Chronic Fatigue Syndrome
What Causes Chronic Fatigue Syndrome?
Date: 28/05/09
What causes chronic fatigue syndrome (CFS/ME)?
Probably a question every CFS/ME sufferer asks their doctor and one that makes many doctors scratch their heads.
Besides the up-hill battle to get a proper diagnosis, when CFS/ME sufferers were asked about their biggest struggles resulting from this condition 33 per cent said education was a major concern. A further 13 per cent said dealing with a disbelieving doctor, 12 per cent said financial worries and dealing with the symptoms and 10 per cent said managing day-to-day. Isolation (44 per cent), losing relationships (31 per cent) and losing independence (20 per cent) were cited as their biggest quality of life issues.
CFS/ME: Difficult prognosis, difficult diagnosis
Despite lots of research, experts haven't been able to pinpoint CFS to one single cause. Some believe CFS (or CFS/ME) develops from multiple contributing factors which manifest as CFS/ME under the right conditions.
Contributing factors may include:
Not all the factors apply to everyone with CFS/ME. It’s more likely that sufferers have a combination of these factors which led to the condition. This in itself makes it very difficult for a doctor or specialist to diagnose CFS/ME.
Different combinations of these factors cause different symptoms and manifests in different ways in the body and for this reason you will find that no two sufferers experience CFS/ME in the same way. Each case of CFS/ME is as individual and unique as the person suffering from it.
Experts have now started to identify categories, or subgroups, of CFS/ME. Eventually, sub-grouping may help sufferers and their doctors to figure out the best way to treat each individual case.
CFS/ME: Genetic Factors & Chronic Fatigue Syndrome
Recent research links CFS/ME with genes involved in the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.
The HPA axis controls your sleep, response to stress, and depression. Researchers looked at DNA that controls how your body reacts to trauma, injury and stress, and they found a common variation that could predict CFS/ME with 76 per cent accuracy. This research could be the first credible evidence of a biological basis for CFS/ME.
Other studies show genetic abnormalities in people with CFS/ME that influence immune function, cellular communication, and the ways cells generate energy.
This research suggests that some people may be genetically predisposed to CFS/ME.
CFS/ME: Central Nervous System & Hormone Abnormalities
Researchers are especially interested in some of the central-nervous-system chemicals and hormones controlled by the HPA axis:
* Neurotransmitter changes: Neurotransmitters are chemicals that communicate messages in your brain. Research has shown that some people with CFS/ME have abnormal fluctuating levels of serotonin and dopamine (both neurotransmitters).
* Stress hormone deficiencies: Research has shown the levels of the stress hormone cortisol are low in CFS/ME sufferers. This could make it hard to deal with stress, either physical (such as infection or exertion) or mental. Cortisol replacement has helped some CFS/ME sufferers. In a US study by the Centre of Disease Control showed that women with CFS/ME had low morning cortisol levels while men with CFS/ME did not, which could help explain why the condition is far more common in women.
* Disturbed circadian rhythms: Your circadian clock (part of the HPA axis) regulates your sleep-wake cycle. Evidence suggests that in some people with CFS/ME this clock is thrown off, possibly by a mentally or physically stressful event. The body is unable to re-established the proper rhythm. Sufferers appear to spend more time in the REM (rapid-eye movement) phase of sleep, which is when you're dreaming. People in this subgroup of CFS/ME get more help from sleep medications than people in other subgroups.
CFS/ME: Infections
Many of the signs and symptoms of CFS/ME are similar to those of a lingering viral illness and it is possible that a viral-infection lies at the heart of CFS/ME. Researchers have examined three infection-related theories, though none has been proven:
1. A virus or bacteria infects the body and damages the immune system. The damage then continues to cause flu-like symptoms even after the virus or bacteria is gone.
2. After an infection, an abnormal action by the immune system triggers a virus that had become inactive to be reactivate.
3. A physiological response to viral infections occurs in people who are susceptible.
While not everyone with CFS/ME shows signs of infection, many do. Research suggest that some cases of CFS/ME are caused at least in part by a virus:
•Enterovirus connection: In a 2007 study, CFS/ME sufferers were four times more likely than healthy people to have evidence of enteroviruses in their stomach tissue. Enteroviruses cause stomach infections, and symptoms of CFS/ME frequently start after some kind of stomach infection.
