"Unstimulated cortisol secretory activity..." (2013)

[Ren]

I didn't see the following posted elsewhere...
(Open access: http://www.sciencedirect.com/science/article/pii/S0306453013002540)

"Unstimulated cortisol secretory activity in everyday life and its relationship with fatigue and chronic fatigue syndrome: A systematic review and subset meta-analysis."

Psychoneuroendocrinology, 2013

Daniel J H Powell, Christina Liossi, Rona Moss-Morris, Wolff Schlotz


ABSTRACT The hypothalamic-pituitary-adrenal (HPA) axis is a psychoneuroendocrine regulator of the stress response and immune system, and dysfunctions have been associated with outcomes in several physical health conditions. Its end product, cortisol, is relevant to fatigue due to its role in energy metabolism.

The systematic review examined the relationship between different markers of unstimulated salivary cortisol activity in everyday life in chronic fatigue syndrome (CFS) and fatigue assessed in other clinical and general populations. Search terms for the review related to salivary cortisol assessments, everyday life contexts, and fatigue. All eligible studies (n=19) were reviewed narratively in terms of associations between fatigue and assessed cortisol markers, including the cortisol awakening response (CAR), circadian profile (CP) output, and diurnal cortisol slope (DCS). Subset meta-analyses were conducted of case-control CFS studies examining group differences in three cortisol outcomes: CAR output; CAR increase; and CP output.

Meta-analyses revealed an attenuation of the CAR increase within CFS compared to controls (d=-.34) but no statistically significant differences between groups for other markers. In the narrative review, total cortisol output (CAR or CP) was rarely associated with fatigue in any population; CAR increase and DCS were most relevant. Outcomes reflecting within-day change in cortisol levels (CAR increase; DCS) may be the most relevant to fatigue experience, and future research in this area should report at least one such marker. Results should be considered with caution due to heterogeneity in one meta-analysis and the small number of studies.

 

[Snow Leopard]

This study is mostly a waste of time. In fact they spoke very little about how variations in salivary cortisol could actually cause symptoms in the first place. There seems to be no attempt to consider the biological context, eg other hormones and receptor activity at the same time. Likewise, most studies did not properly control for other factors like altered sleeping cycles, the possibility of CFS patients having lower anticipation of stress due to being housebound etc.


Strangely, they justify it on claims that glucocorticoid treatments are effective in alleviating short term fatigue.

Cortisol secretory activity
(CSA) is relevant to fatigue due to cortisol’s regulatory role
in energy metabolism, the high prevalence of fatigue in
conditions characterized by low cortisol levels (such as
Addison’s disease), and the relative efficacy of glucocorticoid
treatments in alleviating short-term fatigue (McKenzie
et al., 1998; Cleare et al., 1999; Sapolsky et al., 2000;
Khani and Tayek, 2001).

My opinion is that measuring cortisol, on its own (outside of social and biological contexts) is mostly a waste of time (unless there are severe increases or decreases), and a meta-analysis of such is thus also a waste of time.