Leonard Jason

Leonard A. Jason, PhD, is a professor of psychology at DePaul University in Chicago, Illinois, USA and Director of the Center for Community Research at DePaul University which includes the Depaul University Chronic Fatigue Syndrome Project. He was a voting member of the Health and Human Services's Chronic Fatigue Syndrome Advisory Committee from 04/01/07-04/01/11.

Dr. Jason developed chronic fatigue syndrome after contracting infectious mononucleosis in 1989, necessitating a leave of absence from his university job for a year and a half. After recovering enough to return to work, he began studying chronic fatigue syndrome: “What I found was that the illness had a lousy name, chronic fatigue syndrome,” he recalled. “It had an even worse case definition. The tests used to assess people’s psychological conditions were inappropriate. The treatments being used were inappropriate. And the prevalence data was not very good. So I said to myself, ‘Boy, I’m gonna have business for the next 20 years.’” He has become one of the most respected and prolific researchers of chronic fatigue syndrome.

In 2008, David Tuller profiled for The New York Times Dr. Jason's experience as both living with and researching myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

Education

• 1975 - Ph.D., Clinical/Community Psychology, University of Rochester, Rochester, New York
• 1971 - B.A., Psychology, Brandeis University, Waltham, Massachusetts

Awards

• 2015, American Psychological Association’s award for Distinguished Professional Contributions to Applied Research
• 2013, DePaul University College of Science and Health award for Excellence in Research
• 2011, Rudy Perpich Senior Lectureship Award, presented to a distinguished CFS/FM scientist, physician or healthcare worker awarded by International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis
• 2011, Tom Fellows award for outstanding contributions to the Oxford House organization
• 1997, CSN ACTION Champion Award from the Chronic Fatigue Immune Dysfunction Syndrome Association of America (CAA)

Open letter to The Lancet

Two open letters to the editor of The Lancet urged the editor to commission a fully independent review of the PACE trial, which the journal had published in 2011. The first, written in 2015, was sign by Dr. Jason and 5 of his colleagues. In 2016, thirty-six additional colleagues in the ME/CFS field, signed the second letter.

• 13 November 2015, An open letter to Dr. Richard Horton and The Lancet
• 10 February 2016, An open letter to The Lancet, again - Virology blog

Pediatric case definition

• 2006, "A Pediatric Case Definition for Myalgic Encephalomyelitis and Chronic Fatigue Syndrome"

  "Summary: For a diagnosis of chronic fatigue syndrome (CFS), most researchers use criteria that were developed by Fukuda et al. (1994), with modifications suggested by Reeves et al. (2003). However, this case definition was established for adults rather than children. A Canadian Case Definition (ME/CFS; Myalgic Encephalomyelitis/CFS) has recently been developed, with more specific inclusion criteria (Carruthers et al., 2003). Again, the primary aim of this case definition is to diagnose adult CFS. A significant problem in the literature is the lack of both a pediatric definition of ME/CFS and a reliable instrument to assess it. These deficiencies can lead to criterion variance problems resulting in studies labeling children with a wide variety of symptoms as having ME/CFS. Subsequently, comparisons between articles become more difficult, decreasing the possibility of conducting a meta-analysis. This article presents recommendations developed by the International Association of Chronic Fatigue Syndrome Pediatric Case Definition Working group for a ME/CFS pediatric case definition. It is hoped that this pediatric case definition will lead to more appropriate identification of children and adolescents with ME/CFS."

Studies

• 2017, A content analysis of chronic fatigue syndrome and myalgic encephalomyelitis in the news from 1987 to 2013

  Abstract - "Objectives: The aim of this study was to analyze the content of American newspaper articles (n=214) from 1987 to 2013, in order to understand how the public digests information related to Chronic Fatigue syndrome, a controversial and misunderstood illness. Methods: A novel codebook derived from the scientific literature was applied to 214 newspaper articles collected from Lexis Nexis Academic®. These articles were coded quantitatively and frequency tables were created to delineate the variables as they appeared in the articles. Results: The etiology was portrayed as organic in 64.5% (n=138) of the articles, and there was no mention of case definitions or diagnostic criteria in 56.1% (n=120) of the articles. The most common comorbidity was depression, appearing in 22.9% (n=49) of the articles. In 55.6% (n=119) of the articles, there was no mention of prevalence rates. In 50.9% (n=109) of the articles, there was no mention of any form of treatment for the illness. A total of 19.4% (n=42) of the headlines mislabeled the name of the illness. Discussion: Based on descriptive statistics of all 214 coded articles, media communicated mixed messages for salient variables such as the name of the illness, its etiology and treatment.

• 2017, Clinical criteria versus a possible research case definition in chronic fatigue syndrome/myalgic encephalomyelitis
• 2017, Article - "The PACE trial missteps on pacing and patient selection"

  Abstract - "As others have pointed out a variety of complicating factors with the PACE trial (e.g. changing outcome criteria), I will limit my remarks to issues that involve the composition of adaptive pacing therapy and issues involving patient selection. My key points are that the PACE trial investigators were not successful in designing and implementing a valid pacing intervention and patient selection ambiguity further compromised the study’s outcomes."

• 2017, A Prospective Study of Infectious Mononucleosis in College Students

  "Abstract - Background: The present study aims to prospectively investigate possible biological and psychological factors present in college students who will go on to develop chronic fatigue syndrome (CFS) following Infectious Mononucleosis (IM). Identification of risk factors predisposing patients towards developing CFS may help to understand the underlying mechanisms and ultimately prevent its occurrence. Our study is enrolling healthy college students over the age of 18. Enrollment began in March of 2013 and is ongoing. Methods: Biological and psychological data are collected when students are well (Stage 1), when they develop IM (Stage 2), and approximately 6 months after IM diagnosis (Stage 3). Results: Two case studies demonstrate the progression of student symptomology across all three stages. Conclusion: The Case Studies presented illustrate the usefulness of a prospective research design that tracks healthy."

• 2016, Comparing the DePaul Symptom Questionnaire with physician assessments: a preliminary study

  "Results: The DSQ identified 60 and the physicians identified 56 as having a CCC diagnosis. The overall agreement between the two ratings on the diagnostic assessment part was moderate (Kappa = 0.45, p < .001). The sensitivity of DSQ was good (98%) while the specificity was 38%. Positive and negative predictive values were 92% and 75%, respectively. Conclusion: DSQ is useful for detecting and screening symptoms consistent with a CCC diagnosis in clinical practice and research. However, it is important for initial screening of self-report symptoms to be followed up by subsequent medical and psychiatric examination in order to identify possible exclusionary medical and psychiatric disorders."

