title: Autonomic and adrenocortical reactivity and buccal cell telomere length in kindergarten children.
abstract: OBJECTIVE
  To examine associations between autonomic nervous system and adrenocortical reactivity to laboratory stressors and buccal cell telomere length (BTL) in children.
  
  
  METHODS
  The study sample comprised 78 children, aged 5 to 6 years, from a longitudinal cohort study of kindergarten social hierarchies, biologic responses to adversity, and child health. Buccal cell samples and reactivity measures were collected in the spring of the kindergarten year. BTL was measured by real-time polymerase chain reaction, as the telomere-to-single-copy gene ratio. Parents provided demographic information; parents and teachers reported children's internalizing and externalizing behavior problems. Components of children's autonomic (heart rate, respiratory sinus arrhythmia [RSA], and preejection period [PEP]) and adrenocortical (salivary cortisol) responses were monitored during standardized laboratory challenges. We examined relationships between reactivity, internalizing and externalizing behaviors, and BTL, adjusted for age, race, and sex.
  
  
  RESULTS
  Heart rate and cortisol reactivity were inversely related to BTL, PEP was positively related to BTL, and RSA was unrelated to BTL. Internalizing behaviors were also inversely related to BTL (standardized β = -0.33, p = .004). Split at the median of reactivity parameters, children with high sympathetic activation (decreasing PEP), and parasympathetic withdrawal (decreasing RSA) did not differ with regard to BTL. However, children with both this profile and high cortisol reactivity (n = 12) had significantly shorter BTL (0.80 versus 1.00; χ² = 7.6, p = .006), compared with other children.
  
  
  CONCLUSIONS
  The combination of autonomic and adrenocortical reactivity was associated with shorter BTL in children. These data suggest that psychophysiological processes may influence, and that BTL may be a useful marker of, early biologic aging.
authors.affiliation: Kaiser Permanente Division of Research, 2101 Webster St, Oakland, CA 94612, USA. candyce.h.kroenke@kp.org
authors.forename: Candyce H
authors.initials: CH
authors.lastname: Kroenke
authors.forename: Elissa
authors.initials: E
authors.lastname: Epel
authors.forename: Nancy
authors.initials: N
authors.lastname: Adler
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Bush
authors.forename: Jelena
authors.initials: J
authors.lastname: Obradovic
authors.forename: Jue
authors.initials: J
authors.lastname: Lin
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Blackburn
authors.forename: Juliet Lise
authors.initials: JL
authors.lastname: Stamperdahl
authors.forename: W Thomas
authors.initials: WT
authors.lastname: Boyce
mesh_terms: D000302:Adrenal Cortex / Q000502:physiology*; D000375:Aging / Q000502:physiology; D001007:Anxiety / Q000503:physiopathology; D001146:Arrhythmia, Sinus / Q000503:physiopathology; D001341:Autonomic Nervous System / Q000502:physiology*; D002648:Child; D002675:Child, Preschool; D003863:Depression / Q000503:physiopathology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D008297:Male; D009061:Mouth Mucosa / Q000166:cytology* / Q000502:physiology; D060888:Real-Time Polymerase Chain Reaction; D012463:Saliva / Q000737:chemistry; D013315:Stress, Psychological / Q000503:physiopathology; D016615:Telomere / Q000502:physiology*
chemical_list: D006854:Hydrocortisone