title: Validation of an adapted procedure to collect hair for cortisol determination in adolescents.
abstract: In the last decades, cortisol has been extensively studied in association to early exposure to adversity as well as in the etiology of a number of physical and mental problems. While saliva and blood samples allow the measurement of acute changes in cortisol secretion, hair samples are thought to provide a valid retrospective measure of chronic cortisol secretion over an extended period of time. Nevertheless, the existing protocol for hair collection involves considerable financial and logistical challenges when performed in large epidemiological studies.
  
  
  
  This study aimed to validate an adapted collection protocol asking participants to sample their hair at home and to send it back to our laboratory by regular mail.
  
  
  
  Participants were 34 teenagers between 17 and 18 years of age. They participated in two hair collections: (a) at home, with the help of someone they know, and (b) in our laboratory, with a trained research assistant.
  
  
  
  We noted a strong correlation between cortisol ascertained from hair collected at home and at the laboratory. No mean difference in cortisol levels could be detected between the two protocols. Moreover, we showed that a wide range of hair-related, sociodemographic, lifestyle factors that may be associated with hair cortisol levels did not affect the association between cortisol measures derived from each protocol.
  
  
  
  Our study provides initial support that reliable measures of chronic cortisol secretion could be obtained by asking adolescents to collect a sample of their hair at home and send them to the laboratory by regular mail. This adapted protocol has considerable financial and logistical advantages in large epidemiological studies.
authors.affiliation: School of Criminology, University of Montreal, Montreal, Quebec, H3C 3J7, Canada; Research Center of the Montreal Mental Health University Institute, Montreal, Quebec, H1N 3M5, Canada; Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada. Electronic address: isabelle.ouellet-morin@umontreal.ca.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Ouellet-Morin
authors.affiliation: School of Criminology, University of Montreal, Montreal, Quebec, H3C 3J7, Canada; Research Center of the Montreal Mental Health University Institute, Montreal, Quebec, H1N 3M5, Canada; Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada.
authors.forename: Mélissa
authors.initials: M
authors.lastname: Laurin
authors.affiliation: School of Criminology, University of Montreal, Montreal, Quebec, H3C 3J7, Canada; Research Center of the Montreal Mental Health University Institute, Montreal, Quebec, H1N 3M5, Canada; Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada.
authors.forename: Marie-Pier
authors.initials: MP
authors.lastname: Robitaille
authors.affiliation: Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada; Department of Psychology, University of Quebec at Montreal, Quebec, H2L 2C4, Canada; Sainte-Justine Hospital Research Center, Montréal, Quebec, H3T 1C4, Canada.
authors.forename: Mara
authors.initials: M
authors.lastname: Brendgen
authors.affiliation: Research Center of the Montreal Mental Health University Institute, Montreal, Quebec, H1N 3M5, Canada; Department of Psychiatry, University of Montreal, Montreal, Quebec, H3C 3J7, Canada.
authors.forename: Sonia J
authors.initials: SJ
authors.lastname: Lupien
authors.affiliation: Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada; Department of Psychology, Laval University, Quebec, G1V 0A6, Canada; Institute of Genetic, Neurobiological, and Social Foundations of Child Development, Tomsk State University, Tomsk Oblast, 634050, Russian Federation.
authors.forename: Michel
authors.initials: M
authors.lastname: Boivin
authors.affiliation: Research Group on Child Maladjustment, Quebec, H3T 1C4, Canada; Sainte-Justine Hospital Research Center, Montréal, Quebec, H3T 1C4, Canada; School of Psychoéducation, Université de Montréal, Montréal, Quebec, H3C 3J7, Canada.
authors.forename: Frank
authors.initials: F
authors.lastname: Vitaro
mesh_terms: D000293:Adolescent; D005260:Female; D006197:Hair / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis* / Q000378:metabolism; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012463:Saliva / Q000737:chemistry; D013048:Specimen Handling / Q000379:methods*; D013315:Stress, Psychological / Q000378:metabolism
chemical_list: D006854:Hydrocortisone
keywords: Chronic stress; Collection protocol; Epidemiological studies; HPA axis; Hair cortisol