Theorell, T, Blomkvist, V, Lindh, G et al. · Psychosomatic medicine · 1999 · DOI
This study looked at whether stressful life events and infections in the months before ME/CFS develops might play a role in triggering the illness. Researchers interviewed 46 people with ME/CFS and 46 matched control subjects without the illness, asking them to recall what happened and how they felt month-by-month for a year. They found that people who developed ME/CFS experienced more infections and stressful events—especially in the 3 months right before onset—and their fatigue, pain, and fever symptoms stayed very high even after diagnosis, unlike the control group who recovered.
Understanding whether specific triggers—infections and stressful life events—commonly precede ME/CFS onset may help identify risk factors and inform prevention or early intervention strategies. The study's finding that ME/CFS symptoms remain persistently elevated even after the acute triggering phase suggests the illness involves more than simple stress recovery, supporting the biological basis of ME/CFS.
This study does not prove that life events and infections *cause* ME/CFS, only that they may occur more frequently in the months before onset; correlation does not equal causation. The retrospective design means participants recalled events months or years later, which may introduce memory bias and inaccuracy. It cannot determine whether specific biological mechanisms (cytokine responses, viral reactivation, etc.) mediate the link between these triggers and ME/CFS development.
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
Theorell, T, Blomkvist, V, Lindh, G, & Evengård, B (1999). Critical life events, infections, and symptoms during the year preceding chronic fatigue syndrome (CFS): an examination of CFS patients and subjects with a nonspecific life crisis.. Psychosomatic medicine. https://doi.org/10.1097/00006842-199905000-00009
BibTeX
@article{mecfsatlas-theorell-1999-critical-life,
author = {Theorell, T and Blomkvist, V and Lindh, G and Evengård, B},
title = {Critical life events, infections, and symptoms during the year preceding chronic fatigue syndrome (CFS): an examination of CFS patients and subjects with a nonspecific life crisis.},
journal = {Psychosomatic medicine},
year = {1999},
doi = {10.1097/00006842-199905000-00009},
note = {PubMed: 10367610},
url = {https://www.mecfsatlas.com/evidence/theorell-1999-critical-life},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/theorell-1999-critical-life
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