• 2016, Housebound versus nonhousebound patients with myalgic encephalomyelitis and chronic fatigue syndrome

  "Abstract - Objectives: The objective of this study was to examine individuals with myalgic encephalomyelitis and chronic fatigue syndrome who are confined to their homes due to severe symptomatology. The existing literature fails to address differences between this group, and less severe, nonhousebound patient populations. Methods: Participants completed the DePaul Symptom Questionnaire, a measure of myalgic encephalomyelitis and chronic fatigue syndrome symptomology, and the SF-36, a measure of health impact on physical/mental functioning. ANOVAs and, where appropriate, MANCOVAS were used to compare housebound and nonhousebound patients with myalgic encephalomyelitis and chronic fatigue syndrome across areas of functioning, symptomatology, and illness onset characteristics. Results: Findings indicated that the housebound group represented one quarter of the sample, and were significantly more impaired with regards to physical functioning, bodily pain, vitality, social functioning, fatigue, post-exertional malaise, sleep, pain, neurocognitive, autonomic, neuroendocrine, and immune functioning compared to individuals who were not housebound. Discussion: Findings indicated that housebound patients have more impairment on functional and symptom outcomes compared to those who were not housebound. Understanding the differences between housebound and not housebound groups holds implications for physicians and researchers as they develop interventions intended for patients who are most severely affected by this chronic illness."

• 2016, Estimating the disease burden of ME/CFS in the United States and its relation to research funding

  "Abstract: At the National Institutes of Health (NIH), burden of disease is an important factor in funding decisions along with such factors as scientific opportunity, the quality of the science, and the interest of researchers. Recent studies have quantified the burden for a number of diseases in the United States and the NIH has used that information to analyze how its own funding patterns correspond to disease burden. However, the burden of disease has not been quantified for myalgic encephalomyelitis, also called chronic fatigue syndrome (ME/CFS) and is often underestimated due to a lack of research and the misperceptions about the nature of the disease...Even given the limitations arising from sparse data, this analysis demonstrates that federal research funding for this disease is far less than what would be expected by the burden of the disease. We conclude that the annual research funding for ME/CFS would need to increase twenty-five fold or more to be commensurate with disease burden. This level of funding would best leverage the growing interest of researchers and the significant scientific opportunities that exist to understand the pathology of this disease and to advance diagnostics and treatments."

• 2016, Identifying Key Symptoms Differentiating Myalgic Encephalomyelitis and Chronic Fatigue Syndrome from Multiple Sclerosis

  "Abstract:It is unclear what key symptoms differentiate Myalgic Encephalomyelitis (ME) and Chronic Fatigue syndrome (CFS) from Multiple Sclerosis (MS). The current study compared self-report symptom data of patients with ME or CFS with those with MS. The self-report data is from the DePaul Symptom Questionnaire, and participants were recruited to take the questionnaire online. Data were analyzed using a machine learning technique called decision trees. Five symptoms best differentiated the groups. The best discriminating symptoms were from the immune domain (i.e., flu-like symptoms and tender lymph nodes), and the trees correctly categorized MS from ME or CFS 81.2% of the time, with those with ME or CFS having more severe symptoms. Our findings support the use of machine learning to further explore the unique nature of these different chronic diseases."

• 2016, Mortality in patients with myalgic encephalomyelitis and chronic fatigue syndrome
• 2016, Deconstructing post-exertional malaise: An exploratory factor analysis.

  "Abstract: Post-exertional malaise is a cardinal symptom of myalgic encephalomyelitis and chronic fatigue syndrome. There are two differing focuses when defining post-exertional malaise: a generalized, full-body fatigue and a muscle-specific fatigue. This study aimed to discern whether post-exertional malaise is a unified construct or whether it is composed of two smaller constructs, muscle fatigue and generalized fatigue. An exploratory factor analysis was conducted on several symptoms that assess post-exertional malaise. The results suggest that post-exertional malaise is composed of two empirically different experiences, one for generalized fatigue and one for muscle-specific fatigue."

• 2016, Assessing current functioning as a measure of significant reduction in activity level

  "Abstract - Background: Myalgic encephalomyelitis and chronic fatigue syndrome have case definitions with varying criteria, but almost all criteria require an individual to have a substantial reduction in activity level. Unfortunately, a consensus has not been reached regarding what constitutes substantial reductions. One measure that has been used to measure substantial reduction is the Medical Outcomes Study Short-Form-36 Health Survey (SF-36). Purpose: The current study examined the relationship between the SF-36, a measure of current functioning, and a self-report measure of the percent reduction in hours spent on activities. Results: Findings indicated that select subscales of the SF-36 accurately measure significant reductions in functioning. Further, this measure significantly differentiates patients from controls. Conclusion: Determining what constitutes a significant reduction in activity is difficult because it is subjective to the individual. However, certain subscales of the SF-36 could provide a uniform way to accurately measure and define substantial reductions in functioning.

• 2016, The Role of Infectious and Stress-related Onsets in Myalgic Encephalomyelitis and Chronic Fatigue Syndrome Symptomatology and Functioning
• 2016, Educational Priorities for Healthcare Providers and Name Suggestions for Chronic Fatigue Syndrome: Including the Patient Voice
• 2016, Intrinsic Functional Hypoconnectivity in Core Neurocognitive Networks Suggests Central Nervous System Pathology in Patients with Myalgic Encephalomyelitis: A Pilot Study (FULL TEXT)

  Abstract - Exact low resolution electromagnetic tomography (eLORETA) was recorded from nineteen EEG channels in nine patients with myalgic encephalomyelitis (ME) and 9 healthy controls to assess current source density and functional connectivity, a physiological measure of similarity between pairs of distributed regions of interest, between groups. Current source density and functional connectivity were measured using eLORETA software. We found significantly decreased eLORETA source analysis oscillations in the occipital, parietal, posterior cingulate, and posterior temporal lobes in Alpha and Alpha-2. For connectivity analysis, we assessed functional connectivity within Menon triple network model of neuropathology. We found support for all three networks of the triple network model, namely the central executive network (CEN), salience network (SN), and the default mode network (DMN) indicating hypo-connectivity in the Delta, Alpha, and Alpha-2 frequency bands in patients with ME compared to controls. In addition to the current source density resting state dysfunction in the occipital, parietal, posterior temporal and posterior cingulate, the disrupted connectivity of the CEN, SN, and DMN appears to be involved in cognitive impairment for patients with ME. This research suggests that disruptions in these regions and networks could be a neurobiological feature of the disorder, representing underlying neural dysfunction.

