Relationship of plasma cytokines and clinical biomarkers to memory performance in HIV

The Impact of COVID-19 on People Living with HIV-1 and HIV-1-Associated Neurological Complications

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative pathogen of the coronavirus disease 2019 (COVID-19) pandemic, a fatal respiratory illness. The associated risk factors for COVID-19 are old age and medical comorbidities. In the current combined antiretroviral therapy (cART) era, a significant portion of people living with HIV-1 (PLWH) with controlled viremia is older and with comorbidities, making these people vulnerable to SARS-CoV-2 infection and COVID-19-associated severe outcomes. Additionally, SARS-CoV-2 is neurotropic and causes neurological complications, resulting in a health burden and an adverse impact on PLWH and exacerbating HIV-1-associated neurocognitive disorder (HAND). The impact of SARS-CoV-2 infection and COVID-19 severity on neuroinflammation, the development of HAND and preexisting HAND is poorly explored. In the present review, we compiled the current knowledge of differences and similarities between SARS-CoV-2 and HIV-1, the conditions of the SARS-CoV-2/COVID-19 and HIV-1/AIDS syndemic and their impact on the central nervous system (CNS). Risk factors of COVID-19 on PLWH and neurological manifestations, inflammatory mechanisms leading to the neurological syndrome, the development of HAND, and its influence on preexisting HAND are also discussed. Finally, we have reviewed the challenges of the present syndemic on the world population, with a particular emphasis on PLWH.

Insult to Injury-Potential Contribution of Coronavirus Disease-19 to Neuroinflammation and the Development of HIV-Associated Neurocognitive Disorders

Severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 is responsible for a new coronavirus disease known as coronavirus disease-19 (COVID-19). SARS-CoV-2 reports neurotropic properties and may have neurological implications, and this creates another health burden for people living with HIV. As yet, the impact of COVID-19 on (neuro)inflammation and the development of HIV-associated neurocognitive disorders (HAND) is not fully known. Here, we reviewed preliminary evidence that provides clues that COVID-19 may exacerbate inflammatory mechanisms related to the development of HAND.

NLRP3 and IL-1β Gene Expression Is Elevated in Monocytes From HIV-Treated Patients With Neurocognitive Disorders

BACKGROUND

Systemic immune activation and inflammation in chronic HIV infection are driving factors of non-AIDS-related events, including neurocognitive impairment. The role of inflammasome in monocytes from patients with HIV infection has been extensively studied, but its association with the extent of neurocognitive dysfunction has been poorly investigated.

METHODS

We enrolled 79 HIV-positive patients; 44 with varying levels of HIV-associated neurocognitive disorder (HAND) and 35 without and 8 healthy donors. HAND subtypes included asymptomatic neurocognitive impairment (asymptomatic neurocognitive impairment; n = 19), mild neurocognitive disorder (MND; n = 17), and HIV-associated dementia (n = 8). We quantified plasmatic concentrations of proinflammatory cytokines (TNF-α, IL-6, IL-17A, IL-1β, and IFN-γ) for all HIV patients, and the mRNA expression of genes involved in the inflammasome activity (NLRP3, PYCARD, NAIP, AIM2, IL-1β, and IL-18) in monocytes of a subgroup of 28 HIV patients and 8 healthy donors.

RESULTS

HIV patients' plasma concentrations of IFN-γ, IL-1β, and IL-17A were undetectable. Levels of TNF-α and IL-6 were similar among the HIV patient groups. A trend toward an increased expression of inflammasome genes according to neurocognitive disorder severity was observed. Of note, the NLRP3 mRNA relative expression was higher in MND compared with other groups, and IL-1β was lower in MND than HIV-associated dementia patients.

CONCLUSIONS

Changes in inflammasome components in circulating monocytes according to different HAND severity suggest that NLRP3 may be a possible biomarker or target to better understand and treat the link between systemic inflammation and neurocognitive impairment in HIV infection.

