CFS Cheat Sheet 2026

The 30 highest-yield CFS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is 'multiple chemical sensitivity' (MCS) and its association with CFS? → A condition of sensitivity to chemical exposures that frequently co-occurs with CFS
2. Functional MRI (fMRI) studies during cognitive tasks in CFS patients typically show: → Altered or increased activation patterns suggesting compensatory neural recruitment
3. What causes chronic fatigue syndrome? → It's still unknown
4. What is a 'crash' or 'relapse' in CFS terminology? → A significant worsening of symptoms following overexertion
5. What autonomic condition often diagnosed alongside CFS involves abnormal heart rate increases upon standing? → POTS (Postural Orthostatic Tachycardia Syndrome)
6. Which mental health condition most commonly co-occurs with CFS, though it is considered a comorbidity rather than the cause? → Depression and anxiety disorders
7. Which cognitive domain is generally LEAST affected in CFS patients according to research findings? → Language and vocabulary
8. What significant step did the NIH take in 2016 regarding ME/CFS research? → Launched a major intramural research program to study ME/CFS biology
9. Which gastrointestinal symptom is commonly associated with CFS? → Irritable bowel syndrome (IBS) symptoms
10. How does Chronic Fatigue Syndrome (CFS) impact a person's life? → It can result in social isolation, increased work absences, and lifestyle restrictions.
11. Central sensitization, observed in many CFS patients, primarily affects: → Pain processing pathways in the central nervous system
12. Which type of memory is most frequently found to be impaired in objective testing of CFS patients? → Working memory
13. What does 'aerobic energy impairment' mean in CFS research? → Reduced capacity to generate energy through aerobic (oxygen-dependent) pathways
14. Which of the following self-care strategies is generally CONTRAINDICATED for CFS due to risk of PEM? → Graded exercise therapy that pushes beyond current capacity
15. What was the original nickname given to CFS following an outbreak in Incline Village, Nevada in the 1980s? → Yuppie flu
16. Cerebrospinal fluid (CSF) analysis in CFS research has found which of the following in some patients? → Metabolomic and immune abnormalities compared to healthy controls
17. What does research suggest about mitochondrial function in CFS patients? → Evidence suggests impaired mitochondrial energy production in some CFS patients
18. What is the primary principle of the 'heart rate-based pacing' strategy for CFS? → Stay below the anaerobic threshold to prevent triggering PEM
19. Which cognitive symptom commonly described by CFS patients is sometimes called 'brain fog'? → Cognitive impairment affecting memory and concentration
20. The two-day cardiopulmonary exercise test (2-day CPET) in CFS specifically demonstrates: → Significant decline in performance on the second test day
21. What role does sleep hygiene play in the management of Chronic Fatigue Syndrome (CFS)? → It helps improve sleep quality and overall well-being
22. What is 'orthostatic intolerance' commonly experienced by CFS patients? → Worsening symptoms when upright or standing
23. What is the 'two-hit hypothesis' sometimes proposed for CFS? → An initial trigger (e.g., infection) combined with a second factor perpetuates the illness
24. To diagnose chronic fatigue syndrome, symptoms need to be present longer than ___ months. → 6
25. What is 'pacing' in the context of CFS daily living? → Managing activity levels to avoid exceeding one's energy envelope
26. How does unrefreshing sleep relate to cognitive dysfunction in CFS? → Poor sleep quality contributes to worsening of cognitive symptoms
27. What does 'post-infectious fatigue syndrome' (PIFS) describe in relation to CFS? → A subset of CFS that develops following an acute infection
28. What is the estimated target heart rate range recommended for individuals with Chronic Fatigue Syndrome (CFS) during exercise? → 40-65%
29. Which of the following symptoms is commonly associated with Chronic Fatigue Syndrome (CFS)? → Post-exertional malaise
30. What does 'idiopathic' mean when applied to CFS in a medical context? → A condition of unknown cause