Central nervous system changes in hepatitis C virus infection

Results from a hypothesis generating case-control study: herpes family viruses and schizophrenia among military personnel

BACKGROUND

Herpes family viruses can cause central nervous system inflammatory changes that can present with symptoms indistinguishable from schizophrenia and therefore are of interest in schizophrenia research. Most existing studies of herpes viruses have used small populations and postdiagnosis specimens. As part of a larger research program, we conducted a hypothesis-generating case-control study of selected herpes virus antibodies among individuals discharged from the US military with schizophrenia and pre- and postdiagnosis sera.

METHODS

Cases (n = 180) were servicemembers hospitalized and discharged from military service with schizophrenia. Controls, 3:1 matched on several factors, were members not discharged. The military routinely collects and stores members' serum specimens. We used microplate enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to 6 herpes viruses in pre- and postdiagnosis specimens. Conditional logistic regression was used, and the measure of association was the hazard ratio (HR).

RESULTS

Overall, we found a significant association between human herpes virus type 6 and schizophrenia, with an HR of 1.17 (95% confidence interval [CI] = 1.04, 1.32). Women and blacks had significant negative associations with herpes simplex virus type 2 and cytomegalovirus; among blacks, there was a significant positive association with herpes simplex virus type 1. Among men, there was a HHV-6 temporal effect with an HR of 1.41 (95% CI = 1.02, 1.96) for sera drawn 6-12 months before diagnosis.

DISCUSSION

Findings from previous studies of herpes family viruses and schizophrenia have been inconsistent. Our study is based on a larger population than most previous studies and used serum specimens collected before onset of illness. This study adds to the body of knowledge and provides testable hypotheses for follow-on studies.

IFN-alpha-induced motor slowing is associated with increased depression and fatigue in patients with chronic hepatitis C

Interferon (IFN)-alpha has been used to investigate pathways by which innate immune cytokines influence the brain and behaviour. Previous studies suggest that altered basal ganglia function may contribute to IFN-alpha-induced neuropsychological and behavioural changes. To further examine IFN-alpha effects on neuropsychological functions related to basal ganglia (as well as other brain regions), and explore the relationship between altered neuropsychological function and IFN-alpha-induced depression and fatigue, a selected subset of the Cambridge Neuropsychological Test Automated Battery was administered to 32 hepatitis C patients at baseline (Visit 1) and following approximately 12 weeks (Visit 2) of either no treatment (n=12) or treatment with IFN-alpha plus ribavirin (n=20). Symptoms of depression and fatigue were assessed using the Montgomery-Asberg Depression Rating Scale and the Multidimensional Fatigue Inventory. Compared to control subjects, patients treated with IFN-alpha/ribavirin exhibited significant decreases in motor speed as measured in the simple and five-choice movement segments of the CANTAB reaction time task and slower response times in the rapid visual information processing task, a task of sustained attention. Decreased motor speed on the five-choice movement segments of the reaction time task was in turn correlated with increased symptoms of depression and fatigue (R=0.47, p<0.05 and R=0.48, p<0.05, respectively). IFN-alpha/ribavirin treatment had no effects on executive function, decision time in the reaction time task, or target detection accuracy in the sustained attention task. Motor slowing and its correlation with psychiatric symptoms suggest that altered basal ganglia function may contribute to the pathogenesis of IFN-alpha-induced behavioural changes.

