Bell, I R, Baldwin, C M, Schwartz, G E · The American journal of medicine · 1998 · DOI
Some people with ME/CFS and fibromyalgia react strongly to small amounts of everyday chemicals (like fragrances or pesticides) that don't normally harm others. This paper reviews evidence suggesting that the brain's limbic system—which controls emotions and basic body functions—may become overly sensitive to these chemicals, creating a chain reaction that affects multiple body systems. The authors propose that certain people are born with or develop a heightened sensitivity to this kind of stimulation, which could explain why some ME/CFS patients feel sick from exposure to low levels of chemicals.
Chemical sensitivity affects 20–47% of people with ME/CFS and fibromyalgia, yet the underlying mechanism remains poorly understood. This paper proposes a biologically plausible neural model—involving the limbic system and dopaminergic reward pathways—that could unify observations of multi-system dysfunction in ME/CFS and explain why some patients are disabled by exposures others tolerate. Understanding this mechanism could lead to better diagnostic approaches and targeted treatments.
This review does not establish that chemical sensitization is the primary cause of ME/CFS; rather, it proposes a mechanism in a subgroup of patients. It does not prove that the olfactory-limbic model is correct—it is a theoretical synthesis awaiting rigorous direct testing. The study cannot determine whether neural sensitization is a cause or consequence of ME/CFS, or whether the observed biochemical changes are sufficient to produce the full illness phenotype.
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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