Cardiac vagal regulation across the preschool period: stability, continuity, and implications for childhood adjustment.

Stability and continuity of vagal regulation of the heart, operationalized as suppression of respiratory sinus arrhythmia (RSA) during challenge, was examined in a longitudinal study of preschoolers. A sample of 154 two-year-old children was recruited for participation in a study of the effects of emotional and behavioral challenge on cardiac activity and behavioral indices of adjustment and self-regulation. A total of 122 of these children were assessed again at age 4.5 years. At both ages, the children were assessed in a series of laboratory procedures that were intended to be emotionally and behaviorally challenging, during which time heart rate was recorded. To assess vagal regulation, resting measures of RSA and RSA suppression to the challenge task were derived from these procedures. To assess childhood adjustment and self-regulation, a number of parent-report measures were administered when the children were 4.5 years of age. Results indicated that there was high stability in RSA suppression across the challenge tasks within both ages, modest cross-age stability in RSA suppression, and a significant decrease in the magnitude of RSA suppression across age. Second, children who displayed a pattern of stable and high suppression across the preschool period were less emotionally negative, and had fewer behavior problems and better social skills than other children. (c) 2004 Wiley Periodicals, Inc.