The effects of hepatitis C, HIV, and methamphetamine dependence on neuropsychological performance: biological correlates of disease

The Relationships between HIV-1 Infection, History of Methamphetamine Use Disorder, and Soluble Biomarkers in Blood and Cerebrospinal Fluid

Methamphetamine (METH) use disorder is highly prevalent among people with HIV (PWH) and is a significant public health problem. HIV and METH use are each associated with immune system dysfunction; however, the combined effects on the immune system are poorly understood. This cross-sectional project measured soluble immune biomarkers in plasma and cerebrospinal fluid (CSF) collected from a control group, people with a history of a METH use disorder (METH+), PWH with no history of METH use disorder (HIV+), and PWH with a history of METH use disorder (HIV+/METH+). HIV, METH, and immune dysfunction can also be associated with affective and cognitive deficits, so we characterized mood and cognition in our participants. Two factor analyses were performed for the plasma and CSF biomarkers. Plasma IL-8, Ccl2, VEGF, and 8-isoprostane loaded onto one factor that was highest in the HIV+/METH+ group (p < 0.047) reflecting worse inflammation, vascular injury, and oxidative stress. This plasma factor was also negatively correlated with delayed recall (R = -0.49, p = 0.010), which was worst in the HIV+/METH+ group (p = 0.030 compared to the control group). Overall, these data implicate that combined HIV-1 infection and METH use may exacerbate inflammation, leading to worse cognition.

Hepatitis C related cognitive impairment: Impact of viral and host factors and response to therapy

Chronic hepatitis C virus (HCV) infection is associated with cognitive impairment via several suggested mechanisms including direct neurotoxicity and minimal hepatic encephalopathy. The prevalence of HCV-related cognitive impairment and whether it is reversed by anti-viral therapy is unknown. We aimed to assess predictors and reversibility of cognitive impairment of HCV-infected patients after successful treatment. Consecutive HCV patients treated during the EMERALD study (AbbVie 3D regimen for protease inhibitors failure) underwent neuropsychological (number connection test A [NCTA] and digital symbol test [DST]) and neurophysiological (critical flicker frequency [CFF]) tests at baseline and at 12 weeks post-treatment. Patient self-reported outcomes (PROs) were prospectively collected. Patients with a history of hepatic encephalopathy were excluded. Thirty-two patients underwent the cognitive tests at baseline. Seven of them had abnormal CFF test findings. Twenty-five (25/32, 78%) patients had repeated evaluations 3 months post-treatment. High viral loads were significantly associated with abnormal CFF across fibrosis levels (area under the ROC curve 0.817). CFF results significantly improved following viral eradication, from 40.9 (interquartile range 38.6-42.9) at baseline to 41.5 (39.8-44), p = .042, at follow-up. Both NCTA and DST results improved, but not significantly. There was improvement in the PROs of general health perception and vitality. The NCTA and DST results were more significantly associated with PROs than CFF. This prospective interventional study showed greater cognitive impairment in HCV patients with high viral load and demonstrated partial reversibility of HCV neurotoxicity and subsequent improvement in PROs following treatment.

Peripheral Inflammatory Biomarkers of Methamphetamine Withdrawal Patients Based on the Neuro-Inflammation Hypothesis: The Possible Improvement Effect of Exercise

Methamphetamine (MA) induced addiction and neuroinflammation has been implicated. Based on the neuroinflammation hypothesis, this study aims to investigate how exercise influences the craving of patients in MA withdrawal, and explore the mechanism of peripheral inflammation. A total of 90 patients in MA withdrawal were recruited. No difference was noted in the number of years of drug use and the frequency of drug use among patients, and the withdrawal time was within 2 months. The subjects were grouped based on the degree of craving induced by the cues: non-craving control group (NCC group), craving control group (CC group), and craving exercise group (CE group). The CE group was subjected to aerobic combined resistance training. Then, the ELISA method was used to detect plasma IL-6, TNF-α, and IL-1β concentrations; Visual Analog Scale (VAS) measurement of cue-induced cravings under Virtual Reality (VR) exposure (VR-VAS) and the Desires for Drug Questionnaire (DDQ) were used to assess cravings. Consequently, plasma IL-6, TNF-α, IL-1β, levels, and the VR-VAS and DDQ scores of MA withdrawal patients were significantly reduced after exercise. This study confirmed that 8 weeks of incremental load aerobic combined with resistance training reduces peripheral inflammation and significantly reduces the level of craving for MA.

Up-regulation of the p75 neurotrophin receptor is an essential mechanism for HIV-gp120 mediated synaptic loss in the striatum

Reduced synaptodendritic complexity appears to be a key feature in human immunodeficiency virus (HIV)-associated neurological disorder (HAND). Viral proteins, and in particular the envelope protein gp120, play a role in the pathology of synapses. Gp120 has been shown to increase both in vitro and in vivo the proneurotrophin brain-derived neurotrophic factor, which promotes synaptic simplification through the activation of the p75 neurotrophin receptor (p75NTR). To provide evidence that p75NTR plays a role in gp120-mediated loss of synapses in vivo, we intercrossed gp120tg mice with p75NTR null mice and used molecular, histological and behavioral analyses to establish a link between p75NTR and gp120-mediated synaptic simplification. Synaptosomes obtained from the striatum of gp120tg mice exhibited a significant increase in p75NTR levels concomitantly to a decrease in synaptic markers such as TrkB and PSD95. Analysis of striatal dendritic spines by Golgi staining revealed that gp120tg mice display a reduced proportion of mushroom-type spines in addition to fewer spines overall, when compared to wild type or gp120tg lacking one or two p75NTR alleles. Moreover, removal of one p75NTR allele in gp120 transgenic mice abolished the gp120-driven impairment on a task of striatal-dependent motor learning. These data indicate that p75NTR could be a key player in HIV-mediated synaptic simplification in the striatum.

Substance Use Disorder in the COVID-19 Pandemic: A Systematic Review of Vulnerabilities and Complications

As the world endures the coronavirus disease 2019 (COVID-19) pandemic, the conditions of 35 million vulnerable individuals struggling with substance use disorders (SUDs) worldwide have not received sufficient attention for their special health and medical needs. Many of these individuals are complicated by underlying health conditions, such as cardiovascular and lung diseases and undermined immune systems. During the pandemic, access to the healthcare systems and support groups is greatly diminished. Current research on COVID-19 has not addressed the unique challenges facing individuals with SUDs, including the heightened vulnerability and susceptibility to the disease. In this systematic review, we will discuss the pathogenesis and pathology of COVID-19, and highlight potential risk factors and complications to these individuals. We will also provide insights and considerations for COVID-19 treatment and prevention in patients with SUDs.

HIV influences microtubule associated protein-2: potential marker of HIV-associated neurocognitive disorders

OBJECTIVE

Postmortem brains of patients diagnosed with HIV-1-associated neurocognitive disorders (HAND) exhibit loss of dendrites. However, the mechanisms by which synapses are damaged are not fully understood.

DESIGN

Dendrite length and remodeling occurs via microtubules, the dynamics of which are regulated by microtubule-binding proteins, including microtubule-associated protein 2 (MAP2). The HIV protein gp120 is neurotoxic and interferes with neuronal microtubules. We measured MAP2 concentrations in human cerebrospinal fluid (CSF) and MAP2 immunoreactivity in rat cortical neurons exposed to HIV and gp120.

METHODS

First, we examined whether HIV affects MAP2 levels by analyzing the CSF of 27 persons living with HIV (PLH) whose neurocognitive performance had been characterized. We then used rat cortical neurons to study the mechanisms of HIV-mediated dendritic loss.

