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A glossary of key ME/CFS-related terms.
- Accuracy - The "closeness of an observation to the true clinical state". With respect to diagnostic tests, "accuracy" means how specific and sensitive the test is.
- Adverse reaction - Any unintended or unwanted response to the treatment under investigation in a clinical trial.
- American Psychiatric Association - the main professional organization of psychiatrists and trainee psychiatrists in the United States, and the largest psychiatric organization in the world
- Antibody - Antibodies or immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.
- B cell - B lymphocyte, or a type of white blood cell, which is involved in the immune response by secreting antibodies to ward off infections. In mammals, they are mostly matured in the bone marrow.
- Bias - Bias in research is "a systematic deviation of an observation from the true clinical state".
- BPS - See Biopsychosocial model.
- Bradycardia - A slowness of the heartbeat, so that the pulse rate is less than 60 per minute in an adult.
- Canadian consensus criteria (CCC) - A set of diagnostic criteria used to diagnose ME/CFS, developed by a group of practicing ME/CFS clinicians in 2003. The CCC is often considered to be the most complex criteria, but possibly the most accurate, with the lowest number of patients meeting the criteria. Led to the development of the International Consensus Criteria (ICC) in 2011.
- CBT - See Cognitive behavioral therapy.
- CCC - See Canadian consensus criteria.
- Cell membrane - A very thin membrane, composed of lipids and protein, that surrounds the cytoplasm of a cell and controls the passage of substances into and out of the cell.
- chronic disease - a disease or condition that usually lasts for 3 months or longer and may get worse over time
- CFSAC - See Chronic fatigue syndrome advisory committee.
- Chronic fatigue (CF) - Persistent and abnormal fatigue is a symptom, not an illness. It may be caused by depression, multiple sclerosis, fibromyalgia, chronic fatigue syndrome or many other illnesses. The term "chronic fatigue" should never be confused with the disease chronic fatigue syndrome.
- Chronic Fatigue Syndrome (CFS) - may be more likely to refer to those diagnosed using the Fukuda Criteria or the Oxford definition. Commonly used in the United States as the name of the disease. Viewed by some patients as dismissive and derogatory.
- Chronic fatigue syndrome advisory committee (CFSAC) - (sometimes pronounced SIF-SACK) A US government advisory council that met twice per year, covering current topics related to Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Meetings usually lasted for two days and the results were presented to the Secretary of Health and Human Services (HHS). After 15 years, on September 5, 2018, CFSAC's charter was not renewed by the Department of HHS, effectively dissolving the committee without notice or warning.
- Cognition - Thought processes, including attention, reasoning, and memory.
- Cognitive behavioral therapy (CBT) - A type of psychotherapy geared toward modifying alleged unhealthy thinking, behaviors or illness beliefs. One of the treatment arms used in the controversial PACE trial.
- Conversion disorder - A psychiatric term to describe an alleged condition whereby a person's thoughts somehow cause physical symptoms. The actual existence of such a condition is highly controversial, due to a lack of scientific evidence. It is related to other psychiatric terms, such as "neurasthenia" and "hysteria". A more modern term is "Somatic Symptom Disorder".
- Crash - See Post-exertional malaise.
- Endogenous - Growing or originating from within an organism.
- energy envelope theory - the theory that a person with ME has a limited amount of energy to use each day without causing an exacerbation of symptoms or inducing PEM. This "energy envelope" will vary from day to day and from person to person. See also pacing with a heart rate monitor
- enterovirus - a genus of RNA viruses which typically enter the body through the gastrointestinal tract and can sometimes spread to the central nervous system or other parts of the body. Enteroviruses include those which cause polio and coxsackievirus.
- epigenome - all of the chemical compounds that are not part of the DNA sequence, but are on or attached to DNA as a way to regulate genes activity
- Fukuda criteria - The most commonly used diagnostic criteria for chronic fatigue syndrome, created by the United States Centers for Disease Control (CDC).
- genome - an organism’s complete set of DNA, including all of its genes
- GET - See Graded exercise therapy.
- Graded exercise therapy (GET) - A gradual increase in exercise or activity, according to a pre-defined plan. Focuses on overcoming the patient's alleged unhelpful illness beliefs that exertion can exacerbate symptoms, rather than on reversing physical deconditioning. Considered controversial, and possibly harmful, in the treatment or management of ME. One of the treatment arms of the controversial PACE trial.
- HLA complex (human leukocyte antigen) - a gene complex responsible for encoding certain proteins which help the immune system to distinguish the body's own proteins from proteins which are made by foreign invaders like bacteria and viruses. See also "Dr Ron Davis’s big immune study is looking at HLA genes"
- heart rate monitor (HRM) - a device that measures your heart rate / pulse. Typically a chest strap, wrist strap, or mobile phone app. See also pacing with a heart rate monitor.
- heart rate variability (HRV) - a measurement of the specific changes in time (or variability) between successive heart beats. This is related to autonomic and cardiovascular function. See also pacing with a heart rate monitor.
