Chronic fatigue syndrome: investigation into a strange and still little-known disease
The chronic fatigue syndrome (or "CFS") is not a widely discussed disease. One might be mistaken when hearing or reading "chronic fatigue" here and there, but CFS is indeed a disease in its own right, not a temporary state of tiredness. This syndrome has only been recognized as a disease for a relatively short time, which may explain the uncertainties surrounding it. Of course, this is not about a rare form of glorifying laziness, nor a mysterious and tiring "hair in the hand". Unfortunately, the chronic fatigue in question here is quite different, difficult to grasp both by doctors and patients, and its origins are still uncertain. The doubts surrounding it and its relative "newness" as a recognized disease mean it must be approached with caution, and individuals who might suffer from it must be treated on a case-by-case basis, as no certainty exists to date regarding its treatment.
How can chronic fatigue syndrome be defined?
Chronic fatigue syndrome (" CFS "), also called myalgic encephalomyelitis (" ME "), is a neurological disease characterized by recurrent exhaustion in individuals who suffer from it. This state of intense and persistent fatigue lasts long-term. Affected individuals cannot eliminate this general feeling of fatigue despite hours of sleep (non-restorative sleep), leading to a deterioration of overall health. Victims of CFS-ME often feel misunderstood due to the difficulties in identifying it and not confusing it with a simple temporary state of tiredness, or sometimes, unfortunately, considering it as fictitious fatigue more akin to laziness.
This disease, called "systemic" (abnormal activation of the immune system), is considered neurodegenerative and involves an intolerance to physical and cognitive exertion. It took time to identify it as a disease because fatigue is symptomatic of many diseases. Its diagnosis is therefore complicated. References to SFC-EM can be found as early as the 1750s, but this syndrome has only been considered a disease since 1985, and recognized by the WHO ("World Health Organization") since 1992.
According to l’AFSC1 ("Association Française du Syndrome de Fatigue Chronique"), there are to date "3 main clinical diagnoses of SFC-EM", namely:
- the IOM criteria ("Institute of Medicine of the National Academies"), dating from 2015 and defining "Systemic Exertion Intolerance Disease" ("SEID" or "MISE")
- the consensus criteria for myalgic encephalomyelitis, dating from 2011
- the Fukuda criteria, dating from 1994, are the most used criteria to define SFC
As an anecdote, the first references to SFC date back to the 1750s, and it has been given many names up to today, notably "post-viral syndrome," "neurasthenia" (described by neurologist G.M. Béard in the 19th century or used by Dostoevsky to describe the hero of « Crime and Punishment »), or, more surprisingly, "yuppie syndrome" in the 1980s (for "Young Urban Professionals," as it would mainly affect 20-40 year olds). SFC, or when fatigue becomes a source of inspiration!
Chronic fatigue syndrome in numbers
The SFC-EM is not an easy disease to diagnose, and therefore to quantify. Nevertheless, a study published in 20202 in the « Journal of Translational Medicine » crossed statistics from different studies over the last 40 years, thus allowing a fairly precise idea of the prevalence of chronic fatigue syndrome. This is very low: 0.89% of the population using the Fukuda criteria3. This cross-sectional study also highlights certain trends:
- the prevalence is 1.5 to 2 times higher for women than for men
- ME/CFS is more common among 18-40 year olds (the famous yuppies!)
An article from La Revue Médicale Suisse4 fairly corroborates this prevalence rate, estimating it between 0.3 and 0.9%.
What are the causes of chronic fatigue syndrome?
Regarding the causes of ME/CFS, let's be clear, this is where a large part of its mystery lies! Many theories have "clashed" to identify the causes of this disease: psychological, infectious, or even nutritional. The problem partly stems from the fact that ME/CFS has pathophysiological overlaps with other related diseases, for example fibromyalgia, depression, or somatoform disorders (mental disorders characterized by physical symptoms). It is thus quite difficult to identify the very causes of chronic fatigue syndrome, as they are common with other diseases.
However, all is not lost! Indeed, a relatively recent change in the way ME/CFS is considered and studied has led to certain progress in identifying its origins. Recent and current studies finally seem to converge and tend to highlight a dysfunction of the immune system as the cause of chronic fatigue syndrome, following a viral or bacterial infection. The resulting oxidative stress could then be the root of the problem5.