•Rnase L: Our bodies use the enzyme Rnase L to kill viruses that attack our cells. CFS/ME sufferers frequently have high levels of this enzyme present in their bodies, suggesting chronic immune activity.
•Natural Killer (NK) Cells & T Cells: NK & T cells in your immune system attack virus-infected cells. CFS/ME sufferers frequently have low levels, suggesting chronic immune activity may be depleting them.
•Antibodies: CFS/ME sufferers typically have high levels of antibodies to many infection-causing organisms that cause fatigue and other CFS/ME symptoms. These organisms include those that cause Lyme disease, candida (yeast), human herpesvirus type 6 (HHV-6), measles, parvovirus and Epstein-Barr. Researchers have not been able to show that any of these is a significant cause of CFS/ME.
•Post-illness onset: Up to 80per cent of CFS/ME cases start suddenly after a flu-like condition.
Some researchers suggest that changes in normally harmless bacteria in the intestine may also play a role in the development of CFS/ME.
CFS/ME doesn't spread through direct content, sufferers aren’t contagious, and in spite of well-designed studies, researchers have not been able to link CFS/ME with any specific infections.
CFS/ME: Immune System Abnormalities
Several studies have shown irregularities in the immune systems of CFS/ME sufferers, but researchers have not found a consistent pattern of abnormalities. Among the most common are allergies and an overactive immune system.
Some studies have reported that a majority of CFS/ME sufferers are allergic to such things as pollen, certain foods and metals such as nickel and mercury. So in theory, allergens may trigger a series of immune abnormalities which then lead to CFS/ME. Another theory is that allergies, stress and infection combined may deplete a chemical called adenosine triphosphate (ATP), which stores energy in cells. CFS/ME sufferers typically have low ATP levels.
Some CFS/ME sufferers have high levels of a substance called cytokines, which researchers theorise could cause some of the symptoms of CFS/ME, including fatigue and muscle aches. Various studies have reported T cell imbalances in people with CFS/ME, but other studies have not confirmed the T cell and cytokine abnormalities.
While CFS/ME appears to have a few features in common with autoimmune diseases such as lupus or multiple sclerosis, in which the immune system mistakenly attacks healthy parts of the body, most researchers now believe CFS/ME is probably not caused by autoimmunity. Tests of CFS/ME sufferers do not show markers of the organ damage generally associated with autoimmune disease.
CFS/ME: Stressful Conditions
Researchers believe your psychological makeup, personality and social environment can determine whether you'll develop CFS/ME, but they don't yet fully understand the complex relationship between these factors and the cause of CFS/ME. While these factors are probably not a primary cause of CFS/ME, they're likely to play a role in making people susceptible.
It is important to understand that CFS/ME is not a psychological disease, nor does having it mean someone is psychologically weak or unable to cope with things. While it is sometimes linked to clinical depression, this likely has more to do with neuro-chemical imbalances and/or the impact of the illness.
CFS/ME: Chemicals & Environmental Toxins
Chronic fatigue and chronic pain are often associated with exposure to various harmful chemicals and environmental toxins. These can include solvents, pesticides or heavy metals. However, because most of us have been exposed to these types of chemicals at some point, it's difficult to track down which ones might be causing problems.
A condition called multiple chemical sensitivity (MCS) causes many of the same symptoms as CFS/ME, and the two are believed to be overlapping conditions.
In the next alert in this series, I will look at the treatment options for CFS/ME sufferers.
CFS/ME: Related reading
Understanding Chronic Fatigue Syndrome And Myalgic Encephalomyelitis
Diagnosing Chronic Fatigue Syndrome
Stepping In To The ‘Minefield’ Of Finding The Right Treatment For Chronic Fatigue Syndrome
Chronic Fatigue Syndrome: Natural Measures Can Help Combat This Debilitating Condition
Myalgic Encephalopathy
Exploring The Benefits Of Malic Acid
Myalgic Encephalopathy
Sources:
‘What Causes Chronic Fatigue Syndrome’ By Adrienne Dellwo, published online 18.04.09, chronicfatigue.about.com
‘Chronic fatigue syndrome or myalgic encephalomyelitis’ published online, hcd2.bupa.co.uk
‘InterAction – The magazine of Action for ME’ Issue 68, Summer of 2009.
