title: Age-related differences in the association between stereotypic behaviour and salivary cortisol in young males with an Autism Spectrum Disorder.
abstract: To identify if age influenced the relationship between one of the central symptoms of Autism Spectrum Disorder (ASD) and physiological stress, the association between stereotypic behaviour (SB) and stress-related cortisol concentrations was examined in a sample of 150 young males with an ASD. Parent-rated SB was significantly correlated with cortisol concentrations for boys aged 6 years to 12 years but not for adolescents aged 13 years to 18 years. This age-related difference in this association was not a function of cortisol concentrations but was related to differences in SB across these two age groups. IQ did not have a significant effect on this relationship, suggesting that age-related learning may have been a possible pathway for reduced SB during adolescence. The aspect of SB that was most powerfully related to cortisol was general repetitive behaviour rather than movements of specific body parts. Explanations of these findings are raised for further investigation.
authors.affiliation: Centre for Autism Spectrum Disorders, Bond University, Robina, Queensland, 4229, Australia. Electronic address: vbitsika@bond.edu.au.
authors.forename: Vicki
authors.initials: V
authors.lastname: Bitsika
authors.affiliation: Centre for Autism Spectrum Disorders, Bond University, Robina, Queensland, Australia; Brain-Behaviour Research Group, University of New England, Armidale, 2351, New South Wales, Australia. Electronic address: Csharpl3@une.edu.au.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Sharpley
authors.affiliation: Brain-Behaviour Research Group, University of New England, 2351, Australia. Electronic address: Lagnew2@une.edu.au.
authors.forename: Linda L
authors.initials: LL
authors.lastname: Agnew
authors.affiliation: Brain-Behaviour Research Group, University of New England, 2351, Australia. Electronic address: Nandroni@une.edu.au.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Andronicos
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000067877:Autism Spectrum Disorder / Q000503:physiopathology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D007360:Intelligence; D007361:Intelligence Tests; D008297:Male; D011569:Psychiatric Status Rating Scales; D012044:Regression Analysis; D012463:Saliva / Q000378:metabolism*; D013239:Stereotyped Behavior / Q000502:physiology*
chemical_list: D006854:Hydrocortisone
keywords: Age; Autism; Cortisol; Stereotypical behaviour