Cognitive impairment in older HIV-1-seropositive individuals: prevalence and potential mechanisms

Mechanisms underlying HIV-associated cognitive impairment and emerging therapies for its management

People living with HIV are affected by the chronic consequences of neurocognitive impairment (NCI) despite antiretroviral therapies that suppress viral replication, improve health and extend life. Furthermore, viral suppression does not eliminate the virus, and remaining infected cells may continue to produce viral proteins that trigger neurodegeneration. Comorbidities such as diabetes mellitus are likely to contribute substantially to CNS injury in people living with HIV, and some components of antiretroviral therapy exert undesirable side effects on the nervous system. No treatment for HIV-associated NCI has been approved by the European Medicines Agency or the US Food and Drug Administration. Historically, roadblocks to developing effective treatments have included a limited understanding of the pathophysiology of HIV-associated NCI and heterogeneity in its clinical manifestations. This heterogeneity might reflect multiple underlying causes that differ among individuals, rather than a single unifying neuropathogenesis. Despite these complexities, accelerating discoveries in HIV neuropathogenesis are yielding potentially druggable targets, including excessive immune activation, metabolic alterations culminating in mitochondrial dysfunction, dysregulation of metal ion homeostasis and lysosomal function, and microbiome alterations. In addition to drug treatments, we also highlight the importance of non-pharmacological interventions. By revisiting mechanisms implicated in NCI and potential interventions addressing these mechanisms, we hope to supply reasons for optimism in people living with HIV affected by NCI and their care providers.

Advancing the preclinical study of comorbid neuroHIV and substance use disorders: Current perspectives and future directions

Human immunodeficiency virus (HIV) remains a persistent public health concern throughout the world. Substance use disorders (SUDs) are a common comorbidity that can worsen treatment outcomes for people living with HIV. The relationship between HIV infection and SUD outcomes is likely bidirectional, making clear interrogation of neurobehavioral outcomes challenging in clinical populations. Importantly, the mechanisms through which HIV and addictive drugs disrupt homeostatic immune and CNS function appear to be highly overlapping and synergistic within HIV-susceptible reward and motivation circuitry in the central nervous system. Decades of animal research have revealed invaluable insights into mechanisms underlying the pathophysiology SUDs and HIV, although translational studies examining comorbid SUDs and HIV are very limited due to the technical challenges of modeling HIV infection preclinically. In this review, we discuss preclinical animal models of HIV and highlight key pathophysiological characteristics of each model, with a particular emphasis on rodent models of HIV. We then review the implementation of these models in preclinical SUD research and identify key gaps in knowledge in the field. Finally, we discuss how cutting-edge behavioral neuroscience tools, which have revealed key insights into the neurobehavioral mechanisms of SUDs, can be applied to preclinical animal models of HIV to reveal potential, novel treatment avenues for comorbid HIV and SUDs. Here, we argue that future preclinical SUD research would benefit from incorporating comorbidities such as HIV into animal models and would facilitate the discovery of more refined, subpopulation-specific mechanisms and effective SUD prevention and treatment targets.

Correlation of HIV-Induced Neuroinflammation and Synaptopathy with Impairment of Learning and Memory in Mice with HAND

Over 38 million people worldwide are living with HIV/AIDS, and more than half of them are affected by HIV-associated neurocognitive disorders (HAND). Such disorders are characterized by chronic neuroinflammation, neurotoxicity, and central nervous system deterioration, which lead to short- or long-term memory loss, cognitive impairment, and motor skill deficits that may show gender disparities. However, the underlying mechanisms remain unclear. Our previous study suggested that HIV-1 infection and viral protein R (Vpr) upregulate the SUR1-TRPM4 channel associated with neuroinflammation, which may contribute to HAND. The present study aimed to explore this relationship in a mouse model of HAND. This study employed the HIV transgenic Tg26 mouse model, comparing Tg26 mice with wildtype mice in various cognitive behavioral and memory tests, including locomotor activity tests, recognition memory tests, and spatial learning and memory tests. The study found that Tg26 mice exhibited impaired cognitive skills and reduced learning abilities compared to wildtype mice, particularly in spatial memory. Interestingly, male Tg26 mice displayed significant differences in spatial memory losses (p < 0.001), while no significant differences were identified in female mice. Consistent with our early results, SUR1-TRPM4 channels were upregulated in Tg26 mice along with glial fibrillary acidic protein (GFAP) and aquaporin 4 (AQP4), consistent with reactive astrocytosis and neuroinflammation. Corresponding reductions in neurosynaptic responses, as indicated by downregulation of Synapsin-1 (SYN1) and Synaptophysin (SYP), suggested synaptopathy as a possible mechanism underlying cognitive and motor skill deficits. In conclusion, our study suggests a possible relationship between SUR1-TRPM4-mediated neuroinflammation and synaptopathy with impairments of learning and memory in mice with HAND. These findings could help to develop new therapeutic strategies for individuals living with HAND.

Circulating brain-derived extracellular vesicles expressing neuroinflammatory markers are associated with HIV-related neurocognitive impairment

Background

Neurocognitive impairment remains prevalent in people with HIV (PWH) despite long term virological suppression by antiretroviral therapy (ART) regimens. Systemic and neuro-inflammatory processes are suggested to contribute to the complex pathology leading to cognitive impairment in this population, yet the underlying mechanisms remain unresolved. Extracellular vesicles (EVs) play a central role in intracellular communication and have emerged as key modulators of immunological and inflammatory responses. In this report, we examined the impact of EVs in PWH experiencing cognitive deficits to determine their relevance in HIV associated neuropathology.

Methods

EV phenotypes were measured in plasma samples from 108 PWH with either cognitive impairment (CI, n=92) or normal cognition (NC, n=16) by flow cytometry. Matched cerebrospinal fluid (CSF)-derived EVs were similarly profiled from a subgroup of 84 individuals who underwent a lumbar puncture. Peripheral blood mononuclear cells were assayed by flow cytometry to measure monocyte frequencies in a subset of 32 individuals.

Results

Plasma-EVs expressing CD14, CD16, CD192, C195, and GFAP were significantly higher in HIV-infected individuals with cognitive impairment compared to individuals with normal cognition. Increased CSF-EVs expressing GFAP and CD200 were found in the cognitive impairment group compared to the normal cognition group. Frequencies of patrolling monocytes correlated with plasma-EVs expressing CD14, CD66b, MCSF, MAP2, and GFAP. Frequencies of CD195 expression on monocytes correlated positively with plasma-EVs expressing CD41a, CD62P, and CD63. Expression of CD163 on monocytes correlated positively with CSF-EVs expressing GFAP and CD200. Finally, the expression of CD192 on total monocytes correlated with CSF-EVs expressing CD200, CD62P, and CD63.

Conclusions

EVs expressing monocyte activation and neuronal markers associated with HIV associated cognitive impairment, suggesting that distinct EV subsets may serve as novel biomarkers of neuronal injury in HIV infection. Further circulating platelet EV levels were linked to monocyte activation indicating a potential novel interaction in the pathogenesis of HIV-related cognitive impairment.

Arachidonic Acid Cascade and Eicosanoid Production Are Elevated While LTC4 Synthase Modulates the Lipidomics Profile in the Brain of the HIVgp120-Transgenic Mouse Model of NeuroHIV

BACKGROUND

Combination antiretroviral therapy (cART) has transformed HIV infection from a terminal disease to a manageable chronic health condition, extending patients' life expectancy to that of the general population. However, the incidence of HIV-associated neurocognitive disorders (HANDs) has persisted despite virological suppression. Patients with HIV display persistent signs of immune activation and inflammation despite cART. The arachidonic acid (AA) cascade is an important immune response system responsible for both pro- and anti-inflammatory processes.

METHODS

Lipidomics, mRNA and Western blotting analysis provide valuable insights into the molecular mechanisms surrounding arachidonic acid metabolism and the resulting inflammation caused by perturbations thereof.

RESULTS

Here, we report the presence of inflammatory eicosanoids in the brains of a transgenic mouse model of NeuroHIV that expresses soluble HIV-1 envelope glycoprotein in glial cells (HIVgp120tg mice). Additionally, we report that the effect of LTC4S knockout in HIVgp120tg mice resulted in the sexually dimorphic transcription of COX- and 5-LOX-related genes. Furthermore, the absence of LTC4S suppressed ERK1/2 and p38 MAPK signaling activity in female mice only. The mass spectrometry-based lipidomic profiling of these mice reveals beneficial alterations to lipids in the brain.

