title: Negative life events, emotions and psychological difficulties as determinants of salivary cortisol in Belgian primary school children.
abstract: OBJECTIVE
  This paper describes whether children's life events, emotions and psychological difficulties are related to their salivary cortisol patterns and whether this is different between sexes.
  
  
  METHODS
  In 385 children (5-10 years old) participating in the ChiBS study, salivary cortisol samples were collected when waking up, 30 min and 60 min after wake up and in the evening on two consecutive weekdays. Moreover, data on children's life events, emotions and difficulties were collected. Statistical analysis was done separately for boys and girls by multilevel growth curve modelling with adjustments for age, body mass index, socio-economic status and wake up time.
  
  
  RESULTS
  In boys and girls with more negative life events during the last three months, the diurnal cortisol slope was steeper (more decline). Boys with higher self-reported happiness showed lower overall, morning and evening cortisol levels. In contrast, the diurnal slope was steeper (more decline) in boys with emotional problems due to higher morning values. In girls, peer problems were associated with lower overall and morning cortisol levels.
  
  
  CONCLUSIONS
  Children's salivary cortisol patterns were related to some negative life events, emotions and difficulties, although differently in boys and girls. As such, sex-differences in HPA functioning are already present in young children. Most findings support the upregulation of the cortisol response to stress, although lower morning values were found in the presence of peer problems in girls. Future studies should focus on sex differences, positive emotions and the diurnal cortisol slope.
authors.affiliation: Department of Public Health, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185, B-9000 Ghent, Belgium. Nathalie.michels@ugent.be
authors.forename: Nathalie
authors.initials: N
authors.lastname: Michels
authors.forename: Isabelle
authors.initials: I
authors.lastname: Sioen
authors.forename: Inge
authors.initials: I
authors.lastname: Huybrechts
authors.forename: Karin
authors.initials: K
authors.lastname: Bammann
authors.forename: Barbara
authors.initials: B
authors.lastname: Vanaelst
authors.forename: Tineke
authors.initials: T
authors.lastname: De Vriendt
authors.forename: Licia
authors.initials: L
authors.lastname: Iacoviello
authors.forename: Kenn
authors.initials: K
authors.lastname: Konstabel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ahrens
authors.forename: Stefaan
authors.initials: S
authors.lastname: De Henauw
mesh_terms: D001530:Belgium; D002648:Child; D002675:Child, Preschool; D002940:Circadian Rhythm / Q000502:physiology; D004644:Emotions / Q000502:physiology*; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D008016:Life Change Events; D008297:Male; D011569:Psychiatric Status Rating Scales; D012463:Saliva / Q000737:chemistry*; D012727:Sex Characteristics; D011795:Surveys and Questionnaires
chemical_list: D006854:Hydrocortisone