Natelson, B H, Johnson, S K, DeLuca, J et al. · Clinical infectious diseases : an official publication of the Infectious Diseases Society of America · 1995 · DOI
This study examined whether ME/CFS becomes simpler to understand when researchers focus on patients who did not have mental health conditions before getting sick. The researchers found that when they excluded patients with prior psychiatric problems, ME/CFS patients resembled those with mild multiple sclerosis more than those with depression, suggesting the illness may have a physical cause like an infection or immune system problem.
This study addresses a major challenge in ME/CFS research—the disease's heterogeneity—by proposing that excluding patients with prior psychiatric illness might reveal a more biologically meaningful subgroup. If valid, this approach could improve future research by allowing clearer identification of patients whose symptoms derive from infection or immune dysfunction rather than psychiatric causes, potentially leading to better treatments.
This study does not prove that ME/CFS has an infectious or immunologic cause, only that a stratified subset more resembles MS than depression, which is consistent with but does not establish etiology. It also does not demonstrate that psychiatric symptoms occurring after CFS onset are unrelated to the underlying biology of the disease. The cross-sectional comparison cannot establish causation or temporal relationships.
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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