CONCLUSION

Targeting the AA cascade may hold potential in the treatment of neuroinflammation observed in NeuroHIV and HANDs.

Antiretroviral therapy in older people with HIV

PURPOSE OF REVIEW

The age of people with HIV) continues to rise, and yet older people have tended to be under-represented or excluded from premarketing studies of antiretroviral therapy (ART). In this review, we highlight special considerations for the use of ART in older people with HIV, with a focus on toxicities associated with specific antiretroviral agents or drug classes as well as key research questions moving forward.

RECENT FINDINGS

Like all people with HIV, older people with HIV should be started on ART as soon as possible, regardless of CD4 count, and with a regimen that includes an integrase strand transfer inhibitor (INSTI) and two nucleoside reverse transcriptase inhibitors. Important toxicities to consider when choosing an ART regimen include bone and renal effects related to tenofovir, weight gain related to INSTIs and tenofovir alafenamide, neurocognitive and neuropsychiatric toxicities related to efavirenz, and increased cardiovascular risk associated with abacavir and boosted protease inhibitors. With the ongoing importance of INSTIs as a component of preferred ART regimens, further characterization of INSTI-related weight gain is a critical current research priority in understanding ART toxicity.

SUMMARY

There are multiple potential toxicities of ART to consider when selecting a regimen for older people. Specific agents or drug classes have been implicated in adverse bone or renal effects, weight gain, neuropsychiatric and neurocognitive effects, and cardiovascular risk.

Metabolic Risk Factors as Differential Predictors of Profiles of Neurocognitive Impairment Among Older HIV+ and HIV- Adults: An Observational Study

OBJECTIVE

Neurocognitive performance among older persons, including those living with HIV (people living with HIV [PLWH]), exhibits significant heterogeneity, suggesting subpopulations with differing profiles of neurocognitive impairment (NCI). Metabolic factors are associated with NCI, but their relationships to cluster-derived NCI profiles are unknown.

METHOD

Participants (144 PLWH and 102 HIV uninfected) aged 50+ years completed a neuropsychological battery assessing seven cognitive domains. Latent class analysis (LCA) identified NCI profiles separately by HIV serostatus and in a combined sample. Obtained classes were examined against the Montreal Cognitive Assessment (MoCA) and diagnoses of HIV-associated neurocognitive disorders (HAND). Multinomial regression identified metabolic predictors of classification.

RESULTS

LCA identified three latent classes in each participant sample: Class1Multidomain NCI (high probability of impairment across multiple domains), Class 2Learning & Recall NCI (high probability of impairment in learning and recall), and Class 3NC Unimpaired (low probability of NCI across all domains). Severity of NCI implied by classes corresponded with MoCA scores and HAND diagnoses. In analyses on the combined sample, compared to HIV-uninfected individuals, PLWH were more likely to be in Class1Multidomain NCI. Among PLWH, those with dyslipidemia and hypertension had greater odds of classification in Class 1Multidomain NCI while those with central obesity had higher odds of classification in Class 2Learning & Recall NCI; metabolic syndrome approached significance as a differential predictor. Regardless of HIV status, individuals with diabetes were more likely to be in Class 1Multidomain NCI.

CONCLUSIONS

Metabolic risk factors confer heightened risk of NCI in HIV infection. Interventions to reduce metabolic risk may improve neurocognitive outcomes among PLWH.

HIV Neuropathogenesis in the Presence of a Disrupted Dopamine System

Antiretroviral therapy (ART) has transformed HIV into a chronic condition, lengthening and improving the lives of individuals living with this virus. Despite successful suppression of HIV replication, people living with HIV (PLWH) are susceptible to a growing number of comorbidities, including neuroHIV that results from infection of the central nervous system (CNS). Alterations in the dopaminergic system have long been associated with HIV infection of the CNS. Studies indicate that changes in dopamine concentrations not only alter neurotransmission, but also significantly impact the function of immune cells, contributing to neuroinflammation and neuronal dysfunction. Monocytes/macrophages, which are a major target for HIV in the CNS, are responsive to dopamine. Therefore, defining more precisely the mechanisms by which dopamine acts on these cells, and the changes in cellular function elicited by this neurotransmitter are necessary to develop therapeutic strategies to treat neuroHIV. This is especially important for vulnerable populations of PLWH with chemically altered dopamine concentrations, such as individuals with substance use disorder (SUD), or aging individuals using dopamine-altering medications. The specific neuropathologic and neurocognitive consequences of increased CNS dopamine remain unclear. This is due to the complex nature of HIV neuropathogenesis, and logistical and technical challenges that contribute to inconsistencies among cohort studies, animal models and in vitro studies, as well as lack of demographic data and access to human CNS samples and cells. This review summarizes current understanding of the impact of dopamine on HIV neuropathogenesis, and proposes new experimental approaches to examine the role of dopamine in CNS HIV infection. Graphical abstract HIV Neuropathogenesis in the Presence of a Disrupted Dopamine System. Both substance abuse disorders and the use of dopaminergic medications for age-related diseases are associated with changes in CNS dopamine concentrations and dopaminergic neurotransmission. These changes can lead to aberrant immune function, particularly in myeloid cells, which contributes to the neuroinflammation, neuropathology and dysfunctional neurotransmission observed in dopamine-rich regions in HIV+ individuals. These changes, which are seen despite the use antiretroviral therapy (ART), in turn lead to further dysregulation of the dopamine system. Thus, in individuals with elevated dopamine, the bi-directional interaction between aberrant dopaminergic neurotransmission and HIV infection creates a feedback loop contributing to HIV associated neurocognitive dysfunction and neuroHIV. However, the distinct contributions and interactions made by HIV infection, inflammatory mediators, ART, drugs of abuse, and age-related therapeutics are poorly understood. Defining more precisely the mechanisms by which these factors influence the development of neurological disease is critical to addressing the continued presence of neuroHIV in vulnerable populations, such as HIV-infected older adults or drug abusers. Due to the complexity of this system, understanding these effects will require a combination of novel experimental modalities in the context of ART. These will include more rigorous epidemiological studies, relevant animal models, and in vitro cellular and molecular mechanistic analysis.

Mindfulness-based stress reduction for HIV-associated neurocognitive disorder: Rationale and protocol for a randomized controlled trial in older adults

The symptom burden of HIV-associated neurocognitive disorder (HAND) is high among older individuals, and treatment options are limited. Mindfulness-based stress reduction (MBSR) has potential to improve neurocognitive performance, psychosocial wellbeing, and quality of life, but empirical studies in this growing vulnerable population are lacking. In this trial, participants (N = 180) age 55 and older who are living with HIV infection, are on combination antiretroviral therapy with suppressed viral loads, and yet continue to experience behavioral and cognitive symptoms of HAND, are randomized to MBSR or to a waitlist control arm that receives MBSR following a 16-week period of standard care. Primary outcomes (attention, executive function, stress, anxiety, depression, everyday functioning, quality of life) and potential mediators (affect, mindfulness) and moderators (social support, loneliness) are assessed at baseline and weeks 8, 16, and 48 in both groups, with an additional assessment at week 24 (post-MBSR) in the crossover control group. Assessments include self-report and objective measures (e.g., neuropsychological assessment, neurological exam, clinical labs). In addition, a subset of participants (n = 30 per group) are randomly selected to undergo fMRI to evaluate changes in functional connectivity networks and their relationship to changes in neuropsychological outcomes. Forthcoming findings from this randomized controlled trial have the potential to contribute to a growing public health need as the number of older adults with HAND is expected to rise.

The age-related trajectory of visual attention neural function is altered in adults living with HIV: A cross-sectional MEG study

Background

Despite living a normal lifespan, at least 35% of persons with HIV (PWH) in resource-rich countries develop HIV-associated neurocognitive disorder (HAND). This high prevalence of cognitive decline may reflect accelerated ageing in PWH, but the evidence supporting an altered ageing phenotype in PWH has been mixed.

Methods

We examined the impact of ageing on the orienting of visual attention in PWH using dynamic functional mapping with magnetoencephalography (MEG) in 173 participants age 22–72 years-old (94 uninfected controls, 51 cognitively-unimpaired PWH, and 28 with HAND). All MEG data were imaged using a state-of-the-art beamforming approach and neural oscillatory responses during attentional orienting were examined for ageing, HIV, and cognitive status effects.