Furthermore, a study conducted by Dr. M. Hornig from Columbia's "Mailman School of Public Health" succeeded in demonstrating the biological nature of the origin of ME/CFS, notably by identifying two biomarkers (2 pro- and anti-inflammatory cytokines), present in abnormally high amounts in cases of ME/CFS. He thus concludes: "We now have evidence confirming what millions of people suffering from this disease already know, CFS is not psychological!" From then on, the use of biological diagnostic markers is facilitated, even though these studies still need to be deepened and confirmed.
Moreover, the idea that the biological origin of chronic fatigue syndrome could come “from the gut and not the brain” is increasingly favored, as illustrated by this 2016 study published in the highly reputable “Microbiome6,” which shows that the results “indicate dysbiosis of the gut microbiota in this disease and also suggest an increased incidence of microbial translocation, which could play a role in the inflammatory symptoms of ME/CFS.” Thus, a bacterium such as helicobacter pylori would prove to be a cause of infection and inflammation (gastritis) at the origin of chronic fatigue syndrome.
It should also be noted that chronic fatigue can “be a sign of organic system damage caused by alcohol,” as revealed by an article from the “Revue Médicale Suisse” of 20157.” Excessive consumption of alcohol would therefore be linked to sleep quality (disruption of the circadian rhythm) and would also be a potential cause of ME/CFS due to its negative impact on the body.
Finally, sleep apnea could also have a cause-and-effect relationship with chronic fatigue syndrome, as explained by “The Canadian Consensus Summary” of 20158”: “a number of patients may suffer from upper airway obstruction and sleep apnea.” Here too, a cause-and-effect link is observed because it has been proven that an inflammation marker like CRP (“C-Reactive Protein”) increases in the context of sleep apnea. The decreased ability to adapt to stress then leads to fatigue.
As we can see, the causes of chronic fatigue syndrome would be as varied as they are numerous and often converge towards other pathologies or sleep disorders:
- systemic inflammation
- immunodeficiency
- alteration of the gut microbiome
- neurological inflammation
- metabolic anomalies
- damage to the organ system
From the deepest part of our belly to the loudest sleep apnea, fatigue hides everywhere, but not in our head. Except maybe in the imagination of writers!
Symptoms and diagnosis of ME-CFS
To define chronic fatigue syndrome and characterize its symptoms, we will focus here on the Fukuda criteria, these being the most commonly used and mostly referenced. They are as follows:
- intense and persistent fatigue for more than 6 months, not relieved by rest
- reduction of daily activities by at least 50%
This must be added at least 4 of the following symptoms :
- throat pain, rhinitis
- joint pain, muscle pain
- cognitive disorders (memory, concentration)
- headaches
- non-restorative sleep
- swelling of the neck and armpit lymph nodes
- malaise after exertion (lasting more than 24 hours)
Other symptoms may be considered, such as those from the « Canadian Consensus on ME-CFS ». These include chronic fatigue and post-exertional fatigue, sleep disturbances, and the presence of significant pain. Additionally, the patient must also present at least 2 cognitive or neurological symptoms, as well as at least one symptom of endocrine, immune, or autonomic nervous system type (difficulty standing upright, dizziness, palpitations...)
Given the multitude of symptoms and the difficulty in detecting its causes, how can chronic fatigue syndrome be diagnosed? For such a disease, with such characteristics, it is necessary to rule out many other "fatiguing" diseases before identifying ME/CFS, for example fibromyalgia, hypotension, mononucleosis, or hypothyroidism. This is called an exclusive diagnosis (nothing to do here with an analysis of fidelity in a couple or any kind of global exclusivity, as you can imagine!). This diagnosis can be made in a hospital setting.
Some encouraging advances can be noted for diagnosing this disease, as revealed by the study conducted by members of Cornell University in the United States9, published in "Microbiome" and previously cited. This study describes a simple diagnosis, "non-invasive and accurate in 83% of cases," to detect ME/CFS through the analysis of stool and blood samples, by searching for biological markers (in gut bacteria and microbial inflammatory agents in the blood).
The diagnosis of this chronic fatigue syndrome can therefore lead to "in-depth" and detailed investigations, to say the least! But it has the merit of facilitating the prevention of this disease with serious consequences for the daily life and health of patients.
