Submitted to: Psychophysiology
Publication Type: Abstract Only
Publication Acceptance Date: 6/19/2007
Publication Date: 9/15/2007
Citation: Pivik, R.T., Jing, H., Gilchrist, J.M., Badger, T.M. 2007. Infant diet and the development of cardiovascular reactivity during the first year of life [abstract]. Psychophysiology. 44(S1):S104.
Interpretive Summary: The maturation of heart rate control is important for later behavioral self-regulation and learning. The influence of infant diet on this development has not been studied. We recorded heart rate reactions during the first year of life to sounds that were either brief and loud or longer and less intense in the same infants who were breast-fed or fed milk- or soy-based formula. At 3 months, breast-fed infants were more reactive than bottle-fed infants. After 3 months, all groups showed a similar slowing of heart rate to both kinds of sounds, with greater slowing to loud sounds. These responses reflect the development of processes related to attention in infants. Whether the early differences that were seen have long-term behavioral effects will be determined as this longitudinal study progresses.
Technical Abstract: Despite indications of postnatal programming on a range of developmental processes, the influence of infant diet on the maturation of cardiac control and reactivity has not been documented. In this study heart-rate (HR) responses to acoustic stimuli were evaluated at ages 3, 6, 9 and 12 months in awake healthy, full-term infants exclusively breast-fed (BF; n = 25), or fed milk (MF; n = 42) or soy formula (SF; n = 31) through 6 months. Startle stimuli [1000 Hz, 105 dB, 50 ms] were presented with (pre-conditioned) and without (standard) preceding tones (1000 Hz, 75 dB; 2-sec continuous or 25 ms, 200 ms pre-startle; inter-trial intervals > 25 sec; 4 trials/condition; the initial two trials were standards, remaining trials were randomized). Artifact-free recordings were digitized (1000 Hz), inter-beat intervals determined, interpolated, and downsampled at 5 Hz. Data (1-2 sec pre-, 3-4 sec post-startle stimulus) were analyzed using ANOVAs with post-hoc t-tests. For all groups after 3 months HR deceleration was present to both 2-sec tones and startle stimuli (p < .01) and was greatest to 2-sec tone pre-conditioned startle stimuli (p < .01). BF infants were more reactive than MF or SF infants to the 2-sec tone at 3 months (p < .03). However, at later ages group effects for the 2-sec tone and post-startle responses were non-significant. These are preliminary data from a longitudinal prospective study of the effects of infant feeding on cardiovascular activity related to child behavior and the long-term behavioral significance of these early diet-related differences is unknown.