RESULTS

PLH who had HAND had greater MAP2 concentrations within the CSF than cognitive normal PLH. In cortical neurons, the deleterious effect of HIV on MAP2-positive dendrites occurred through a gp120-mediated mechanism. The neurotoxic effect of HIV was blocked by a CCR5 antagonist and prevented by Helix-A, a peptide that displaces gp120 from binding to microtubules, conjugated to a nanolipoprotein particle delivery platform.

CONCLUSION

Our findings support that HIV at least partially effects its neurotoxicity via neuronal cytoskeleton modifications and provide evidence of a new therapeutic compound that could be used to prevent the HIV-associated neuropathology.

Functional MRI and delay discounting in patients infected with hepatitis C

Hepatitis C virus-infected (HCV+) adults evidence increased rates of psychiatric and cognitive difficulties. This is the first study to use functional magnetic resonance imaging (fMRI) to examine brain activation in untreated HCV+ adults. To determine whether, relative to non-infected controls (CTLs), HCV+ adults exhibit differences in brain activation during a delay discounting task (DDT), a measure of one's tendency to choose smaller immediate rewards over larger delayed rewards-one aspect of impulsivity. Twenty adults with HCV and 26 CTLs completed an fMRI protocol during the DDT. Mixed effects regression analyses of hard versus easy trials of the DDT showed that, compared with CTLs, the HCV+ group exhibited less activation in the left lateral occipital gyrus, precuneus, and superior frontal gyrus. There were also significant interactive effects for hard-easy contrasts in the bilateral medial frontal gyrus, left insula, left precuneus, left inferior parietal lobule, and right temporal occipital gyrus; the CTL group evidenced a positive relationship between impulsivity and activation, while the HCV+ group exhibited a negative relationship. Within the HCV+ group, those with high viral load chose immediate rewards more often than those with low viral load, regardless of choice difficulty; those with low viral load chose immediate rewards more often on hard choices relative to easy choices. Results show that HCV+ patients exhibit greater impulsive behavior when presented with difficult choices, and impulsivity is negatively related to activation in regions important for cognitive control. Thus, interventions that decrease impulsive choice may be warranted with some HCV+ patients.

Depression, fatigue and neurocognitive deficits in chronic hepatitis C

Patients with chronic hepatitis C virus (HCV) infection experience a range of symptoms including depression, fatigue and neurocognitive deficits, impairing quality of life. Depression, in particular, may be reactive to increased psychosocial stress, and the physical symptoms of advanced HCV or associated comorbidities. However, even patients at an early stage of HCV infection, with minimal hepatic inflammation or comorbidities, report more depressive symptoms and fatigue than the general population. Similarly, specific neurocognitive deficits occur in early stage HCV infection and are independent of the presence of depression or encephalopathy. Therefore, intracerebral neurobiological changes associated with HCV may potentially explain these symptoms. These changes may arise from infiltration of the brain by peripherally induced cytokines, as well as direct neuropathic effects of HCV viral particles penetrating the blood-brain barrier. These phenomena parallel those reported in human immunodeficiency virus (HIV) infection. HCV-associated intracerebral changes include upregulated inflammatory responses, altered neurotransmitter levels, hormonal dysregulation, and release of neurotoxic substances. These may subsequently lead to abnormal neuronal conduction and function in areas of the brain governing affective responses, emotional processing, motivation, attention and concentration. Although direct-acting antiviral medications lead to high rates of HCV clearance, intracerebral changes may not be subsequently reversed and symptoms of depression, fatigue and neurocognitive deficits may persist. There is an ongoing role for multidisciplinary care and pharmacotherapy to manage these symptoms in HCV patients. Furthermore, there may be opportunities for future therapies to specifically target and ameliorate HCV-associated intracerebral changes.

The Aging Brain With HIV Infection: Effects of Alcoholism or Hepatitis C Comorbidity

As successfully treated individuals with Human Immunodeficiency Virus (HIV)-infected age, cognitive and health challenges of normal aging ensue, burdened by HIV, treatment side effects, and high prevalence comorbidities, notably, Alcohol Use Disorders (AUD) and Hepatitis C virus (HCV) infection. In 2013, people over 55 years old accounted for 26% of the estimated number of people living with HIV (~1.2 million). The aging brain is increasingly vulnerable to endogenous and exogenous insult which, coupled with HIV infection and comorbid risk factors, can lead to additive or synergistic effects on cognitive and motor function. This paper reviews the literature on neuropsychological and in vivo Magnetic Resonance Imaging (MRI) evaluation of the aging HIV brain, while also considering the effects of comorbidity for AUD and HCV.

Neurocognitive impairment with hepatitis C and HIV co-infection in Southern Brazil

Although cognitive impairment has been well documented in human immunodeficiency virus (HIV) and hepatitis C virus (HCV) mono-infections, research on neurocognitive effects is limited in the context of HIV/HCV co-infection. The aims of this study were to explore the interplay between HIV and HCV infections in the expression of neurocognitive impairment (NCI), and to examine the differences in test performance between HIV/HCV co-infected and HIV or HCV mono-infected patients. A total of 128 participants from Southern Brazil underwent a comprehensive neuropsychological (NP) battery comprising 18 tests. Participants were grouped according to their serological status: HCV mono-infected (n = 20), HIV mono-infected (n = 48), HIV/HCV co-infected (n = 12), and HIV-/HCV-uninfected controls (n = 48). The frequencies of HIV subtypes B and C between the HIV mono-infected and HIV/HCV co-infected groups were comparable. There was greater prevalence of neuropsychological impairment among all three infection groups compared with the uninfected control group, but no statistically significant differences among mono- and co-infected groups were found. HCV infection was associated with cognitive deficits, independently of liver dysfunction. HCV infection did not show an additive effect on neurocognitive function among HIV+. NCI was independent of HCV RNA on peripheral blood, CSF, and hepatic injury. While we did not find additive global effect, in the present study, there was some evidence of additive HIV/HCV co-infection effects in speed of information processing, executive function, and verbal fluency domains when comparing the co-infected group with the other three groups. NP impairment was not dependent on HCV subtypes.

Extended-access methamphetamine self-administration elicits neuroinflammatory response along with blood-brain barrier breakdown

Methamphetamine (METH) is a highly addictive psychostimulant drug that can lead to neurological and psychiatric abnormalities. Several studies have explored the central impact of METH use, but the mechanism(s) underlying blood-brain barrier (BBB) dysfunction and associated neuroinflammatory processes after chronic METH consumption are still unclear. Important findings in the field are mainly based on in vitro approaches and animal studies using an acute METH paradigm, and not much is known about the neurovascular alterations under a chronic drug use. Thus, the present study aimed to fill this crucial gap by exploring the effect of METH-self administration on BBB function and neuroinflammatory responses. Herein, we observed an increase of BBB permeability characterized by Evans blue and albumin extravasation in the rat hippocampus and striatum triggered by extended-access METH self-administration followed by forced abstinence. Also, there was a clear structural alteration of blood vessels showed by the down-regulation of collagen IV staining, which is an important protein of the endothelial basement membrane, together with a decrease of intercellular junction protein levels, namely claudin-5, occludin and vascular endothelial-cadherin. Additionally, we observed an up-regulation of vascular cell and intercellular adhesion molecule, concomitant with the presence of T cell antigen CD4 and tissue macrophage marker CD169 in the brain parenchyma. Rats trained to self-administer METH also presented a neuroinflammatory profile characterized by microglial activation, astrogliosis and increased pro-inflammatory mediators, namely tumor necrosis factor-alpha, interleukine-1 beta, and matrix metalloproteinase-9. Overall, our data provide new insights into METH abuse consequences, with a special focus on neurovascular dysfunction and neuroinflammatory response, which may help to find novel approaches to prevent or diminish brain dysfunction triggered by this overwhelming illicit drug.

