Lower whole blood glutathione peroxidase (GPX) activity in depression, but not in myalgic encephalomyelitis / chronic fatigue syndrome: another pathway that may be associated with coronary artery disease and neuroprogression in depression. — CFSMEATLAS
Lower whole blood glutathione peroxidase (GPX) activity in depression, but not in myalgic encephalomyelitis / chronic fatigue syndrome: another pathway that may be associated with coronary artery disease and neuroprogression in depression.
Maes, Michael, Mihaylova, Ivanka, Kubera, Marta et al. · Neuro endocrinology letters · 2011
Quick Summary
This study looked at a protective enzyme called GPX that helps defend cells from damage in people with depression and ME/CFS. The researchers found that people with depression had lower levels of this enzyme compared to healthy people, but people with ME/CFS had normal levels. Both groups showed connections between low enzyme levels and symptoms like mood problems and autonomic nervous system dysfunction.
Why It Matters
This research helps clarify different biological mechanisms underlying depression versus ME/CFS, two conditions that share overlapping symptoms but may involve distinct biochemical pathways. Understanding these differences could lead to more targeted treatments for each condition and may explain why some interventions work differently in depression versus ME/CFS.
Observed Findings
Whole blood GPX activity was significantly lower in depressed patients (p=0.001) compared to healthy controls.
GPX activity in ME/CFS patients was not significantly different from healthy controls.
Inverse correlations existed between GPX activity and depressed mood, autonomic symptoms, and Fibromyalgia/CFS rating scale items in both depression and ME/CFS groups.
In depression specifically, GPX activity correlated inversely with Hamilton Depression Rating Scale (HDRS) scores.
Inferred Conclusions
Reduced GPX activity represents a specific antioxidant deficiency in depression that may not characterize ME/CFS, suggesting different underlying biological mechanisms.
Lowered GPX activity in depression may contribute to inflammatory and neuroprogressive pathways linked to coronary artery disease risk.
Common symptoms (autonomic dysfunction, mood disturbance) in both conditions correlate with GPX status despite different baseline enzyme levels.
Remaining Questions
Would interventions to restore GPX activity (Ebselen, glutathione, N-Acetyl-L-Cysteine, or selenium supplementation) actually improve symptoms or outcomes in depression and/or ME/CFS?
Why do ME/CFS patients show normal GPX levels despite elevated oxidative stress markers reported in some ME/CFS research?
What This Study Does Not Prove
This study does not prove that low GPX causes depression or neuroprogression—only that an association exists. It also does not establish whether supplementing GPX-boosting substances would be effective in treating either condition, despite the authors' suggestions. The cross-sectional design means causality cannot be determined, and findings in whole blood may not reflect GPX activity in brain tissue where it matters clinically.