• 2016 - qEEG / LORETA in Assessment of Neurocognitive Impairment in a Patient with Chronic Fatigue Syndrome: A Case Report (FULL TEXT)

  Abstract - Importance: Chronic Fatigue Syndrome (CFS) is a chronic disease resulting in considerable and widespread cognitive deficits. Accurate and accessible measurement of the extent and nature of these deficits can aid healthcare providers and researchers in the diagnosis of this condition, choosing interventions and tracking treatment effects. Here, we present a case of a middle-aged man diagnosed with CFS which began following a typical viral illness. Observations: LORETA source density measures of surface EEG connectivity at baseline were performed on 3 minutes of eyes closed deartifacted19-channel qEEG. The techniques used to analyze the data are described along with the hypothesized effects of the deregulation found in this data set. Nearly all (>90%) patients with CFS complain of cognitive deficits such as slow thinking, difficulty in reading comprehension, reduced learning and memory abilities and an overall feeling of being in a “fog.”Therefore, impairment may be seen in deregulated connections with other regions (functional connectivity); this functional impairment may serve as one cause of the cognitive decline in CFS. Here, the functional connectivity networks of this patient were sufficiently deregulated to cause the symptoms listed above. Conclusions and significance: This case report increased our understanding of CFS from the perspective of brain functional networks by offering some possible explanations for cognitive deficits in patients with CFS. There are only a few reports of using source density analysis or qEEG connectivity analysis for cognitive deficits in CFS. While no absolute threshold exists to advise the physician as to when to conduct such analyses, the basis of his or her decision whether or not to use these tools should be a function of clinical judgment and experience. These analyses may potentially aid in clinical diagnosis, symptom management, treatment response and can alert the physician as to when intervention may be warranted.

• 2016 - Functional Neural Network Connectivity in Myalgic Encephalomyelitis (FULL TEXT)

  Abstract - Myalgic Encephalomyelitis (ME) is a chronic illness with debilitating neurocognitive impairment that remains poorly understood. Previous studies have characterized cognitive deficits as a process by which brain abnormalities are inferred from pre-established testing paradigms using neuroimaging with low temporal resolution. Unfortunately, this approach has been shown to provide limited predictive power, rendering it inadequate for the study of neuronal communication between synchronized regions. More recent developments have highlighted the importance of modeling spatiotemporal dynamic interactions within and between large-scale and small-scale neural networks on a millisecond time scale. Here, we focus on recent emergent principles of complex cortical systems, suggesting how subtle disruptions of network properties could be related to significant disruptions in cognition and behavior found in ME. This review, therefore, discusses how electrical neuroimaging methods with time-dependent metrics (e.g., coherence, phase, cross-frequency coupling) can be a useful approach for the understanding of the cognitive symptoms in ME. By providing a platform for utilizing real-time alterations of the perpetual signals as an outcome, the disruptions to higher-level cognition typically seen in ME can be readily identified, creating new opportunities for better diagnosis and targeted treatments.

• 2016, Case definitions integrating empiric and consensus perspectives
• 2016, Comparing the DePaul Symptom Questionnaire with physician assessments: a preliminary study

  "Results: The DSQ identified 60 and the physicians identified 56 as having a CCC diagnosis. The overall agreement between the two ratings on the diagnostic assessment part was moderate (Kappa = 0.45, p < .001). The sensitivity of DSQ was good (98%) while the specificity was 38%. Positive and negative predictive values were 92% and 75%, respectively. Conclusion: DSQ is useful for detecting and screening symptoms consistent with a CCC diagnosis in clinical practice and research. However, it is important for initial screening of self-report symptoms to be followed up by subsequent medical and psychiatric examination in order to identify possible exclusionary medical and psychiatric disorders."

• 2016, Housebound versus nonhousebound patients with myalgic encephalomyelitis and chronic fatigue syndrome

  "Abstract - Objectives: The objective of this study was to examine individuals with myalgic encephalomyelitis and chronic fatigue syndrome who are confined to their homes due to severe symptomatology. The existing literature fails to address differences between this group, and less severe, nonhousebound patient populations. Methods: Participants completed the DePaul Symptom Questionnaire, a measure of myalgic encephalomyelitis and chronic fatigue syndrome symptomology, and the SF-36, a measure of health impact on physical/mental functioning. ANOVAs and, where appropriate, MANCOVAS were used to compare housebound and nonhousebound patients with myalgic encephalomyelitis and chronic fatigue syndrome across areas of functioning, symptomatology, and illness onset characteristics. Results: Findings indicated that the housebound group represented one quarter of the sample, and were significantly more impaired with regards to physical functioning, bodily pain, vitality, social functioning, fatigue, post-exertional malaise, sleep, pain, neurocognitive, autonomic, neuroendocrine, and immune functioning compared to individuals who were not housebound. Discussion: Findings indicated that housebound patients have more impairment on functional and symptom outcomes compared to those who were not housebound. Understanding the differences between housebound and not housebound groups holds implications for physicians and researchers as they develop interventions intended for patients who are most severely affected by this chronic illness."

• 2016, The Relationship between Age and Illness Duration in Chronic Fatigue Syndrome

  "Abstract:Chronic fatigue syndrome (CFS) is a debilitating illness, but it is unclear if patient age and illness duration might affect symptoms and functioning of patients. In the current study, participants were categorized into four groups based upon age (under or over age 55) and illness duration (more or less than 10 years). The groups were compared on functioning and symptoms. Findings indicated that those who were older with a longer illness duration had significantly higher levels of mental health functioning than those who were younger with a shorter or longer illness duration and the older group with a shorter illness duration. The results suggest that older patients with an illness duration of over 10 years have significantly higher levels of mental health functioning than the three other groups. For symptoms, the younger/longer illness duration group had significantly worse immune and autonomic domains than the older/longer illness group. In addition, the younger patients with a longer illness duration displayed greater autonomic and immune symptoms in comparison to the older group with a longer illness duration. These findings suggest that both age and illness duration need to be considered when trying to understand the influence of these factors on patients.

• 2015, Caring for people with severe myalgic encephalomyelitis: An interpretative phenomenological analysis of parents’ experiences

  "Abstract: Experiences of parents who care for sons or daughters with severe myalgic encephalomyelitis are rarely discussed within the literature. Narratives of parent–carers in Lost Voices from a Hidden Illness were analyzed using interpretative phenomenological analysis. This study aimed to give voices to those who care for individuals with myalgic encephalomyelitis and are often stigmatized and inform future research supporting parent–carers. Results included themes of identity change, guilt, feeling like outsiders, uncertainty, changing perceptions of time, coping mechanisms, and improvement/symptom management. Findings could inform the development of carer-focused interventions and provide vital information to health professionals about parent–carers’ lived experience."