Findings

All participants responded slower during trials that required attentional reorienting. Our functional mapping results revealed HIV-by-age interactions in left prefrontal theta activity, alpha oscillations in the left parietal, right cuneus, and right frontal eye-fields, and left dorsolateral prefrontal beta activity (p<.005). Critically, within PWH, we observed a cognitive status-by-age interaction, which revealed that ageing impacted the oscillatory gamma activity serving attentional reorienting differently in cognitively-normal PWH relative to those with HAND in the left temporoparietal, inferior frontal gyrus, and right prefrontal cortices (p<.005).

Interpretation

This study provides key evidence supporting altered ageing trajectories across vital attention circuitry in PWH, and further suggests that those with HAND exhibit unique age-related changes in the oscillatory dynamics serving attention function. Additionally, our neural findings suggest that age-related changes in PWH may serve a compensatory function.

Funding

National Institutes of Health, USA.

Identification and Nanomechanical Characterization of the HIV Tat-Amyloid β Peptide Multifibrillar Structures

HIV transactivator of transcription (Tat) protein could interact with amyloid β (Aβ) peptide which cause the growth of Aβ plaques in the brain and result in Alzheimer's disease in HIV-infected patients. Herein, we employ high-resolution atomic force microscopy and quantitative nanomechanical mapping to investigate the effects of Tat protein in Aβ peptide aggregation. Our results demonstrate that the Tat protein could bind to the Aβ fibril surfaces and result in the formation of Tat-Aβ multifibrillar structures. The resultant Tat-Aβ multifibrillar aggregates represent an increase in stiffness compared with Aβ fibrils due to the increase in β-sheet formation. The identification and characterization of the Tat-Aβ intermediate aggregates is important to understanding the interactions between Tat protein and Aβ peptide, and the development of novel therapeutic strategy for Alzheimer's disease-like disorder in HIV infected individuals.

HIV-1 Tat-mediated astrocytic amyloidosis involves the HIF-1α/lncRNA BACE1-AS axis

Increased life expectancy of patients diagnosed with HIV in the current era of antiretroviral therapy is unfortunately accompanied with the prevalence of HIV-associated neurocognitive disorders (HANDs) and risk of comorbidities such as Alzheimer-like pathology. HIV-1 transactivator of transcription (Tat) protein has been shown to induce the production of toxic neuronal amyloid protein and also enhance neurotoxicity. The contribution of astrocytes in Tat-mediated amyloidosis remains an enigma. We report here, in simian immunodeficiency virus (SIV)+ rhesus macaques and patients diagnosed with HIV, brain region-specific up-regulation of amyloid precursor protein (APP) and Aβ (40 and 42) in astrocytes. In addition, we find increased expression of β-site cleaving enzyme (BACE1), APP, and Aβ in human primary astrocytes (HPAs) exposed to Tat. Mechanisms involved up-regulation of hypoxia-inducible factor (HIF-1α), its translocation and binding to the long noncoding RNA (lncRNA) BACE1-antisense transcript (BACE1-AS), resulting, in turn, in the formation of the BACE1-AS/BACE1 RNA complex, subsequently leading to increased BACE1 protein, and activity and generation of Aβ-42. Gene silencing approaches confirmed the regulatory role of HIF-1α in BACE1-AS/BACE1 in Tat-mediated amyloidosis. This is the first report implicating the role of the HIF-1α/lncRNABACE1-AS/BACE1 axis in Tat-mediated induction of astrocytic amyloidosis, which could be targeted as adjunctive therapies for HAND-associated Alzheimer-like comorbidity.

Age of Last Alcohol Use Disorder Relates to Processing Speed Among Older Adults Living with HIV

AIMS

Older persons living with HIV (PLWH) and past alcohol use disorder (AUD) are at higher risk for neurocognitive deficits compared to those with either condition alone; however, factors underlying this relationship are unknown. Given that aging potentiates multi-system damage from alcohol misuse, the current study examined whether neurocognitive functioning among older adults relates to the age at which they last met criteria for AUD (i.e. 'age of last AUD'), and whether this relationship differed by HIV serostatus.

METHODS

All participants (aged between 50 and 75 years) were grouped by HIV/AUD status: 345 HIV+/AUD+, 148 HIV-/AUD+, 273 HIV+/AUD-, and 206 HIV-/AUD-. Neurocognitive functioning was assessed globally and within seven domains. Among only the two AUD+ groups, multivariable linear regressions examined the interaction between age of last AUD and HIV status on neurocognitive functioning, controlling for demographics and clinical characteristics.

RESULTS

Older age of last AUD related to worse processing speed among PLWH (b = -0.03; P = 0.006); however, this relationship was not significant among persons without HIV (b = 0.01; P = 0.455). The interaction between age of last AUD and HIV status did not predict neurocognitive functioning in other domains. Processing speed appeared clinically important, as slower speed related to worse everyday functioning, including more reported cognitive difficulties (r = -0.26, P < 0.001) and higher rates of functional dependence (OR = 0.87, 95%CI = 0.80-0.95, P = 0.002).

CONCLUSIONS

Our novel findings, demonstrating slower processing speed when a past AUD occurred at an older age in PLWH, highlight the value in assessing older PLWH for processing speed deficits, even if other cognitive domains appear to be intact.

Dopaminergic impact of cART and anti-depressants on HIV neuropathogenesis in older adults

The success of combination antiretroviral therapy (cART) has transformed HIV infection into a chronic condition, resulting in an increase in the number of older, cART-treated adults living with HIV. This has increased the incidence of age-related, non-AIDS comorbidities in this population. One of the most common comorbidities is depression, which is also associated with cognitive impairment and a number of neuropathologies. In older people living with HIV, treating these overlapping disorders is complex, often creating pill burden or adverse drug-drug interactions that can exacerbate these neurologic disorders. Depression, NeuroHIV and many of the neuropsychiatric therapeutics used to treat them impact the dopaminergic system, suggesting that dopaminergic dysfunction may be a common factor in the development of these disorders. Further, changes in dopamine can influence the development of inflammation and the regulation of immune function, which are also implicated in the progression of NeuroHIV and depression. Little is known about the optimal clinical management of drug-drug interactions between cART drugs and antidepressants, particularly in regard to dopamine in older people living with HIV. This review will discuss those interactions, first examining the etiology of NeuroHIV and depression in older adults, then discussing the interrelated effects of dopamine and inflammation on these disorders, and finally reviewing the activity and interactions of cART drugs and antidepressants on each of these factors. Developing better strategies to manage these comorbidities is critical to the health of the aging, HIV-infected population, as the older population may be particularly vulnerable to drug-drug interactions affecting dopamine.

Olive Oil Intake Associated with Increased Attention Scores in Women Living with HIV: Findings from the Chicago Women's Interagency HIV Study

Women aging with human immunodeficiency virus (HIV) are particularly vulnerable to cognitive decline. Recent studies have highlighted the potential protective effects of olive oil on cognition in persons living without HIV. We sought to evaluate the association between olive oil consumption and domain-specific cognitive performance (dCog) t-scores (adjusted for age, race, education, reading level, practice effects) in women living with HIV (WLWH) and sociodemographically similar women living without HIV. A total of 166 women (113 WLWH and 53 women living without HIV) participating in the Cook County Women’s Interagency HIV Study (WIHS) completed cognitive testing and a Block 2014 Food Frequency Questionnaire within 18 months. Use of olive oil was associated with a 4.2 point higher attention/concentration (p = 0.02), 4.0 point higher for verbal learning (p = 0.02), and 1.91 point higher for verbal memory (p = 0.05). Associations between using olive oil and attention/concentration cognitive domain were seen in WLWH but not in women living without HIV. Associations between olive oil and verbal learning and memory were only seen in women without HIV. Our data suggest that using olive oil as a primary cooking oil may contribute to differential effects in attention/concentration, verbal learning, and verbal memory between women living with and without HIV.