Prevalence and Correlates of Persistent HIV-1 RNA in Cerebrospinal Fluid During Antiretroviral Therapy

BACKGROUND

 Neurocognitive disorders remain common among human immunodeficiency virus (HIV)-positive adults, perhaps owing to persistent HIV-1 RNA in cerebrospinal fluid (CSF) during antiretroviral therapy (ART).

METHODS

 Using a single-copy assay, we measured HIV-1 RNA levels in CSF and plasma specimens from 220 HIV-positive adults who were taking suppressive ART. Fifty-five participants were tested twice.

RESULTS

 HIV-1 RNA was detected in 42.3% of CSF and 65.2% of plasma samples. Correlates of higher CSF HIV-1 RNA levels included higher nadir and current CD4⁺ T-cell counts, a plasma HIV-1 RNA level of ≥ 1 copy/mL, and a lower central nervous system penetration-effectiveness score (model P < .001). Worse neurocognitive performance was associated with discordance in HIV-1 RNA detection between plasma and CSF, lower overall CSF HIV-1 RNA level, and longer ART duration, among others (model P < .001). In the longitudinal subgroup, CSF HIV-1 RNA persisted in most participants (69%) over 7 months.

CONCLUSIONS

 Low-level HIV-1 RNA in CSF is common during suppressive ART and is associated with low-level HIV-1 RNA in blood, better immune status, and lower ART drug distribution into CSF. The association between HIV-1 RNA discordance and HIV-associated neurocognitive disorder (HAND) may reflect compartmentalization. The relationship between HAND, lower HIV-1 RNA levels in CSF, and lower CD4⁺ T-cell counts may reflect disturbances in the immune response to HIV-1 in the CNS.

Sleep disturbance in substance use disorders and comorbid chronic viral infections

Sleep disruption is associated with both substance use disorders and chronic viral infections, which commonly co-occur. A greater understanding of how sleep is affected by substance abuse and comorbid chronic viral infections is needed, as fatigue, depression and other neuropsychiatric impairments caused by chronic viral infections can affect response to addiction treatment adversely.

Fibroblast growth factors 1 and 2 in cerebrospinal fluid are associated with HIV disease, methamphetamine use, and neurocognitive functioning

Background

Human immunodeficiency virus (HIV) and methamphetamine use commonly affect neurocognitive (NC) functioning. We evaluated the relationships between NC functioning and two fibroblast growth factors (FGFs) in volunteers who differed in HIV serostatus and methamphetamine dependence (MAD).

Methods

A total of 100 volunteers were categorized into four groups based on HIV serostatus and MAD in the prior year. FGF-1 and FGF-2 were measured in cerebrospinal fluid by enzyme-linked immunosorbent assays along with two reference biomarkers (monocyte chemotactic protein [MCP]-1 and neopterin). Comprehensive NC testing was summarized by global and domain impairment ratings.

Results

Sixty-three volunteers were HIV+ and 59 had a history of MAD. FGF-1, FGF-2, and both reference biomarkers differed by HIV and MAD status. For example, FGF-1 levels were lower in subjects who had either HIV or MAD than in HIV− and MAD− controls (P=0.003). Multivariable regression identified that global NC impairment was associated with an interaction between FGF-1 and FGF-2 (model R²=0.09, P=0.01): higher FGF-2 levels were only associated with neurocognitive impairment among subjects who had lower FGF-1 levels. Including other covariates in the model (including antidepressant use) strengthened the model (model R²=0.18, P=0.004) but did not weaken the association with FGF-1 and FGF-2. Lower FGF-1 levels were associated with impairment in five of seven cognitive domains, more than FGF-2, MCP-1, or neopterin.

Conclusion

These findings provide in vivo support that HIV and MAD alter expression of FGFs, which may contribute to the NC abnormalities associated with these conditions. These cross-sectional findings cannot establish causality and the therapeutic benefits of recombinant FGF-1 need to be investigated.

The impact of human immune deficiency virus and hepatitis C coinfection on white matter microstructural integrity

The purpose of the present study is to examine the integrity of white matter microstructure among individuals coinfected with HIV and HCV using diffusion tensor imaging (DTI). Twenty-five HIV+ patients, 21 HIV+/HCV+ patients, and 25 HIV- controls were included in this study. All HIV+ individuals were stable on combination antiretroviral therapy (cART; ≥3 months). All participants completed MRI and neuropsychological measures. Clinical variables including liver function, HIV-viral load, and CD4 count were collected from the patient groups. DTI metrics including mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), and fractional anisotropy (FA) from five subregions of the corpus callosum were compared across groups. The HIV+/HCV+ group and HIV+ group were similar in terms of HIV clinical variables. None of the participants met criteria for cirrhosis or fibrosis. Within the anterior corpus callosum, significant differences were observed between both HIV+ groups compared to HIV- controls on DTI measures. HIV+ and HIV+/HCV+ groups had significantly lower FA values and higher MD and RD values compared to HIV- controls; however, no differences were present between the HIV+ and HIV+/HCV+ groups. Duration of HIV infection was significantly related to DTI metrics in total corpus callosum FA only, but not other markers of HIV disease burden or neurocognitive function. Both HIV+ and HIV+/HCV+ individuals had significant alterations in white matter integrity within the corpus callosum; however, there was no evidence for an additive effect of HCV coinfection. The association between DTI metrics and duration of HIV infection suggests that HIV may continue to negatively impact white matter integrity even in well-controlled disease.

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.

Extrahepatic morbidity and mortality of chronic hepatitis C

Chronic hepatitis C virus (HCV) infection is associated with several extrahepatic manifestations. Patients with HCV may develop mixed cryoglobulinemia and its sequelae, ranging from cutaneous and visceral vasculitis to glomerulonephritis and B-cell non-Hodgkin lymphoma. HCV-infected patients have increased rates of insulin resistance, diabetes, and atherosclerosis, which may lead to increased cardiovascular morbidity and mortality. Neurological manifestations of HCV infection include fatigue and cognitive impairment. The mechanisms causing the extrahepatic effects of HCV infection are likely multifactorial and may include endocrine effects, HCV replication in extrahepatic cells, or a heightened immune reaction with systemic effects. Successful eradication of HCV with interferon alfa and ribavirin was shown to improve some of these extrahepatic effects; sustained virological response is associated with resolution of complications of cryoglobulinemia, reduced levels of insulin resistance, reduced incidence of diabetes and stroke, and improved fatigue and cognitive functioning. The availability of new interferon-free, well-tolerated anti-HCV treatment regimens is broadening the spectrum of patients available for therapy, including those in whom interferon was contraindicated, and will likely result in greater improvements in the extrahepatic manifestations of HCV. If these regimens are shown to confer significant benefit in the metabolic, cardiovascular, or neuropsychiatric conditions associated with HCV infection, extrahepatic manifestations of HCV may become a major indication for treatment even in the absence of liver disease.

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.

