Chronic fatigue syndrome

Many of us will have suffered fatigue at some point in our lives, but usually a good night’s sleep or treating the underlying medical cause puts an end to it. For some, fatigue continues for a prolonged period without any apparent medical explanation, and involves other debilitating symptoms that limit physical and social activity.

It is unclear precisely how prevalent chronic fatigue syndrome is, with an estimated 84–91% of those with the condition going undiagnosed. It is a difficult illness to diagnose and once a diagnosis has been made, individuals with chronic fatigue syndrome can be disheartened by the limited treatment options available. Chronic fatigue syndrome also costs $17–24bn each year in terms of medical expenses and loss of productivity.

This article will consider what we know about chronic fatigue syndrome and how those diagnosed with the condition can manage their symptoms based on up-to-date research findings.

What is chronic fatigue syndrome?

Fatigue can be acute, prolonged or chronic. Acute fatigue lasts less than 1 month and disappears after resting or treating the underlying condition causing the fatigue. Prolonged fatigue lasts 1–6 months, while chronic fatigue continues beyond 6 months, and both limit the individual’s ability to engage in physical and social activities.

Chronic fatigue syndrome (CFS) should be considered an entirely separate condition to types of chronic fatigue, such as idiopathic chronic fatigue (ICF). While they can present with similar symptoms, CFS is thought to be a complex, multisystem nueroimmune disease involving issues related to the brain and central nervous system.

There is some debate about what CFS should be called, with some experts preferring to use the term myalgic encephalmyelitis (ME) and others opting for ‘ME/CFS’. The US Institute of Medicine (IOM) has recommended use of the term ‘systemic exertion intolerance disease’ (SEID) to reflect the possibility that CFS is entirely distinct from chronic fatigue-related conditions.

According to the IOM, diagnosis of CFS requires the presence of the following 3 symptoms for more than 6 months, and the intensity of symptoms should be moderate to severe for at least 50% of the time:

• substantial impairment to everyday activities due to fatigue, which is not improved by rest;
• post-exertional malaise (PEM) — symptoms are worse after physical activities or cognitive stressors;
• unrefreshing sleep.

Diagnosis also requires the presence of one of the following symptoms:

• cognitive impairment — problems with concentration, memory or executive function;
• orthostatic intolerance — dizziness or light-headedness when moving from a lying down or sitting position to a standing position.

The symptoms of CFS can vary from person to person and their severity can fluctuate from day to day. Beyond the main symptoms outlined above, you may also experience sleep problems, a sore throat, headaches, enlarged lymph nodes in the neck or armpits, unexplained muscle or joint pain and diarrhea.

If you are experiencing persistent or excessive fatigue, you should consult a doctor.

The process of diagnosing CFS is complicated as there is no single test to confirm that a person has CFS and the symptoms are common to other illnesses. Doctors will often start with a variety of different tests to rule out other illnesses. Once it is clear that the fatigue is unrelated to any underlying medical condition, the doctor will then consider whether the symptoms align with the official diagnostic criteria for CFS, outlined above.

There is no evidence that CFS increases the risk of mortality and any person of any age could be affected by CFS. The data suggests that it is more common amongst middle-aged white women, however this may be because this group is more likely to report symptoms. A small proportion of children suffer from CFS, though it is more common in teenagers.

Children with CFS tend to experience more orthostatic intolerance, headaches and stomach pain, and less muscle and joint pain, compared to adults with CFS. It is difficult to identify CFS in children because sleep naturally changes due to puberty and children cannot always accurately articulate how they are feeling, leaving adults to inaccurately interpret symtpoms.

What causes chronic fatigue syndrome?

Researchers continue to examine the potential causes of CFS but the answer remains elusive. Currently, CFS is thought to be a complex, multifaceted condition involving multiple systems in the body, which may be triggered by a range of events.

It has been suggested that a number of viral infections could trigger CFS, but there is no consistent or conclusive data to suggest any causal relationship between the two. CFS may be a chronic activation of the immune system that is triggered by a viral infection.