Alzheimer's disease: pathogenesis, diagnostics, and therapeutics

Currently, 47 million people live with dementia globally, and it is estimated to increase more than threefold (~131 million) by 2050. Alzheimer's disease (AD) is one of the major causative factors to induce progressive dementia. AD is a neurodegenerative disease, and its pathogenesis has been attributed to extracellular aggregates of amyloid β (Aβ) plaques and intracellular neurofibrillary tangles made of hyperphosphorylated τ-protein in cortical and limbic areas of the human brain. It is characterized by memory loss and progressive neurocognitive dysfunction. The anomalous processing of APP by β-secretases and γ-secretases leads to production of Aβ40 and Aβ42 monomers, which further oligomerize and aggregate into senile plaques. The disease also intensifies through infectious agents like HIV. Additionally, during disease pathogenesis, the presence of high concentrations of Aβ peptides in central nervous system initiates microglial infiltration. Upon coming into vicinity of Aβ, microglia get activated, endocytose Aβ, and contribute toward their clearance via TREM2 surface receptors, simultaneously triggering innate immunoresponse against the aggregation. In addition to a detailed report on causative factors leading to AD, the present review also discusses the current state of the art in AD therapeutics and diagnostics, including labeling and imaging techniques employed as contrast agents for better visualization and sensing of the plaques. The review also points to an urgent need for nanotechnology as an efficient therapeutic strategy to increase the bioavailability of drugs in the central nervous system.

Clinical and neuroimaging correlates of cognition in HIV

This study investigated whether HIV-positive participants, stable on combined antiretroviral therapy (cART), showed cognitive impairments relative to HIV-negative controls; and whether clinical and neuroimaging factors correlated with cognitive function in the HIV-positive participants. One hundred and twenty-six white men who have sex with men, of whom 78 were HIV-positive and stable on cART and 48 were HIV negative, were recruited to this cross-sectional study. The median age of HIV-positive participants in this study was 47. They underwent clinical and neuropsychological evaluation and magnetic resonance imaging of the brain, including diffusion tensor imaging (DTI). Cognitive scores for both groups were compared, and regression models were run to explore the influence of clinical, psychiatric, lifestyle, and neuroimaging variables on cognition. The prevalence of neurocognitive impairment, using the multivariate normative comparison criteria, was 28% in HIV-positive participants and 5% in HIV-negative participants. After covarying for age, years of education, and non-English speaking background, there were significant differences between the HIV group and the controls across four cognitive domains. The HIV group showed significantly higher mean diffusivity (MD) and lower fractional anisotropy (FA) than the control group on DTI. Although anxiety levels were clinically low, anxiety and DTI measures were the only variables to show significant correlations with cognitive function. In the HIV group, poorer cognitive performance was associated with higher MD and lower FA on DTI and higher (albeit clinically mild) levels of anxiety. Our findings suggest that white matter changes and subtle anxiety levels contribute independently to cognitive impairment in HIV.

HIV and Alzheimer's disease: complex interactions of HIV-Tat with amyloid β peptide and Tau protein

In patients infected with the human immunodeficiency virus (HIV), the HIV-Tat protein may be continually produced despite adequate antiretroviral therapy. As the HIV-infected population is aging, it is becoming increasingly important to understand how HIV-Tat may interact with proteins such as amyloid β and Tau which accumulate in the aging brain and eventually result in Alzheimer's disease. In this review, we examine the in vivo data from HIV-infected patients and animal models and the in vitro experiments that show how protein complexes between HIV-Tat and amyloid β occur through novel protein-protein interactions and how HIV-Tat may influence the pathways for amyloid β production, degradation, phagocytosis, and transport. HIV-Tat may also induce Tau phosphorylation through a cascade of cellular processes that lead to the formation of neurofibrillary tangles, another hallmark of Alzheimer's disease. We also identify gaps in knowledge and future directions for research. Available evidence suggests that HIV-Tat may accelerate Alzheimer-like pathology in patients with HIV infection which cannot be impacted by current antiretroviral therapy.

Global HIV neurology: a comprehensive review

: Neurological conditions associated with HIV remain major contributors to morbidity and mortality and are increasingly recognized in the aging population on long-standing combination antiretroviral therapy (cART). Importantly, growing evidence shows that the central nervous system (CNS) may serve as a reservoir for viral replication, which has major implications for HIV eradication strategies. Although there has been major progress in the last decade in our understanding of the pathogenesis, burden, and impact of neurological conditions associated with HIV infection, significant scientific gaps remain. In many resource-limited settings, antiretrovirals considered second or third line in the United States, which carry substantial neurotoxicity, remain mainstays of treatment, and patients continue to present with severe immunosuppression and CNS opportunistic infections. Despite this, increased global access to cART has coincided with an aging HIV-positive population with cognitive sequelae, cerebrovascular disease, and peripheral neuropathy. Further neurological research in low-income and middle-income countries (LMICs) is needed to address the burden of neurological complications in HIV-positive patients, particularly regarding CNS viral reservoirs and their effects on eradication.

Withaferin A Suppresses Beta Amyloid in APP Expressing Cells: Studies for Tat and Cocaine Associated Neurological Dysfunctions

Neurological disorders are the biggest concern globally. Out of ~36 million human immunodeficiency virus (HIV) positive people, about 30%-60% exhibit neurological disorders, including dementia and Alzheimer's disease (AD) like pathology. In AD or AD like neurological disorders, the pathogenesis is mainly due to the abnormal accumulation of extracellular amyloid beta (Aβ). In this era of antiretroviral therapy, the life span of the HIV-infected individuals has increased leading towards increased neurocognitive dysfunction in nearly 30% of HIV-infected individuals, specifically older people. Deposition of the Aβ plaques in the CNS is one the major phenomenon happening in aging HIV patients. ART suppresses the viral replication, but the neurotoxic protein (Tat) is still produced and results in increased levels of Aβ. Furthermore, drugs of abuse like cocaine (coc) is known to induce the HIV associated neurocognitive disorders as well as the Aβ secretion. To target the Tat and coc induced Aβ secretion, we propose a potent bifunctional molecule Withaferin A (WA) which may act as a neuro-protectant against Aβ neurotoxicity. In this study, we show that WA reduces secreted Aβ and induced neurotoxicity in amyloid precursor protein (APP)-plasmid transfected SH-SY5Y cells (SH-APP). In this study, we show that in SH-APP cells, Aβ secretion is induced in the presence of HIV-1 Tat (neurotoxic) and drug of abuse coc. Our fluorescent microscopy studies show the increased concentration of Aβ40 in Tat (50 ng/ml) and coc (0.1 μM) treated SH-APP cells as compared to control. Our dose optimization study show, lower concentrations (0.5-2 μM) of WA significantly reduce the Aβ40 levels, without inducing cytotoxicity in the SH-APP cells. Additionally, WA reduces the Tat and cocaine induced Aβ levels. Therefore, we propose that Aβ aggregation is induced by the presence of Tat and coc and WA is potent in reducing the secreted Aβ and induced neurotoxicity. Our study provides new opportunities for exploring the pathophysiology and targeting the neurological disorders.

Carotid Artery Stiffness and Cognitive Decline Among Women With or at Risk for HIV Infection

BACKGROUND

Vascular stiffness is associated with aging and cognitive impairment in older populations without HIV. HIV has been linked to increased vascular stiffness. We examined whether vascular stiffness relates to cognitive decline at younger ages in women with or at risk for HIV.

METHODS

We evaluated the association of carotid artery stiffness with decline in neuropsychological test performance among participants in the Women's Interagency HIV Study and assessed whether HIV modified the association. Baseline carotid stiffness, defined by the distensibility index, was determined at a single visit using carotid artery ultrasound. Longitudinal neuropsychological testing from 2004-2016 included Trail Making Tests A and B and the Symbol Digit Modalities Test. Relationships were assessed with linear mixed-effect models adjusted for demographic, behavioral, cardiometabolic, and neuropsychological factors.

RESULTS

Among 1662 women (1192 [72%] HIV+), median baseline age was 41 years (interquartile range 34-47), with 60% non-Hispanic black and 28% Hispanic. Lower baseline distensibility (greater carotid stiffness) was associated with greater decline in neuropsychological test scores over 10-year follow-up as measured by Symbol Digit Modalities Test (adjusted β = -0.06 per SD, P < 0.001), Trail Making Test A (β = -0.08 per SD; P < 0.001), and Trail Making Test B (β = -0.08 per SD; P < 0.001). Changes in cognitive function did not differ by HIV serostatus, or HIV-related factors.

CONCLUSIONS

Higher carotid stiffness was independently associated with faster decline in executive functioning, information processing, and psychomotor speed even in mostly middle-aged minority women and regardless of HIV serostatus. Our study highlights the need for cardiovascular risk factor modification to prevent premature cognitive deterioration in this at-risk population.

