HIV-associated neurocognitive disorders before and during the era of combination antiretroviral therapy: differences in rates, nature, and predictors

Dynamics of peripheral T cell exhaustion and monocyte subpopulations in neurocognitive impairment and brain atrophy in chronic HIV infection

BACKGROUND

HIV-associated neurocognitive disorders (HAND) is hypothesized to be a result of myeloid cell-induced neuro-inflammation in the central nervous system that may be initiated in the periphery, but the contribution of peripheral T cells in HAND pathogenesis remains poorly understood.

METHODS

We assessed markers of T cell activation (HLA-DR + CD38+), immunosenescence (CD57 + CD28-), and immune-exhaustion (TIM-3, PD-1 and TIGIT) as well as monocyte subsets (classical, intermediate, and non-classical) by flow cytometry in peripheral blood derived from individuals with HIV on long-term stable anti-retroviral therapy (ART). Additionally, normalized neuropsychological (NP) composite test z-scores were obtained and regional brain volumes were assessed by magnetic resonance imaging (MRI). Relationships between proportions of immune phenotypes (of T-cells and monocytes), NP z-scores, and brain volumes were analyzed using Pearson correlations and multiple linear regression models.

RESULTS

Of N = 51 participants, 84.3% were male, 86.3% had undetectable HIV RNA < 50 copies/ml, median age was 52 [47, 57] years and median CD4 T cell count was 479 [376, 717] cells/uL. Higher CD4 T cells expressing PD-1 + and/or TIM-3 + were associated with lower executive function and working memory and higher CD8 T cells expressing PD-1+ and/or TIM-3+ were associated with reduced brain volumes in multiple regions (putamen, nucleus accumbens, cerebellar cortex, and subcortical gray matter). Furthermore, higher single or dual frequencies of PD-1 + and TIM-3 + expressing CD4 and CD8 T-cells correlated with higher CD16 + monocyte numbers.

CONCLUSIONS

This study reinforces evidence that T cells, particularly those with immune exhaustion phenotypes, are associated with neurocognitive impairment and brain atrophy in people living with HIV on ART. Relationships revealed between T-cell immune exhaustion and inflammatory in CD16+ monocytes uncover interrelated cellular processes likely involved in the immunopathogenesis of HAND.

Neurocognitive profile in HIV subjects on INSTI-regimen- one year follow up: Is there room for optimism?

The introduction of antiretroviral therapy (ART) has successfully changed the clinical course of people with HIV, leading to a significant decline in the incidence of HIV-related neurocognitive disorders. Integrase strand transferase inhibitors (INSTI) are recommended and preferred first-line ART for the treatment of HIV-1 infection in ART-naïve subjects. This type of therapy regimen is expected to have higher CNS penetration, which may bring more cognitive stability or even make significant cognitive improvement in people with HIV. The study aimed to follow up on neurocognitive performance in HIV subjects on two types of INSTI therapy regimens at two-time points, one year apart. The study sample consisted of 61 ART naïve male participants, of which 32 were prescribed raltegravir (RAL) and 29 dolutegravir (DTG). There was no significant difference between subsamples according to the main sociodemographic (age, education level) and clinical characteristics (duration of therapy, nadir CD4 cells level, CD4 cells count, CD8 cells, CD4/CD8 ratio). For neurocognitive assessment, six measures were used: general cognitive ability (MoCA test), verbal fluency (total sum score for phonemic and category fluency), verbal working memory (digit span forward), cognitive capacity (digit span backwards), sustained attention (Color Trail Test 1), and divided attention (Color Trail Test 2). In both therapy groups (RAL and DTG), there was no significant decrease in neurocognitive achievement on all used measures over a one-year follow-up in both therapy groups. A statistically significant interactive effect of time and type of therapy was found on the measure of divided attention-DTG group showed slight improvement, whereas RAL group showed slight decrease in performance. During the one-year follow-up of persons on INSTI-based regimen, no significant changes in cognitive achievement were recorded, which suggests that the existing therapy can have a potentially positive effect on the maintenance of neurocognitive achievement.

