title: Symptom-specific associations between low cortisol responses and functional somatic symptoms: the TRAILS study.
abstract: BACKGROUND
  Functional somatic symptoms (FSS), like chronic pain and overtiredness, are often assumed to be stress-related. Altered levels of the stress hormone cortisol could explain the association between stress and somatic complaints. We hypothesized that low cortisol levels after awakening and low cortisol levels during stress are differentially associated with specific FSS.
  
  
  METHODS
  This study is performed in a subsample of TRAILS (Tracking Adolescents' Individual Lives Survey) consisting of 715 adolescents (mean age: 16.1 years, SD=0.6, 51.3% girls). Adolescents' cortisol levels after awakening and during a social stress task were assessed. The area under the curve with respect to the ground (AUCg) and the area under the curve above the baseline (AUCab) were calculated for these cortisol levels. FSS were measured using the Youth Self-Report and pain questions. Based upon a factor analysis, FSS were divided into two clusters, one consisting of headache and gastrointestinal symptoms and the other consisting of overtiredness, dizziness and musculoskeletal pain.
  
  
  RESULTS
  Regression analyses revealed that the cluster of headache and gastrointestinal symptoms was associated with a low AUCg of cortisol levels during stress (β=-.09, p=.03) and the cluster of overtiredness, dizziness and musculoskeletal pain with a low AUCg of cortisol levels after awakening (β=-.15, p=.008). All these analyses were adjusted for the potential confounders smoking, physical activity level, depression, corticosteroid use, oral contraceptive use, gender, body mass index and, if applicable, awakening time.
  
  
  CONCLUSIONS
  Two clusters of FSS are differentially associated with the stress hormone cortisol.
authors.affiliation: Interdisciplinary Center for Psychiatric Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. k.a.m.janssens@med.umcg.nl
authors.forename: Karin A M
authors.initials: KA
authors.lastname: Janssens
authors.forename: Albertine J
authors.initials: AJ
authors.lastname: Oldehinkel
authors.forename: Frank C
authors.initials: FC
authors.lastname: Verhulst
authors.forename: Joke A M
authors.initials: JA
authors.lastname: Hunfeld
authors.forename: Johan
authors.initials: J
authors.lastname: Ormel
authors.forename: Judith G M
authors.initials: JG
authors.lastname: Rosmalen
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D008297:Male; D010912:Pituitary-Adrenal Function Tests / Q000379:methods / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology; D012463:Saliva / Q000378:metabolism; D013001:Somatoform Disorders / Q000150:complications / Q000378:metabolism*; D013315:Stress, Psychological / Q000150:complications / Q000378:metabolism*; D014851:Wakefulness
chemical_list: D015415:Biomarkers; D006854:Hydrocortisone