title: Peer problems are associated with elevated serum leptin levels in children.
abstract: BACKGROUND
  Leptin is thought to act as an important mediator in stress reactions. To date, no study has examined the association between psychological stress and leptin levels in children. This study aimed to assess the association between emotional symptoms and peer problems and serum leptin levels in children aged 10 years of the two population-based GINI-plus and LISA-plus birth cohorts.
  
  
  METHODS
  Cross-sectional data from 2827 children aged 10 years were assessed with regard to leptin concentrations in serum and behavioral problems using the parent-reported Strengths and Difficulties Questionnaire (SDQ). Linear regression modeling was applied to determine the likelihood of elevated leptin levels in children with emotional symptoms and peer problems, controlling for socio-economic status (SES), body mass index (BMI), fasting serum leptin levels, pubertal development and sex hormones.
  
  
  RESULTS
  We found that increases in emotional symptoms (exp β adj = 1.03, s.e. = 0.02, p < 0.04) and peer problems (exp β adj = 1.05, s.e. = 0.01, p = 0.0001) were significantly associated with higher serum leptin levels controlled for BMI and sociodemographic factors. Similar results were found when the fasting serum leptin sample was examined (exp β adj = 1.08, s.e. = 0.04, p = 0.0294). Gender-stratified analyses showed a significant relationship between serum leptin and peer problems in girls (exp β adj = 1.05, s.e. = 0.02, p = 0.03), and a borderline significant association in boys (exp β adj = 1.04, s.e. = 0.02, p = 0.05).
  
  
  CONCLUSIONS
  Children with peer problems have higher stress and eat more, acquire a higher body fat mass and thus, through increased leptin resistance, exhibit higher leptin levels.
authors.affiliation: Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Epidemiology I, Neuherberg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Kohlboeck
authors.affiliation: Department of Child and Adolescent Psychiatry and Psychotherapy, University Hospital Wuerzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Romanos
authors.affiliation: Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Epidemiology I, Neuherberg, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Tiesler
authors.affiliation: Dr von Hauner Children's Hospital, Ludwig-Maximilians-University of Munich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Koletzko
authors.affiliation: University Leipzig, Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Kratzsch
authors.affiliation: University Leipzig, Institute of Laboratory Medicine, Clinical Chemistry and Molecular Diagnostics, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Thiery
authors.affiliation: Department of Pediatrics, Technical University of Munich, Germany.
authors.forename: C-P
authors.initials: CP
authors.lastname: Bauer
authors.affiliation: Department of Pediatrics, Marien-Hospital Wesel, Germany.
authors.forename: A
authors.initials: A
authors.lastname: von Berg
authors.affiliation: Department of Pediatrics, Marien-Hospital Wesel, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Berdel
authors.affiliation: Leibniz Research Institute for Environmental Medicine, University of Düsseldorf, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Hoffmann
authors.affiliation: Medical Practice for Pediatrics, Bad Honnef, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schaaf
authors.affiliation: UFZ-Center for Environmental Research, Leipzig, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Lehmann
authors.affiliation: University Leipzig, Faculty of Medicine, Environmental Medicine and Hygiene, Leipzig, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Herbarth
authors.affiliation: Helmholtz Zentrum Muenchen, German Research Center for Environmental Health, Institute of Epidemiology I, Neuherberg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Heinrich
mesh_terms: D001526:Behavioral Symptoms / Q000097:blood* / Q000453:epidemiology; D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D004644:Emotions / Q000502:physiology; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D007398:Interpersonal Relations; D020738:Leptin / Q000096:biosynthesis / Q000097:blood*; D008297:Male; D010379:Peer Group; D012737:Sex Factors; D012959:Socioeconomic Factors; D013315:Stress, Psychological / Q000097:blood
chemical_list: D020738:Leptin