Correlates of cortisol in human hair: implications for epidemiologic studies on health effects of chronic stress

Abstract

Assessment of cortisol concentrations in hair is one of the latest innovations for measuring long-term cortisol exposure. We performed a systematic review of correlates of cortisol in human hair to inform the design, analysis and interpretation of future epidemiologic studies. Relevant publications were identified through electronic searches on PubMed, WorldCat, and Web of Science using keywords, “cortisol” “hair” “confounders” “chronic” “stress” and “correlates.” Thirty-nine studies were included in this review. Notwithstanding scarce data and some inconsistencies, investigators have found hair cortisol concentrations to be associated with stress-related psychiatric symptoms and disorders (e.g., PTSD), medical conditions indicating chronic activation of the hypothalamic-pituitary-adrenal axis (e.g., Cushing´s syndrome) and other life situations associated with elevated risk of chronic stress (e.g., shiftwork). Results from some studies suggest that physical activity, adiposity, and substance abuse may be correlates of hair cortisol concentrations. In contrast to measures of short-term cortisol release (saliva, blood, and urine), cigarette smoking and use of oral contraceptives appear to not be associated with hair cortisol concentrations. Studies of pregnant women indicate increased hair cortisol concentrations across successive trimesters. The study of hair cortisol presents a unique opportunity to assess chronic alterations in cortisol concentrations in epidemiologic studies.

Validation of an adapted procedure to collect hair for cortisol determination in adolescents

“…The small sample size, primarily composed of females of moderate-to-high socioeconomic status may, however, have restricted the statistical power to detect these effects. Mixed findings have also been found in regards to BMI and cigarette, alcohol and drug consumption, although the available data are insufficient to draw meaningful conclusions at this point in time (Wosu et al, 2013; although see Rippe et al, 2016). The investigation further contributes to existing research aiming to identify the hair cortisol's potential confounders.…”

“…Blood collection is invasive, may inadvertently increase the measurement of acute cortisol secretion, requires trained research assistants (Wosu et al, 2013) and both blood and saliva require storage equipment (e.g. freezers).…”

“…Considering that the use of hair samples to ascertain chronic cortisol secretion is still at an early stage, much work remains to be done to clearly identify its potential confounders, such as hairrelated (e.g., frequency of wash) and sociodemographic and lifestyle factors (e.g., sex, body mass index (BMI); Wosu et al, 2013;Rippe et al, 2016).…”

Hair cortisol and self-reported stress in healthy, working adults

“…Evidence is accumulating for the potential application of HCC in clinical and epidemiological studies (Wester and van Rossum, 2015;Wosu et al, 2013) and various relationships have been demonstrated between HCC and, for example, Cushing's Syndrome (Manenschijn et al, 2012), cardiovascular disease (Manenschijn et al, 2013), depression and mood disorders (Dettenborn et al, 2012b), and anxiety (Steudte et al, 2011). However, the association between HCC and subjectively measured stress remains unclear.…”

Hair cortisol as a novel biomarker of HPA suppression by inhaled corticosteroids in children

“…Additional confounding may be present with the analysis of older hair segments. While the majority of studies have not found an association with the frequency of hair washing, some have reported declining hair cortisol in older hair segments (22). This may be in part due to repeated shampooing as found by Hamel et al (23).…”