E0 ConsensusModerate confidencePEM unclearReview-NarrativePeer-reviewedReviewed
Hypothalamic-Pituitary-Adrenal Hypofunction in Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) as a Consequence of Activated Immune-Inflammatory and Oxidative and Nitrosative Pathways.
Morris, Gerwyn, Anderson, George, Maes, Michael · Molecular neurobiology · 2017 · DOI
Quick Summary
This review examines why people with ME/CFS often have low cortisol levels (a stress hormone). The researchers found that the problem likely starts with an overactive immune system producing excessive inflammatory markers, which then damages the body's stress-hormone system. This is important because it suggests the low cortisol is a consequence of the disease, not its cause.
Why It Matters
Understanding whether HPA axis dysfunction causes or results from immune activation has critical implications for treatment strategies. If immune activation drives HPA suppression, therapeutic approaches should target immune pathways rather than attempting hormone replacement. This reframing could redirect research and clinical practice toward more mechanistically appropriate interventions.
Observed Findings
- Elevated tumor necrosis factor-α (TNF-α) levels in ME/CFS patients
- Dysregulated T regulatory responses with increased interleukin-10 (IL-10) and transforming growth factor-β (TGF-β)
- Elevated nitric oxide levels
- Lowered baseline glucocorticoid and ACTH levels
- Viral and bacterial-mediated immune activation in disease presentation
Inferred Conclusions
- Immune-inflammatory and O&NS pathway activation is likely primary and causative rather than secondary to HPA axis hypofunction
- HPA axis hypoactivity in ME/CFS represents a consequence of chronic immune activation, not its etiology
- Mechanisms involving cytokine dysregulation and oxidative stress may explain how immune pathways suppress HPA function
- Therapeutic strategies should target activated immune pathways rather than attempting HPA axis correction alone
Remaining Questions
- What initiates the initial immune activation that drives HPA suppression—viral infection, post-infectious sequelae, genetic predisposition, or environmental trigger?
- Do all ME/CFS patients follow the same pathophysiologic pathway, or are there mechanistically distinct disease subtypes?
What This Study Does Not Prove
This review does not establish definitive causal mechanisms—it interprets correlational data from multiple studies. It does not prove that immune pathways are the sole cause of HPA dysfunction, nor does it demonstrate whether these pathways are primary disease drivers or secondary amplifiers. Individual patient heterogeneity may mean different subgroups have different underlying mechanisms.
Tags
Symptom:Fatigue
Biomarker:CytokinesBlood Biomarker
Method Flag:Exploratory OnlyWeak Case Definition
Metadata
- DOI
- 10.1007/s12035-016-0170-2
- PMID
- 27766535
- Review status
- Editor reviewed
- Evidence level
- Established evidence from major reviews, guidelines, or evidence maps
- Last updated
- 12 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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