- Iatrogenesis - Accidental harm caused by a doctor, by medical treatment, or by diagnostic procedures.
- ICD - International Classification of Diseases. A system of medical codes created by the World Health Organization (WHO) for diseases and other health related conditions for the purpose of international consistency. The 11th revision, or ICD-11, is due in 2018.
- Immunoglobulin - See Antibody.
- IOM - Institute of Medicine, (National Academy of Medicine (NAM) as of June 2015) is an American non-profit, non-governmental organization which provides expert advice on issues relating to biomedical science, medicine and health.
- immunomodulator - a substance that affects the functioning of the immune system
- Institute of Medicine report - or IOM Report, was published by the Institute of Medicine on February 10 2015. The report Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness proposed the name Systemic Exertion Intolerance Disease (SEID). Among its key findings were that "This disease is characterized by profound fatigue, cognitive dysfunction, sleep abnormalities, autonomic manifestations, pain, and other symptoms that are made worse by exertion of any sort." — "Between 836,000 and 2.5 million Americans suffer from myalgic encephalomyelitis/chronic fatigue syndrome."
- invisible illness - a chronic condition or illness, such as ME/CFS, which may not be apparent to others. Sufferers may look healthy, yet be in poor health. Symptoms of the illness may not be visible and can be misunderstood or go unnoticed by others. Also, patients may wind up secluded or homebound due to the illness and become "invisible".
- magnetic levitation device - uses ferrofluid (a liquid which can become magnetized) in a glass capillary tube surrounded by magnets. This creates a density gradient and cells move to their respective densities within the tube. White blood cells in CFS patients have been discovered to be less dense than those of healthy controls, indicating the possible use of the device as an inexpensive diagnostic test. This technology is being developed by Ron Davis' team at Stanford University. See also OMF Funded Diagnostic Technology Development
- mass spectrometer - a device which converts molecules to ions, or charged particles. It then uses magnetic and electric fields to sort the ions according to their mass (similar to weight) and charge, and measure their characteristics.
- ME - See Myalgic encephalomyelitis.
- ME/CFS - An acronym that combines myalgic encephalomyelitis with chronic fatigue syndrome. Sometimes they are combined because people have trouble distinguishing one from the other. Sometimes they are combined because people see them as synonyms of each other.
- medically unexplained physical symptoms (MUPS) - technically the term means that there is no known medical cause or explanation for the patient's symptoms. However, MUS or MUPS are generally lumped into a psychosomatic, or psychologically caused category by those in the medical profession.
- medically unexplained symptoms (MUS) - see medically unexplained physical symptoms
- metabolic trap hypothesis - hypothesis proposed by Dr. Robert Phair. Based on preliminary data from the OMF-funded ME/CFS Severely Ill Patient Study (SIPS), which found several genes which may carry mutations in people with ME. These mutations may cause enzymes which process important metabolites to slow down and cause a metabolic trap, which could explain some symptoms in ME/CFS.
- metabolite - a substance produced by, or involved in metabolism.
- metabolomics - the study and analysis of the chemical processes of metabolites within cells, tissues or organisms.
- microbiome - the collective of microscopic organisms (including bacteria, viruses and fungi) and their genetic material, which are present in a particular environment, particularly in the human body.
- Millions Missing - a global campaign, first led by #MEAction in May 2016, which aims to gain awareness, community, education, research, funding and treatment equality for Myalgic Encephalomeyelitis. See also #MillionsMissing on Twitter.
- mitochondria - organelles or subunits within a cell. Their primary role is to take in nutrients and produce energy for the cell in the form of ATP (adenosine triphosphate). This process requires oxygen and is called aerobic respiration.
- Myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.
- Myalgic encephalopathy - An alternate term that is sometimes used for myalgic encephalomyelitis, by people who believe the evidence for inflammation in ME is insufficient. This terminology reflects the belief that the "-itis" suffix implies inflammation.
- nanoneedle - a nanofabricated device (one nanometer = one millionth of a millimeter) which measures electrical impedance from a drop of blood. The electrical impedance increased in the blood cells of 10 ME/CFS patients when stressed with salt, but not in healthy controls. This device may be able to distinguish ME/CFS patients from healthy controls and is being developed by Ron Davis' team at Standford University. See also OMF Funded Diagnostic Technology Development
- NASA 10-minute lean test - variation of a test used by NASA researchers to test for orthostatic intolerance. A simple test which is recommended by the Bateman Horne Center for ME and Fibromyalgia patients. Instructions for medical providers Instructions for patients
- naturopath - a system of treatment of disease that avoids drugs and surgery and emphasizes the use of natural agents (such as air, water, and herbs) and physical means (such as tissue manipulation and electrotherapy)
- orthostatic intolerance (OI) - the development of symptoms when standing upright which are relieved when reclining; may be due to dysautonomia
- PACE trial - a controversial study which claims that CBT and GET are effective in treating CFS/ME. Its results and methodology are disputed by patients, scientists and peer-reviewed scientific literature.