A recent study found that people with CFS had normal natural killer cell numbers but low natural killer activity, suggesting some kind of inability to replenish activated natural killer cells. This could explain how a triggering event, such as a viral infection, produces abnormalities in the immune system. This theory remains speculative and more research is required to confirm this relationship.

In the context of the COVID-19 pandemic, those who have developed ‘long COVID’ may experience CFS. However, more research is required in this area and the Centre for Disease Control and Prevention (CDC) has not identified CFS as a medical condition that increases your vulnerability to COVID-19.

There is some evidence to suggest that CFS involves the central nervous system but the data has been inconsistent. Diagnostic imaging studies have suggested that those with CFS have neurologic abnormalities, but the data is inconclusive.

A study showed a higher prevalence of allergies amongst those with CFS compared with the general population. Other studies have shown that those with CFS are more susceptible to atopic diseases. This indicates that allergens could trigger the immune system and/or central nervous system, leading to the development of symptoms specific to CFS.

Due to the absence of organic causes of fatigue and the higher instances of depression and excessive emotion in those with CFS, some physicians have dismissed the illness as psychosomatic or a symptom of clinical depression. However, those with CFS also present physical symptoms that are not usually associated with depression.

Those with CFS often report muscle or joint pain, suggesting a muscular component is present in cases of CFS. However, those with CFS do not show typical signs of musculoskeletal disorders.

Treatment

There is no known cure for CFS and treatment focuses on symptom relief. Any treatment plan for CFS should include appropriate exercise, a healthy diet and improvements in sleep hygiene.

There is growing evidence to support the use of cognitive behavioural therapy (CBT) and graded exercise therapy (GET). The former has been rejected by some US and UK experts and patients due to the biases and other limitations associated with CBT studies. Whilst GET may aid sleep, physical functioning and general health, research suggests that it does not improve pain, quality of life or mental health.

Pacing — the process of managing activity levels — can help those with CFS to avoid post-exertional malaise (PEM). It involves balancing physical and social activities with rest and keeping track of how the individual feels in order to identify their limits. Pacing can include finding ways to make everyday activities easier and using a heart rate monitor to ensure that the body is not being overworked.

Consulting your doctor will give you the opportunity to discuss whether medications could help you to avoid sleep problems, including insomnia, extreme daytime sleepiness, intense and vivid dreams, restless legs syndrome and nighttime muscle spasms. Alternatively, you could seek the guidance of a sleep specialist.

To ease any pain that those with CFS may be experiencing, a doctor could recommend over-the-counter pain relief, a pain specialist and long-term counselling. Stretching and movement therapies, gentle massage, heat and water therapies, toning exercises and acupuncture can also help to relieve pains.

Those experiencing mental health symptoms may benefit from anti-depressants and anti-anxiety medications, although some of these drugs have side effects that could worsen other CFS symptoms. This is why you must seek the guidance of a healthcare professional, preferably one with mental health expertise. Deep breathing, muscle relaxation, massage and movement therapies are also useful tools for improving mental health.

For orthostatic intolerance, a doctor may refer you to a cardiologist or neurologist to assess whether there are any underlying health conditions causing these symptoms. Increasing your daily intake of fluids and salt and using support stockings can help ease dizziness. If these symptoms do not improve, medications could be prescribed.

Memory aids, such as organisers and calenders, can help with memory problems. Stimulant medications, such as those used to treat attention-deficit/hyperactivity disorder (ADHD), can improve concentration but should not be used in a way that undermines an individual’s pacing practices.

Many people seeking to manage their CFS symptoms turn to alternative medicines, including herbal teas. Although there have been some indications that traditional Chinese medicines are effective for combatting fatigue, larger, more controlled clinical research is required to confirm these potential benefits.

Although our knowledge about CFS is narrow at the moment, there is hope for the future. Technological advances in neuroimaging, genotype profiling, monitoring of the immune system and medications have great potential to bolster scientific research and bring us closer to delivering clinically-proven treatments.