Molecular Insight into the Effect of HIV-TAT Protein on Amyloid-β Peptides

Increased deposition of amyloid-β (Aβ) plaques in the brain is a frequent pathological feature observed in human immunodeficiency virus (HIV)-positive patients. Emerging evidence indicates that HIV regulatory proteins, particularly the transactivator of transcription (TAT) protein, could interact with Aβ peptide, accelerating the formation of Aβ plaques in the brain and potentially contributing to the onset of Alzheimer's disease in individuals with HIV infection. Nevertheless, the molecular mechanisms underlying these processes remain unclear. In the present study, we have used long all-atom molecular dynamics simulations to probe the direct interactions between the TAT protein and Aβ peptide at the molecular level. Sampling over 28.0 μs, our simulations show that TAT protein induces a shift in the Aβ monomer ensemble toward elongated conformations, exposing aggregation-prone regions on the surface and thereby inducing subsequent aggregation. TAT protein also appears to enhance the stability of preformed Aβ fibrils, while increasing the β-sheet content within these fibrils. Our atomistically detailed simulations qualitatively agree with previous in vitro and in vivo studies. Importantly, our simulations identify key interactions between Aβ and the TAT protein that drive the Aβ aggregation process and stabilize the preformed Aβ aggregates, which are particularly challenging to obtain through current experimental techniques.

Cannabinoid receptor 1 positive allosteric modulator ZCZ011 shows differential effects on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

The cannabinoid receptor type 1 (CB1R) is a promising therapeutic target for various neurodegenerative diseases, including HIV-1-associated neurocognitive disorder (HAND). However, the therapeutic potential of CB1R by direct activation is limited due to its psychoactive side effects. Therefore, research has focused on indirectly activating the CB1R by utilizing positive allosteric modulators (PAMs). Studies have shown that CB1R PAMs (ZCZ011 and GAT211) are effective in mouse models of Huntington's disease and neuropathic pain, and hence, we assess the therapeutic potential of ZCZ011 in a well-established mouse model of neuroHIV. The current study investigates the effect of chronic ZCZ011 treatment (14 days) on various behavioral paradigms and the endocannabinoid system in HIV-1 Tat transgenic female and male mice. Chronic ZCZ011 treatment (10 mg/kg) did not alter body mass, locomotor activity, or anxiety-like behavior regardless of sex or genotype. However, differential effects were noted in hot plate latency, motor coordination, and recognition memory in female mice only, with ZCZ011 treatment increasing hot plate latency and improving motor coordination and recognition memory. Only minor effects or no alterations were seen in the endocannabinoid system and related lipids except in the cerebellum, where the effect of ZCZ011 was more pronounced in female mice. Moreover, AEA and PEA levels in the cerebellum were positively correlated with improved motor coordination in female mice. In summary, these findings indicate that chronic ZCZ011 treatment has differential effects on antinociception, motor coordination, and memory, based on sex and HIV-1 Tat expression, making CB1R PAMs potential treatment options for HAND without the psychoactive side effects.

Cognitive impairment in children and adolescents living with perinatal HIV disease in the ART era: a meta-analysis

Background

Despite improved survival and overall health outcomes from modern antiretroviral therapy (ART), children and adolescents living with HIV are facing pervasive impairments in neurodevelopment including cognitive impairment, but there remains a lack of consensus on the cognitive domains that are affected in those children and adolescents. The objective of this meta-analysis was to evaluate the impact of perinatal HIV-infection on executive function, working memory, and speed of information processing in the ART era.

Methods

The PubMed database was searched for studies published between 1997 and 2024, plus additional search with the ScienceDirect, bioRxiv, and medRxiv databases. A meta-analysis was conducted on thirty-five studies published between 2012 and 2023 that encompassed a total of 4066 perinatally-infected HIV patients, 2349 HIV-exposed uninfected (HEU) controls, and 2466 HIV-unexposed, uninfected (HUU) controls. Performance scores on executive function, working memory, and processing speed were pooled using random-effects meta-analysis.

Findings

Compared to HEU and HUU controls, perinatally HIV-infected children and adolescents presented with significant impairments in processing speed (Hedges g = -0.64, p < 0.00001), working memory (Hedges g = -0.69, p < 0.00001), and to a lesser degree, executive function (Hedges g = -0.35, p = 0.02). Meta-regression analysis suggested that the effect estimate of processing speed impairment negatively correlated with Gross National Income (GNI) per capita of the study countries (CALHIV vs HUU, p = 0.0016; CALHIV vs HEU, p = 0.0019), even though HIV-infected cases were compared to sociodemographically matched HUU controls from the same countries. Sub-group meta-analyses with participants from high-income or low-/middle-income countries provided further evidence suggesting that the performance gap between HIV-infected cases and HUU/HEU controls may be larger in low-/middle-income countries than high-income countries.

Interpretation

In the ART era, cognitive impairment (especially reduced processing speed and working memory) persists in children and adolescents living with HIV. These impairments may be more pronounced among those children and adolescents living with HIV in low-income countries, suggesting that there may be global health inequities in treatment outcomes with perinatal HIV-infection. However, meta-analysis and meta-regression analysis have their limitations, which calls for future collaborative multi-country international studies to directly investigate this important topic. Nevertheless, there is an unmet need to assure equity in timely assessments and interventions to optimize neurocognitive development and outcomes among children and adolescents with perinatal HIV globally.

