University of Western Ontario - Electronic Thesis and Dissertation Repository

Degree

Master of Science

Program

Pharmacology and Toxicology

Supervisor

Gideon Koren & Michael Rieder

Delay of Publication

1

Abstract

This thesis examines methodological and clinical aspects of hair cortisol analysis. The methodological study examines the role of sweat as a contributor to hair cortisol concentrations. Hair cortisol analysis is an effective measure of chronic stress. Cortisol is assumed to enter the hair via blood, sebum, and sweat, however the extent to which sweat contributes to hair cortisol content was unknown. This study concluded that human sweat contains cortisol that likely contributes to hair cortisol content. Subjects with prolonged sweating at the time of hair collection may have increased hair cortisol concentrations that cannot be decreased with conventional laboratory washing procedures. Clinically, hair cortisol analysis is explored as a tool to determine if obstructive sleep apnea (OSA) is associated with increased stress. OSA is a common sleep disorder with serious cardiovascular and metabolic co-morbidities that may be mediated by increased cortisol secretion. Recent studies have focused on the ability of continuous positive airway pressure (CPAP) to reduce cortisol secretion in OSA patients, but the results have been mixed and only point measures of cortisol measurement have been used. Hair cortisol analysis presents a means of non-invasively and retrospectively examining cortisol production in these patients. This study examined whether hair cortisol concentrations are increased in OSA patients. Further, the effect of CPAP on hair cortisol concentrations was examined. It was concluded that cortisol secretion may be up-regulated in severe cases of OSA. The psychological stress of OSA may be reduced with CPAP, however physiological stress may remain unchanged after 3 months of treatment.