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    Chronic fatigue syndrome, or myalgic encephalomyelitis (ME/CFS), is a potentially serious, debilitating, long-term illness. As per definition, people with chronic fatigue syndrome experience fatigue for longer than six months that prevents them from doing their usual activities. Estimates vary, but approximately 0.5% to 1% of adults meet the criteria for the condition.

    Women are much more likely to have chronic fatigue syndrome than men. Most people with ME/CFS are between ages 40 and 60, though people of all ages, including children and adolescents, may be affected. White patients are more commonly diagnosed with ME/CFS in the U.S. than any other race or ethnicity. However, as many as 90% of people with ME/CFS go undiagnosed, which is especially a problem among minority groups in the U.S.

    Current medical knowledge and understanding of ME/CFS is limited, so researchers continue to explore possible causes and treatments. Additionally, experts are studying a potential relationship between chronic fatigue syndrome and coronavirus disease 2019 (COVID-19). Preliminary research from the Centers for Disease Control and Prevention indicates that COVID-19 may lead to prolonged illness. Fatigue is among the top, persistent symptoms of that prolonged illness. More research is needed to determine if COVID-19 can cause ME/CFS.

    What Is Fatigue?

    When you feel tired, a good night’s sleep can usually help you feel refreshed. In contrast, fatigue is a prolonged feeling of tiredness and lack of energy that typically isn’t resolved by sleeping. As much as 50% of the people report symptoms of fatigue at some point. Fatigue is common after sleep deprivation, long periods of stress, and physical activity. However, fatigue can also be a symptom of an underlying health concern.

    Experts classify fatigue in one of three categories:

    • Acute Fatigue: less than one month duration
    • Prolonged Fatigue: greater than one month, less than six months duration
    • Chronic Fatigue: greater than six months duration

    ME/CFS is a common cause of chronic fatigue.

    What Is Chronic Fatigue Syndrome?

    People with chronic fatigue syndrome experience persistent fatigue lasting longer than six months that does not get better with rest. They have an abnormal lack of energy and sometimes are confined to bed. In fact, the fatigue of patients with ME/CFS is so severe that they must reduce their usual activities by 50%. The disorder can negatively impact everything in daily life, from taking a shower to holding a job.

    For some people with ME/CFS, day-to-day activities, both physical and mental, can worsen the fatigue, even if these activities would not have been a problem before the onset of the syndrome. The medical term for this experience is post-exertional malaise (PEM). People who experience ME/CFS describe the worsening fatigue as a “crash” or “relapse.”

    Chronic Fatigue Syndrome Symptoms

    Most people diagnosed with ME/CFS were functioning at a normal level prior to their diagnosis. The arrival of ME/CFS is often abrupt and sometimes follows a stressful medical or psychological event.

    The core symptoms of ME/CFS are:

    • Severe, continued fatigue even after rest. This fatigue reduces the ability to perform typical daily activities
    • Worsened fatigue after mental or physical activity.
    • Sleep problems, which may include difficulty falling or staying asleep.

    People with ME/CFS also experience one or both of the following:

    • Difficulty with memory, thinking, or concentrating. Patients may struggle to recall information or experience “brain fog” or “foggy thinking.”
    • Increased symptoms when standing or sitting up. Dizziness, lightheadedness, or weakness can happen upon standing or sitting upright.

    Additional symptoms may include:

    • Chronic pain or muscle weakness
    • Sore throat
    • Tender lymph nodes
    • New or worsened headaches
    • Chills and night sweats
    • Sensitivity or allergy to foods, scents, noise or light
    • Depression, especially if symptoms worsen

    Chronic Fatigue Syndrome Symptoms in Children and Adolescents

    Children exhibit symptoms of ME/CFS similarly to adults, with a few exceptions:

    • Increased likelihood of dizziness when standing. Also called orthostatic intolerance, this symptom tends to be the worst in children and adolescents and exacerbates other symptoms.
    • Headache and stomachache. Rather than experiencing muscle weakness or pain, children report increased headaches and stomach pains.
    • Sleep problems. These include daytime sleepiness, difficulty falling or staying asleep, and vivid dreams.

    Causes of Chronic Fatigue Syndrome

    While most fatigue has an identifiable cause, such as a sleep disorder, depression, or cancer, the cause of ME/CFS is not yet clear.