Peripheral immune dysregulation in the ART era of HIV-associated neurocognitive impairments: A systematic review

Human immunodeficiency virus-associated neurocognitive impairment (HANI) remains problematic despite the effective use of antiretroviral therapy (ART) and viral suppression. A dysregulated immune response contributes to the development of HANI but findings on the association between peripheral blood immune markers and HANI have been inconsistent. We therefore conducted a systematic review of studies of the association of peripheral blood immune markers with neurocognitive performance in ART experienced HIV-positive participants. Thirty-seven studies were eligible, including 12 longitudinal studies and 25 cross-sectional studies. Findings consistently show that HIV-positive participants have altered immune marker levels, including elevated markers of monocyte activation (neopterin, sCD14, sCD163) and inflammation (CCL2, IL-8, IL-18, IP-10, IFN-α, sTNFR-II and TNF-α). These elevated levels persist in HIV-positive participants despite ART. The majority of studies found associations of HANI with immune markers, including those linked to monocyte activation (sCD14 and sCD163) and inflammation (IL-18 and IP-10). Despite the heterogeneity of studies reviewed, due to the presence of raised peripheral markers, our narrative review provides evidence of chronic inflammation despite ART. The raised levels of these markers may suggest certain mechanisms are active, potentially those involved in the neuropathophysiology of HANI.

The association of peripheral immune markers with brain cortical thickness and surface area in South African people living with HIV

A spectrum of cognitive impairments known as HIV-associated neurocognitive disorders (HAND) are consequences of the effects of HIV-1 within the central nervous system. Regardless of treatment status, an aberrant chronic neuro-immune regulation is a crucial contributor to the development of HAND. However, the extent to which inflammation affects brain structures critical for cognitive status remains unclear. The present study aimed to determine associations of peripheral immune markers with cortical thickness and surface area. Participants included 65 treatment-naïve HIV-positive individuals and 26 HIV-negative controls. Thickness and surface area of all cortical regions were derived using automated parcellation of T1-weighted images acquired at 3 T. Peripheral immune markers included C-C motif ligand 2 (CCL2), matrix metalloproteinase 9 (MMP9), neutrophil gelatinase-associated lipocalin (NGAL), thymidine phosphorylase (TYMP), transforming growth factor (TGF)-β1, and vascular endothelial growth factor (VEGF), which were measured using enzyme-linked immunosorbent assays. Associations of these markers with thickness and surface area of cortical regions were evaluated. A mediation analysis examined whether associations of inflammatory markers with cognitive functioning were mediated by brain cortical thickness and surface area. After controlling for multiple comparisons, higher NGAL was associated with reduced thickness of the bilateral orbitofrontal cortex in HIV-positive participants. The association of NGAL with worse motor function was mediated by cortical thickness of the bilateral orbitofrontal region. Taken together, this study suggests that NGAL plays a potential role in the neuropathophysiology of neurocognitive impairments of HIV.

Remitted depression and cognition in HIV: The role of cortisol and inflammation

In major depressive disorder (MDD) and remitted MDD (rMDD) alterations in cortisol and inflammation are associated with cognitive difficulties, but these relationships have not been investigated in HIV. We used secondary data from a placebo-controlled, cross-over study of cognitive performance following a probe of the hypothalamic-pituitary-adrenal (HPA) axis (low dose hydrocortisone; LDH 10 mg) in 65 people with HIV (PWH; 36 women). Using placebo data, we examined sex-specific associations between two biomarkers - basal afternoon salivary cortisol and salivary inflammatory cytokines - cognition, and rMDD. Salivary cortisol and inflammatory biomarkers were sampled across the 5 -h study. The panel of inflammatory markers included interleukin (IL)-6, IL-8, IL-1β, tumor necrosis factor-(TNF)-α, CRP, interferon gamma-induced protein (IP-10), monocyte chemotactic protein (MCP)-1, monokine induced by interferon (MIG), matrix metalloproteinase MMP-9, and MMP-1. Learning, memory, attention/concentration, and executive function were assessed 30 min and 4 h after the placebo intervention; visuospatial ability was also assessed 30 min after the placebo intervention. For women but not men with HIV, basal cortisol concentrations were higher in rMDD versus noMDD groups, and related to poorer learning and memory. For men and women with HIV, basal inflammatory cytokines were higher in rMDD versus noMDD groups, but were negatively related to cognition independent of rMDD status. Cortisol and cytokines relate to cognition in PWH, but the associations depended on sex, rMDD status, and their interaction.

