Morris, Gerwyn, Carvalho, André F, Anderson, George et al. · Current pharmaceutical design · 2016 · DOI
When the body has chronic inflammation and immune activation, it breaks down an amino acid called tryptophan differently than usual, creating byproducts called TRYCATs. Some of these byproducts can damage nerve cells and mitochondria (the energy factories in cells), while others may protect the brain but at the cost of causing brain fog and emotional problems. This review examines how this abnormal tryptophan breakdown might contribute to ME/CFS and other neurological conditions.
ME/CFS patients frequently experience cognitive dysfunction, neuroinflammation, and mitochondrial dysfunction. This review proposes a unifying biochemical mechanism—dysregulated tryptophan catabolism—that could explain multiple pathological features of ME/CFS and suggests specific biomarkers and potential therapeutic targets worth investigating in patient cohorts.
This is a mechanistic review, not an empirical study with ME/CFS patient data; it does not prove that elevated TRYCATs actually occur in ME/CFS patients or that they cause disease in this population. The review cannot establish causation or rule out that TRYCAT elevation is secondary to other primary pathological processes. No clinical trials or outcome data are presented.
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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Primary citation
Morris, Gerwyn, Carvalho, André F, Anderson, George, Galecki, Piotr, & Maes, Michael (2016). The Many Neuroprogressive Actions of Tryptophan Catabolites (TRYCATs) that may be Associated with the Pathophysiology of Neuro-Immune Disorders.. Current pharmaceutical design. https://doi.org/10.2174/1381612822666151215102420
BibTeX
@article{mecfsatlas-morris-2016-many-neuroprogressive,
author = {Morris, Gerwyn and Carvalho, André F and Anderson, George and Galecki, Piotr and Maes, Michael},
title = {The Many Neuroprogressive Actions of Tryptophan Catabolites (TRYCATs) that may be Associated with the Pathophysiology of Neuro-Immune Disorders.},
journal = {Current pharmaceutical design},
year = {2016},
doi = {10.2174/1381612822666151215102420},
note = {PubMed: 26667000},
url = {https://www.mecfsatlas.com/evidence/morris-2016-many-neuroprogressive},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-30. https://www.mecfsatlas.com/evidence/morris-2016-many-neuroprogressive
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