Neuroimmune basis of methamphetamine toxicity

Although it is not known which antigen-specific immune responses (or if antigen-specific immune responses) are relevant or required for methamphetamine's neurotoxic effects, it is apparent that methamphetamine exposure is associated with significant effects on adaptive and innate immunity. Alterations in lymphocyte activity and number, changes in cytokine signaling, impairments in phagocytic functions, and glial activation and gliosis have all been reported. These drug-induced changes in immune response, particularly within the CNS, are now thought to play a critical role in the addiction process for methamphetamine dependence as well as for other substance use disorders. In Section 2, methamphetamine's effects on glial cell (e.g., microglia and astrocytes) activity and inflammatory signaling cascades are summarized, including how alterations in immune cell function can induce the neurotoxic and addictive effects of methamphetamine. Section 2 also describes neurotransmitter involvement in the modulation of methamphetamine's inflammatory effects. Section 3 discusses the very recent use of pharmacological and genetic animal models which have helped elucidate the behavioral effects of methamphetamine's neurotoxic effects and the role of the immune system. Section 4 is focused on the effects of methamphetamine on blood-brain barrier integrity and associated immune consequences. Clinical considerations such as the combined effects of methamphetamine and HIV and/or HCV on brain structure and function are included in Section 4. Finally, in Section 5, immune-based treatment strategies are reviewed, with a focus on vaccine development, neuroimmune therapies, and other anti-inflammatory approaches.

Central and peripheral markers of neurodegeneration and monocyte activation in HIV-associated neurocognitive disorders

HIV-associated neurocognitive disorders (HAND) affect up to 50 % of HIV-infected adults, independently predict HIV morbidity/mortality, and are associated with neuronal damage and monocyte activation. Cerebrospinal fluid (CSF) neurofilament subunits (NFL, pNFH) are sensitive surrogate markers of neuronal damage in several neurodegenerative diseases. In HIV, CSF NFL is elevated in individuals with and without cognitive impairment, suggesting early/persistent neuronal injury during HIV infection. Although individuals with severe cognitive impairment (HIV-associated dementia (HAD)) express higher CSF NFL levels than cognitively normal HIV-infected individuals, the relationships between severity of cognitive impairment, monocyte activation, neurofilament expression, and systemic infection are unclear. We performed a retrospective cross-sectional study of 48 HIV-infected adults with varying levels of cognitive impairment, not receiving antiretroviral therapy (ART), enrolled in the CNS Anti-Retroviral Therapy Effects Research (CHARTER) study. We quantified NFL, pNFH, and monocyte activation markers (sCD14/sCD163) in paired CSF/plasma samples. By examining subjects off ART, these correlations are not confounded by possible effects of ART on inflammation and neurodegeneration. We found that CSF NFL levels were elevated in individuals with HAD compared to cognitively normal or mildly impaired individuals with CD4+ T-lymphocyte nadirs ≤200. In addition, CSF NFL levels were significantly positively correlated to plasma HIV-1 RNA viral load and negatively correlated to plasma CD4+ T-lymphocyte count, suggesting a link between neuronal injury and systemic HIV infection. Finally, CSF NFL was significantly positively correlated with CSF pNFH, sCD163, and sCD14, demonstrating that monocyte activation within the CNS compartment is directly associated with neuronal injury at all stages of HAND.

Methamphetamine effects on blood-brain barrier structure and function

Methamphetamine (Meth) is a widely abuse psychostimulant. Traditionally, studies have focused on the neurotoxic effects of Meth on monoaminergic neurotransmitter terminals. Recently, both in vitro and in vivo studies have investigated the effects of Meth on the BBB and found that Meth produces a decrease in BBB structural proteins and an increase in BBB permeability to various molecules. Moreover, preclinical studies are validated by clinical studies in which human Meth users have increased concentrations of toxins in the brain. Therefore, this review will focus on the structural and functional disruption of the BBB caused by Meth and the mechanisms that contribute to Meth-induced BBB disruption. The review will reveal that the mechanisms by which Meth damages dopamine and serotonin terminals are similar to the mechanisms by which the blood-brain barrier (BBB) is damaged. Furthermore, this review will cover the factors that are known to potentiate the effects of Meth (McCann et al., 1998) on the BBB, such as stress and HIV, both of which are co-morbid conditions associated with Meth abuse. Overall, the goal of this review is to demonstrate that the scope of damage produced by Meth goes beyond damage to monoaminergic neurotransmitter systems to include BBB disruption as well as provide a rationale for investigating therapeutics to treat Meth-induced BBB disruption. Since a breach of the BBB can have a multitude of consequences, therapies directed toward the treatment of BBB disruption may help to ameliorate the long-term neurodegeneration and cognitive deficits produced by Meth and possibly even Meth addiction.

Role of the immune system in HIV-associated neuroinflammation and neurocognitive implications

Individuals living with HIV who are optimally treated with combination antiretroviral therapy (cART) can now lead an extended life. In spite of this remarkable survival benefit from viral suppression achieved by cART in peripheral blood, the rate of mild to moderate cognitive impairment remains high. A cognitive decline that includes impairments in attention, learning and executive function is accompanied by increased rates of mood disorders that together adversely impact the daily life of those with chronic HIV infection. The evidence is clear that cells in the brain are infected with HIV that has crossed the blood-brain barrier both as cell-free virus and within infected monocytes and T cells. Viral proteins that circulate in blood can induce brain endothelial cells to release cytokines, invoking another source of neuroinflammation. The difficulty of efficient delivery of cART to the central nervous system (CNS) contributes to elevated viral load in the CNS, resulting in a persistent HIV-associated neurocognitive disorders (HAND). The pathogenesis of HAND is multifaceted, and mounting evidence indicates that immune cells play a major role. HIV-infected monocytes and T cells not only infect brain resident cells upon migration into the CNS but also produce proinflammatory cytokines such as TNF and IL-1ß, which in turn, further activate microglia and astrocytes. These activated brain resident cells, along with perivascular macrophages, are the main contributors to neuroinflammation in HIV infection and release neurotoxic factors such as excitatory amino acids and inflammatory mediators, resulting in neuronal dysfunction and death. Cytokines, which are elevated in the blood of patients with HIV infection, may also contribute to brain inflammation by entering the brain from the blood. Host factors such as aging and co-morbid conditions such as cytomegalovirus co-infection and vascular pathology are important factors that affect the HIV-host immune interactions in HAND pathogenesis. By these diverse mechanisms, HIV-1 induces a neuroinflammatory response that is likely to be a major contributor to the cognitive and behavior changes seen in HIV infection.

Chronic inflammation and the role for cofactors (hepatitis C, drug abuse, antiretroviral drug toxicity, aging) in HAND persistence

HIV-associated neurocognitive disorders (HAND) is a group of syndromes of varying degrees of cognitive impairment affecting up to 50 % of HIV-infected individuals. The neuropathogenesis of HAND is thought to be driven by HIV invasion and productive replication within brain perivascular macrophages and endogenous microglia, and to some degree by restricted infection of astrocytes. The persistence of HAND in individuals experiencing suppression of systemic HIV viral load with antiretroviral therapy (ART) is incompletely explained, and suggested factors include chronic inflammation, persistent HIV replication in brain macrophages, effects of aging on brain vulnerability, and co-morbid conditions including hepatitis C (HCV) co-infection, substance abuse, and CNS toxicity of ART, among other factors. This review discusses several of these conditions: chronic inflammation, co-infection with HCV, drugs of abuse, aging, and antiretroviral drug effects. Effectively managing these co-morbid conditions in individuals with and without HAND is critical for improving neurocognitive outcomes and decreasing HIV-associated morbidity.

Impact of methamphetamine on infection and immunity

The prevalence of methamphetamine (METH) use is estimated at ~35 million people worldwide, with over 10 million users in the United States. METH use elicits a myriad of social consequences and the behavioral impact of the drug is well understood. However, new information has recently emerged detailing the devastating effects of METH on host immunity, increasing the acquisition of diverse pathogens and exacerbating the severity of disease. These outcomes manifest as modifications in protective physical and chemical defenses, pro-inflammatory responses, and the induction of oxidative stress pathways. Through these processes, significant neurotoxicities arise, and, as such, chronic abusers with these conditions are at a higher risk for heightened consequences. METH use also influences the adaptive immune response, permitting the unrestrained development of opportunistic diseases. In this review, we discuss recent literature addressing the impact of METH on infection and immunity, and identify areas ripe for future investigation.

