A systematic review of studies utilizing hair glucocorticoids as a measure of stress suggests the marker is more appropriate for quantifying short-term stressors

Abstract

Quantitating glucocorticoids (GCs) in hairs is a popular method for assessing chronic stress in studies of humans and animals alike. The cause-and-effect relationship between stress and elevated GC levels in hairs, sampled weeks later, is however hard to prove. This systematic review evaluated the evidence supporting hair glucocorticoids (hGCs) as a biomarker of stress. Only a relatively small number of controlled studies employing hGC analyses have been published, and the quality of the evidence is compromised by unchecked sources of bias. Subjects exposed to stress mostly demonstrate elevated levels of hGCs, and these concentrations correlate significantly with GC concentrations in serum, saliva and feces. This supports hGCs as a biomarker of stress, but the dataset provided no evidence that hGCs are a marker of stress outside of the immediate past. Only in cases where the stressor persisted at the time of hair sampling could a clear link between stress and hGCs be established.

The effect of a mindfulness-based therapy on different biomarkers among patients with inflammatory bowel disease: a randomised controlled trial

“…There is mounting evidence that the cortisol content of hair reflects the corresponding systemic plasma levels of this hormone over time and so these can be used to estimate both psychological and physiological chronic stress and the extent of hypothalamic pituitary-adrenal axis disorders such as Cushing syndrome and Addison disease 23,27,43,[45][46][47] . However, the validity of the methods used to measure cortisol responses has been questioned 48 , and factors including age, sex, hair-washing frequency, hair treatments, or the use of oral contraceptives can produce misleading results 49 . The efficacy of MBI to affect cortisol responses reported by others was also lower than expected.…”

A Ten-Stage Protocol for Assessing the Welfare of Individual Non-Captive Wild Animals: Free-Roaming Horses (Equus Ferus Caballus) as an Example

“…However, interpretation of many of these indices is not straightforward. For example, while faecal [108][109][110] and hair [111,112] cortisol concentrations have been employed as a physiological index of stress [108][109][110][111][112], the significance of non-specific stress for an animal's mental experience is unclear [52,113]. Cortisol and many other physiological parameters are non-specific and do not indicate if the experience was positive (e.g., excitement, arousal) or negative (e.g., pain, fear, hunger).…”

<p>Fetal Programming of Semen Quality (FEPOS) Cohort – A DNBC Male-Offspring Cohort</p>

“…The hair strands were stuck on paper with adhesive tape (Lyreco, Marly, France) with clear indication of the hair root, and stored in an envelope at room temperature. The thought was to conduct hair analysis as an indicator of eg stress, 41,42 but no specific studies are planned yet.…”