Back to topProbably a question every CFS/ME sufferer asks their doctor and one that makes many doctors scratch their heads.
Besides the up-hill battle to get a proper diagnosis, when CFS/ME sufferers were asked about their biggest struggles resulting from this condition 33 per cent said education was a major concern. A further 13 per cent said dealing with a disbelieving doctor, 12 per cent said financial worries and dealing with the symptoms and 10 per cent said managing day-to-day. Isolation (44 per cent), losing relationships (31 per cent) and losing independence (20 per cent) were cited as their biggest quality of life issues.
CFS/ME: Difficult prognosis, difficult diagnosis
Despite lots of research, experts haven't been able to pinpoint CFS to one single cause. Some believe CFS (or CFS/ME) develops from multiple contributing factors which manifest as CFS/ME under the right conditions.
Contributing factors may include:
- * Genetic factors
* Central nervous system and hormone abnormalities
* A virus or other infection
* Immune system abnormalities
* Stressful conditions
* Toxins
Not all the factors apply to everyone with CFS/ME. It’s more likely that sufferers have a combination of these factors which led to the condition. This in itself makes it very difficult for a doctor or specialist to diagnose CFS/ME.
Different combinations of these factors cause different symptoms and manifests in different ways in the body and for this reason you will find that no two sufferers experience CFS/ME in the same way. Each case of CFS/ME is as individual and unique as the person suffering from it.
Experts have now started to identify categories, or subgroups, of CFS/ME. Eventually, sub-grouping may help sufferers and their doctors to figure out the best way to treat each individual case.
CFS/ME: Genetic Factors & Chronic Fatigue Syndrome
Recent research links CFS/ME with genes involved in the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system.
The HPA axis controls your sleep, response to stress, and depression. Researchers looked at DNA that controls how your body reacts to trauma, injury and stress, and they found a common variation that could predict CFS/ME with 76 per cent accuracy. This research could be the first credible evidence of a biological basis for CFS/ME.
Other studies show genetic abnormalities in people with CFS/ME that influence immune function, cellular communication, and the ways cells generate energy.
This research suggests that some people may be genetically predisposed to CFS/ME.
CFS/ME: Central Nervous System & Hormone Abnormalities
Researchers are especially interested in some of the central-nervous-system chemicals and hormones controlled by the HPA axis:
* Neurotransmitter changes: Neurotransmitters are chemicals that communicate messages in your brain. Research has shown that some people with CFS/ME have abnormal fluctuating levels of serotonin and dopamine (both neurotransmitters).
* Stress hormone deficiencies: Research has shown the levels of the stress hormone cortisol are low in CFS/ME sufferers. This could make it hard to deal with stress, either physical (such as infection or exertion) or mental. Cortisol replacement has helped some CFS/ME sufferers. In a US study by the Centre of Disease Control showed that women with CFS/ME had low morning cortisol levels while men with CFS/ME did not, which could help explain why the condition is far more common in women.
* Disturbed circadian rhythms: Your circadian clock (part of the HPA axis) regulates your sleep-wake cycle. Evidence suggests that in some people with CFS/ME this clock is thrown off, possibly by a mentally or physically stressful event. The body is unable to re-established the proper rhythm. Sufferers appear to spend more time in the REM (rapid-eye movement) phase of sleep, which is when you're dreaming. People in this subgroup of CFS/ME get more help from sleep medications than people in other subgroups.
CFS/ME: Infections
Many of the signs and symptoms of CFS/ME are similar to those of a lingering viral illness and it is possible that a viral-infection lies at the heart of CFS/ME. Researchers have examined three infection-related theories, though none has been proven:
1. A virus or bacteria infects the body and damages the immune system. The damage then continues to cause flu-like symptoms even after the virus or bacteria is gone.
2. After an infection, an abnormal action by the immune system triggers a virus that had become inactive to be reactivate.
3. A physiological response to viral infections occurs in people who are susceptible.
While not everyone with CFS/ME shows signs of infection, many do. Research suggest that some cases of CFS/ME are caused at least in part by a virus:
•Enterovirus connection: In a 2007 study, CFS/ME sufferers were four times more likely than healthy people to have evidence of enteroviruses in their stomach tissue. Enteroviruses cause stomach infections, and symptoms of CFS/ME frequently start after some kind of stomach infection.