Exploring the Etiological Links behind Neurodegenerative Diseases: Inflammatory Cytokines and Bioactive Kynurenines

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases (NDs), presenting a broad range of symptoms from motor dysfunctions to psychobehavioral manifestations. A common clinical course is the proteinopathy-induced neural dysfunction leading to anatomically corresponding neuropathies. However, current diagnostic criteria based on pathology and symptomatology are of little value for the sake of disease prevention and drug development. Overviewing the pathomechanism of NDs, this review incorporates systematic reviews on inflammatory cytokines and tryptophan metabolites kynurenines (KYNs) of human samples, to present an inferential method to explore potential links behind NDs. The results revealed increases of pro-inflammatory cytokines and neurotoxic KYNs in NDs, increases of anti-inflammatory cytokines in AD, PD, Huntington's disease (HD), Creutzfeldt-Jakob disease, and human immunodeficiency virus (HIV)-associated neurocognitive disorders, and decreases of neuromodulatory KYNs in AD, PD, and HD. The results reinforced a strong link between inflammation and neurotoxic KYNs, confirmed activation of adaptive immune response, and suggested a possible role in the decrease of neuromodulatory KYNs, all of which may contribute to the development of chronic low grade inflammation. Commonalities of multifactorial NDs were discussed to present a current limit of diagnostic criteria, a need for preclinical biomarkers, and an approach to search the initiation factors of NDs.

The Association of Immune Markers with Cognitive Performance in South African HIV-Positive Patients

Dysregulated expression of neuro-immune markers has previously been linked to HIV-associated neurocognitive impairment. We undertook an exploratory approach in a HIV clade-C cohort, investigating the association between eight immune markers and neurocognitive performance in 99 HIV+ and 51 HIV- participants. Markers were selected on preliminary and putative evidence of their link to key neuro-immune functions. Cognitive performance was established using a battery of tests sensitive to HIV-associated neurocognitive impairment, with domain-based scores utilized in analysis. The markers Thymidine phosphorylase (TYMP) and Neutrophil gelatinase-associated lipocalin (NGAL) were significantly higher while Matrix Metalloproteinase (MMP)9 was significantly lower in HIV+ participants. Our results further showed that in the HIV+ group, worse psychomotor processing speed was associated with higher TYMP and NGAL levels and worse motor function was associated with higher NGAL levels. Future studies should explore the underlying mechanisms of these markers in HIV-associated neurocognitive impairment. Graphical Abstract The association of peripheral immune markers with neurocognitive performance in South African HIV-positive patients.

A single low dose of hydrocortisone enhances cognitive functioning in HIV-infected women

OBJECTIVE

Low-dose hydrocortisone (LDH) enhances aspects of learning and memory in select populations including patients with posttraumatic stress disorder and HIV-infected men. HIV-infected women show impairments in learning and memory, but the cognitive effects of LDH in HIV-infected women are unknown.

DESIGN

Double-blind, placebo-controlled, cross-over study examining the time-dependent effects of a single low-dose administration of hydrocortisone (10 mg oral) on cognition in 36 HIV-infected women. Participants were first randomized to LDH or placebo and then received the opposite treatment one month later.

METHODS

Cognitive performance was assessed 30 min and 4 h after pill administration to assess, respectively, nongenomic and genomic effects. Self-reported stress/anxiety and salivary cortisol were assessed throughout sessions.

RESULTS

LDH significantly increased salivary cortisol levels versus placebo; levels returned to baseline 4-h postadministration. At the 30-min assessment, LDH enhanced verbal learning and delayed memory, working memory, behavioral inhibition, and visuospatial abilities. At the 4-h assessment, LDH enhanced verbal learning and delayed memory compared with placebo. LDH-induced cognitive benefits related to reductions in cytokines and to a lesser extent to increases in cortisol.

CONCLUSION

The extended benefits from 30 min to 4 h of a single administration of LDH on learning and delayed memory suggest that targeting the hypothalamic-pituitary-adrenal axis may have potential clinical utility in HIV-infected women. These findings contrast with our findings in HIV-infected men who showed improved learning only at the 30-min assessment. Larger, longer term studies are underway to verify possible cognitive enhancing effects of LDH and the clinical significance of these effects in HIV.

Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and Functional Connectivity Alterations in Hippocampus

Patients with minimal hepatic encephalopathy (MHE) show mild cognitive impairment associated with alterations in attentional and executive networks. There are no studies evaluating the relationship between memory in MHE and structural and functional connectivity (FC) changes in the hippocampal system. This study aimed to evaluate verbal learning and long-term memory in cirrhotic patients with (C-MHE) and without MHE (C-NMHE) and healthy controls. We assessed the relationship between alterations in memory and the structural integrity and FC of the hippocampal system. C-MHE patients showed impairments in learning, long-term memory, and recognition, compared to C-NMHE patients and controls. Cirrhotic patients showed reduced fimbria volume compared to controls. Larger volumes in hippocampus subfields were related to better memory performance in C-NMHE patients and controls. C-MHE patients presented lower FC between the L-presubiculum and L-precuneus than C-NMHE patients. Compared to controls, C-MHE patients had reduced FC between L-presubiculum and subiculum seeds and bilateral precuneus, which correlated with cognitive impairment and memory performance. Alterations in the FC of the hippocampal system could contribute to learning and long-term memory impairments in C-MHE patients. This study demonstrates the association between alterations in learning and long-term memory and structural and FC disturbances in hippocampal structures in cirrhotic patients.

Peripheral TNFα elevations in abstinent alcoholics are associated with hepatitis C infection

Substantial evidence supports the view that inflammatory processes contribute to brain alterations in HIV infection. Mechanisms recently proposed to underlie neuropathology in Alcohol Use Disorder (AUD) include elevations in peripheral cytokines that sensitize the brain to the damaging effects of alcohol. This study included 4 groups: healthy controls, individuals with AUD (abstinent from alcohol at examination), those infected with HIV, and those comorbid for HIV and AUD. The aim was to determine whether inflammatory cytokines are elevated in AUD as they are in HIV infection. Cytokines showing group differences included interferon gamma-induced protein 10 (IP-10) and tumor necrosis factor α (TNFα). Follow-up t-tests revealed that TNFα and IP-10 were higher in AUD than controls but only in AUD patients who were seropositive for Hepatitis C virus (HCV). Specificity of TNFα and IP-10 elevations to HCV infection status was provided by correlations between cytokine levels and HCV viral load and indices of liver integrity including albumin/globulin ratio, fibrosis scores, and AST/platelet count ratio. Because TNFα levels were mediated by HCV infection, this study provides no evidence for elevations in peripheral cytokines in "uncomplicated", abstinent alcoholics, independent of liver disease or HCV infection. Nonetheless, these results corroborate evidence for elevations in IP-10 and TNFα in HIV and for IP-10 levels in HIV+HCV co-infection.

Variability in C-reactive protein is associated with cognitive impairment in women living with and without HIV: a longitudinal study

Despite the availability of effective antiretroviral therapies, cognitive impairment (CI) remains prevalent in HIV-infected (HIV+) individuals. Evidence from primarily cross-sectional studies, in predominantly male samples, implicates monocyte- and macrophage-driven inflammatory processes linked to HIV-associated CI. Thus, peripheral systemic inflammatory markers may be clinically useful biomarkers in tracking HIV-associated CI. Given sex differences in immune function, we focused here on whether mean and intra-individual variability in inflammatory marker-predicted CI in HIV+ and HIV- women. Seventy-two HIV+ (36 with CI) and 58 HIV- (29 with CI) propensity-matched women participating in the Women's Interagency HIV Study completed a neuropsychological battery once between 2009 and 2011, and performance was used to determine CI status. Analysis of 13 peripheral immune markers was conducted on stored biospecimens at three time points (7 and 3.5 years before neuropsychological data collection and concurrent with data collection). HIV+ women showed alterations in 8 immune markers compared to HIV- women. The strongest predictors of CI across HIV+ and HIV- women were lower mean soluble tumor necrosis factor receptor I (sTNFRI) levels, higher mean interleukin (IL)-6 levels, and greater variability in C-reactive protein (CRP) and matrix metalloproteinase (MMP)-9 (p values < 0.05). Stratified by HIV, the only significant predictor of CI was greater variability in CRP for both HIV+ and HIV- women (p values < 0.05). This variability predicted lower executive function, attention/working memory, and psychomotor speed in HIV+ but only learning in HIV- women (p values < 0.05). Intra-individual variability in CRP levels over time may be a good predictor of CI in predominately minority low-socioeconomic status midlife women.

