title: Heritability and Temporal Stability of Ambulatory Autonomic Stress Reactivity in Unstructured 24-Hour Recordings.
abstract: OBJECTIVE
  Measurements of ambulatory autonomic reactivity can help with our understanding of the long-term health consequences of exposure to psychosocial stress in real-life settings.
  
  
  METHODS
  In this study, unstructured 24-hour ambulatory recordings of cardiac parasympathetic and sympathetic control were obtained in 1288 twins and siblings, spanning both work time and leisure time. These data were used to define two ambulatory baseline (sleep, leisure) and four stress conditions (wake, work, work_sitting, work_peak) from which six ambulatory stress reactivity measures were derived. The use of twin families allowed for estimation of heritability and testing for the amplification of existing or emergence of new genetic variance during stress compared with baseline conditions.
  
  
  RESULTS
  Temporal stability of ambulatory reactivity was assessed in 62 participants and was moderate to high over a 3-year period (0.36 < r < 0.91). Depending on the definition of ambulatory reactivity used, significant heritability was found, ranging from 29% to 40% for heart rate, 34% to 47% for cardiac parasympathetic control (indexed as respiratory sinus arrhythmia), and 10% to 19% for cardiac sympathetic control (indexed as the preejection period). Heritability of ambulatory reactivity was largely due to newly emerging genetic variance during stress compared with periods of rest. Interestingly, reactivity to short standardized stressors was poorly correlated with the ambulatory reactivity measures implying poor laboratory-real-life correspondence.
  
  
  CONCLUSIONS
  Ambulatory autonomic reactivity extracted from an unstructured real-life setting shows reliable, stable, and heritable individual differences. Real-life situations uncover a new and different genetic variation compared with that seen in resting baseline conditions, including sleep.
authors.affiliation: From the Department of Biological Psychology (Neijts, Lien, Kupper, Boomsma, Willemsen, de Geus), VU University Amsterdam, Amsterdam, the Netherlands; EMGO+ Institute for Health and Care Research (Neijts, Lien, Boomsma, Willemsen, de Geus), VU University Medical Center, Amsterdam, the Netherlands; and CoRPS-Center of Research on Psychology in Somatic diseases, Department of Medical & Clinical Psychology (Kupper), Tilburg University, Tilburg, the Netherlands.
authors.forename: Melanie
authors.initials: M
authors.lastname: Neijts
authors.forename: Rene
authors.initials: R
authors.lastname: van Lien
authors.forename: Nina
authors.initials: N
authors.lastname: Kupper
authors.forename: Dorret
authors.initials: D
authors.lastname: Boomsma
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.forename: Eco J C
authors.initials: EJ
authors.lastname: de Geus
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000235:genetics*; D006801:Humans; D007206:Individuality; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000706:statistics & numerical data*; D009426:Netherlands; D012042:Registries; D065809:Respiratory Sinus Arrhythmia / Q000235:genetics; D035781:Siblings; D013315:Stress, Psychological / Q000235:genetics*; D014427:Twins