    Researchers have hypothesized the following possible causes:

    • Infection. Many patients describe the onset of ME/CFS as beginning with a viral-like illness. Possible culprits include Epstein-Barr virus, Ross River virus, or Coxiella burnetti, (Q fever). However, a clear relationship between viruses and ME/CFS has not yet been established. These infections are not specific to ME/CFS.
    • Genetics. Current evidence shows that relatives of patients with ME/CFS have a higher risk for developing the syndrome themselves. Other studies have identified genetic markers linked to ME/CFS.
    • Stress in the Body. Patients with ME/CFS have lower levels of the “stress hormone” cortisol than people without ME/CFS. Although patients with ME/CFS have lower levels of cortisol, these levels are typically still within the normal range. Therefore, a test of cortisol levels cannot confirm the presence of ME/CFS.
    • Immune System Dysregulation. Some immunologic differences between those with CFS and those without have been reported. People with CFS are not at increased risk for developing an infection.).
    • Sleep Disorders. Some studies have shown an association between ME/CFS and delayed dim light melatonin onset. This connection suggests a delayed circadian rhythm could be a contributing factor to ME/CFS. However, while melatonin assists in regulating the circadian rhythm, there is no evidence of melatonin relieving ME/CFS.

    Risk Factors for Chronic Fatigue Syndrome

    People who meet one or more of the following criteria may have a higher likelihood of developing the syndrome:

    • Woman
    • Age 40–60
    • Family history of ME/CFS
    • Caucasian

    There are no known preventative measures for reducing the risk of ME/CFS.

      Chronic Fatigue Syndrome Diagnosis

      As more research is done on ME/CFS, the criteria for diagnosis continue to be updated. There are a few possible sets of criteria physicians may choose to use in their diagnosis. However, most of these criteria sets require the following:

      • Fatigue
      • Post-exertional malaise (PEM), or worsened fatigue after performing usual activities
      • Unrefreshing sleep or other sleep problems
      • Widespread pain or discomfort, such as muscle or joint pain or headache
      • Two or more types of neurological or cognitive dysfunction, such as impaired memory and concentration
      • Symptoms lasting longer than six months

      There is no chronic fatigue syndrome test to verify whether or not a person has the syndrome. Instead, physicians take a history of patient symptoms, including family history. They often conduct tests to rule out the possibility of other diseases, including urine and blood tests. Physicians may also refer patients to specialists to ensure other diagnoses are ruled out.

      Experts note that patients may be diagnosed with both ME/CFS and an additional source of chronic fatigue. Some comorbidities of ME/CFS include:

      • Fibromyalgia
      • Irritable bowel syndrome
      • Interstitial cystitis
      • Migraines
      • Depression
      • Allergies and sensitivities

      Treatment for Chronic Fatigue Syndrome

      Unfortunately, there is no cure for ME/CFS. People with the disorder shouldn’t give up hope, however. A variety of treatments may be used to lessen or eliminate symptoms.

      • Cognitive Behavioral Therapy (CBT). CBT teaches patients how to recognize fears of potential fatigue. With the aid of CBT, patients can also learn how to redirect thoughts that may provide a more positive outlook about recovery.
      • Exercise. Through graded exercise therapy, patients with ME/CFS exercise to increase overall physical and mental function.
      • Sleep Management. Poor sleep is a common symptom of ME/CFS. Treatment of sleep disorders that accompany ME/CFS can lessen its overall effects. Patients can begin by improving their sleep hygiene. However, additional steps, such as prescription medications or therapies for specific sleep disorders may be necessary.
      • Pharmacologic Therapy. Currently, there are no drugs that specifically target ME/CFS. Instead, patients may take drugs to treat symptoms of ME/CFS, such as pain, depression, and sleep deprivation.
      • Stress Reduction and Relaxation. Certain practices can help with managing chronic pain and fatigue. These include meditation, massage, and acupuncture.

      Talk to Your Doctor About Chronic Fatigue Syndrome

      If you suspect you may have ME/CFS, consult your doctor. You might keep an activity log or health journal to note changes in your wellbeing and help your physician understand your situation. With the aid of your physician, you can eliminate other possible causes of your fatigue. Then, together you can develop a plan for treatment and relief of symptoms.

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      Fact Checked

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      Written by

      Elise Chahine

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