• 2015 - Myalgic Encephalomyelitis: Symptoms and Biomarkers (FULL TEXT)

  Abstract - Myalgic Encephalomyelitis (ME) continues to cause significant morbidity worldwide with an estimated one million cases in the United States. Hurdles to establishing consensus to achieve accurate evaluation of patients with ME continue, fueled by poor agreement about case definitions, slow progress in development of standardized diagnostic approaches, and issues surrounding research priorities. Because there are other medical problems, such as early MS and Parkinson’s Disease, which have some similar clinical presentations, it is critical to accurately diagnose ME to make a differential diagnosis. In this article, we explore and summarize advances in the physiological and neurological approaches to understanding, diagnosing, and treating ME. We identify key areas and approaches to elucidate the core and secondary symptom clusters in ME so as to provide some practical suggestions in evaluation of ME for clinicians and researchers. This review, therefore, represents a synthesis of key discussions in the literature, and has important implications for a better understanding of ME, its biological markers, and diagnostic criteria. There is a clear need for more longitudinal studies in this area with larger data sets, which correct for multiple testing.

• 2015, Functional level of patients with chronic fatigue syndrome reporting use of alternative vs. traditional treatments
• 2015, Chronic fatigue syndrome versus systemic exertion intolerance disease
• 2015, Variability in symptoms complicates utility of case definitions. Abstract
• 2015, Comparing and contrasting consensus versus empirical domains. Abstract
• 2015, Test–retest reliability of the DePaul Symptom Questionnaire Abstract

  "Methods: Test–retest reliability of the measure was examined with a sample of 26 adults self-identifying as having either ME/CFS, ME, and/or CFS and 25 adults who did not self-identify as having these illnesses and were otherwise healthy controls. Results: Overall, the majority of items on the DSQ exhibited good to excellent test–retest reliability, with Pearson's or kappa correlation coefficients that were 0.70 or higher."

• 2014, Validating a measure of myalgic encephalomyelitis/chronic fatigue syndrome symptomatology. Abstract

  "Methods: Exploratory factor analysis (EFA) was used to establish the underlying factor structure of the DePaul Symptom Questionnaire (DSQ) using a well-characterized sample of individuals (92.6% met the Fukuda et al. criteria and/or the Clinical Canadian Criteria) and this structure was then tested on a less stringently recruited sample of individuals utilizing a confirmatory factor analysis (CFA). Convergent and discriminant validity of the DSQ were also examined utilizing alternative measures of symptomatology and functioning. Results: A three-factor solution was found using EFA (Neuroendocrine, Autonomic, and Immune Symptoms; Neurological/Cognitive Dysfunction; Post-Exertional Malaise) and the fit of this factor structure was adequate for the second sample. The DSQ was found to have good convergent and discriminant validity. Conclusions: The DSQ is a valid tool for assessing ME/CFS symptoms. There may be two core ME/CFS symptom clusters: post-exertional malaise and cognitive dysfunction."

• 2014, Chronic Fatigue Syndrome: The Current Status and Future Potentials of Emerging Biomarkers. (FULL TEXT)
• 2014, Predictors of post-infectious chronic fatigue syndrome in adolescents

  "Abstract - This study focused on identifying risk factors for adolescent post-infectious chronic fatigue syndrome (CFS), utilizing a prospective, nested case–control longitudinal design in which over 300 teenagers with infectious mononucleosis (IM) were identified through primary care sites and followed. Baseline variables that were gathered several months following IM, included autonomic symptoms, days in bed since IM, perceived stress, stressful life events, family stress, difficulty functioning and attending school, family stress, and psychiatric disorders. A number of variables were predictors of post-infectious CFS at six months; however, when autonomic symptoms were used as a control variable, only days spent in bed since mono was a significant predictor. Step-wise logistic regression findings indicated that baseline autonomic symptoms as well as days spent in bed since mono, which reflect the severity of illness, were the only significant predictors of those who met CFS criteria at six months."

• 2014, Examining case definition criteria for chronic fatigue syndrome and myalgic encephalomyelitis. Abstract
• 2013, Energy conservation/envelope theory interventions. Full Text
• 2013, The implications of sensitization and kindling for chronic fatigue syndrome
• 2013, Contrasting chronic fatigue syndrome versus myalgic encephalomyelitis/chronic fatigue syndrome. Abstract
• 2012, Factor analysis of the Beck Depression Inventory-II with patients with chronic fatigue syndrome
• 2012, Antibody to Epstein-Barr Virus Deoxyuridine Triphosphate Nucleotidohydrolase and Deoxyribonucleotide Polymerase in a Chronic Fatigue Syndrome Subset (FULL TEXT)

  Abstract - "Background: A defined diagnostic panel differentiated patients who had been diagnosed with chronic fatigue syndrome (CFS), based upon Fukuda/Carruthers criteria. This diagnostic panel identified an Epstein-Barr virus (EBV) subset of patients (6), excluding for the first time other similar “clinical” conditions such as cytomegalovirus (CMV), human herpesvirus 6 (HHV6), babesiosis, ehrlichiosis, borreliosis, Mycoplasma pneumoniae, Chlamydia pneumoniae, and adult rheumatic fever, which may be mistakenly called CFS. CFS patients were treated with valacyclovir (14.3 mg/kg q6h) for ≥12 months. Each patient improved, based upon the Functional Activity Appraisal: Energy Index Score Healthcare Worker Assessment (EIPS), which is a validated (FSS-9), item scale with high degree of internal consistency measured by Cronbach's alpha. Methods: Antibody to EBV viral capsid antigen (VCA) IgM, EBV Diffuse Early Antigen EA(D), and neutralizing antibodies against EBV-encoded DNA polymerase and EBV-encoded dUTPase were assayed serially approximately every three months for 13–16 months from sera obtained from patients with CFS (6) and from sera obtained from twenty patients who had no history of CFS. Results: Antibodies to EBV EA(D) and neutralizing antibodies against the encoded-proteins EBV DNA polymerase and deoxyuridine triphosphate nucleotidohydrolase (dUTPase) were present in the EBV subset CFS patients. Of the sera samples obtained from patients with CFS 93.9% were positive for EA(D), while 31.6% of the control patients were positive for EBV EA(D). Serum samples were positive for neutralizing antibodies against the EBV-encoded dUTPase (23/52; 44.2%) and DNA polymerase (41/52; 78.8%) in EBV subset CFS patients, but negative in sera of controls. Conclusions: There is prolonged elevated antibody level against the encoded proteins EBV dUTPase and EBV DNA polymerase in a subset of CFS patients, suggesting that this antibody panel could be used to identify these patients, if these preliminary findings are corroborated by studies with a larger number of EBV subset CFS patients."

