during this period. Results point to a possible developmental window in which feeding practices shape parasympathetic determinants of childhood CAB.

Authors

• Kelsey M Quigley, Pennsylvania State University
  Presenting Author

• Penina Backer, Pennsylvania State University
  Non-Presenting Author

• Ginger A Moore, Pennsylvania State University
  Non-Presenting Author

• Cindy Stifter, Pennsylvania State University
  Non-Presenting Author