Category: Etiology

Chronic Fatigue Syndrome and Herpesviruses: the Fading Evidence

Abstract:

Herpesviruses, in particular Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus 6 (HHV-6), have, for the past two decades, come under considerable scrutiny as aetiological agents of chronic fatigue syndrome (CFS). However, virological findings of herpesviruses in CFS have not been consistent between different studies, and the unusual patterns of serological responses to EBV, CMV and HHV-6 have not been specific for CFS, being observed also in asymptomatic individuals. In addition, patients with symptomatology suggestive of CFS do not appear to have an increased frequency of these herpesviruses, as detected by culture or polymerase chain reaction, compared with controls, which argues against an ongoing active herpetic infection. Studies have also shown that the presumable elevation of antibody titres to EBV, CMV or HHV-6 in CFS are not observed only with these viruses, but also with other organisms such as herpes simplex virus and measles.

 

Source: Soto NE, Straus SE. Chronic Fatigue Syndrome and Herpesviruses: the Fading Evidence. Herpes. 2000 May;7(2):46-50. http://www.ncbi.nlm.nih.gov/pubmed/11867001

 

Chronic fatigue syndrome

Comment on:

Chronic fatigue syndrome. [Br J Gen Pract. 2001]

Frequency of attendance in general practice and symptoms before development of chronic fatigue syndrome: a case-control study. [Br J Gen Pract. 2001]

 

Professor Murdoch in the September BJGP 1 uses his study of Down’s syndrome,2 which demonstrated that mothers had an increased number of reported illnesses in the year before the birth, to undermine our interpretation of the findings in our chronic fatigue syndrome (CFS) study in the July BJGP. 3 He asks why anyone should believe CFS is caused by behavioural factors.

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1314178/pdf/11766858.pdf

 

Source: Hamilton W. Chronic fatigue syndrome. Br J Gen Pract. 2001 Dec;51(473):1015. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1314178/pdf/11766858.pdf (Full comment)

 

Sexual abuse, physical abuse, chronic fatigue, and chronic fatigue syndrome: a community-based study

Abstract:

Using a randomly selected community-based sample, this investigation examined whether histories of childhood sexual, physical, and death threat abuse predicted adulthood outcomes of specific medical and psychiatric conditions involving chronic fatigue. This study also tested prior suggestions that most individuals with chronic fatigue syndrome report a past history of interpersonal abuse.

Multinomial logistic regression was used to examine the relationship between abuse history and chronic fatigue group outcomes while controlling for the effects of sociodemographics. Compared with healthy controls, childhood sexual abuse was significantly more likely to be associated with outcomes of idiopathic chronic fatigue, chronic fatigue explained by a psychiatric condition, and chronic fatigue explained by a medical condition. None of the abuse history types were significant predictors of chronic fatigue syndrome.

A closer examination of individuals in the chronic fatigue syndrome group revealed that significantly fewer individuals with CFS reported abuse as compared with those who did not. The implications of these findings are discussed.

 

Source: Taylor RR, Jason LA. Sexual abuse, physical abuse, chronic fatigue, and chronic fatigue syndrome: a community-based study. J Nerv Ment Dis. 2001 Oct;189(10):709-15. http://www.ncbi.nlm.nih.gov/pubmed/11708672

 

A family history study of chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome (CFS) is characterized by unexplained, disabling fatigue and is associated with high rates of comorbid depression. While the aetiology is unknown, findings from recent twin surveys suggest that genetic factors may be relevant to prolonged fatigue states (> 1 month). To date, however, there has been no exploration of the role of familial/genetic factors in operationally defined CFS.

The aims of the present study were: (i) to examine whether CFS is familial by comparing the rates of CFS in the first-degree relatives of CFS cases and medical control subjects; and (ii) to determine whether the high rate of comorbid depression in CFS is reflected in a greater familial loading for affective disorder.

Twenty-five CFS cases and 36 medical control subjects were assessed for fatigue symptoms based on the Centre for Disease Control (CDC) criteria for CFS, and for lifetime psychiatric symptoms using the Schedule for Schizophrenia and Affective Disorders-Lifetime Version. Informant family history was obtained regarding first-degree relatives using the CDC criteria and the Family History Research Diagnostic Criteria. In addition, informant history was supplemented by sending a questionnaire to first-degree relatives.

There were significantly higher rates of CFS in the relatives of CFS cases compared with the relatives of control subjects. The rate of depression in the CFS cases was similar to previous studies but did not appear to reflect a greater familial loading for depression when compared with control subjects. However, these analyses were complicated by higher than expected rates of depression in the control group. These findings suggest that familial factors are important in the aetiology of chronic fatigue syndrome.