What are the treatments for chronic fatigue syndrome?
The uncertainty about the exact causes of ME/CFS means there is no "classic" or "systematic" treatment. The doctor is competent, on a case-by-case basis, to find a treatment that best matches the profile of their patient. However, this disease requires the patient to actively participate in the treatment process.
If no specific treatment has clearly demonstrated its effectiveness, it is still possible to relieve symptoms to reduce physical and mental fatigue. The goal is to "empower" the patient by teaching them to maximize their autonomy in order to maintain a sufficient level of physical and intellectual activity for their well-being. Thus, many approaches exist to help fight fatigue and muscle pain, for example:
- lifestyle hygiene: regularly practice physical activity in very short periods (2-3 minutes), monitor diet (avoid excessive consumption of fast sugars which, once assimilated, cause the body's energy to "drop" too quickly)
- avoid overwork and stress as much as possible
- plan activities according to one's "peak" of form (unique to each person, but generally between 10 a.m. and 2 p.m.)
- avoid caffeine and alcohol consumption
- ensure a sufficient intake of vitamins and magnesium
- have a regular sleep cycle (as much as possible)
- practice relaxation (" Hoomband " can prove to be a very good ally!), yoga, sophrology, meditation…
- participate in support groups
In addition to these behavioral self-management measures, it is essential to treat certain pathologies:
- treat sleep disorders, especially sleep apnea
- treat allergies, particularly rhinitis
- monitor the balance of the intestinal flora: examinations, regular screenings
- regularly treat infectious foci: teeth, sinuses…
All these recommendations fit within a logic of medical follow-up with the doctor, who helps the patient practice a self-therapy strategy to learn to anticipate and adapt to their own constraints related to chronic fatigue syndrome
Furthermore, it is also possible to relieve the symptoms of ME-CFS through a medication treatment, in agreement with one's doctor, and with certain risks of side effects to consider:
- pain: analgesics, paracetamol, aspirin, ibuprofen
- fatigue: methylphenidate, modafinil, vitamin B12
- cognitive disorders: methylphenidate, nimodipine, dextroamphetamines
Its exact causes are still uncertain, but progress has been made through recent studies, and its heavy consequences for patients' daily lives can partly be alleviated by various approaches. Chronic fatigue syndrome is a recent disease in the scale of science, protean, and still requires much attention from scientists, but also from patients who must learn how to live better with it. Everyone can find motivation and inspiration by imagining themselves as a character from Pagnol or Dostoevsky, a tired or sick hero, but oh so memorable!
To get a clearer idea of what CFS-ME represents, here is a video excerpt from a documentary made by Jennifer Brea, posted on the site « EMaction ». The film from which this passage is taken, « Unrest », is autobiographical and very inspiring, showing us what life with this disease is like.
To go deeper, here is an article and a video explaining the progress made in identifying chronic fatigue syndrome as a biological disease, featuring Dr. Mady Hornig, American psychiatrist and associate professor of epidemiology at the « Mailman School of Public Health of Columbia University ».
In a lighter tone and to illustrate the approach "plan your activities" and "avoid overexertion", here is an excerpt from the film “Alexandre le bienheureux”, which may give hope to all the tired people in the world!
Sources:
[1] Chronic Fatigue Syndrome or Myalgic Encephalomyelitis?, site « Association Française du Syndrome de fatigue Chronique », 2020 [2] Systematic review and meta-analysis of the prevalence of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME), E.J. Lim, Y.C. Ahn et al, « Journal of Translational Medicine », February 2020 [3] Fukuda criteria, site « ME-Pedia », 2020 [4] and [5] Chronic fatigue syndrome, A. Gonthier, B. Favrat, « Revue Médicale Suisse » (volume 11), 2015 [6] and [9] Reduced diversity and altered composition of the gut microbiome in individuals with myalgic encephalomyelitis/chronic fatigue syndrome, L. Giloteaux, J.K. Gooodrich et al, « Microbiome », 2016 [7] Fatigue in cases of dependency diseases, C. Aichmüller, M. Soyka, « Revue Médicale Suisse », 2015 [8] Summary of the Canadian Consensus, Dr B.M. Carruthers, M.I. Van de Sand, site « Asso-SFC », 2020