Cerebral function tests reveal differences in HIV-infected subjects with and without chronic HCV co-infection

Mechanisms of neuropathogenesis in HIV and HCV: similarities, differences, and unknowns

HIV and hepatitis C virus (HCV) have both been associated with cognitive impairment. Combination antiretroviral therapy (cART) has dramatically changed the nature of cognitive impairment in HIV-infected persons, while the role of direct-acting antivirals (DAA) in neurocognition of HCV-infected individuals remains unclear. Also, whether HIV and HCV interact to promote neurocognitive decline or whether they each contribute an individual effect continues to be an open question. In this work, we review the virally mediated mechanisms of HIV- and HCV-mediated neuropathogenesis, with an emphasis on the role of dual infection, and discuss observed changes with HIV viral suppression and HCV functional cure on neurocognitive impairments.

Human Immunodeficiency Virus in the Brain-Culprit or Facilitator?

Introduction:

Human immunodeficiency virus (HIV) enters the brain early, where it can persist, evolve, and become compartmentalized. Central nervous system (CNS) disease can be attributed to HIV alone or to the complex interplay between the virus and other neurotropic pathogens.

Aim:

The current review aims to describe the direct impact of HIV on the brain as well as its relationship with other pathogens from a practitioner’s perspective, to provide a general clinical overview, brief workup, and, whenever possible, treatment guidance.

Methods:

A review of PubMed was conducted to identify studies on neuropathogenesis of HIV in relation to host responses. Furthermore, the interaction between the CNS pathogens and the host damage responses were revised in the setting of advanced and also well-controlled HIV infection.

Results:

Similar to other pathogens, HIV leads to CNS immune activation, inflammation, and viral persistence. Therefore, almost half of the infected individuals present with neurocognitive disorders, albeit mild. Compartmentalized HIV in the CNS can be responsible in a minority of cases for the dramatic presentation of symptomatic HIV escape. Disruption of the immune system secondary to HIV may reactivate latent infections or allow new pathogens to enter the CNS. Opportunistic infections with an inflammatory component are associated with elevated HIV loads in the cerebrospinal fluid and also with greater cognitive impairment. The inflammatory immune reconstitution syndrome associated with CNS opportunistic infections can be a life-threatening condition, which needs to be recognized and managed by efficiently controlling the pathogen burden and timely balanced combination antiretroviral therapy. Latent neurotropic pathogens can reactivate in the brain and mimic HIV-associated severe neurological diseases or contribute to neurocognitive impairment in the setting of stable HIV infection.

Conclusions:

As HIV can be responsible for considerable brain damage directly or by facilitating other pathogens, more effort is needed to recognize and manage HIV-associated CNS disorders and to eventually target HIV eradication from the brain.

Subjective memory complaints are associated with poorer cognitive performance in adults with HIV

With successful antiretroviral therapy in the US, HIV-positive adults now routinely survive into old age. However, increased life expectancy with HIV introduces the added complication of age-related cognitive decline. Aging with HIV has been associated with poorer cognitive outcomes compared to HIV-negative adults. While up to 50% of older HIV-positive adults will develop some degree of cognitive impairment over their lifetime, cognitive symptoms are often not consistently monitored, until those symptoms are significant enough to impair daily life. In this study we found that subjective memory complaint (SMC) ratings correlated with measurable memory performance impairments in HIV-positive adults, but not HIV-negative adults. As the HIV-positive population ages, structured subjective cognitive assessment may be beneficial to identify the early signs of cognitive impairment, and subsequently allow for earlier interventions to maintain cognitive performance as these adults continue to survive into old age.

Cognitive impairment in HIV and HCV co-infected patients: a systematic review and meta-analysis

Cognitive impairment has been well documented in HIV and hepatitis C virus (HCV) mono-infections. However, in the context of HIV/HCV co-infection the research is more limited. The aim of this systematic review was to describe the characteristics of cognitive impairment in HIV/HCV co-infection and to examine the differences in cognitive performance between HIV/HCV and HIV and HCV mono-infected patients. Of the 437 records initially screened, 24 papers met the inclusion criteria and were included in the systematic review. Four studies were included in the meta-analysis. Most studies indicated that HIV/HCV co-infected patients had a higher level of cognitive impairment than HIV mono-infected patients. Meta-analysis indicated, however, that HIV mono-infected patients had a significantly higher global deficit score than co-infected patients. The results also indicated that co-infected patients were more likely to be impaired in information processing speed than HIV mono-infected patients. These findings can be challenged by biasing factors such as the small number of studies, heterogeneity of the samples, and a large diversity of methodological procedures. Future research with consistent and comprehensive neuropsychological batteries and covering a greater diversity of risk factors is needed, in order to clarify the effects of both viruses on cognitive function and the mechanisms that underlie these effects. Because cognitive impairments may pose significant challenges to medication adherence, quality of life and overall functioning, such knowledge may have important implications to the planning and implementation of effective interventions aimed at optimising the clinical management of these infections.