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.

Investigation of menopausal stage and symptoms on cognition in human immunodeficiency virus-infected women

OBJECTIVE

We evaluated the separate and interactive associations of menopausal stage, menopausal symptoms, and human immunodeficiency virus (HIV) infection with cognition. We hypothesized that HIV-infected perimenopausal women would show the greatest cognitive difficulties and that menopausal symptoms would be inversely associated with cognition.

METHODS

This cross-sectional study included 708 HIV-infected and 278 HIV-uninfected premenopausal, perimenopausal, or postmenopausal women (64% African American; median age, 44 y) from the Women's Interagency HIV Study. Participants completed tests of verbal learning and memory, attention/processing speed, and executive function. We administered a menopausal symptom questionnaire that assessed anxiety, vasomotor, and sleep symptoms and obtained measures of depressive symptoms.

RESULTS

In multivariable regression analyses controlling for relevant covariates, HIV infection, but not menopausal stage, was associated with worse performance on all cognitive measures (P's < 0.05). Depressive symptoms were associated with lower cognitive performance on measures of verbal learning and memory, attention, and executive function (P's < 0.05); anxiety symptoms were associated with lower performance on measures of verbal learning and memory (P's < 0.05). Vasomotor symptoms were associated with worse attention (P < 0.05). HIV and anxiety symptoms interacted to influence verbal learning (P's < 0.05); elevated anxiety was associated with worse verbal learning in HIV-infected women only.

CONCLUSIONS

Vasomotor, depressive, and anxiety symptoms, but not menopausal stage, are associated with worse cognitive performance in both HIV-infected and HIV-uninfected women, although elevated anxiety symptoms are more associated with verbal learning deficits in HIV-infected women. Because cognitive problems can interfere with everyday functioning, including treatment adherence, it may be important to screen and treat anxiety in HIV-infected women.

HIV protease inhibitor exposure predicts cerebral small vessel disease

OBJECTIVE

HIV-associated neurocognitive disorders (HANDs) remain prevalent in patients who receive HAART and may be associated with cumulative exposure to antiretroviral medications and other factors. We proposed that chronic toxic effects of antiretroviral drugs could contribute to cerebral small vessel disease (CSVD), which might be one of the key underpinnings of HAND.

DESIGN

Clinicopathological cross-sectional study of HIV-infected adults in the California NeuroAIDS Tissue Network.

METHODS

We employed multivariable logistic regression methods to determine associations between HAART exposure (protease inhibitor-based, nonprotease inhibitor-based, or no HAART) and CSVD occurrence (standard histopathology: moderate/severe, mild, or absent). We also associated HAND (relative to normal cognition) with CSVD, HIV-related neuropathologic changes, older age at death (≥50 years), sex, or hepatitis C virus infection.

RESULTS

We found that both mild and moderate/severe CSVD were associated with protease inhibitor-based HAART exposure after adjusting for diabetes mellitus [odds ratio (OR) 2.8 (95% confidence interval, CI 1.03-7.9) and 2.6 (95% CI 1.03-6.7), respectively, n = 134]. Moderate/severe CSVD was associated with diabetes after adjusting for HAART exposure [OR 7.4 (95% CI 1.6-70.7), n = 134]. Notably, HAND was associated with mild CSVD [OR 4.8 (95% CI 1.1-21.2), n = 63], which remained statistically significant after adjusting for vessel mineralization, HIV encephalitis, microglial nodular lesions, white matter lesions, or older age.

CONCLUSION

Protease inhibitor-based HAART exposure may increase the risk of CSVD and thereby neurocognitive impairment in HIV-infected adults. Apart from the possible direct toxicity to cerebral small vessels, protease inhibitor-based HAART may contribute indirectly to CSVD by inducing metabolic abnormalities.

Crack cocaine use impairs anterior cingulate and prefrontal cortex function in women with HIV infection

Crack cocaine use is associated with impaired verbal memory in HIV-infected women more than uninfected women. To understand the neural basis for this impairment, this study examined the effects of crack cocaine use on activation of the prefrontal cortex (PFC) and strategic encoding during a verbal memory task in HIV-infected women. Three groups of HIV-infected women from the Chicago Consortium of the Women's Interagency HIV Study were compared: current users of crack cocaine (n = 10), former users of cocaine (n = 11), and women who had never used cocaine (n = 9). Participants underwent functional magnetic resonance imaging during a verbal memory task and completed a neuropsychological test of verbal memory. On the neuropsychological test, current crack users performed significantly worse than other groups on semantic clustering, a measure of strategic encoding, p < 0.05. During encoding, activation in left anterior cingulate cortex (ACC) was lower in current and former cocaine users compared to never users. During recognition, activation in bilateral PFC, specifically left dorsal medial PFC and bilateral dorsolateral PFC, was lower in current and former users compared to women who had never used cocaine. Lower activation in left dorsolateral PFC was correlated with worse performance on the recognition task, p < 0.05. The verbal learning and memory deficits associated with cocaine use in women with HIV may be partially accounted for by alterations in ACC and PFC function.

Detrimental impact of remote methamphetamine dependence on neurocognitive and everyday functioning in older but not younger HIV+ adults: evidence for a legacy effect?

Prior studies examining the combined adverse effects of HIV and methamphetamine (MA) on the central nervous system (CNS) have focused on younger to middle-aged adults with recent MA use diagnoses. Aging, HIV, and MA all converge on prefrontal and temporolimbic neural systems and confer independent risk for neurocognitive and functional decline. Thus, this study sought to determine the residual impact of a remote history of MA dependence on neurocognitive and real-world outcomes in older people living with HIV (PLWH). Participants included 116 older (≥50 years) and 94 younger (<40 years) adults classified into one of six study groups based on HIV serostatus (HIV+/HIV-) and lifetime histories of MA dependence (MA+/MA-): older HIV-MA- (n = 36), older HIV+MA- (n = 49), older HIV+MA+ (n = 31), younger HIV-MA- (n = 27), younger HIV+MA- (n = 33), and younger HIV+MA+ (n = 34). No participant-met criteria for current MA use disorders and histories of MA dependence were remote in both the older (average of nearly 9 years prior to evaluation) and younger (average of over 2 years prior to evaluation) HIV+MA+ groups. Findings revealed that a remote history of MA dependence exerts a significant detrimental impact on specific aspects of neurocognitive performance (e.g., memory) and a broad range of real-world functioning outcomes (e.g., employment) among older, but not younger PLWH. These results suggest that MA-associated neurotoxicity may have significant "legacy" effects on both neurocognitive and functional outcomes to which older PLWH are particularly vulnerable.

Characteristics and impact of methamphetamine use in patients with chronic hepatitis C

OBJECTIVES

Methamphetamine (MA) use has increased in the United States in the last 20 years and is a risk factor for hepatitis C virus(HCV) infection. The purpose of this study was to determine the characteristics and HCV infection outcomes of patients with a history of MA use.

METHODS

Subjects consisted of newly entered patients in the Veterans Affairs (VA) HCV registry at a single VA medical center from January 1, 2004, to June 30, 2004, and from January 1, 2007, to June 30, 2007. Univariate and multivariate analyses related to HCV infection antiviral treatment outcomes through 2010 was performed.