Neurocognitive functioning predicts frailty index in HIV

OBJECTIVE

To evaluate the association between a frailty index (i.e., scale of accumulated deficits) and neurocognitive functioning among persons living with HIV/AIDS (PLWHA).

METHODS

Observational, cross-sectional data were gathered from the University of California, San Diego, HIV Neurobehavioral Research Program from 2002 to 2016. Eight hundred eleven PLWHA aged 18 to 79 years completed comprehensive physical, neuropsychological, and neuromedical evaluations. The frailty index was composed of 26 general and HIV-specific health maintenance measures, and reflects the proportion of accumulated deficits from 0 (no deficits) to 1 (all 26 deficits). Multiple linear regression was used to examine the association between continuous frailty index scores and neurocognitive functioning.

RESULTS

Participants had a mean age of 44.6 years (11.2), and were mostly male (86.9%) and white (60.2%) with a mean frailty index of 0.26 (0.11). Over the study period, prevalence of HIV-related components (e.g., low CD4) decreased, while non-HIV comorbidities (e.g., diabetes) increased. There were no changes in the frailty index by study year. Higher frailty index was associated with worse global neurocognitive functioning, even after adjusting for covariates (age, employment, and premorbid intellectual functioning; b = -0.007; 95% confidence interval [CI] = -0.0112 to -0.003; p < 0.001). The cognitive domains of verbal fluency (b = -0.004; 95% CI = -0.006 to -0.002), executive functioning (b = -0.004; 95% CI = -0.006 to -0.002), processing speed (b = -0.005; 95% CI = -0.007 to -0.003), and motor skills (b = -0.006; 95% CI = -0.007 to -0.005) also significantly predicted worse frailty index score (p values <0.001).

CONCLUSION

A frailty index can standardize how clinicians identify PLWHA who may be at higher risk of neurocognitive impairment.

Distinct biomarker signatures in HIV acute infection associate with viral dynamics and reservoir size

Estimating the size of the viral reservoir is critical for HIV cure strategies. Biomarkers in peripheral circulation may give insights into the establishment of the viral reservoir in compartments not easily accessible. We therefore measured systemic levels of 84 soluble biomarkers belonging to a broad array of immune pathways in acute HIV infection in both antiretroviral therapy-naive (ART-naive) individuals as well as individuals who began ART upon early detection of HIV infection. These biomarkers were measured longitudinally during acute and chronic infection and their relationship to viral reservoir establishment and persistence was assessed. We observed several distinct biomarker pathways induced following HIV infection such as IFN-γ-signaled chemokines, proinflammatory markers, and TNF-α-family members. Levels of several of these factors directly correlated with contemporaneous viral loads and/or frequency of peripheral blood mononuclear cells harboring HIV DNA during acute HIV infection. MCP-1, MIP-3β, sTNFR-II, and IL-10 levels prior to ART associated with HIV DNA levels after 96 weeks of treatment, suggesting a link between early immune signaling events and the establishment and persistence of the viral reservoir during ART. Furthermore, they offer potentially novel tools for gaining insight into relative reservoir size in acutely infected individuals and the potential of associated risks of treatment interruption.

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.

Global developments in HIV neurology

Neurologic conditions associated with HIV remain major contributors to morbidity and mortality, and are increasingly recognized in the aging population on long-standing combination antiretroviral therapy (cART). Importantly, growing evidence suggests that the central nervous system (CNS) serves as a reservoir for viral replication with major implications for human immunodeficiency virus (HIV) eradication strategies. Though there has been major progress in the last decade in our understanding of the pathogenesis, burden, and impact of HIV-associated neurologic conditions, significant scientific gaps remain. In many low-income settings, second- and third-line cART regimens that carry substantial neurotoxicity remain treatment mainstays. Further, patients continue to present severely immunosuppressed with CNS opportunistic infections. Public health efforts should emphasize improvements in access and optimizing treatment of HIV-positive patients, specifically in resource-limited settings, to reduce the risk of neurologic sequelae.

Doxycycline-inducible and astrocyte-specific HIV-1 Tat transgenic mice (iTat) as an HIV/neuroAIDS model

HIV-1 Tat is known to be neurotoxic and important for HIV/neuroAIDS pathogenesis. However, the overwhelming majority of the studies involved use of recombinant Tat protein. To understand the contributions of Tat protein to HIV/neuroAIDS and the underlying molecular mechanisms of HIV-1 Tat neurotoxicity in the context of a whole organism and independently of HIV-1 infection, a doxycycline-inducible astrocyte-specific HIV-1 Tat transgenic mouse (iTat) was created. Tat expression in the brains of iTat mice was determined to be in the range of 1-5 ng/ml and led to astrocytosis, loss of neuronal dendrites, and neuroinflammation. iTat mice have allowed us to define the direct effects of Tat on astrocytes and the molecular mechanisms of Tat-induced GFAP expression/astrocytosis, astrocyte-mediated Tat neurotoxicity, Tat-impaired neurogenesis, Tat-induced loss of neuronal integrity, and exosome-associated Tat release and uptake. In this review, we will provide an overview about the creation and characterization of this model and its utilities for our understanding of Tat neurotoxicity and the underlying molecular mechanisms.

Mechanisms of HIV Neuropathogenesis: Role of Cellular Communication Systems

BACKGROUND

One of the major complications of Human Immunodeficiency Virus (HIV) infection is the development of HIV-Associated Neurocognitive Disorders (HANDs) in approximately 50-60% of HIV infected individuals. Despite undetectable viral loads in the periphery owing to anti-retroviral therapy, neuroinflammation and neurocognitive impairment are still prevalent in HIV infected individuals. Several studies indicate that the central nervous system (CNS) abnormalities observed in HIV infected individuals are not a direct effect of viral replication in the CNS, rather these neurological abnormalities are associated with amplification of HIV specific signals by unknown mechanisms. We propose that some of these mechanisms of damage amplification are mediated by gap junction channels, pannexin and connexin hemichannels, tunneling nanotubes and microvesicles/exosomes.

OBJECTIVE

Our laboratory and others have demonstrated that HIV infection targets cell to cell communication by altering all these communication systems resulting in enhanced bystander apoptosis of uninfected cells, inflammation and viral infection. Here we discuss the role of these communication systems in HIV neuropathogenesis.

CONCLUSION

In the current manuscript, we have described the mechanisms by which HIV "hijacks" these host cellular communication systems, leading to exacerbation of HIV neuropathogenesis, and to simultaneously promote the survival of HIV infected cells, resulting in the establishment of viral reservoirs.

HIV Tat Impairs Neurogenesis through Functioning As a Notch Ligand and Activation of Notch Signaling Pathway

Alterations in adult neurogenesis have been noted in the brain of HIV-infected individuals and are likely linked to HIV-associated neurocognitive deficits, including those in learning and memory. But the underlying molecular mechanisms are not fully understood. In the study, we took advantage of doxycycline-inducible and astrocyte-specific HIV-1 Tat transgenic mice (iTat) and determined the relationship between Tat expression and neurogenesis. Tat expression in astrocytes was associated with fewer neuron progenitor cells (NPCs), fewer immature neurons, and fewer mature neurons in the dentate gyrus of the hippocampus of the mouse brain. In vitro NPC-derived neurosphere assays showed that Tat-containing conditioned media from astrocytes or recombinant Tat protein inhibited NPC proliferation and migration and altered NPC differentiation, while immunodepletion of Tat from Tat-containing conditioned media or heat inactivation of recombinant Tat abrogated those effects. Notch signaling downstream gene Hes1 promoter-driven luciferase reporter gene assay and Western blotting showed that recombinant Tat or Tat-containing conditioned media activated Hes1 transcription and protein expression, which were abrogated by Tat heat inactivation, immunodepletion, and cysteine mutation at position 30. Last, Notch signaling inhibitor N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester (DAPT) significantly rescued Tat-impaired NPC differentiation in vitro and neurogenesis in vivo Together, these results show that Tat adversely affects NPCs and neurogenesis through Notch signaling and point to the potential of developing Notch signaling inhibitors as HIV/neuroAIDS therapeutics.