Long-term efavirenz use is associated with worse neurocognitive functioning in HIV-infected patients

Neurocognitive (NC) complications continue to afflict a substantial proportion of HIV-infected people taking effective antiretroviral therapy (ART). One contributing mechanism for this is antiretroviral neurotoxicity. Efavirenz (EFV) is associated with short-term central nervous system (CNS) toxicity, but less is known about its long-term effects. Our objective was to compare NC functioning with long-term use of EFV to that of a comparator, lopinavir-ritonavir (LPV/r), in a cohort of well-characterized adults. Four hundred forty-five patients were selected from the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) cohort based on their use of either EFV (n = 272, mean duration 17.9 months) or LPV/r (n = 173, mean duration 16.4 months) and the lack of severe NC comorbidities. All patients had undergone standardized comprehensive NC testing. Univariable and multivariable analyses to predict NC outcomes were performed. Compared with LPV/r users, EFV users were more likely to be taking their first ART regimen (p < 0.001), were less likely to have AIDS (p < 0.001) or hepatitis C virus (HCV) coinfection (p < 0.05), had higher CD4+ T cell nadirs (p < 0.001), had lower peak (p < 0.001) and current (p < 0.001) plasma HIV RNA levels, and were less likely to have detectable HIV RNA in cerebrospinal fluid (CSF) (p < 0.001). Overall, EFV users had worse speed of information processing (p = 0.04), verbal fluency (p = 0.03), and working memory (p = 0.03). An interaction with HCV serostatus was present: Overall among HCV seronegatives (n = 329), EFV users performed poorly, whereas among HCV seropositives (n = 116), LPV/r users had overall worse performance. In the subgroup with undetectable plasma HIV RNA (n = 269), EFV users had worse speed of information processing (p = 0.02) and executive functioning (p = 0.03). Substantial differences exist between EFV and LPV/r users in this observational cohort, possibly because of channeling by clinicians who may have prescribed LPV/r to more severely ill patients or as second-line therapy. Despite these differences, EFV users had worse functioning in several cognitive abilities. A potentially important interaction was identified that could indicate that the NC consequences of specific antiretroviral drugs may differ based on HCV coinfection. The complexity of these data is substantial, and findings would best be confirmed in a randomized clinical trial.

Absence of neurocognitive effect of hepatitis C infection in HIV-coinfected people

OBJECTIVE

To investigate the effect of hepatitis C virus (HCV) on neurocognitive performance in chronically HIV-infected patients enrolled in the CNS HIV Antiretroviral Therapy Effects Research (CHARTER) study.

METHODS

A total of 1,582 participants in CHARTER who were tested for HCV antibody underwent neurocognitive testing; serum HCV RNA was available for 346 seropositive patients. Neurocognitive performance was compared in 408 HCV-seropositive and 1,174 HCV-seronegative participants and in a subset of 160 seropositive and 707 seronegative participants without serious comorbid neurologic conditions that might impair neurocognitive performance, using linear regression and taking into account HIV-associated and demographic factors (including IV drug use) and liver function.

RESULTS

Neurocognitive performance characterized by global deficit scores and the proportion of individuals who were impaired were the same in the HCV-seropositive and HCV-seronegative groups. In univariable analyses in the entire sample, only verbal domain scores showed small statistically different superior performance in the HCV+ group that was not evident in multivariable analysis. In the subgroup without significant comorbidities, scores in all 7 domains of neurocognitive functioning did not differ by HCV serostatus. Among the HCV-seropositive participants, there was no association between neurocognitive performance and serum HCV RNA concentration.

CONCLUSION

In HIV-infected patients, HCV coinfection does not contribute to neurocognitive impairment, at least in the absence of substantial HCV-associated liver damage, which was not evident in our cohort.

Neurocognitive function in HIV infected patients on antiretroviral therapy

OBJECTIVE

To describe factors associated with neurocognitive (NC) function in HIV-positive patients on stable combination antiretroviral therapy.

DESIGN

We undertook a cross-sectional analysis assessing NC data obtained at baseline in patients entering the Protease-Inhibitor-Monotherapy-Versus-Ongoing-Triple therapy (PIVOT) trial.

MAIN OUTCOME MEASURE

NC testing comprised of 5 domains. Raw results were z-transformed using standard and demographically adjusted normative datasets (ND). Global z-scores (NPZ-5) were derived from averaging the 5 domains and percentage of subjects with test scores >1 standard deviation (SD) below population means in at least two domains (abnormal Frascati score) calculated. Patient characteristics associated with NC results were assessed using multivariable linear regression.

RESULTS

Of the 587 patients in PIVOT, 557 had full NC results and were included. 77% were male, 68% Caucasian and 28% of Black ethnicity. Mean (SD) baseline and nadir CD4+ lymphocyte counts were 553(217) and 177(117) cells/µL, respectively, and HIV RNA was <50 copies/mL in all. Median (IQR) NPZ-5 score was -0.5 (-1.2/-0) overall, and -0.3 (-0.7/0.1) and -1.4 (-2/-0.8) in subjects of Caucasian and Black ethnicity, respectively. Abnormal Frascati scores using the standard-ND were observed in 51%, 38%, and 81%, respectively, of subjects overall, Caucasian and Black ethnicity (p<0.001), but in 62% and 69% of Caucasian and Black subjects using demographically adjusted-ND (p = 0.20). In the multivariate analysis, only Black ethnicity was associated with poorer NPZ-5 scores (P<0.001).

