Yamamoto, Shigeyuki, Ouchi, Yasuomi, Onoe, Hirotaka et al. · Neuroreport · 2004 · DOI
Researchers used brain imaging (PET scans) to study a chemical messenger in the brain called serotonin in ME/CFS patients compared to healthy people. They found that ME/CFS patients had lower levels of serotonin transporters—the proteins that carry serotonin—in a specific brain region called the rostral anterior cingulate. This suggests that serotonin system dysfunction may be involved in ME/CFS symptoms.
This research provides objective neurobiological evidence supporting the involvement of serotonin dysfunction in ME/CFS pathophysiology, moving beyond symptom description to identify brain-level mechanisms. Understanding serotonergic abnormalities may eventually inform targeted therapeutic approaches and help validate ME/CFS as a biological disorder.
This study demonstrates association between reduced serotonin transporters and ME/CFS diagnosis, but does not establish causation—the serotonin abnormality could be a consequence rather than cause of ME/CFS. The findings are specific to one brain region and cannot be generalized to explain all ME/CFS symptoms. The study does not demonstrate that correcting serotonin levels would improve symptoms.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Yamamoto, Shigeyuki, Ouchi, Yasuomi, Onoe, Hirotaka, Yoshikawa, Etsuji, Tsukada, Hideo, Takahashi, Hidetoshi, et al. (2004). Reduction of serotonin transporters of patients with chronic fatigue syndrome.. Neuroreport. https://doi.org/10.1097/00001756-200412030-00002
BibTeX
@article{mecfsatlas-yamamoto-2004-reduction-serotonin,
author = {Yamamoto, Shigeyuki and Ouchi, Yasuomi and Onoe, Hirotaka and Yoshikawa, Etsuji and Tsukada, Hideo and Takahashi, Hidetoshi and Iwase, Masao and Yamaguti, Kouzi and Kuratsune, Hirohiko and Watanabe, Yasuyoshi},
title = {Reduction of serotonin transporters of patients with chronic fatigue syndrome.},
journal = {Neuroreport},
year = {2004},
doi = {10.1097/00001756-200412030-00002},
note = {PubMed: 15570154},
url = {https://www.mecfsatlas.com/evidence/yamamoto-2004-reduction-serotonin},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-26. https://www.mecfsatlas.com/evidence/yamamoto-2004-reduction-serotonin
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