SIGNIFICANCE STATEMENT

HIV infection of the CNS causes cognitive and memory deficits, which have become more prevalent in the era of combination antiretroviral therapy (cART). Neurogenesis is impaired in HIV-infected individuals. But the underlying molecular mechanisms remain largely unknown. In this study, we have discovered that HIV Tat impairs neurogenesis through the Notch signaling pathway. These findings are particularly important because Tat protein has recently been detected in the brain of HIV-infected individuals with HIV replication in the periphery being effectively controlled by cART. The current study not only further highlights the importance of HIV Tat protein in HIV/neuroAIDS, but also presents a new strategy to develop novel HIV/neuroAIDS therapeutics, particularly in the era of cART.

Higher Cystatin C Levels Are Associated With Neurocognitive Impairment in Older HIV+ Adults

OBJECTIVE

The study aims to determine whether cystatin C is associated with HIV disease and HIV-associated neurocognitive impairment (NCI).

METHODS

Participants included 124 (HIV+ n = 77; HIV- n = 47) older adults (age ≥ 50 years) examined at the University of California, San Diego HIV Neurobehavioral Research Program. Cystatin C, a biomarker of kidney functioning that has been linked to poor health outcomes, was measured in blood. Participants completed a comprehensive neurocognitive assessment that was used to define both global and domain NCI.

RESULTS

The HIV+ group had significantly higher cystatin C concentrations than the HIV- group (d = 0.79 P < 0.001). Among HIV+ participants, those with NCI had higher cystatin C concentrations than those without NCI (d = 0.42, P = 0.055), particularly among participants taking tenofovir (d = 0.78, P = 0.004). A receiver-operator characteristic curve identified that cystatin C levels ≥0.75 mg/L were associated with NCI in the HIV+ group. Using this binary variable and including relevant covariates, multivariate modeling confirmed that NCI was associated with higher cystatin C levels (OR = 3.0; P = 0.03).

CONCLUSIONS

Our results confirm that HIV+ older adults have higher cystatin C than HIV- older adults and further identify that cystatin C may be associated with NCI in this population, particularly if they use tenofovir. This blood biomarker may be a useful clinical tool to identify older HIV+ persons at greater risk for cognitive decline.

Testing a Computerized Cognitive Training Protocol in Adults Aging With HIV-Associated Neurocognitive Disorders: Randomized Controlled Trial Rationale and Protocol

Background

HIV-associated neurocognitive disorders occur in nearly 50% of adults with HIV. Such disorders can interfere with everyday functioning such as driving and medication adherence. Therefore, cognitive interventions are needed to address such neurocognitive disorders as well as improve everyday functioning, especially as people age with HIV.

Objective

This article reports and discusses the overall rationale and development of speed of processing training, a computerized Internet cognitive training program, to improve this specific neurocognitive ability as well as everyday functioning and quality of life in adults aging with HIV. Although this protocol has been shown to improve speed of processing, everyday functioning, and quality of life in healthy, community-dwelling older adults in the advanced cognitive training in vital elderly (ACTIVE) study, its efficacy in adults aging with HIV has not been established. Nevertheless, such a cognitive intervention is particularly germane as 52%-59% of adults with HIV experience HIV-associated neurocognitive disorders (HAND), and both the frequency and severity of such disorders may increase with advancing age.

Methods

The description of this longitudinal randomized controlled trial covers the following: (1) rationale for speed of processing training in this clinical population, (2) overview of overall study design, (3) eligibility criteria and HAND, (4) intervention dosage, (5) assessment battery, and (6) examination of biomarkers.

Results

The project was funded in April 2016 and enrolment is on-going. The first results are expected to be submitted for publication in 2020.

Conclusions

Similar novel cognitive intervention approaches are suggested as they may be of value to those with HAND and may utilize similar features of this current randomized controlled trial (RCT) protocol to examine their therapeutic efficacy.

Trial Registration

ClinicalTrials.gov NCT02758093; https://clinicaltrials.gov/ct2/show/NCT02758093 (Archived by Webcite at http://www.webcitation.org/6p8C5fBCX)

Accelerated and accentuated neurocognitive aging in HIV infection

There is debate as to whether the neurocognitive changes associated with HIV infection represent an acceleration of the typical aging process or more simply reflect a greater accentuated risk for age-related declines. We aimed to determine whether accelerated neurocognitive aging is observable in a sample of older HIV-infected individuals compared to age-matched seronegatives and older old (i.e., aged ≥65) seronegative adults. Participants in a cross-sectional design included 48 HIV-seronegative (O-) and 40 HIV-positive (O+) participants between the ages of 50-65 (mean ages = 55 and 56, respectively) and 40 HIV-seronegative participants aged ≥65 (OO-; mean age = 74) who were comparable for other demographics. All participants were administered a brief neurocognitive battery of attention, episodic memory, speeded executive functions, and confrontation naming (i.e., Boston Naming Test). The O+ group performed more poorly than the O- group (i.e., accentuated aging), but not differently from the OO- on digit span and initial recall of a supraspan word list, consistent with an accelerating aging profile. However, the O+ group's performance was comparable to the O- group on all other neurocognitive tests (ps > 0.05). These data partially support a model of accelerated neurocognitive aging in HIV infection, which was observed in the domain of auditory verbal attention, but not in the areas of memory, language, or speeded executive functions. Future studies should examine whether HIV-infected adults over 65 evidence accelerated aging in downstream neurocognitive domains and subsequent everyday functioning outcomes.

HIV Tat protein and amyloid-β peptide form multifibrillar structures that cause neurotoxicity

Deposition of amyloid-β plaques is increased in the brains of HIV-infected individuals, and the HIV transactivator of transcription (Tat) protein affects amyloidogenesis through several indirect mechanisms. Here, we investigated direct interactions between Tat and amyloid-β peptide. Our in vitro studies showed that in the presence of Tat, uniform amyloid fibrils become double twisted fibrils and further form populations of thick unstructured filaments and aggregates. Specifically, Tat binding to the exterior surfaces of the Aβ fibrils increases β-sheet formation and lateral aggregation into thick multifibrillar structures, thus producing fibers with increased rigidity and mechanical resistance. Furthermore, Tat and Aβ aggregates in complex synergistically induced neurotoxicity both in vitro and in animal models. Increased rigidity and mechanical resistance of the amyloid-β-Tat complexes coupled with stronger adhesion due to the presence of Tat in the fibrils may account for increased damage, potentially through pore formation in membranes.

A High Prevalence Rate of a Positive Screen for Cognitive Impairment in Patients With Human Immunodeficiency Virus Attending an Irish Clinic

Background

Human immunodeficiency virus (HIV)-associated neurocognitive disorders occurs in 20%–50% of HIV-positive patients. We undertook this study to assess the prevalence of a positive screen for cognitive impairment in the clinic population at our institution and to demonstrate the feasibility of implementing a screening program in routine clinical encounters.

Methods

This was a cross-sectional study, and patients were recruited prospectively between December 2010 and February 2013. Inclusion criteria were as follows: patients were HIV positive, over the age of 18, capable of giving informed consent, and had sufficient ability to communicate in English. Patients were screened for cognitive impairment using the Brief Neurocognitive Screen.

Results

A total of 604 patients were recruited, and 51.5% had a positive screen for cognitive impairment. The majority of the study cohort were male (78.8%), mean age was 40.9 (standard deviation, 10.2) years, 70.9% were Irish, the most common mode of transmission was men who have sex with men (49.3%), 83% were on antiretroviral therapy, and 88.7% were virally suppressed. Logistic regression showed that the main factors predictive of a positive screen for cognitive impairment were the endorsement of cognitive symptoms (P = .024), being born in Africa (P < .000001), the use of benzodiazepines (P = .00341), being unemployed (P = .008), and consumption of more than 40 units of alcohol weekly (P = .035). There was a positive screen for depression in 9.1% and a positive screen for anxiety in 24.5%.

Conclusions

The study highlights the necessity for a structured, prospective, large-scale screening program for cognitive impairment across countries with limited resources and demonstrates the feasibility of easily implementing this with minimal training.