• 2012, Minimum data elements for research reports on CFS. Full text

  Abstract: "Chronic fatigue syndrome (CFS) is a debilitating condition that has received increasing attention from researchers in the past decade. However, it has become difficult to compare data collected in different laboratories due to the variability in basic information regarding descriptions of sampling methods, patient characteristics, and clinical assessments. The issue of variability in CFS research was recently highlighted at the NIH's 2011 State of the Knowledge of CFS meeting prompting researchers to consider the critical information that should be included in CFS research reports. To address this problem, we present our consensus on the minimum data elements that should be included in all CFS research reports, along with additional elements that are currently being evaluated in specific research studies that show promise as important patient descriptors for subgrouping of CFS. These recommendations are intended to improve the consistency of reported methods and the interpretability of reported results. Adherence to minimum standards and increased reporting consistency will allow for better comparisons among published CFS articles, provide guidance for future research and foster the generation of knowledge that can directly benefit the patient."

• 2010, Possible Genetic Dysregulation in Pediatric CFS (FULL TEXT)

  Abstract: "Hypocortisolism is a frequent finding in individuals with chronic fatigue syndrome (CFS) and could play an explanatory role in the development of illness symptomatology. The etiologic mechanism behind this finding could be genetic variance in glucocorticoid receptor expression (GR) or increased resistance to the effects of glucocorticoids. Several investigators believe that allelic variance in a GR (NR3C1) mediates the expression of chronic fatigue possibly through influence on hypothalamic-pituitary-adrenal (HPA) axis function [1]. In addition, several immunologic variables are associated with CFS. The nuclear factor kappa beta (NFkB) pathway is heavily involved in cellular transcription and regulation and has been shown to be associated with the development of CFS. The NFkB pathway is directly regulated by and influences the presence of GR [2]. Our study focused on assessing whether such inflammatory transcription is occurring during adolescent years. Findings indicated decreased expression of NFKB1, NFKB2, and NR3C1. A decrease in the expression of these genes may have effects on immune cell function and cytokine production that could explain immunologic findings seen in individuals with CFS."

• 2009, Activity Logs as a Measure of Daily Activity Among Patients with Chronic Fatigue Syndrome. (Full text)
• 2009, The impact of energy modulation on physical functioning and fatigue severity among patients with ME/CFS. (Full text)
• 2008, The associations between basal salivary cortisol levels and illness symptomatology in chronic fatigue syndrome. (Full text)

  "Abstract: Hypocortisolism has been reported in chronic fatigue syndrome (CFS), with the significance of this finding to disease etiology unclear. This study examined cortisol levels and their relationships with symptoms in a group of 108 individuals with CFS. CFS symptoms examined included fatigue, pain, sleep difficulties, neurocognitive functioning, and psychiatric status. Alterations in cortisol levels were examined by calculation of mean daily cortisol, while temporal variation in cortisol function was examined by means of a regression slope. Additionally, deviation from expected cortisol diurnal pattern was determined via clinical judgment. Results indicated that fatigue and pain were associated with salivary cortisol levels. In particular, variance from the expected pattern of cortisol was associated with increased levels of fatigue. The implications of these findings are discussed."

• 2008, The Energy Envelope Theory and myalgic encephalomyelitis/chronic fatigue syndrome. (Full text)
• 2007, The Effectiveness of Early Educational Intervention in Improving Future Physicians' Attitudes Regarding CFS/FM

  "Abstract - Objective: To assess the effects of an early educational intervention program's ability to alter the perceptions and attitudes of future physicians regarding chronic fatigue syndrome/fibromyalgia (CFS/FM), improve their understanding and acceptance of these diseases, make them feel more comfortable in diagnosing and treating patients. Method: Third-year medical students were surveyed before and after an educational intervention program. The three questions posed to the students in the survey were: (1) How comfortable do you feel you are in diagnosing and treating patients with CFS /FM?, (2) Do you consider CFS/FM legitimate illnesses?, and (3) Do you want to treat patients with CFS/FM? Results: The educational intervention program helped about half of the future physicians feel comfortable in diagnosing and treating patients with CFS/FM and improved by over 25% their willingness to treat patients with CFS. Conclusion: An educational intervention program appeared to improve future physicians' understanding and appreciation of CFS/FM, made them feel more comfortable diagnosing and treating these diseases, and increased their willingness to treat patients with CFS/FM."

• 2007, Baseline Cortisol Levels Predict Treatment Outcomes in Chronic Fatigue Syndrome Nonpharmacologic Clinical Trial

  "Abstract - Objective: Understanding how nonpharmacologic interventions differentially affect the subgroups of patients with chronic fatigue syndrome (CFS) might provide insights into the pathophysiology of this illness. In this exploratory study, baseline measures of normal versus abnormal cortisol were compared on a variety of immune markers and other self-report measures. Normal versus abnormal cortisol ratings were used as predictors in a nurse-delivered nonpharmacologic intervention. Methods: Participants diagnosed with CFS were assigned to 6-month nonpharmacologic interventions. Individuals were classified as having abnormal or normal cortisol levels on the basis of scores over the five testing times. Cortisol levels were considered abnormal if they continued to rise, were flat, or were at abnormally low over time. Results: Across interventions, those with abnormal cortisol at the baseline appeared not to improve over time, whereas those with normal baseline cortisol evidenced improvements on a number of immunologic and self-report measures. Conclusion: It appears that, in subgroups of individuals with CFS, baseline cortisol markers are associated with outcome trajectories for nonpharmacologic treatment trials. The implications of these findings are discussed."

• 2007, How Science Can Stigmatize: The Case of Chronic Fatigue Syndrome

  "Abstract - "Objective: This article reviews issues involving the name of an illness, chronic fatigue syndrome (CFS), along with flawed epidemiologic approaches, which may have further contributed to the diagnostic skepticism and stigma that those with CFS encounter. Methods: Patient groups around the world are currently engaged in a major effort to rename this syndrome as either myalgic encephalomyelitis or myalgic encephalopathy, to undo the negative effects of the name previously given to this illness by scientists. Moreover, during the last 15 years, estimated rates of CFS have dramatically increased in both Great Britain and the United States. Results: We suggest that the increases in both the United States and Great Britain are due to a broadening of the case definition to additionally include cases with primary psychiatric conditions. Conclusion: Using a broad or narrow definition of CFS will have crucial influences on CFS epidemiologic findings, on rates of psychiatric comorbidity, and ultimately on the likelihood of finding a biological marker and identified etiology."