Clinicopathologic correlates of hepatitis C virus in brain: a pilot study

Hepatitis C virus (HCV) has been detected in the brain tissues of 10 individuals reported to date; it is unclear what clinical factors are associated with this, and with what frequency it occurs. Accordingly, a pilot analysis utilizing reverse transcriptase-polymerase chain reaction (RT- PCR) to detect and sequence HCV in premortem plasma and postmortem brain and liver from 20 human immunodeficiency virus (HIV)-infected and 10 HIV-naive individuals was undertaken. RNA encoding the first 126 amino acids of the HCV E1 envelope protein and the majority of the E1 signal sequence was analyzed in parallel with an 80-base-long segment of the 5' untranslated region (UTR). Liver HCV was detected only in subjects with premortem HCV viremia (10 HIV-infected and 3 HIV-naive). Brain HCV was detected in 6/10 HCV/HIV-coinfected and 1/3 HCV-monoinfected subjects. In the setting of HIV, the magnitude of plasma HCV load did not correlate with the presence of brain HCV. However, coinfected patients with brain HCV were more often off antiretroviral therapy and tended to have higher plasma HIV loads than those with HCV restricted to liver. Furthermore, premortem cerebrospinal fluid (CSF) analysis revealed that HCV/HIV-coinfected patients with brain HCV had detectable CSF HIV, whereas those without brain HCV had undetectable CSF HIV loads (P = .0205). Neuropsychologic tests showed a trend for hierarchical impairment of abstraction/executive functioning in HIV/HCV coinfection, with mean T scores for HIV monoinfected patients 43.2 (7.3), for liver-only HCV 39.5 (9.0), and for those with HCV in brain and liver 33.2 (5.1) (P = .0927). Predominant brain HCV sequences did not match those of the plasma or liver in 4 of the 6 coinfected patients analyzed. We conclude that in the setting of HIV/HCV coinfection, brain HCV is a common phenomenon unrelated to the magnitude of HCV viremia, but related to active HIV disease and detectable CSF HIV. Furthermore, there is sequence evidence of brain compartmentalization. Differences in abstraction/executive function of HCV/HIV coinfected patients compared to HIV monoinfected warrant further studies to determine if neuropsychiatric effects are predicated upon brain infection.

Cognitive dysfunction in chronic hepatitis C: a review

The hepatitis C virus (HCV) is a common blood-borne illness that affects up to 2% of the world's population and almost 4 million Americans. Cognitive impairment, or difficulty with thinking, has become a well-established symptom in persons with end stage liver disease. It was previously assumed that cognitive impairment was a consequence of cirrhosis-associated hepatic encephalopathy. Recent evidence, however, suggests that approximately one-third of people with chronic HCV experience cognitive impairment even in the absence of cirrhosis and that its occurrence is unrelated to other indices of liver function, such as laboratory values, viral load, and genotype. In the present review, evidence outlining the presence of cognitive deficits associated with HCV, possible etiological factors, effects of antiviral therapy, and co-infection with human immunodeficiency virus (HIV) is presented. Implications of these findings and directions for future work are discussed.

The Widespread Evolutionary Significance of Viruses

In the last 30 years, the study of virus evolution has undergone a transformation. Originally concerned with disease and its emergence, virus evolution had not been well integrated into the general study of evolution. This chapter reviews the developments that have brought us to this new appreciation for the general significance of virus evolution to all life. We now know that viruses numerically dominate all habitats of life, especially the oceans. Theoretical developments in the 1970s regarding quasispecies, error rates, and error thresholds have yielded many practical insights into virus–host dynamics. The human diseases of HIV-1 and hepatitis C virus cannot be understood without this evolutionary framework. Yet recent developments with poliovirus demonstrate that viral fitness can be the result of a consortia, not one fittest type, a basic Darwinian concept in evolutionary biology. Darwinian principles do apply to viruses, such as with Fisher population genetics, but other features, such as reticulated and quasispecies-based evolution distinguish virus evolution from classical studies. The available phylogenetic tools have greatly aided our analysis of virus evolution, but these methods struggle to characterize the role of virus populations. Missing from many of these considerations has been the major role played by persisting viruses in stable virus evolution and disease emergence. In many cases, extreme stability is seen with persisting RNA viruses. Indeed, examples are known in which it is the persistently infected host that has better survival. We have also recently come to appreciate the vast diversity of phage (DNA viruses) of prokaryotes as a system that evolves by genetic exchanges across vast populations (Chapter 10). This has been proposed to be the “big bang” of biological evolution. In the large DNA viruses of aquatic microbes we see surprisingly large, complex and diverse viruses. With both prokaryotic and eukaryotic DNA viruses, recombination is the main engine of virus evolution, and virus host co-evolution is common, although not uniform. Viral emergence appears to be an unending phenomenon and we can currently witness a selective sweep by retroviruses that infect and become endogenized in koala bears.

