Natelson, Benjamin H, Lange, Gudrun · Environmental health perspectives · 2002 · DOI
Quick Summary
This review examines why people develop ME/CFS, a condition marked by extreme tiredness and other symptoms that doctors struggle to explain. The authors suggest that ME/CFS likely isn't caused by a single thing, but rather by several different problems—including brain issues, difficulty handling stress, and concerns about making symptoms worse through activity. They note that while severe infections can trigger ME/CFS, the condition seems to persist through different biological mechanisms than the original infection itself.
Why It Matters
This foundational status report advocates for a heterogeneous disease model of ME/CFS, which has influenced subsequent research strategy and helped legitimize investigation into multiple biological and psychological mechanisms. Recognition that ME/CFS has multiple causes rather than a single etiology has important implications for treatment development and personalized medicine approaches in this population.
Observed Findings
No convincing data support an ongoing infectious or immunologic process maintaining CFS despite clear association with severe infection onset
Evidence points toward several possible pathophysiological processes including covert encephalopathy, impaired physiological stress response, and psychological factors
Environmental agents have been documented as capable of eliciting chronic fatigue states
CFS is medically unexplained and characterized by disabling fatigue with infectious, rheumatological, and neuropsychiatric symptom overlap
Inferred Conclusions
ME/CFS likely represents multiple disease entities with distinct etiologies rather than a single disease
Investigation should focus on identifying biological mechanisms (encephalopathy, stress response impairment) and psychological factors rather than assuming persistent infection
Multiple causes—biological, psychological, and environmental—likely contribute to ME/CFS pathogenesis
Future research should aim to characterize and stratify ME/CFS subgroups by cause and pathophysiology
Remaining Questions
Which specific pathophysiological mechanisms predominate in which patient subgroups?
How do psychological factors related to symptom concern interact with biological dysfunction in disease maintenance?
What This Study Does Not Prove
This review does not establish which specific pathophysiological mechanisms predominate in individual patients or provide definitive evidence for any single causal pathway. The authors explicitly note they cannot be certain CFS comprises multiple subgroups—this remains a conceptual framework requiring empirical validation. The review also does not provide quantitative meta-analysis of existing data.