Childhood maltreatment and HIV-associated neurocognitive disorders share similar pathophysiology: a potential sensitisation mechanism?

HIV-associated neurocognitive disorders (HAND) are increasingly prevalent despite the use of antiretroviral therapies. Previous research suggests that individual host factors play an important role in determining susceptibility to HAND. In this review, we propose that childhood trauma (CT) and HAND share several common aetiological mechanisms, namely hypothalamic-pituitary-adrenal axis dysregulation, neuroinflammation and oxidative stress. These convergent and consequent mechanisms may translate into an increased risk of developing HAND in individuals who have experienced early life stress. We provide an overview of basic and clinical research relating to these pathophysiological mechanisms and suggest that further research examine brain-derived neurotrophic factor and telomere length as common mediating factors and potential therapeutic targets for HAND and CT. Graphical abstract Both childhood trauma and HIV-associated neurocognitive disorders are associated with HPA axis dysregulation, inflammation and oxidative stress.

Neurocognitive profile of HIV-positive adults on combined antiretroviral therapy: A single-centre study in Serbia

The advent of combined antiretroviral therapy (cART) has prolonged the life expectancy of HIV + individuals and decreased the incidence of HIV-associated dementia. However, milder forms of neurocognitive impairment remain common and are often associated with poor daily functioning and lower medication adherence. This paper presents a research aimed at exploring the cognitive status differences between HIV + subjects (N = 39) on cART therapy and a group of demographically comparable healthy subjects (N = 39) in Serbia. The significance of differences between the HIV + group and the healthy control group in performance in six cognitive domains was tested using the multivariate analysis of variance. Results showed a lower performance of the HIV + group in the domains of attention/working memory, and learning. HIV-related clinical variables were not significantly associated with cognitive performance. An older age in HIV + patients was significantly related to a lower performance in all six cognitive domains, as opposed to healthy subjects, implying a synergistic interaction between HIV and aging, resulting in accentuated cognitive difficulties. Our findings suggest that even with the absence of a subjective experience of cognitive deficits and with a good basic control of the illness, a certain degree of cognitive deficit can be observed in the tested group.

Brief Report: CD14+ Enriched Peripheral Cells Secrete Cytokines Unique to HIV-Associated Neurocognitive Disorders

Monocytes play a vital role in HIV-associated neurocognitive disorder (HAND), postulated to transport HIV into the brain and secrete pro-inflammatory cytokines. We analyzed cytokines released by cultured peripheral blood mononuclear cells enriched with the CD14 marker isolated from HIV-infected individuals with HAND and normal cognition (NC) in combination antiretroviral therapy naive and after 1 year on treatment. Interleukin-8 and monocyte chemoattractant protein-1 levels were higher in HAND compared with NC at baseline (P = 0.002 and P < 0.0001). These cytokines remained higher in HAND patients 1 year after combination antiretroviral therapy and were significant when NC patients who were initially HAND were excluded (P = 0.012 and P = 0.002). Both correlated with baseline CD14 peripheral blood mononuclear cell HIV DNA levels supporting the role of HIV DNA reservoir size and monocyte cytokines in HAND persistence.