- pacing - the practice of staying within one's "energy envelope" by interspersing periods of activity with periods of rest. Patients may use pacing with a heart rate monitor as an objective measure of exertion.
- Plasma membrane - See Cell membrane.
- Pharyngitis - An irritation or swelling of the top part of the throat, at the back of the mouth, usually caused by an infection such as Streptococcus. The hallmark symptom is a sore throat without cough.
- Phase three - Last phase of clinical trials before a drug can be approved for public use. Whereas Phase one assesses basic safety, and Phase two assesses basic efficacy, Phase three uses many trial participants to fully assess both safety and efficacy.
- Post-exertional malaise (PEM) - A notable exacerbation of symptoms brought on by small physical or cognitive exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others.
- Post-exertional neuroimmune exhaustion (PENE) - An alternative term for post-exertional malaise (PEM), used by people who find that the word 'malaise' fails to capture the serious nature of the condition. Used in the Institute of Medicine (IOM) report.
- Postural orthostatic tachycardia syndrome (POTS) - A form of orthostatic intolerance where the cardinal symptom is excessive tachycardia due to changing position (e.g. from lying down to sitting up).
- POTS - See Postural orthostatic tachycardia syndrome.
- PwME - Acronym for a "Person with ME" (myalgic encephalomyelitis).
- Ramsay definition - Melvin Ramsay's definition of ME
- Randomized controlled trial (RCT) - A trial in which participants are randomly assigned to two groups, with one group receiving the treatment being studied and a control or comparison group receiving a sham treatment, placebo, or comparison treatment.
- RCT - See Randomized controlled trial.
- Seahorse analyzer - an instrument which measures oxygen consumption rate and extracellular acidification rate in live cells, in real time, producing information regarding important cellular functions such as mitochondrial respiration and glycolysis.
- SEID - See Systemic exertion intolerance disease.
- Severely Ill Patient Study (SIPS) - a study funded by the OMF (Open Medicine Foundation) and led by Dr. Ronald Davis and Wenzhong Xiao, PhD. It includes over 1000 tests per patient, including the patients' genome, gene expression, metabolomics, microbiome, and many others. See also ME/CFS Severely Ill Big Data Study for details, a complete list of tests and Spring 2018 update.
- SF-36 (Short Form (36) Health Survey) - a 36 item patient reported questionnaire, used to determine patient health status and quality of life.
- Side effect - See Adverse reaction.
- Single nucleotide polymorphism (SNP) - A single nucleotide polymorphism (SNP, pronounced "snip") is a potential genetic mutation that occurs in a single spot in the human genome; a difference in a single DNA building block. SNPs are often represented by an "rs" number, such as "rs53576".
- SNP - See Single nucleotide polymorphism.
- somatic - relating to the physical body. In biology, all the cells of the body, except those which form egg or sperm. Easily confused with "somatoform" or "psychosomatic".
- Somatic symptom disorder - See Conversion disorder.
- somatoform disorder - a mental health disorder in which a patient experiences symptoms which can not be explained by current medical knowledge. Symptoms are considered real, even though the cause is never found and is assumed to be psychological. Patients who disagree with the psychological diagnosis of somatoform disorder and the lack of further investigation into their symptoms are often met with skepticism or even disdain by the medical community.
- Spoon theory - An analogy which equates the amount of ability that someone with chronic illness has to complete daily tasks to a limited number of spoons.
- spoonie - a person, usually with a chronic illness, with a limited amount of energy or health, or "spoons". See also Spoon Theory
- Stress fracture - A tiny crack in a bone caused by repetitive forces such as running or by normal use of a bone that's weakened by a condition such as osteoporosis.
- serum - the clear yellowish fluid that remains from blood plasma after clotting factors have been removed by clot formation
- Systemic exertion intolerance disease (SEID) - A term for ME/CFS that aims to avoid the stigma associated with the term "chronic fatigue syndrome", while emphasizing the defining characteristic of post-exertional malaise (PEM). SEID was defined as part of the diagnostic criteria put together by the Institute of Medicine (IOM) report of 10 February 2015.
- T cell - T lymphocyte, or a type of white blood cell, which is mostly produced or matured in the thymus gland (hence T-cell) and is involved in immune response on a cellular level. See also Dr. Mark Davis Research Update video
- Tachycardia - An unusually rapid heart beat. Can be caused by exercise or illness. A symptom of postural orthostatic tachycardia syndrome (POTS). (Learn more: www.heart.org)
- Virome - The human virome is the collection of all viruses that are found in or on humans
- VO2max - the maximum amount of oxygen the body can utilize during a specified period of usually intense exercise
- WHO - See World Health Organization.
- World Health Organization (WHO) - "A specialized agency of the United Nations that is concerned with public health. It was established on 7 April 1948, and is headquartered in Geneva, Switzerland. The WHO is a member of the United Nations Development Group. Its predecessor, the Health Organization, was an agency of the League of Nations." The International Statistical Classification of Diseases and Related Health Problems (ICD) is maintained by WHO.
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