RESULTS

A total of 198 consecutive eligible HCV registry patients were analyzed, and 40% had a history of MA use. Of patients with MA use history, 46% (36/79) had active use (within 6 months) at initial contact. Active MA users were significantly younger (mean age, 45.5 years), with more concomitant drug use (86%), compared with patients without MA use (mean age, 53.5 years; 42% minority; 29% other drug use). Overall, 71% of the 198 patients reported a history of problematic alcohol use, and 47% of those reported active abuse. Logistic regression analyses indicated that MA use did not significantly adversely affect antiviral treatment initiation, completion, or sustained virological response rates compared with that in patients without MA use. Active alcohol users had lower treatment initiation than patients without alcohol use.

CONCLUSIONS

MA use is common in recent US veterans with HCV infection and occurs in younger patients with polysubstance use. Prior history or active MA use does not seem to adversely affect HCV infection clinic treatment compared with that in HCV-infected patients without MA use.

Modulation of BK channel by MicroRNA-9 in neurons after exposure to HIV and methamphetamine

MicroRNAs (miR) regulate phenotype and function of neurons by binding to miR-response elements (MRE) in the 3' untranslated regions (3'UTR) of various messenger RNAs to inhibit translation. MiR expression can be induced or inhibited by environmental factors like drug exposure and viral infection, leading to changes in cellular physiology. We hypothesized that the effects of methamphetamine (MA) and human immunodeficiency virus (HIV)-infection in the brain will induce changes in miR expression, and have downstream regulatory consequences in neurons. We first used a PCR-based array to screen for differential expression of 380 miRs in frontal cortex autopsy tissues of HIV-positive MA abusers and matched controls. These results showed significantly increased expression of the neuron-specific miR-9. In vitro, we used SH-SY5Y cells, an experimental system for dopaminergic studies, to determine miR expression by quantitative PCR after exposure to MA in the presence or absence of conditioned media from HIV-infected macrophages. Again, we found that miR-9 was significantly increased compared to controls. We also examined the inwardly rectifying potassium channel, KCNMA1, which has alternative splice variants that contain an MRE to miR-9. We identified alternate 3'UTRs of KCNMA1 both in vitro and in the autopsy specimens and found differential splice variant expression of KCNMA1, operating via the increased miR-9. Our results suggest that HIV and MA -induced elevated miR-9, leading to suppression of MRE-containing splice variants of KCNMA1, which may affect neurotransmitter release in dopaminergic neurons.

Applications and limitations of inflammatory biomarkers for studies on neurocognitive impairment in HIV infection

Despite reduced prevalence of severe forms of HIV-associated neurocognitive disorders (HAND) on current antiretroviral therapy (ART) regimens, milder forms of neurocognitive impairment (NCI) remain prevalent in HIV-infected populations. These mild forms of HAND consist of subtypes, probably reflecting distinct, though possibly overlapping, pathophysiological mechanisms. Factors associated with HAND in HIV patients with prolonged viral suppression on ART include older age, low nadir CD4, active HCV co-infection, and cardiovascular risk factors, but underlying mechanisms and their relationship to innate immune activation, chronic inflammation, and other features of systemic disease are poorly understood. In this article, we discuss applications and limitations of plasma inflammatory biomarkers for studies on HAND in HIV patients on ART and describe an analysis pipeline to reduce common sources of noise and increase likelihood of identifying relevant inflammatory biomarkers. Clinical covariates and comorbidities that influence inflammatory biomarkers, such as aging, obesity, metabolic abnormalities, HCV co-infection, and substance abuse, are also reviewed. As an example for using this analytic pipeline, we present an exploratory study of 22 plasma inflammatory biomarkers (IFN-α 2b and -γ, 16 cytokines/chemokines, sIL-2R, sCD14, HA, and YKL-40) in a cohort of HIV-infected individuals with advanced disease, frequent HCV co-infection, and viral suppression on ART. The identification of inflammatory biomarkers associated with HAND in HIV+ patients on ART may be useful to distinguish between HAND subtypes with distinct pathophysiology, and is important for achieving a systems-level understanding of the biology of these disorders, developing effective therapies, and evaluating therapeutic outcomes.

Cognitive reserve during neuropsychological performance in HIV intravenous drug users

HIV-associated neurocognitive disorders are frequently observed in people with HIV. We aimed to evaluate the influence of cognitive reserve on the neuropsychological performance of seropositive drug users. We carried out a neuropsychological assessment and compared the performance of seropositive drug users (n = 75) with that of a group of seronegative drug users (n = 48). The results showed that a low cognitive reserve makes the seropositive patients neuropsychologically vulnerable. Likewise, we found that a high cognitive reserve has a protective effect in the presence of neuropsychological impairment associated with HIV. In the seronegative group, differences in a small number of tests were found between participants with low and high cognitive reserve. Overall, these data suggest that seropositivity is not sufficient to explain the neuropsychological alterations of seropositive drug users; rather, these alterations are multifactorial.

Protective effects of higher cognitive reserve for neuropsychological and daily functioning among individuals infected with hepatitis C

Higher levels of cognitive reserve (CR) can be protective against the neuropsychological manifestation of neural injury across a variety of clinical disorders. However, the role of CR in the expression of neurocognitive deficits among persons infected with the hepatitis C virus (HCV) is not well understood. Thirty-nine HCV-infected participants were classified as having either high (n = 19) or low (n = 20) CR based on educational attainment, oral word reading, and IQ scores. A sample of 40 demographically comparable healthy adults (HA) was also included. All participants completed the Neuropsychological Assessment Battery, Delis-Kaplan Executive Function System, and Behavioral Rating Inventory of Executive Function, Adult Version (BRIEF-A). Linear regression analyses, controlling for gender, depression, and lifetime substance use disorders, found significant effects of HCV/CR group on verbal fluency, executive functions, and daily functioning T scores, but not in learning or the BRIEF-A. Pairwise comparisons revealed that the HCV group with low CR performed significantly below the HCV high CR and HA cohorts, who did not differ from one another. Findings indicate that higher levels of CR may be a protective factor in the neurocognitive and real-world manifestation of neural injury commonly associated with HCV infection.

HIV and recent illicit drug use interact to affect verbal memory in women

OBJECTIVE

HIV infection and illicit drug use are each associated with diminished cognitive performance. This study examined the separate and interactive effects of HIV and recent illicit drug use on verbal memory, processing speed, and executive function in the multicenter Women's Interagency HIV Study.

METHODS

Participants included 952 HIV-infected and 443 HIV-uninfected women (mean age = 42.8, 64% African-American). Outcome measures included the Hopkins Verbal Learning Test-Revised and the Stroop test. Three drug use groups were compared: recent illicit drug users (cocaine or heroin use in past 6 months, n = 140), former users (lifetime cocaine or heroin use but not in past 6 months, n = 651), and nonusers (no lifetime use of cocaine or heroin, n = 604).

RESULTS

The typical pattern of recent drug use was daily or weekly smoking of crack cocaine. HIV infection and recent illicit drug use were each associated with worse verbal learning and memory (P < 0.05). Importantly, there was an interaction between HIV serostatus and recent illicit drug use such that recent illicit drug use (compared with nonuse) negatively impacted verbal learning and memory only in HIV-infected women (P < 0.01). There was no interaction between HIV serostatus and illicit drug use on processing speed or executive function on the Stroop test.

CONCLUSIONS

The interaction between HIV serostatus and recent illicit drug use on verbal learning and memory suggests a potential synergistic neurotoxicity that may affect the neural circuitry underlying performance on these tasks.