CONCLUSIONS

In this large group of HIV-infected subjects with viral load suppression, ethnicity but not HIV-disease factors is closely associated with NC results. The prevalence of abnormal results is highly dependent on control datasets utilised.

TRIAL REGISTRY

ClinicalTrials.gov, NCT01230580.

HIV-associated neurocognitive disease: case studies and suggestions for diagnosis and management in different patient subgroups

The incidence of HIV-associated dementia has decreased significantly with the introduction of combination antiretroviral therapy; however, milder or more subtle forms of neurocognitive disorders associated with HIV appear to remain common. There is a lack of consensus on when to screen and on which methods are most appropriate for identifying patients at risk of neurocognitive impairment. Multiple factors (demographic, social, genetic, psychological and medical) can play a role in its aetiology and progression, including potential central nervous system toxicity of antiviral therapy. It is important to identify these factors in order to apply relevant management strategies. In this review, we discuss a series of case studies that address some of the challenges presented by the diagnosis and management of HIV-associated neurocognitive impairment in different patient types.

Hepatitis C virus and the brain

Hepatitis C virus (HCV) is an enveloped, positive-strand RNA virus of the family Flaviviridae that primarily infects hepatocytes, causing acute and chronic liver disease. HCV is also associated with a variety of extrahepatic symptoms including central nervous system (CNS) abnormalities, cognitive dysfunction, fatigue and depression. These symptoms do not correlate with the severity of liver disease and are independent of hepatic encephalopathy. HCV RNA has been associated with CNS tissue, and reports of viral sequence diversity between brain and liver tissue suggest independent viral evolution in the CNS and liver. This review will explore the data supporting HCV infection of the CNS and how this fits into our current understanding of HCV pathogenesis.

Substance Abuse, Hepatitis C, and Aging in HIV: Common Cofactors that Contribute to Neurobehavioral Disturbances

Although the prevalence of neurocognitive disturbances among individuals with HIV has decreased in recent years, rates of impairment still remain high. This review presents findings from comorbid conditions that may contribute to further neurocognitive impairments in this already vulnerable population. We will focus on three co-factors that have received substantial attention in the neuroAIDS literature: drug use, hepatitis C co-infection (HCV), and aging. All three conditions commonly co-occur with HIV and likely interact with HIV in complex ways. Collectively, the extant literature suggests that drug use, HCV, and aging serve to worsen the neurocognitive profile of HIV through several overlapping mechanisms. A better understanding of how specific comorbidities interact with HIV may reveal specific phenotypes of HIV-associated neurocognitive disorder that may aid in the development of more targeted behavioral and pharmacological treatment efforts.

Effects of different antiretroviral agents on cerebral function in HIV-infected individuals

Since the advent of effective antiretroviral therapy, the incidence of severe HIV-associated brain disease has declined dramatically; however, more subtle forms of cerebral impairment, known as HIV-associated neurocognitive disorders, are becoming increasingly recognized. Some of the risk factors for this impairment are well described and include nadir CD4+ cell count. However, the effects of different antiretroviral agents on cerebral function are only beginning to be unraveled. Overall, there are clear beneficial effects on neurocognitive function from antiretroviral therapy. Recent data suggest that some antiretroviral agents have more potent effects on improving cerebral function, whereas other antiretroviral agents may even be associated with direct cerebral toxicities.

HIV-associated central nervous system diseases in the recent combination antiretroviral therapy era

BACKGROUND AND PURPOSE

Data describing the incidence and survival of HIV-related central nervous system diseases (CNS-D) in recent years are sparse.

METHODS

Between 1996 and 2007, adult subjects without previous CNS-D within a large UK cohort were included (n=30,954). CNS-D were HIV encephalopathy (HIVe), progressive multifocal leucoencephalopathy (PML), cerebral toxoplasmosis (TOXO) and cryptococcal meningitis (CRYP). Associations between demographic, clinical and laboratory parameters with incidence and survival of CNS-D were evaluated using Poisson regression analysis and Kaplan-Meier techniques.

RESULTS

Six hundred and thirteen new CNS-D occurred in 574 subjects (HIVe:187, PML:113, TOXO:184, CRYP:129). Incidence of all CNS-D declined from 13.1 per 1000 PY in 1996/1997 to 1.0 per 1000 PY in 2006/2007 (P=0.0001). Current CD4+ cell count below 200 cells/ul and plasma HIV RNA above 100,000 copies/ml were independently associated with the development of CNS-D. Calendar year 1996/1997, older age, prior AIDS diagnosis and PML diagnosis were significantly associated with shorter survival.

CONCLUSIONS

An ongoing decline in the incidence of CNS-D has been observed in very recent years. Mortality following such a diagnosis remains high.