title: Cortisol circadian rhythms and response to stress in children with autism.
abstract: BACKGROUND
  Autism is a severe neurodevelopmental disorder characterized by impairment in communication, social interaction, repetitive behaviors and difficulty adapting to novel experiences. The Hypothalamic-Pituitary-Adrenocortical (HPA) system responds consistently to perceived novel or unfamiliar situations and can serve as an important biomarker of the response to a variety of different stimuli. Previous research has suggested that children with autism may exhibit dysfunction of the HPA system, but it is not clear whether altered neuroendrocrine regulation or altered responsiveness underlies the differences between children with and without autism. In order to provide preliminary data concerning HPA regulation and responsiveness, we compared circadian rhythms and response to a non-social, environmental stressor in children with and without autism.
  
  
  METHODS
  Circadian rhythms of cortisol were estimated in children with (N=12) and without (N=10) autism via analysis of salivary samples collected in the morning, afternoon and evening on 2 consecutive days. HPA responsiveness was assessed by examining the time course of changes in salivary cortisol in response to a mock MRI.
  
  
  RESULTS
  Both groups showed expected circadian variation with higher cortisol concentration in morning than in the evening samples. The children with autism, but not typical children, showed a more variable circadian rhythm as well as statistically significant elevations in cortisol following exposure to a novel, nonsocial stimulus.
  
  
  CONCLUSIONS
  The results suggest that children with autism process and respond idiosyncratically to novel and threatening events resulting in an exaggerated cortisol response.
authors: Department of Psychiatry and Behavioral Sciences, University of California at Davis, 2825 50th Street, Sacramento, CA 95817, USA. blythe.corbett@ucdmc.ucdavis.edu
authors: Blythe A
authors: BA
authors: Corbett
authors: Sally
authors: S
authors: Mendoza
authors: Maryam
authors: M
authors: Abdullah
authors: Jacob A
authors: JA
authors: Wegelin
authors: Seymour
authors: S
authors: Levine
mesh_terms: D001321:Autistic Disorder / Q000378:metabolism* / Q000523:psychology; D002648:Child; D002940:Circadian Rhythm / Q000502:physiology*; D004777:Environment; D030141:Feedback, Psychological; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D008297:Male; D012463:Saliva / Q000378:metabolism; D012677:Sensation / Q000502:physiology; D013048:Specimen Handling; D013315:Stress, Psychological / Q000378:metabolism* / Q000523:psychology; D011795:Surveys and Questionnaires
chemical_list: D006854:Hydrocortisone