Association of midlife smoking status with change in processing speed and mental flexibility among HIV-seropositive and HIV-seronegative older men: the Multicenter AIDS Cohort Study

Smoking is a potential risk factor for age-related cognitive decline. To date, no study has examined the association between smoking and cognitive decline in men living with human immunodeficiency virus (HIV). The aim of this present study is to examine whether smoking status and severity in midlife is associated with a rate of decline in cognitive processing speed among older HIV-seropositive and HIV-seronegative men who have sex with men. Data from 591 older HIV-seropositive and HIV-seronegative men who have sex with men from the Multicenter AIDS Cohort Study were examined. All participants had information on smoking history collected before age 50 years and at least 5 years of follow-up after age 50. Smoking history was categorized as never smoker, former smoker, and current smoker and cumulative pack years was calculated. The raw scores of three neuropsychological tests (Trail Making A, Trail Making B, and Symbol Digit Modalities tests) were log transformed (Trail Making A and B) and used in linear mixed models to determine associations between smoking history and at least subsequent 5-year decline in cognitive processing speed. There were no significant differences in the rates of neurological decline among never smokers, former smokers, and current smokers. Findings were similar among HIV-seropositive participants. However, an increase of 5 pack-years was statistically significantly associated with a greater rate of decline in the Trail Making Test B score and Composite Score (β -0.0250 [95% CI, -0.0095 to -0.0006] and -0.0077 [95% CI, -0.0153 to -0.0002], respectively). We found no significant association between smoking treated as a categorical variable (never smoked, former smoker, or current smoker) and a small change in every increase of 5 pack-years on measures of psychomotor speed and cognitive flexibility. To optimize healthy aging, interventions for smoking cessation should be tailored to men who have sex with men.

The effects of HIV and aging on subcortical shape alterations: A 3D morphometric study

Standard volumetric neuroimaging studies have demonstrated preferential atrophy of subcortical structures among individuals with HIV. However, to our knowledge, no study has investigated subcortical shape alterations secondary to HIV and whether advancing age impacts that relationship. This study employed 3D morphometry to examine the independent and interactive effects of HIV and age on shape differences in nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, and thalamus in 81 participants ranging in age from 24 to 76 including 59 HIV+ individuals and 22 HIV-seronegative controls. T1-weighted MRI underwent a preprocessing pipeline followed by automated subcortical segmentation. Parametric statistical analyses were used to determine independent effects of HIV infection and age on volume and shape in each region of interest (ROI) and the interaction between age and HIV serostatus in predicting volume/shape in each ROI. Significant main effects for HIV were found in the shape of right caudate and nucleus accumbens, left pallidum, and hippocampus. Age was associated with differences in shape in left pallidum, right nucleus accumbens and putamen, and bilateral caudate, hippocampus, and thalamus. Of greatest interest, an age × HIV interaction effect was found in the shape of bilateral nucleus accumbens, amygdala, caudate, and thalamus as well as right pallidum and putamen such that increasing age in HIV participants was associated with greater shape alterations. Traditional volumemetric analyses revealed main effects for both HIV and age but no age × HIV interaction. These findings may suggest that age and HIV infection conferred additional deleterious effects on subcortical shape abnormalities beyond the independent effects of these factors. Hum Brain Mapp 38:1025-1037, 2017. © 2016 Wiley Periodicals, Inc.

Effects of HIV and Methamphetamine on Brain and Behavior: Evidence from Human Studies and Animal Models

Methamphetamine (Meth) use is frequent among HIV-infected persons. Combined HIV and Meth insults may exacerbate neural injury in vulnerable neuroanatomic structures or circuitries in the brain, leading to increased behavioral disturbance and cognitive impairment. While acute and chronic effects of Meth in humans and animal models have been studied for decades, the neurobehavioral effects of Meth in the context of HIV infection are much less explored. In-depth understanding of the scope of neurobehavioral phenotypes and mechanisms in HIV/Meth intersection is needed. The present report summarizes published research findings, as well as unpublished data, in humans and animal models with regard to neurobehavioral disturbance, neuroimaging, and neuropathology, and in vitro experimental systems, with an emphasis on findings emerging from the National Institute on Drug Abuse (NIDA) funded Translational Methamphetamine AIDS Research Center (TMARC). Results from human studies and animal (primarily HIV-1 gp120 transgenic mouse) models thus far suggest that combined HIV and Meth insults increase the likelihood of neural injury in the brain. The neurobehavioral effects include cognitive impairment and increased tendencies toward impaired behavioral inhibition and social cognition. These impairments are relevant to behaviors that affect personal and social risks, e.g. worse medication adherence, riskier behaviors, and greater likelihood of HIV transmission. The underlying mechanisms may include electrochemical changes in neuronal circuitries, injury to white matter microstructures, synaptodendritic damage, and selective neuronal loss. Utilization of research methodologies that are valid across species is instrumental in generating new knowledge with clinical translational value.

The effects of HIV disease and older age on laboratory-based, naturalistic, and self-perceived symptoms of prospective memory: does retrieval cue type and delay interval matter?

There is a rising prevalence of older HIV+ adults who are at risk of deficits in higher order neurocognitive functions and associated problems in everyday functioning. The current study applied multiprocess theory to examine the effects of HIV and aging on measures of laboratory-based, naturalistic, and self-perceived symptoms of prospective memory (PM). Participants included 125 Younger (48 with HIV, age = 32 ± 4.6 years) and 189 Older (112 with HIV, age = 56 ± 4.9 years) adults. Controlling for global neurocognitive functioning, mood, and other demographics, older age and HIV had independent effects on long-delay time-based PM in the laboratory, whereas on a naturalistic PM task older HIV- adults performed better than older HIV+ adults and younger persons. In line with the naturalistic findings, older age, but not HIV, was associated with a relative sparing of self-perceived PM failures in daily life across longer delay self-cued intervals. Findings suggest that, even in relatively younger aging cohorts, the effects of HIV and older age on PM can vary across PM delay intervals by the strategic demands of the retrieval cue type, are expressed differently in the laboratory and in daily life, and are independent of other higher order neurocognitive functions (e.g., retrospective memory).

Understanding and optimizing brain health in HIV now: protocol for a longitudinal cohort study with multiple randomized controlled trials

Background

Chronic HIV infection commonly affects both cognition and mental health, even with excellent systemic viral control. The causes of compromised brain health are likely to be a multi-factorial combination of HIV-related biological factors, co-morbidities such as aging and cerebrovascular disease, and the erosion of coping skills, physical health, and social supports resulting from the strains of living with a chronic illness.

Methods/design

This study aims to provide a better understanding of the relationship between cognitive complaints, depression, and objectively measured cognitive impairment in HIV, and of the key factors, whether biological or personal, which relate to these presentations and to their evolution over time. Characterization of this heterogeneity will permit more focused pathophysiological studies, and allow more targeted interventions. The project makes extensive use of Web-based research and health care delivery tools, aiming to provide cost-effective, “clinic ready” tools to improve brain health in HIV. This project has two overarching aims, reflecting our dual goals of understanding and improving brain health in HIV, focusing on cognitive impairment, its contributors and consequences.

The objectives are to contribute evidence for the validity of a brief brain health assessment, to estimate the extent to which HIV-related cognition-relevant clinical factors and patient-centered outcomes inter-relate and evolve over time, allowing identification of the mechanisms underpinning longitudinal change in brain health and to contribute evidence for the feasibility, effectiveness potential, acceptability, and underlying mechanisms of promising interventions for optimizing brain health. We adopt a cohort multiple randomized control trials design. A total of 900 participants will be characterized prospectively over a 27-month period to answer questions about the evolution of outcomes of interest. All participants will be offered basic brain health self-management information. Sub-groups will participate in pilot studies of specific, more intensive interventions to provide pragmatic evidence for feasibility, effectiveness, and comparative effectiveness.

Discussion

This work will provide needed estimates of the burden, heterogeneity, evolution, and mechanisms underlying compromised brain health in HIV, and test a range of promising non-pharmacological interventions. This is an on-going study; the trials nested within this cohort that are currently recruiting participants were registered on 7 October 2015 (Clinicaltrials.gov NCT02571504 and NCT02571595).

Journeying with HIV patients across the health care spectrum - an examination of a seamless model of HIV Psychiatry of a large urban general hospital

OBJECTIVE

To describe a model of HIV psychiatry used in an urban hospital in Toronto and examine it against current literature.

METHOD

Using a narrative method, we elaborate on how this model delivers care across many different settings and the integral roles that the HIV psychiatrist plays in each of these settings. This is articulated against a backdrop of existing literature regarding models of HIV care.

RESULTS

This model is an example of an integrated model as opposed to a traditional consultation-liaison model and is able to deliver seamless care while remaining focused on patient-centric care.

CONCLUSION

An HIV psychiatrist delivers seamless and patient-centric care by journeying with patients across the healthcare spectrum and playing different roles in different care settings.

Does the informal caregiver notice HIV associated mild cognitive impairment in people living with HIV?