• 2006, Psychosocial and Physical Impact of Chronic Fatigue in a Community-Based Sample of Children and Adolescents

  "Abstract - Background: Few studies have examined the problem of chronic fatigue in children and adolescents and its potential impact on functioning. Chronic fatigue may have a negative impact on school functioning, family activities, psychological well-being, physical functioning, and severity of medical symptomatology. Objectives: This study compared psychosocial, family, and physical functioning between a randomly selected community based sample of 36 children and adolescents with chronic fatigue and a group of 21 children and adolescents without fatigue. Methods: Children and parents completed a comprehensive medical history questionnaire and questionnaires assessing psychological functioning, family functioning, and school attendance. Results: Results indicated that children with chronic fatigue tended to have more difficulties in overall physical and psychological functioning, as measured by the Child Health Questionnaire and the Child Behavior Checklist. In addition, children in the chronic fatigue group experienced disruptions in a range of activities and reported more severe physical symptomatology when compared to children without fatigue. Conclusions: Findings suggest that children and adolescents with chronic fatigue may have a range of associated difficulties, including limitations in physical and psychosocial functioning and a negative impact on the ability to engage in normative activities."

• 2006, Reliability of a Chronic Fatigue Syndrome Questionnaire

  "Abstract - Background: A diagnostic instrument, the CFS Questionnaire, was developed for clinicians and researchers to administer to their patients as a screening instrument for CFS. The CFS Questionnaire is comprehensive, covering the inclusionary and exclusionary self-report criteria of the current U.S. case definition (Fukuda, 1994). The instrument also assesses past and current activity levels, and symptoms of post-exertional malaise to ensure these items are adequately assessed. Objectives: The goal of the present study was to evaluate the diagnostic reliability of an experimental measure for assessing chronic fatigue syndrome (CFS). Methods: This instrument was administered to 15 persons with CFS, 15 persons with major depressive disorder (MDD), and 15 controls. Using the Fukuda et al. (Fukuda, 1994) diagnostic criteria, raters independently reviewed participants' CFS Questionnaire responses and rated whether each study participant met criteria for chronic fatigue syndrome. Results: This instrument demonstrated good inter-rater reliability. Further, this instrument demonstrated adequate classification accuracy, with a 9.3 positive likelihood ratio and a .08 negative likelihood ratio. Overall, the CFS Questionnaire demonstrated good test-retest reliability, with intra-class correlation coefficients and kappa coefficients at .70 or higher for most items. Lower test-retest reliability coefficients were found for some items assessing temporal symptoms or items requiring an estimate of time. Conclusion: The present study suggests that the CFS Questionnaire is a reliable diagnostic tool. Use of the CFS Questionnaire should promote higher levels of diagnostic reliability because it allows for accurate classification of individuals with CFS."

• 2006, Causes of death among patients with chronic fatigue syndrome
• 2006, Differential diagnosis of chronic fatigue syndrome and major depressive disorder
• 2004, Family Medical History of Persons with Chronic Fatigue Syndrome

  "Abstract - Background: Little research has examined the family history of persons with CFS, although a few studies have found people with CFS may be more likely to have family members with fatigue or CFS-like conditions, cancers, autoimmune illness, and early parental death. Research into the family history of fatigue, chronic fatigue syndrome, and other medical or psychiatric illness may help inform the etiology of this illness. Objectives: The present investigation examined the occurrence of medical and psychiatric illness in the family history of persons with CFS, and then compared these results with the family history of medical illness reported by a control group of persons without fatigue. Methods: Family medical history data was obtained from questionnaire responses, a medical assessment, and medical records, and were then classified into specific illness categories, using the International Classification of Diseases, Tenth Revision (ICD-10). Family history data was compared among three groups using logistic regression analyses. Results: Results indicated that persons with chronic fatigue syndrome were significantly more likely to report a family history of endocrine/ metabolic disorders when compared to the control group. Conclusions: Findings suggest an underlying familial predisposition toward the development of both CFS and endocrine/metabolic disorders. This finding is consistent with the hypothesis that CFS represents a deregulation of the endocrine system.

• 2004, Comparing the Fukuda et al. Criteria and the Canadian Case Definition for Chronic Fatigue Syndrome

  "Abstract - Because the pathogenesis of Chronic Fatigue Syndrome (CFS) has yet to be determined, case definitions have relied on clinical observation in classifying signs and symptoms for diagnosis. The selection of diagnostic signs and symptoms has major implications for which individuals are diagnosed with CFS and how seriously the illness is viewed by health care providers, disability insurers and rehabilitation planners, and patients and their families and friends. Diagnostic criteria also have implications for whether research based on varying definitions can be synthesized. The current investigation examined differences between CFS as defined by Fukuda et al. (1994) and a set of criteria that has been proposed for a clinical Canadian Case definition. There were twenty-three participants who met the Canadian criteria, 12 in the CFS (Fukuda et al. (7) criteria) group and the 33 from the chronic fatigue (CF)-psychiatric group. Dependent measures included: work status, psychiatric comorbidity, symptoms, and functional impairment (measured by the Medical Outcomes Study). People meeting the Fukuda et al. and Canadian criteria were compared with people who had a chronically fatiguing illness explained by a psychiatric condition. Statistical tests used included binomial logistic regression and analysis of variance. The Canadian criteria group, in contrast to the Fukuda et al. criteria group, had more variables that statistically significantly differentiated them from the psychiatric comparison group. Overall, there were 17 symptom differences between the Canadian and CF-psychiatric group, but only 7 symptom differences between the CFS and CF-psychiatric group. The findings suggest that both the Canadian and Fukuda et al. case definitions select individuals who are statistically significantly different from psychiatric controls with chronic fatigue, with the Canadian criteria selecting cases with less psychiatric co-morbidity, more physical functional impairment, and more fatigue/weakness, neuropsychiatric, and neurological symptoms."

