Ursin, H, Eriksen, H R · Annals of the New York Academy of Sciences · 2001 · DOI
This study proposes that a process called 'sensitization'—where the body becomes increasingly reactive to triggers over time—may underlie many chronic conditions including ME/CFS, fibromyalgia, and chemical sensitivities. The authors suggest that prolonged stress and sustained arousal (keeping your nervous system in a heightened alert state) may make the body more likely to develop this sensitization, particularly affecting muscles and pain perception.
For ME/CFS patients, this framework offers a potential explanation for why the condition often co-occurs with multiple overlapping symptoms (pain, chemical sensitivity, cognitive issues) and why stress amplifies disease severity. Understanding sensitization as a core mechanism could guide future research into shared biological pathways and inform treatment strategies targeting nervous system arousal.
This review article does not establish causality between sustained arousal and sensitization, nor does it provide direct evidence that all these conditions are manifestations of a single disease process. It cannot prove that sensitization is the primary mechanism—only that it is a plausible hypothesis worth investigating. The absence of new experimental data means these proposals require validation in controlled studies.
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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