The effects of HCV infection and management on health-related quality of life

Infection with HCV leads to an array of symptoms that compromise health-related quality of life (HRQL). Chronic hepatitis C is treated primarily with pegylated interferon (peg-IFN) and an inosine 5' monophosphate dehydrogenase inhibitor, ribavirin (RBV), with the goal of achieving a sustained virologic response (SVR). SVR reduces the rate of hepatic fibrosis and other disease-related complications and, in turn, increases HRQL. Although combination therapy with peg-IFN and RBV produces SVRs in more than 50% of treated patients, it is associated with side effects that can reduce short-term HRQL, can lead to dose reductions and discontinuations, and may impair treatment response. Fatigue and depression are common symptoms of chronic HCV infection that may also be caused by IFN-based therapy. Hemolytic anemia and IFN-mediated bone marrow suppression are well-known consequences of IFN/RBV therapy, often resulting in dose reductions or discontinuations, and have the potential to affect SVR rates. Management of these symptoms is vital to successful outcomes and generally relies on therapy that is adjunctive to the primary treatment of the viral infection itself. Several new drugs with the potential to increase SVR rates without compromising HRQL are in development.

CONCLUSION

The relationship of chronic HCV infection, treatment, and HRQL is complex. Successful treatment of chronic hepatitis C requires an understanding of the intricacies of this relationship and appropriate management of treatment-related symptoms.

[Hepatitis C viral infection and depression]

About 170 million individuals can be found with chronic hepatitis C viral infection all over the world. The occurrence of depression is more frequent among the persons than in the healthy population, this depression can be found in 58 per cent of patients with chronic hepatitis C. On the basis of the literature the authors review the aetiology of depression in liver diseases, examining the neuropathogenic effect of HCV. They demonstrate the scientific results which are evidences of hepatitis C viral infection for the alterations in the central nerve system. The depression is one of the side effects of the alpha-interferon treatment used in the therapy of HCV. The authors demonstrate the biological basis, development, consequences of depression produced by interferon and they give a review of the protocol in the diagnostic procedure of a patient with depression. They summarize the steps of psychiatric drug therapy in chronic liver diseases. That is also important whether the chronic HCV infected patient with depression can be treated with interferon. The loss of interferon treatment can lead to the fatal outcome of liver disease. In order to have the correct decision a collaboration between internist and psychiatric specialist is necessary.

Methodological approaches in the assessment of interferon-alfa-induced depression in patients with chronic hepatitis C - a critical review

In recent years, research on interferon (IFN)-induced depressive symptoms in antivirally treated patients suffering from chronic hepatitis C (CHC) has considerably intensified. Profound scientific knowledge of this complication is of great relevance with regard to adherence, compliance, and premature therapy discontinuation. Presently, there is considerable variability of both, the frequency and extent of IFN-induced depression reported in different cohorts of patients. The aim of the presented study was to systematically review recent literature of research within this field; and particularly (1) to identify to what extent methodological bias contributed to inconsistent results in different studies, (2) to critically appraise methods and results of studies published so far, and (3) to suggest directions for future work, especially with respect to alternative and improved methodological approaches. The results of this critical review suggest that the variability of findings seem to be largely due to different study populations, treatment regimens, methodological approaches, and sometimes arbitrary or at least poorly defined choice of screening instruments for depression, particularly criteria for clinically relevant depression (cut-off criteria). Study designs and methodological approaches to investigate IFN-alfa-induced depression in patients with CHC have been incoherent. Future research in this field needs agreement on the use of standardized assessment of IFN-induced depression in CHC. Furthermore, objective criteria and guidelines for the treatment of IFN-induced depression in these patients are needed in clinical practice.