• 2003, Identification of ambiguities in the 1994 chronic fatigue syndrome research case definition and recommendations for resolution
• 2001, Measuring Attributions About Chronic Fatigue Syndrome

  "Summary - Three studies explored the effects of different diagnostic labels and different types of recommended treatments for Chronic Fatigue Syndrome upon attributions regarding its cause, nature, severity, contagion, prognosis, and treatment. Attributions for Chronic Fatigue Syndrome appear to change based upon the diagnostic label given for the syndrome and the type of treatment recommended. Results suggest that, in comparison to the Chronic Fatigue Syndrome label, the Myalgic Enceph-alopathy label prompts attributions that this syndrome is a serious condition associated with a physiologically-based etiology, a poor prognosis, and decreased potential for organ donation. Results also suggest that, compared with cognitive coping skills treatment, treatment with ampligen appears to be associated with perceptions of Chronic Fatigue Syndrome as an accurate diagnosis and as a severely disabling condition."

• 2001, Assessing attitudes toward new names for chronic fatigue syndrome.

  "Abstract: A questionnaire was distributed at the American Association of Chronic Fatigue Syndrome's biannual convention in Washington in January 2001 as well as through various Internet Web sites and listserves during early February and March of 2001. The sample consisted of 432 respondents. Most respondents (86%) indicated they wanted a name change, although more patients than scientists were in favor of this change. It was also apparent that the patients and physicians were clearly split between adopting a name such as myalgic encephalopathy versus one such as neuro-endocrine immune disorder. Also, among those respondents who selected either of these two choices for a new name, less than 30% of them supported the other name. Although the majority of respondents feel the name should be changed at this time, this survey suggests there are different stakeholders involved in the name-change process, each with strong and sometimes disparate feelings about changing the name."

• 2001, Subtypes of Chronic Fatigue Syndrome: A Review of Findings

  "Summary - Most studies of Chronic Fatigue Syndrome (CFS) have been based on patients recruited from primary or tertiary care settings. Patients from such settings might not be typical of patients in the general population and may not accurately reflect the heterogeneity among individuals diagnosed with this condition. The current paper reviews four community-based studies that examined subtypes of individuals with CFS. Distinctions between subtype groups based on sociodemographics, illness onset and duration, stressful precipitating events, symptom frequency, and comorbidity characteristics are made with respect to outcome measures of fatigue and symptom severity, functional ability, and psychiatric comorbidity.

• 2000, Chronic fatigue syndrome: sociodemographic subtypes in a community-based sample.
• 2000, Defining Chronic Fatigue Syndrome: Methodological Challenges

  "Abstract - Accurate diagnosis of Chronic Fatigue Syndrome (CFS) is greatly complicated by the vague wording of many of the major diagnostic criteria (i.e., substantial reductions in previous levels of occupational, educational, social, or personal activities) and the absence of guidelines for health care professionals to follow. The lack of operationally explicit criteria has forced health care professionals to rely heavily on their own clinical judgement, which may be biased by personal and highly idiosyncratic factors. Thus, in the case of CFS, the lack of consensus among clinicians regarding the interpretation and application of the diagnostic criteria has likely produced problems in diagnostic reliability. Data from a recent community based epidemiologic study are presented to illustrate these problems and provide recommendations for improving criterion reliability."

• 1999, A Community-Based Study of Chronic Fatigue Syndrome

  Results: There was a 65.1% completion rate for the telephone interviews during the first phase of the study. Findings indicated that CFS occurs in about 0.42% (95% confidence interval, 0.29%-0.56%) of this random community-based sample. The highest levels of CFS were consistently found among women, minority groups, and persons with lower levels of education and occupational status. Conclusions: Chronic fatigue syndrome is a common chronic health condition, especially for women, occurring across ethnic groups. Earlier findings suggesting that CFS is a syndrome primarily affecting white, middle-class patients were not supported by our findings.

• 1997, Research with Children and Adolescents with Chronic Fatigue Syndrome: Methodologies, Designs, and Special Considerations
• 1997, A Screening Instrument for Chronic Fatigue Syndrome: Reliability and Validity

Talks & Interviews

• Mar 2017, Leonard Jason's Presentation to European Network on "Current Situation on Prevalence and Diagnostic Crieria for ME and CFS"
• Jan 2017, Leonard Jason's talk to the Ethical Humanist Society of Chicago on "Understanding Unexplained Illness: From Knowledge to Action" Slides for "Understanding Unexplained Illness: From Knowledge to Action"
• 2016, Leonard Jason's comments at Sept. 27th, 2016 #millionsmissing protest in Chicago
• 2016, 12th International IACFS/ME Biennial Clinical and Research Conference, Emerging Science and Clinical Care, Behavioral Assessment and Treatment of ME/CFS and Fibromyalgia(Workshop given with Fred Friedberg, Ph.D.)
• 2016 - "qEEG LORETA CFS Case study - Sci Forschen Inc." with Leonard Jason, Marcie Zinn, and Mark Zinn
• Oct 2015, Defining essential features of myalgic encephalomyelitis and chronic fatigue syndrome (Sweden)]
• 2015, DePaul Chili Challenge video
• 2014, Leonard Jason answering questions from members of the Institute of Medicine panel on case definition issues

Invest in ME International ME Conference

• 2010, Speaker at the 5th Invest in ME International ME Conference on Key Note Speech: How Case Definitions Can Stigmatize: Implications for Epidemiology, Etiology, and Pathophysiology DVD available
• 2008, Speaker at the 3rd Invest in ME International ME Conference on Case Definitions of ME/CFS – including paediatric case definition DVD available

ME/CFS Alert

• 2011, ME/CFS Alert Episode 10 - Dr. Leonard Jason, Pt. 3
• 2011, ME/CFS Alert Episode 09 - Dr. Leonard Jason, Pt. 2
• 2011, ME/CFS Alert Episode 08 - Dr. Leonard Jason, Pt. 1

Web seminars Science for Patients / Wetenschap voor patienten (The Netherlands, english spoken, dutch subtitles)

• 2014, 50. Introduction - Experience with ME / Introductie - Ervaring met ME Prof. Leonard Jason
• 2014, 51. Criteria and Diagnosis part 1 / Criteria en diagnose deel 1 - Prof. Leonard Jason
• 2014, 52. Criteria and Diagnosis part 2 / Criteria en diagnose deel 2 - Prof. Leonard Jason
• 2014, 53. ME versus Psychiatric Disorders / ME versus psychiatrische aandoeningen - Prof. Leonard Jason
• 2014, 54. Treating and managing ME / Behandelen van en omgaan met ME -Prof. Leonard Jason
• 2014, 55. Symptoms of ME and treatments / Symptomen van ME en behandelingen - Prof. Leonard Jason
• 2014, 56. Population and Social Impact / Populatie en sociale gevolgen - Prof. Leonard Jason
• 2014, 57. Future and Teaching about ME / Toekomst en onderwijs geven over ME - Prof. Leonard Jason