Lower total and regional grey matter brain volumes in youth with perinatally-acquired HIV infection: Associations with HIV disease severity, substance use, and cognition

Despite improved survival due to combination antiretroviral therapy (cART), youth with perinatally-acquired HIV (PHIV) show cognitive deficits and developmental delay at increased rates. HIV affects the brain during critical periods of development, and the brain may be a persistent reservoir for HIV due to suboptimal blood brain barrier penetration of cART. We conducted structural magnetic resonance imaging (sMRI) and cognitive testing in 40 PHIV youth (mean age=16.7years) recruited from the NIH Pediatric HIV/AIDS Cohort Study (PHACS) who are part of the first generation of PHIV youth surviving into adulthood. Historical and current HIV disease severity and substance use measures were also collected. Total and regional cortical grey matter brain volumes were compared to a group of 334 typically-developing, HIV-unexposed and uninfected youth (frequency-matched for age and sex) from the Pediatric Imaging, Neurocognition, and Genetics (PING) study (mean age=16.1years). PHIV youth had smaller (2.8-5.1%) total and regional grey matter volumes than HIV-unexposed and uninfected youth, with smallest volumes seen among PHIV youth with higher past peak viral load (VL) and recent unsuppressed VL. In PHIV youth, worse cognitive performance correlated with smaller volumes. This pattern of smaller grey matter volumes suggests that PHIV infection may influence brain development and underlie cognitive dysfunction seen in this population. Among PHIV youth, smaller volumes were also linked to substance use (alcohol use: 9.0-13.4%; marijuana use: 10.1-16.0%). In this study, collection of substance use information was limited to the PHIV cohort; future studies should also collect substance use information in controls to further address interactions between HIV and substance use on brain volume.

Cytokines, Hepatic Fibrosis, and Antiretroviral Therapy Role in Neurocognitive Disorders HIV Related

The HIV may trigger a process of neuronal loss and axonal degeneration throughout the brain, which is carried on by the immune system releasing of proinflammatory cytokines, so that chronic inflammation associated with dysregulated innate immune response, glial cell dysfunction, and adverse antiretroviral therapy (ART) effect play an important role causing milder HIV-associated neurocognitive disorders or asymptomatic neurocognitive impairment. All patients have been tested for neurocognitive functioning through a comprehensive, five-domain neuropsychological battery performed in the study. Human cytokine (interleukin [IL]-6, IL-8, IL-18, and tumor necrosis factor [TNF]-α) and brain-derived neurotrophic factor serum levels were quantified using ELISAs, and the hepatic fibrosis was estimated using the noninvasive Fibrosis 4 (FIB-4) score. The study showed a group of 40 HIV-infected individuals and it was observed that almost 40% of HIV⁺ individuals, even if clinically asymptomatic, displayed some degree of neurocognitive dysfunction, compared to normative performance standards, at least in two cognitive areas. The functions affected the most were memory, attention, executive function, and psychomotor processing speed. Three cytokines (IL-6, IL-8, and IL-18) to be significantly linked to test results in specific neurocognitive domain were found. Treatments with nucleoside reverse transcriptase inhibitor plus non-nucleoside reverse transcriptase inhibitor alone were instead associated with poor neurocognitive outcome, especially in verbal fluency, fine motility, and Zung Depression Scale. Elevated value of FIB-4 score showed an opposite connection with cognitive performance as well, underlining the direct association between hepatic steatosis and neurocognitive deficit. The cytokine panel and the FIB-4 score can predict presence or worsening of neurocognitive functions in HIV-infected individuals. An ART switch can be suggested according to the neurocognitive domain involved the most, advising a therapy with protease inhibitors or/and integrase inhibitors to improve fluency, executive functions, and to prevent depression.

Body mass index, inflammatory biomarkers and neurocognitive impairment in HIV-infected persons

To determine the relationships among body mass index (BMI), and HIV-associated neurocognitive impairment and the potential mediating effects of inflammatory cytokines. Among the HIV-infected individuals (N = 90) included in this study, obesity was associated with slower processing speed (β = -.229, standard error (SE) = 2.15, p = .033), compared to participants with a normal BMI, after controlling for psychosocial and HIV clinical factors. Serum concentrations of the interleukin-16 (IL-16) cytokine were significantly associated with slowed processing speed (β = -.235, SE = 1.62, p = .033) but did not mediate the relationship between obesity and processing speed These findings suggest that obesity may contribute to cognitive processing speed deficits in HIV-infected adults. Elevated concentrations of IL-16 are also associated with slowing, though the results suggest that obesity and IL-16 may exert independent effects.