 

Source: Walsh CM, Zainal NZ, Middleton SJ, Paykel ES. A family history study of chronic fatigue syndrome. Psychiatr Genet. 2001 Sep;11(3):123-8. http://www.ncbi.nlm.nih.gov/pubmed/11702053

 

A twin study of the etiology of prolonged fatigue and immune activation

Abstract:

Risk factors to prolonged fatigue syndromes (PFS) are controversial. Pre-morbid and/or current psychiatric disturbance, and/or disturbed cell-mediated immunity (CMI), have been proposed as etiologic factors.

Self-report measures of fatigue and psychologic distress and three in vitro measures of CMI were collected from 124 twin pairs. Crosstwin-crosstrait correlations were estimated for the complete monozygotic (MZ; 79 pairs) and dizygotic (DZ; 45 pairs) twin groups. Multivariate genetic and environmental models were fitted to explore the patterns of covariation between etiologic factors. For fatigue, the MZ correlation was more than double the DZ correlation (0.49 versus 0.16) indicating strong genetic control of familial aggregation.

By contrast, for in vitro immune activation measures MZ and DZ correlations were similar (0.49-0.69 versus 0.42-0.53) indicating the etiologic role of shared environments. As small univariate associations were noted between prolonged fatigue and the in vitro immune measures (r = -0.07 to -0.12), multivariate models were fitted. Relevant etiologic factors included: a common genetic factor accounting for 48% of the variance in fatigue which also accounted for 4%, 6% and 8% reductions in immune activation; specific genetic factors for each of the in vitro immune measures; a shared environment factor influencing the three immune activation measures; and, most interestingly, unique environmental influences which increased fatigue but also increased markers of immune activation.

PFS that are associated with in vitro measures of immune activation are most likely to be the consequence of current environmental rather than genetic factors. Such environmental factors could include physical agents such as infection and/or psychologic stress.

 

Source: Hickie IB, Bansal AS, Kirk KM, Lloyd AR, Martin NG. A twin study of the etiology of prolonged fatigue and immune activation. Twin Res. 2001 Apr;4(2):94-102. http://www.ncbi.nlm.nih.gov/pubmed/11665341

 

Common etiology of posttraumatic stress disorder, fibromyalgia, chronic fatigue syndrome and multiple chemical sensitivity via elevated nitric oxide/peroxynitrite

Abstract:

Three types of overlap occur among the disease states chronic fatigue syndrome (CFS), fibromyalgia (FM), multiple chemical sensitivity (MCS) and posttraumatic stress disorder (PTSD). They share common symptoms. Many patients meet the criteria for diagnosis for two or more of these disorders and each disorder appears to be often induced by a relatively short-term stress which is followed by a chronic pathology, suggesting that the stress may act by inducing a self-perpetuating vicious cycle. Such a vicious cycle mechanism has been proposed to explain the etiology of CFS and MCS, based on elevated levels of nitric oxide and its potent oxidant product, peroxynitrite.

Six positive feedback loops were proposed to act such that when peroxynitrite levels are elevated, they may remain elevated. The biochemistry involved is not highly tissue-specific, so that variation in symptoms may be explained by a variation in nitric oxide/peroxynitrite tissue distribution. The evidence for the same biochemical mechanism in the etiology of PTSD and FM is discussed here, and while less extensive than in the case of CFS and MCS, it is nevertheless suggestive. Evidence supporting the role of elevated nitric oxide/peroxynitrite in these four disease states is summarized, including induction of nitric oxide by common apparent inducers of these disease states, markers of elevated nitric oxide/peroxynitrite in patients and evidence for an inductive role of elevated nitric oxide in animal models.

This theory appears to be the first to provide a mechanistic explanation for the multiple overlaps of these disease states and it also explains the origin of many of their common symptoms and similarity to both Gulf War syndrome and chronic sequelae of carbon monoxide toxicity. This theory suggests multiple studies that should be performed to further test this proposed mechanism. If this mechanism proves central to the etiology of these four conditions, it may also be involved in other conditions of currently obscure etiology and criteria are suggested for identifying such conditions.

Copyright 2001 Harcourt Publishers Ltd.

Comment in: Nitric oxide and the etiology of chronic fatigue syndrome: giving credit where credit is due. [Med Hypotheses. 2005]

 

Source: Pall ML. Common etiology of posttraumatic stress disorder, fibromyalgia, chronic fatigue syndrome and multiple chemical sensitivity via elevated nitric oxide/peroxynitrite. Med Hypotheses. 2001 Aug;57(2):139-45. http://www.ncbi.nlm.nih.gov/pubmed/11461161

 

Free radicals in chronic fatigue syndrome: cause or effect?