Books

• 2008, Fatigue Science for Human Health, edited by Yatanabe, Y., Evengard, B., Natelson, B.H., Jason, L.A., & Kuratsune, H.
• 2003, The Handbook of Chronic Fatigue Syndrome by Leonard Jason, Patricia Fennell and Renée R. Taylor.
• 2001, Clinician's Guide To Controversial Illnesses: Chronic Fatigue Syndrome, Fibromyalgia, and Multiple Chemical Sensitivities, by Renee R. Taylor, Fred Friedberg, and Leonard A. Jason
• 1998, Understanding Chronic Fatigue Syndrome: An Empirical Guide to Assessment and Treatment, by Fred Friedberg and Leonard Jason

Online Presence

• Website
• Twitter

Learn More

• Wikipedia - Leonard Jason
• Leonard Jason's Home Page at DePaul University

See Also

• DePaul symptom questionnaire

Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS) - Chronic Fatigue and Immune Dysfunction Syndrome is another term for Chronic Fatigue Syndrome, but one which emphasizes the immunological aspects of the disease. Popular in the 1990s, this term has apparently fallen into disuse.

myalgic encephalomyelitis (M.E.) - 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.

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.

etiology The cause of origin, especially of a disease.

PACE trial A controversial study which claimed that CBT and GET were effective in treating "CFS/ME", despite the fact that its own data did not support this conclusion. Its results and methodology were widely disputed by patients, scientists, and the peer-reviewed scientific literature.

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.

Short Form 36-Item Health Survey (SF-36) - A 36-item patient-reported questionnaire, used to determine patient health status and quality of life.

post-exertional malaise (PEM) - A notable exacerbation of symptoms brought on by small physical or cognitive exertions. PEM may be referred to as a "crash" or "collapse" and can last for days or weeks. Symptoms can include cognitive impairments, muscle pain, trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, and others.

neuroendocrine relating to hormones that influence the nervous system

National Institutes of Health (NIH) - A set of biomedical research institutes operated by the U.S. government, under the auspices of the Department of Health and Human Services.

chronic disease a disease or condition that usually lasts for 3 months or longer and may get worse over time. Chronic diseases are long-term (typically incurable and requiring long-term management) but are not necessarily severe.

central nervous system (CNS) - One of the two parts of the human nervous system, the other part being the peripheral nervous system. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system consists of nerves that travel from the central nervous system into the various organs and tissues of the body.

physiological Concerning living organisms, such as cells or the human body.  Physio logical (as in physio) is not to be confused with psych ological (emotional stress).

cognition Thought processes, including attention, reasoning, and memory.

chronic disease a disease or condition that usually lasts for 3 months or longer and may get worse over time. Chronic diseases are long-term (typically incurable and requiring long-term management) but are not necessarily severe.

cognition Thought processes, including attention, reasoning, and memory.

cognition Thought processes, including attention, reasoning, and memory.

cytomegalovirus (CMV) - A common herpesvirus found in humans. Like other herpesviruses, it is a life-long infection that remains in a latent state inside the human body, until it is 'reactivated' by appropriate conditions. CMV infects between 60% to 70% of adults in industrialized countries and close to 100% in emerging countries. Much is unknown about this virus, although it has been found in salivary glands and myeloid blood cells such as monocytes. It has also been linked to the development of certain cancers. Congenital CMV is a leading infectious cause of deafness, learning disabilities, and intellectual disability. A common treatment for CMV is valganciclovir, commonly known as Valcyte.

cytomegalovirus (CMV) - A common herpesvirus found in humans. Like other herpesviruses, it is a life-long infection that remains in a latent state inside the human body, until it is 'reactivated' by appropriate conditions. CMV infects between 60% to 70% of adults in industrialized countries and close to 100% in emerging countries. Much is unknown about this virus, although it has been found in salivary glands and myeloid blood cells such as monocytes. It has also been linked to the development of certain cancers. Congenital CMV is a leading infectious cause of deafness, learning disabilities, and intellectual disability. A common treatment for CMV is valganciclovir, commonly known as Valcyte.

antibodies Antibody/immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

antibodies Antibody/immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

antibodies Antibody/immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

assay 1. (verb) analysis (as of an ore or drug) to determine the presence, absence, or quantity of one or more components. 2. (noun) In biochemistry, any laboratory protocol used to test a sample for one or more qualities.

serum The clear yellowish fluid that remains from blood plasma after clotting factors have been removed by clot formation. (Blood plasma is simply blood that has had its blood cells removed.)

antibodies Antibody/immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

serum The clear yellowish fluid that remains from blood plasma after clotting factors have been removed by clot formation. (Blood plasma is simply blood that has had its blood cells removed.)

antibodies Antibody/immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

β β / Β. Greek letter beta (a symbol used in science), equivalent to "b".

cytokine any class of immunoregulatory proteins secreted by cells, especially immune cells. Cytokines are small proteins important in cell signaling that modulate the immune system. (Learn more: me-pedia.org)

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.

myalgic encephalomyelitis (M.E.) - 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.

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.

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.

International Classification of Diseases (ICD) - A system of medical diagnostic codes, created by the World Health Organization (WHO), to classify diseases and other health related conditions for the purpose of international diagnostic consistency. By having common diagnostic codes around the world, health researchers are better able to quantify and track disease burdens. The most current version is called ICD-11. (Learn more: www.who.int)

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.

physiological Concerning living organisms, such as cells or the human body.  Physio logical (as in physio) is not to be confused with psych ological (emotional stress).

neuroendocrine relating to hormones that influence the nervous system

bias Bias in research is "a systematic deviation of an observation from the true clinical state". (Learn more: me-pedia.org)

etiology The cause of origin, especially of a disease.

chronic illness any long-term illness, regardless of the severity. Chronic illnesses are typically incurable, requiring long-term management.

Energy Envelope Theory A self-management tool developed and tested by Dr. Leonard Jason to reduce symptom severity and the frequency of post-exertional malaise or relapses for people with ME/CFS. According to this theory, ME/CFS patients should not expend more energy than they perceive they have, as this results in post-exertional malaise and higher disability. Instead patients are advised to stay within their energy envelope, meaning the physical limits the disease has imposed upon them. As the energy envelope theory also cautions about the dangers of under-exertion, its principles are almost identical to ‘pacing’, an activity management strategy for ME patients devised by Ellen Goudsmit in the UK.