Immune activation and neuroinflammation in alcohol use and HIV infection: evidence for shared mechanisms

BACKGROUND

Emerging research points to innate immune mechanisms in the neuropathological and behavioral consequences of heavy alcohol use. Alcohol use is common among people living with HIV infection (PLWH), a chronic condition that carries its own set of long-term effects on brain and behavior. Notably, neurobiological and cognitive profiles associated with heavy alcohol use and HIV infection share several prominent features. This observation raises questions about interacting biological mechanisms as well as compounded impairment when HIV infection and heavy drinking co-occur.

OBJECTIVE AND METHOD

This narrative overview discusses peer-reviewed research on specific immune mechanisms of alcohol that exhibit apparent potential to compound the neurobiological and psychiatric sequelae of HIV infection. These include microbial translocation, systemic immune activation, blood-brain barrier compromise, microglial activation, and neuroinflammation.

RESULTS

Clinical and preclinical evidence supports overlapping mechanistic actions of HIV and alcohol use on peripheral and neural immune systems. In preclinical studies, innate immune signaling mediates many of the detrimental neurocognitive and behavioral effects of alcohol use. Neuropsychopharmacological research suggests potential for a feed-forward cycle in which heavy drinking induces innate immune signaling, which in turn stimulates subsequent alcohol use behavior.

CONCLUSION

Alcohol-induced immune activation and neuroinflammation are a serious health concern for PLWH. Future research to investigate specific immune effects of alcohol in the context of HIV infection has potential to identify novel targets for therapeutic intervention.

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.

A review of the neuro- and systemic inflammatory responses in post concussion symptoms: Introduction of the "post-inflammatory brain syndrome" PIBS

Post-concussion syndrome is an aggregate of symptoms that commonly present together after head injury. These symptoms, depending on definition, include headaches, dizziness, neuropsychiatric symptoms, and cognitive impairment. However, these symptoms are common, occurring frequently in non-head injured controls, leading some to question the existence of post-concussion syndrome as a unique syndrome. Therefore, some have attempted to explain post-concussion symptoms as post-traumatic stress disorder, as they share many similar symptoms and post-traumatic stress disorder does not require head injury. This explanation falls short as patients with post-concussion syndrome do not necessarily experience many key symptoms of post-traumatic stress disorder. Therefore, other explanations must be sought to explain the prevalence of post-concussion like symptoms in non-head injury patients. Many of the situations in which post-concussion syndrome like symptoms may be experienced such as infection and post-surgery are associated with systemic inflammatory responses, and even neuroinflammation. Post-concussion syndrome itself has a significant neuroinflammatory component. In this review we examine the evidence of neuroinflammation in post-concussion syndrome and the potential role systemic inflammation plays in post-concussion syndrome like symptoms. We conclude that given the overlap between these conditions and the role of inflammation in their etiologies, a new term, post-inflammatory brain syndromes (PIBS), is necessary to describe the common outcomes of many different inflammatory insults. The concept of post-concussion syndrome is in its evolution therefore, the new term post-inflammatory brain syndromes provides a better understanding of etiology of its wide-array of symptoms and the wide array of conditions they can be seen in.

Factors related to HIV-associated neurocognitive impairment differ with age

Over 50% of HIV-infected (HIV+) persons are expected to be over age 50 by 2015. The pathogenic effects of HIV, particularly in cases of long-term infection, may intersect with those of age-related illnesses and prolonged exposure to combined antiretroviral therapy (cART). One potential outcome is an increased prevalence of neurocognitive impairment in older HIV+ individuals, as well as an altered presentation of HIV-associated neurocognitive disorders (HANDs). In this study, we employed stepwise regression to examine 24 features sometimes associated with HAND in 40 older (55-73 years of age) and 30 younger (32-50 years of age) HIV+, cART-treated participants without significant central nervous system confounds. The features most effective in generating a true assessment of the likelihood of HAND diagnosis differed between older and younger cohorts, with the younger cohort containing features associated with drug abuse that were correlated to HAND and the older cohort containing features that were associated with lipid disorders mildly associated with HAND. As the HIV-infected population grows and the demographics of the epidemic change, it is increasingly important to re-evaluate features associated with neurocognitive impairment. Here, we have identified features, routinely collected in primary care settings, that provide more accurate diagnostic value than a neurocognitive screening measure among younger and older HIV individuals.