Substance use disorders: psychoneuroimmunological mechanisms and new targets for therapy

An estimated 76.4 million people worldwide meet criteria for alcohol use disorders, and 15.3 million meet criteria for drug use disorders. Given the high rates of addiction and the associated health, economic, and social costs, it is essential to develop a thorough understanding of the impact of substance abuse on mental and physical health outcomes and to identify new treatment approaches for substance use disorders (SUDs). Psychoneuroimmunology is a rapidly expanding, multidisciplinary area of research that may be of particular importance to addiction medicine, as its focus is on the dynamic and complex interactions among behavioral factors, the central nervous system, and the endocrine and immune systems (Ader, 2001). This review, therefore, focuses on: 1) the psychoneuroimmunologic effects of SUDs by substance type and use pattern, and 2) the current and future treatment strategies, including barriers that can impede successful recovery outcomes. Evidence-based psychosocial and pharmacotherapeutic treatments are reviewed. Psychological factors and central nervous system correlates that impact treatment adherence and response are discussed. Several novel therapeutic approaches that are currently under investigation are introduced; translational data from animal and human studies is presented, highlighting immunotherapy as a promising new direction for addiction medicine.

The aggregate effects of multiple comorbid risk factors on cognition among HIV-infected individuals

This study developed and then cross-validated a novel weighting algorithm based on multiple comorbid risk factors (stimulant use, vascular disease, hepatitis C, HIV disease severity, cognitive reserve) to predict cognitive functioning among 366 HIV+ adults. The resultant "risk severity score" was used to differentially weight, as a function of age, the impact and magnitude of multiple risk factors on cognition. Among older adults (≥50 years) the risk severity index was differentially predictive of learning/memory and verbal fluency, whereas among younger adults it was linked to working memory and executive function. Cognitive reserve was found to be the most robust predictor of neurocognition.

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.

Differential cognitive impairment in HCV coinfected men with controlled HIV compared to HCV monoinfection

BACKGROUND

Individuals infected with both HIV and hepatitis C virus (HCV) have shown impaired performance on different neuropsychological (NP) tests; however, whether coinfected individuals with controlled HIV and minimal liver damage in the era of antiretroviral therapy have impairment is understudied.

METHODS

Nineteen HCV monoinfected, 17 HIV/HCV coinfected, and 17 control male participants were evaluated for depression, attention, executive function, information processing, fine motor speed, and verbal/visual learning/memory. Eleven controls and 14 HIV monoinfected participants with controlled viral load from a previous study were also included for comparison. At time of testing, participants were not using drugs or alcohol and did not have cirrhosis. A global deficit score (GDS) was calculated from 7 domains of NP tests and alterations in specific domains were determined.

RESULTS

HIV/HCV subjects had a higher depression score (11.1 ± 7.5) than controls (5.4 ± 4.1, P = 0.010) and a higher GDS score (0.77 ± 0.47) than HCV (0.46 ± 0.34, P = 0.036), HIV (0.45 ± 0.36, P = 0.008), and controls (0.30 ± 0.29, P = 0.001). Coinfection was associated with worse scores in attention working memory (P =0.007), executive function (P = 0.01), fine motor function (P = 0.011), verbal learning/memory (P < 0.001), and visual learning/memory (P < 0.001) compared to controls. Within the HCV group, viral load was associated with lower attention, executive function, and information processing speed and positively with GDS.

CONCLUSIONS

Coinfection significantly increased the risk of cognitive impairment in subjects with controlled HIV viral loads. In HCV monoinfected but not coinfected subjects, HCV viral load correlated with worsening GDS, suggesting different pathways for NP impairment.

Modulation of intracellular restriction factors contributes to methamphetamine-mediated enhancement of acquired immune deficiency syndrome virus infection of macrophages

Epidemiological studies have demonstrated that the use of methamphetamine (METH), a sympathomimetic stimulant, is particularly common among patients infected with HIV. In vitro studies have determined that METH enhances HIV infection of CD4+ T cells, monocyte-derived dendritic cells, and macrophages. In addition, animal studies have also showed that METH treatment increases brain viral load of SIV-infected monkeys and promotes HIV replication and viremia in HIV/hu-CycT1 transgenic mice. However, the mechanisms (s) of METH actions on HIV remain to be determined. In this study, we investigated the impact of METH on intracellular restriction factors against HIV and SIV. We demonstrated that METH treatment of human blood mononuclear phagocytes significantly affected the expression of anti-HIV microRNAs and several key elements (RIG-I, IRF-3/5, SOCS-2, 3 and PIAS-1, 3, X, Y) in the type I IFN pathway. The suppression of these innate restriction factors was associated with a reduced production of type I IFNs and the enhancement of HIV or SIV infection of macrophages. These findings indicate that METH use impairs intracellular innate antiviral mechanism(s) in macrophages, contributing to cell susceptibility to the acquired immune deficiency syndrome (AIDS) virus infection.

Programming of neurotoxic cofactor CXCL-10 in HIV-1-associated dementia: abrogation of CXCL-10-induced neuro-glial toxicity in vitro by PKC activator

Background

More than 50% of patients undergoing lifelong suppressive antiviral treatment for HIV-1 infection develop minor HIV-1-associated neurocognitive disorders. Neurological complications during HIV-1 infection are the result of direct neuronal damage by proinflammatory products released from HIV-1-infected or -uninfected activated lymphocytes, monocytes, macrophages, microglia and astrocytes. The specific pro-inflammatory products and their roles in neurotoxicity are far from clear. We investigated proinflammatory cytokines and chemokines in the cerebrospinal fluid (CSF) of HIV-demented (HIV-D) and HIV-nondemented (HIV-ND) patients and studied their affect on neuroglial toxicity.

Methods and results

Bioplex array showed elevated levels of signatory chemokines or cytokines (IL-6, IFN-γ, CXCL10, MCP-1 and PDGF) in the CSF of HIV-D patients (n = 7) but not in that of HIV-ND patients (n = 7). Among the signatory cytokines and chemokines, CXCL10 was distinctly upregulated in-vitro in HIV-1 (NLENG1)-activated human fetal astrocytes, HIV-1 (Ba-L)-infected macrophages, and HIV-1 (NLENG1)-infected lymphocytes. Virus-infected macrophages also had increased levels of TNF-α. Consistently, human fetal astrocytes treated with HIV-1 and TNF-α induced the signatory molecules. CXCL10 in combination with HIV-1 synergistically enhanced neuronal toxicity and showed chemotactic activity (~ 40 fold) for activated peripheral blood mononuclear cells (PBMC), suggesting the intersection of signaling events imparted by HIV-1 and CXCL10 after binding to their respective surface receptors, CXCR4 and CXCR3, on neurons. Blocking CXCR3 and its downstream MAP kinase (MAPK) signaling pathway suppressed combined CXCL10 and HIV-1-induced neurotoxicity. Bryostatin, a PKC modulator and suppressor of CXCR4, conferred neuroprotection against combined insult with HIV-1 and CXCL10. Bryostatin also suppressed HIV-1 and CXCL10-induced PBMC chemotaxis. Although, therapeutic targeting of chemokines in brain may have adverse consequences on the host, current findings and earlier evidence suggest that CXCL10 could strongly impede neuroinflammation.

Conclusion

We have demonstrated induction of CXCL10 and other chemokines/cytokines during HIV-1 infection in the brain, as well as synergism of CXCL10 with HIV-1 in neuronal toxicity, which was dampened by bryostatin.

Acute HCV/HIV coinfection is associated with cognitive dysfunction and cerebral metabolite disturbance, but not increased microglial cell activation

BACKGROUND

Microglial cell activation and cerebral function impairment are described in both chronic hepatitis C viral (HCV) and Human-Immune-Deficiency viral (HIV) infections. The aim of this study was to investigate the effect of acute HCV infection upon cerebral function and microglial cell activation in HIV-infected individuals.

