RESUMO
INTRODUCTION: Previously, we found that reported infant rhinorrhea and watery eyes without a cold (RWWC) predicted school age exercise-induced wheeze, emergency department visits, and hospitalizations. These findings were independent of allergic sensitization, and we theorized that increased parasympathetic tone underlay the association. We also reported that increased heart-rate variability (HRV) in infants predicted wheeze in 2-3 year-olds. In a convenience sample of children participating in a birth cohort study, we tested the hypothesis that infants with RWWC would have elevated HRV, indicating increased parasympathetic tone. METHODS: RWWC symptoms since birth were queried for 3-month-old children. At 4-months, HRV was assessed (root mean square of successive differences [RMSSD]) during a standardized infant-mother still-face paradigm, which included 2 minutes of mother/child play immediately followed by 2 minutes of the mother maintaining a still-face. RESULTS: Among participants (n=38), RWWC was common for girls (32%) and boys (21%). The children with the greatest decrease in RMSSD between play and still-face challenge (lowest tertile) had a higher prevalence of RWWC as compared with children in the higher tertiles (50% vs 16%, P=0.045). In a logistic regression model controlling for sex, age and time between HRV and RWWC assessment, children with greater decrease in HRV between play and still-face (lowest tertile) had greater odds of having RWWC (odds ratio=6.0, P=0.029). CONCLUSION: In this relatively small study, we demonstrated greater decreases in HRV in response to a stressor among children with reported RWWC, suggesting that these children might have increased parasympathetic tone and/or overall greater vagal reactivity.