Abstract:

We have demonstrated that certain morphological and biochemical changes occur in chronic fatigue syndrome (CFS) and in rheumatoid arthritis (RA). These changes in RA can be explained by the well-established inappropriate increase in free radical generation. The similar changes in CFS suggest a similar explanation and a possible role for free radicals in the aetiology of this condition.

 

Source: Richards RS, Roberts TK, Dunstan RH, McGregor NR, Butt HL. Free radicals in chronic fatigue syndrome: cause or effect? Redox Rep. 2000;5(2-3):146-7. http://www.ncbi.nlm.nih.gov/pubmed/10939298

 

Chronic fatigue syndrome: a matter of enzyme deficiencies?

Abstract:

The etiology of chronic fatigue syndrome (CFS) remains an enigma. But literature concerning chronic fatigue which does not focus on CFS points to all sorts of enzyme deficiencies as possible causes. The deficiencies are probably dismissed as causes of CFS because other characteristic symptoms are lacking in CFS patients. But these symptoms are often also lacking in patients with a deficiency. Symptom patterns in enzyme deficiencies are extremely variable. Therefore, patients with CFS should be screened systematically for enzyme deficiencies.

Copyright 2000 Harcourt Publishers Ltd.

 

Source: van der Steen WJ. Chronic fatigue syndrome: a matter of enzyme deficiencies? Med Hypotheses. 2000 May;54(5):853-4. http://www.ncbi.nlm.nih.gov/pubmed/10859701

 

Demonstration of borna disease virus nucleic acid in a patient with chronic fatigue syndrome

Comment on: Borna disease virus in human brains with a rare form of hippocampal degeneration but not in brains of patients with common neuropsychiatric disorders. [J Infect Dis. 1999]

 

To the Editor

Czygan et al. [1]reported the detection of Borna disease virus (BDV) nucleic acid in 3 cases of a rare form of hippocampal degeneration, whereas the brains of patients with other neuropsychiatric disorders tested negative for BDV. Chronic fatigue syndrome (CFS) is another, more frequently diagnosed neuropsychiatric disease that is associated with BDV infection. However, the published findings are highly controversial. Nakaya et al. [2, 3] and Kitani et al. [4] showed both BDV-specific antibodies and RNA in a high percentage of Japanese patients with CFS. Bode et al. [5]isolated BDV from peripheral blood mononuclear cells (PBMC) of an American patient with CFS; however, in an earlier publication, Bode et al. [6], as well as Evengård et al. [7] and Yamaguchi et al. [8] in recent publications, did not find serologie evidence for BDV in patients with CFS. A possible explanation for the controversial results is that the term “chronic fatigue syndrome” probably includes several similar clinical conditions that may have different etiologies. In the study by Czygan et al. [1], brain tissue samples from patients who had CFS were not included. Unfortunately, none of the BDV sequences of the CFS cases mentioned above are available in the GenBank database.

You can read the rest of this comment here: http://jid.oxfordjournals.org/content/181/5/1860.long

 

Source: Nowotny N, Kolodziejek J. Demonstration of borna disease virus nucleic acid in a patient with chronic fatigue syndrome. J Infect Dis. 2000 May;181(5):1860-2. http://jid.oxfordjournals.org/content/181/5/1860.long (Full article)

 

Elevated, sustained peroxynitrite levels as the cause of chronic fatigue syndrome

Abstract:

The etiology of chronic fatigue syndrome (CFS) has been both obscure and highly contentious, leading to substantial barriers to both clear diagnosis and effective treatment.

I propose here a novel hypothesis of CFS in which either viral or bacterial infection induces one or more cytokines, IL-1beta IL-6, TNF-alpha and IFN-gamma. These induce nitric oxide synthase (iNOS), leading to increased nitric oxide levels. Nitric oxide, in turn, reacts with superoxide radical to generate the potent oxidant peroxynitrite. Multiple amplification and positive feedback mechanisms are proposed by which once peroxynitrite levels are elevated, they tend to be sustained at a high level.

This proposed mechanism may lower the HPA axis activity and be maintained by consequent lowered glucocorticoid levels. Similarities are discussed among CFS and autoimmune and other diseases previously shown to be associated with elevated peroxynitrite. Multiple pharmacological approaches to the treatment of CFS are suggested by this hypothesis.

Comment in: Nitric oxide and the etiology of chronic fatigue syndrome: giving credit where credit is due. [Med Hypotheses. 2005]

 

Source: Pall ML. Elevated, sustained peroxynitrite levels as the cause of chronic fatigue syndrome. Med Hypotheses. 2000 Jan;54(1):115-25. http://www.ncbi.nlm.nih.gov/pubmed/10790736