METHODS

A case-control study was conducted. Subjects with acute HCV and chronic HIV coinfection (aHCV) were compared to matched controls with chronic HIV monoinfection (HIVmono). aHCV was defined as a new positive plasma HCV RNA within 12 months of a negative RNA test. Subjects underwent neuro-cognitive testing (NCT), cerebral proton magnetic resonance spectroscopy ((1)H-MRS) and positron emission tomography (PET) using a (11)C-radiolabeled ligand (PK11195), which is highly specific for translocator protein 18 kDA receptors on activated microglial cells. Differences between cases and controls were assessed using linear regression modelling.

RESULTS

Twenty-four aHCV cases completed NCT and (1)H-MRS, 8 underwent PET. Of 57 HIVmono controls completing NCT, 12 underwent (1)H-MRS and 8 PET. Subjects with aHCV demonstrated on NCT, significantly poorer executive function (mean (SD) error rate 26.50(17.87) versus 19.09(8.12), p = 0.001) and on (1)H-MRS increased myo-inositol/creatine ratios (mI/Cr, a marker of cerebral inflammation) in the basal ganglia (ratio of 0.71(0.22) versus 0.55(0.23), p = 0.03), compared to subjects with HIVmono. On PET imaging, no difference in (11)C-PK11195 binding potential (BP) was observed between study groups (p>0.10 all cerebral locations), however lower BPs were associated with combination antiretroviral therapy (cART) use in the parietal (p = 0.01) and frontal (p = 0.03) cerebral locations.

DISCUSSION

Poorer cognitive performance and disturbance of cerebral metabolites are observed in subjects with aHC,V compared to subjects with HIVmono. Higher (11)C-PK11195 BP was not observed in subjects with aHCV, but was observed in subjects not on cART.

The effects of psychostimulant drugs on blood brain barrier function and neuroinflammation

The blood brain barrier (BBB) is a highly dynamic interface between the central nervous system (CNS) and periphery. The BBB is comprised of a number of components and is part of the larger neuro(glio)vascular unit. Current literature suggests that psychostimulant drugs of abuse alter the function of the BBB which likely contributes to the neurotoxicities associated with these drugs. In both preclinical and clinical studies, psychostimulants including methamphetamine, MDMA, cocaine, and nicotine, produce BBB dysfunction through alterations in tight junction protein expression and conformation, increased glial activation, increased enzyme activation related to BBB cytoskeleton remodeling, and induction of neuroinflammatory pathways. These detrimental changes lead to increased permeability of the BBB and subsequent vulnerability of the brain to peripheral toxins. In fact, abuse of these psychostimulants, notably methamphetamine and cocaine, has been shown to increase the invasion of peripheral bacteria and viruses into the brain. Much work in this field has focused on the co-morbidity of psychostimulant abuse and human immunodeficiency virus (HIV) infection. As psychostimulants alter BBB permeability, it is likely that this BBB dysfunction results in increased penetration of the HIV virus into the brain thus increasing the risk of and severity of neuro AIDS. This review will provide an overview of the specific changes in components within the BBB associated with psychostimulant abuse as well as the implications of these changes in exacerbating the neuropathology associated with psychostimulant drugs and HIV co-morbidity.

Intra-individual variability across neurocognitive domains in chronic hepatitis C infection: elevated dispersion is associated with serostatus and unemployment risk

Approximately one-third of persons infected with the hepatitis C virus (HCV) evidence mild cognitive impairment that is consistent with frontostriatal systems dysfunction, including cognitive dyscontrol, and impacts everyday functioning. The present study examined the effects of HCV on neurocognitive dispersion, or within-person variability in neurocognitive performance across domains, which may be a function of poor sustained cognitive control. High dispersion was also hypothesized to increase risk for unemployment. The study sample included 37 individuals with HCV infection (HCV+) and 45 demographically comparable uninfected comparison participants (HCV-). Dispersion was operationalized as an intra-individual standard deviation (ISD) calculated across the demographically adjusted T-scores of 13 standard neuropsychological tests. Multiple linear regression and logistic regression approaches were used to evaluate associations between dispersion and HCV serostatus and employment status, respectively. HCV serostatus was significantly associated with higher dispersion, independent of mean level of neurocognitive ability, psychiatric factors, and liver disease severity. Within the HCV+ group, higher dispersion was associated with an increased risk of unemployment among individuals with higher overall mean neurocognitive ability. Increased neurocognitive dispersion among HCV+ individuals may indicate vulnerability to cognitive dyscontrol expressed as poor regulation of performance across tasks. Higher dispersion may manifest as functional difficulties in daily life, particularly among neurocognitively normal HCV-infected persons, which speaks to the potential clinical value of considering intra-individual variability when evaluating risk for everyday function problems in this population.

Factors associated with cerebrospinal fluid HIV RNA in HIV infected subjects undergoing lumbar puncture examination in a clinical setting

BACKGROUND

Cerebrospinal fluid (CSF) HIV RNA load may be associated with central nervous system (CNS) disease in HIV infected subjects. We investigated parameters associated with CSF HIV RNA within a large clinical cohort.

METHODS

All HIV infected subjects undergoing CSF examination including assessment of CSF HIV RNA at St. Mary's Hospital, London, UK between January 2008 and October 2010 were included. Parameters associated with a detectable CSF HIV RNA load were assessed using linear regression modelling. CSF viral escape was defined as CSF RNA >0.5 log(10) copies/mL greater than plasma HIV RNA and >200 copies/mL where plasma HIV RNA <50 copies/mL.

RESULTS

Of 142 subjects, 99 were receiving antiretroviral therapy (ART). Plasma HIV RNA was <50 copies/mL in 69 subjects. CSF examination was performed for investigation of presumed HIV encephalopathy (IxHE, n = 57), other CNS diseases considered HIV related (n = 39), syphilis (n = 20) and CNS presentations not considered HIV related (n = 26). CSF viral escape was present in 30/142 (21%) subjects overall and in 9/69 (13%) of those on ART with undetectable plasma HIV RNA. Overall, plasma HIV RNA load was significantly associated with detectable CSF HIV RNA (p ≤ 0.001). In subjects with plasma HIV RNA <50 copies/mL, only CNS penetration effectiveness (CPE, 2008) score of <2 was significantly associated with detectable CSF HIV RNA (p = 0.044). In patients undergoing LP for IxHE both plasma HIV RNA and CPE scores were independently associated with detectable CSF HIV RNA (p = 0.019 & 0.003 respectively) which was not observed in subjects undergoing CSF examination for other medical reasons.

CONCLUSIONS

In a clinical setting, CSF viral escape is observed frequently in 21% of subjects and is associated with different parameters depending on the clinical scenario.

Effects of hepatitis C and HIV on cognition in women: data from the Women's Interagency HIV Study

OBJECTIVE

To compare neuropsychological scores in women infected with HIV, women infected with both HIV and hepatitis C, and uninfected subjects.

BACKGROUND

Some, but not all, studies have demonstrated that dual infection with Hepatitis C virus (HCV) and HIV has worse effects on cognition than infection with HIV alone.

DESIGN/METHODS

The Women's Interagency HIV Study is an ongoing prospective study of the natural history of HIV in women where participants are reevaluated every 6 months. In a cross-sectional analysis, we evaluated the effects of active HIV and HCV infections on scores on symbol-digit modalities test, the Stroop interference test, and trails A and B after controlling for age, ethnicity, education, depression, liver disease, and current or past substance abuse.

RESULTS

Data were available for 1338 women-17.8 % had detectable hepatitis C virus and 67% were HIV seropositive. In fully adjusted general linear models, HCV viremia was not associated with scores on any of the cognitive tests.

CONCLUSIONS

In this large sample of women, active HCV infection was not associated with scores on a small battery of neuropsychological tests.