•Rnase L: Our bodies use the enzyme Rnase L to kill viruses that attack our cells. CFS/ME sufferers frequently have high levels of this enzyme present in their bodies, suggesting chronic immune activity.
•Natural Killer (NK) Cells & T Cells: NK & T cells in your immune system attack virus-infected cells. CFS/ME sufferers frequently have low levels, suggesting chronic immune activity may be depleting them.
•Antibodies: CFS/ME sufferers typically have high levels of antibodies to many infection-causing organisms that cause fatigue and other CFS/ME symptoms. These organisms include those that cause Lyme disease, candida (yeast), human herpesvirus type 6 (HHV-6), measles, parvovirus and Epstein-Barr. Researchers have not been able to show that any of these is a significant cause of CFS/ME.
•Post-illness onset: Up to 80per cent of CFS/ME cases start suddenly after a flu-like condition.
Some researchers suggest that changes in normally harmless bacteria in the intestine may also play a role in the development of CFS/ME.
CFS/ME doesn't spread through direct content, sufferers aren’t contagious, and in spite of well-designed studies, researchers have not been able to link CFS/ME with any specific infections.
CFS/ME: Immune System Abnormalities
Several studies have shown irregularities in the immune systems of CFS/ME sufferers, but researchers have not found a consistent pattern of abnormalities. Among the most common are allergies and an overactive immune system.
Some studies have reported that a majority of CFS/ME sufferers are allergic to such things as pollen, certain foods and metals such as nickel and mercury. So in theory, allergens may trigger a series of immune abnormalities which then lead to CFS/ME. Another theory is that allergies, stress and infection combined may deplete a chemical called adenosine triphosphate (ATP), which stores energy in cells. CFS/ME sufferers typically have low ATP levels.
Some CFS/ME sufferers have high levels of a substance called cytokines, which researchers theorise could cause some of the symptoms of CFS/ME, including fatigue and muscle aches. Various studies have reported T cell imbalances in people with CFS/ME, but other studies have not confirmed the T cell and cytokine abnormalities.
While CFS/ME appears to have a few features in common with autoimmune diseases such as lupus or multiple sclerosis, in which the immune system mistakenly attacks healthy parts of the body, most researchers now believe CFS/ME is probably not caused by autoimmunity. Tests of CFS/ME sufferers do not show markers of the organ damage generally associated with autoimmune disease.
CFS/ME: Stressful Conditions
Researchers believe your psychological makeup, personality and social environment can determine whether you'll develop CFS/ME, but they don't yet fully understand the complex relationship between these factors and the cause of CFS/ME. While these factors are probably not a primary cause of CFS/ME, they're likely to play a role in making people susceptible.
It is important to understand that CFS/ME is not a psychological disease, nor does having it mean someone is psychologically weak or unable to cope with things. While it is sometimes linked to clinical depression, this likely has more to do with neuro-chemical imbalances and/or the impact of the illness.
CFS/ME: Chemicals & Environmental Toxins
Chronic fatigue and chronic pain are often associated with exposure to various harmful chemicals and environmental toxins. These can include solvents, pesticides or heavy metals. However, because most of us have been exposed to these types of chemicals at some point, it's difficult to track down which ones might be causing problems.
A condition called multiple chemical sensitivity (MCS) causes many of the same symptoms as CFS/ME, and the two are believed to be overlapping conditions.
In the next alert in this series, I will look at the treatment options for CFS/ME sufferers.
CFS/ME: Related reading
Understanding Chronic Fatigue Syndrome And Myalgic Encephalomyelitis
Diagnosing Chronic Fatigue Syndrome
Stepping In To The ‘Minefield’ Of Finding The Right Treatment For Chronic Fatigue Syndrome
Chronic Fatigue Syndrome: Natural Measures Can Help Combat This Debilitating Condition
Myalgic Encephalopathy
Exploring The Benefits Of Malic Acid
Myalgic Encephalopathy
Sources:
‘What Causes Chronic Fatigue Syndrome’ By Adrienne Dellwo, published online 18.04.09, chronicfatigue.about.com
‘Chronic fatigue syndrome or myalgic encephalomyelitis’ published online, hcd2.bupa.co.uk
‘InterAction – The magazine of Action for ME’ Issue 68, Summer of 2009.
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