Orthostatic intolerance and neurocognitive impairment in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).
Gaglio, Caroline L, Islam, Mohammed F, Cotler, Joseph et al. · Epidemiologic methods · 2022 · DOI
Quick Summary
This study looked at how often people with ME/CFS experience two symptoms that doctors use to diagnose the condition: difficulty thinking clearly (brain fog, memory problems) and dizziness when standing up. The researchers found that nearly all participants reported thinking and memory problems, while only a small number had standing-up dizziness without also having cognitive problems. This suggests these two symptoms overlap heavily in ME/CFS patients.
Why It Matters
This study challenges the current diagnostic framework used to identify ME/CFS by showing that the either/or approach to neurocognitive impairment and orthostatic intolerance may not accurately reflect how these symptoms occur in patients. Improving diagnostic criteria could help ensure more accurate diagnosis and better research comparability across studies.
Observed Findings
93.4% of ME/CFS participants reported neurocognitive impairment
Orthostat intolerance without concurrent neurocognitive symptoms allowed only 1.7-4.5% additional participants to meet IOM criteria
Substantial overlap exists between orthostatic intolerance and neurocognitive impairment symptoms in the study population
Currently available self-report methods for measuring OI lack standardization and validation
Inferred Conclusions
The IOM's recommendation to include neurocognitive impairment and orthostatic intolerance as interchangeable core symptoms does not align with actual symptom patterns in ME/CFS patients
Neurocognitive impairment is nearly universal in ME/CFS while isolated orthostatic intolerance is rare, suggesting they may represent different aspects of the condition rather than alternatives
Standardized, validated measurement tools for orthostatic intolerance are essential for accurate ME/CFS research and diagnosis
Remaining Questions
What is the biological mechanism explaining why neurocognitive impairment and orthostatic intolerance overlap so heavily in ME/CFS?
How should diagnostic criteria be revised to better reflect the true symptom patterns observed in ME/CFS patients?
What This Study Does Not Prove
This study does not establish causation or explain the biological mechanism linking neurocognitive impairment and orthostatic intolerance. As a cross-sectional survey study, it cannot determine whether one symptom causes the other or whether they stem from a common underlying dysfunction. The findings are also limited to patients who responded to the questionnaire and may not represent all ME/CFS presentations equally.
Tags
Method Flag:PEM_UNCLEARWeak Case DefinitionNo ControlsExploratory Only
Which specific self-report items most accurately capture orthostatic intolerance in ME/CFS, and should these be validated against objective physiological measures?
Do neurocognitive impairment and orthostatic intolerance represent distinct subtypes of ME/CFS or manifestations of the same underlying pathophysiology?