HIV associated minor neurocognitive disorder (MND) may be difficult to identify as key signs and symptoms (S & S) may be due to other clinical conditions. Using a self-assessment booklet "HIV and associated MND" we recruited 123 people living with HIV (PLHIV) from three sites: two hospital HIV clinics and a sexual health clinic in Sydney, Australia. Patients may down play S & S. Caregivers may notice subtle changes. By including caregivers, we aimed to find whether the caregivers noticed S & S undetected by the PLHIV. This is a sub-study of a prospective observational multi-site study aimed to validate the usefulness of a patient self-assessment tool (HIV-associated MND booklet). Using the booklet, participants and their caregivers subsequently identified S & S of MND. Sixty-four per cent (79) did not nominate a caregiver to be contacted. Participants from 2 sites 44 (36%) nominated caregivers to be contacted. Twenty-five caregivers identified more than four S & S of MND. S & S reported most by caregivers related to participants being more tired at the end of the day (76%). Participants agreed (77%). Participants also reported that they found it more difficult to remember things such as taking medications or attending medical appointments (67%). The most agreed on symptom was the requirement for increased concentration to get the same things done (Kappa P 0.599 <0.001 and McNemar 0.289). For each question at least one caregiver identified a symptom when the PLHIV did not. Caregivers were more likely than participants to report irritability and communication difficulties. It is important to include caregivers when investigating PLHIV for MND, as caregivers may validate the experience of the patient, and may also be uniquely placed to identify S & S not otherwise identified.

HIV effects on age-associated neurocognitive dysfunction: premature cognitive aging or neurodegenerative disease?

Marked improvements in survival and health outcome for people infected with HIV have occurred since the advent of combination antiretroviral therapy over a decade ago. Yet HIV-associated neurocognitive disorders continue to occur with an alarming prevalence. This may reflect the fact that infected people are now living longer with chronic infection. There is mounting evidence that HIV exacerbates age-associated cognitive decline. Many middle-aged HIV-infected people are experiencing cognitive decline similar that to that found among much older adults. An increased prevalence of vascular and metabolic comorbidities has also been observed and is greatest among older adults with HIV. Premature age-associated neurocognitive decline appears to be related to structural and functional brain changes on neuroimaging, and of particular concern is the fact that pathology indicative of neurodegenerative disease has been shown to occur in the brains of HIV-infected people. Yet notable differences also exist between the clinical presentation and brain disturbances occurring with HIV and those occurring in neurodegenerative conditions such as Alzheimer’s disease. HIV interacts with the aging brain to affect neurological structure and function. However, whether this interaction directly affects neurodegenerative processes, accelerates normal cognitive aging, or contributes to a worsening of other comorbidities that affect the brain in older adults remains an open question. Evidence for and against each of these possibilities is reviewed.

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.

HIV-associated neurocognitive disorders: the relationship of HIV infection with physical and social comorbidities

The prevalence of HIV (human immunodeficiency virus) associated neurocognitive disorders (HAND) will undoubtedly increase with the improved longevity of HIV-infected persons. HIV infection, itself, as well as multiple physiologic and psychosocial factors can contribute to cognitive impairment and neurologic complications. These comorbidities confound the diagnosis, assessment, and interventions for neurocognitive disorders. In this review, we discuss the role of several key comorbid factors that may contribute significantly to the development and progression of HIV-related neurocognitive impairment, as well as the current status of diagnostic strategies aimed at identifying HIV-infected individuals with impaired cognition and future research priorities and challenges.

Engagement Along the HIV Care Continuum and the Potential Role f Mental Health and Substance Use Disorders

Increasing access to mental health and substance use services, particularly through integrated care models, as well as addressing issues of HIV-related stigma, may positively impact engagement in HIV clinical care.

The Montreal cognitive assessment to screen for cognitive impairment in HIV patients older than 60 years

Progress in HIV treatments has led to HIV-infected patients living into their 60s and older. Because HIV-associated neurocognitive disorder (HAND) in older age is associated with more executive dysfunction, cognitive screening instruments tapping this domain may be optimal. We examined the Montreal Cognitive Assessment to identify HAND in 67 HIV-infected patients older than 60 years, of which 40% were diagnosed with HAND. Receiver operating characteristic curve identified an optimal cutpoint of ≤ 25 for HAND with a sensitivity of 72% and specificity of 67%. We conclude that the Montreal Cognitive Assessment has only moderate performance characteristics for cognitive screening of HIV-infected elders.

Can Speed of Processing Training Ameliorate Depressive Symptomatology in Adults with HIV?

Despite advances in combination Antiretroviral Therapy (cART), adults with HIV continue to experience cognitive impairments. In addition to these cognitive impairments, research suggests as many as 40% and 20% of adults with HIV are diagnosed with depression and anxiety, respectively. The impact of these cognitive and emotional deficits increases caregiver burden, impairs occupational and driving performance, contributes to poor emotional processing, increases cognitive complaints, and reduces quality of life. Fortunately, cognitive remediation therapy improves targeted cognitive abilities along with general cognitive processes. Speed of processing training, a type of cognitive remediation therapy, has been shown to improve cognitive performance on measures of visual attention, speed of processing, and timed-task performances. Furthermore, studies suggest that speed of processing training could also enhance neuromodulatory systems which have direct implications for improving mood functions (depression and anxiety). The benefits of the improvement in these cognitive and emotional systems are a decrease or slowing in cognitive decline along with the potential to protect against clinically significant depressive symptoms. Studies support the need for deeper investigation into the short-term and long-term benefits of speed of processing training as a behavioral adjunct for the pharmacologically-burdened HIV population.

Older individuals with HIV infection have greater memory deficits than younger individuals

The prevalence of HIV-associated neurocognitive disorder (HAND) remains persistently high in the era of combination antiretroviral therapy. We aimed to characterize the pattern of neurocognitive dysfunction in older subjects with HAND in particular amnestic versus non-amnestic impairment. One hundred six subjects from the Johns Hopkins University NIMH Clinical Outcomes cohort underwent standardized neuropsychological (NP) testing between November 2006 and June 2010. We examined performance in seven cognitive domains (memory, attention, speed of processing,visuospatial, language, motor, and executive). Older subjects were defined as age >50 years at the time of NP testing.Subjects were diagnosed with HAND according to established criteria and dichotomized into amnestic cognitive impairment or non-amnestic cognitive impairment with deficit defined as z scores <−1.5 for the verbal and nonverbal memory domains.There were 32 older subjects with a mean age (SD) of 54.2 (2.8) years and 74 younger subjects, 43.7 (4.3) years. Older age was associated with a 4.8-fold higher odds of memory deficits adjusted for potential confounders (p =0.035) identified a priori. With age modeled as a continuous covariate,every 1 year increase in age was associated with a 1.11-fold higher odds of memory deficit (p =0.05). There was a higher proportion of amnestic cognitive impairment among older subjects than younger subjects with HIV infection. Neurodegenerative processes other than those directly due to HIV maybe increasingly important as individuals with chronic HIV infection and HAND survive into older age.

Verbal memory declines more rapidly with age in HIV infected versus uninfected adults

OBJECTIVES

In the current era of effective antiretroviral treatment, the number of older adults living with HIV is rapidly increasing. This study investigated the combined influence of age and HIV infection on longitudinal changes in verbal and visuospatial learning and memory.

METHOD

In this longitudinal, case-control design, 54 HIV seropositive and 30 seronegative individuals aged 40-74 years received neurocognitive assessments at baseline visits and again one year later. Assessment included tests of verbal and visuospatial learning and memory. Linear regression was used to predict baseline performance and longitudinal change on each test using HIV serostatus, age, and their interaction as predictors. Multivariate analysis of variance (MANOVA) was used to assess the effects of these predictors on overall baseline performance and overall longitudinal change.

RESULTS

The interaction of HIV and age significantly predicted longitudinal change in verbal memory performance, as did HIV status, indicating that although the seropositive group declined more than the seronegative group overall, the rate of decline depended on age such that greater age was associated with a greater decline in this group. The regression models for visuospatial learning and memory were significant at baseline, but did not predict change over time. HIV status significantly predicted overall baseline performance and overall longitudinal change.

CONCLUSIONS

This is the first longitudinal study focused on the effects of age and HIV on memory. Findings suggest that age and HIV interact to produce larger declines in verbal memory over time. Further research is needed to gain a greater understanding of the effects of HIV on the aging brain.

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.