Funding

This research was supported in part by NIH R01MH108466, NIH R56NS124422, and NIH R01NS124422.

Brain N -acetyl-aspartyl-glutamate is associated with cognitive function in older virally suppressed people with HIV

OBJECTIVES

Cognitive impairment persists in virally suppressed people with HIV (VS-PWH) especially in higher order domains. One cortical circuit, linked to these domains, is regulated by N -acetyl-aspartyl glutamate (NAAG), the endogenous agonist of the metabotropic glutamate receptor 3. The enzyme glutamate carboxypeptidase II (GCPII) catabolizes NAAG and is upregulated in aging and disease. Inhibition of GCPII increases brain NAAG and improves learning and memory in rodent and primate models.

DESIGN

As higher order cognitive impairment is present in VS-PWH, and NAAG has not been investigated in earlier magnetic resonance spectroscopy studies (MRS), we investigated if brain NAAG levels measured by MRS were associated with cognitive function.

METHODS

We conducted a retrospective analysis of 7-Tesla MRS data from a previously published study on cognition in older VS-PWH. The original study did not separately quantify NAAG, therefore, work for this report focused on relationships between regional NAAG levels in frontal white matter (FWM), left hippocampus, left basal ganglia and domain-specific cognitive performance in 40 VS-PWH after adjusting for confounds. Participants were older than 50 years, negative for affective and neurologic disorders, and had no prior 3-month psychoactive-substance use.

RESULTS

Higher NAAG levels in FWM were associated with better attention/working memory. Higher left basal ganglia NAAG related to better verbal fluency. There was a positive relationship between hippocampal NAAG and executive function which lost significance after correction for confounds.

CONCLUSION

These data suggest brain NAAG serves as a biomarker of cognition in VS-PWH. Pharmacological modulation of brain NAAG warrants investigation as a therapeutic approach for cognitive deficits in VS-PWH.

The Impact of Cannabis Use on Cognition in People with HIV: Evidence of Function-Dependent Effects and Mechanisms from Clinical and Preclinical Studies

PURPOSE OF REVIEW

Cannabis may have beneficial anti-inflammatory effects in people with HIV (PWH); however, given this population's high burden of persisting neurocognitive impairment (NCI), clinicians are concerned they may be particularly vulnerable to the deleterious effects of cannabis on cognition. Here, we present a systematic scoping review of clinical and preclinical studies evaluating the effects of cannabinoid exposure on cognition in HIV.

RECENT FINDINGS

Results revealed little evidence to support a harmful impact of cannabis use on cognition in HIV, with few eligible preclinical data existing. Furthermore, the beneficial/harmful effects of cannabis use observed on cognition were function-dependent and confounded by several factors (e.g., age, frequency of use). Results are discussed alongside potential mechanisms of cannabis effects on cognition in HIV (e.g., anti-inflammatory), and considerations are outlined for screening PWH that may benefit from cannabis interventions. We further highlight the value of accelerating research discoveries in this area by utilizing translatable cross-species tasks to facilitate comparisons across human and animal work.

CRISPR/CAS as a Powerful Tool for Human Immunodeficiency Virus Cure: A Review

Despite care and the availability of effective antiretroviral treatment, some human immunodeficiency virus (HIV)-infected individuals suffer from neurocognitive disorders associated with HIV (HAND) that significantly affect their quality of life. The different types of HAND can be divided into asymptomatic neurocognitive impairment, mild neurocognitive disorder, and the most severe form known as HIV-associated dementia. Little is known about the mechanisms of HAND, but it is thought to be related to infection of astrocytes, microglial cells, and macrophages in the human brain. The formation of a viral reservoir that lies dormant as a provirus in resting CD4+ T lymphocytes and in refuge tissues such as the brain contributes significantly to HIV eradication. In recent years, a new set of tools have emerged: the gene editing based on the clustered regularly interspaced palindromic repeats (CRISPR)/Cas9 system, which can alter genome segments by insertion, deletion, and replacement and has great therapeutic potential. This technology has been used in research to treat HIV and appears to offer hope for a possible cure for HIV infection and perhaps prevention of HAND. This approach has the potential to directly impact the quality of life of HIV-infected individuals, which is a very important topic to be known and discussed.

Molecular mechanisms underpinning the protection against antiretroviral drug-induced sperm-endocrine aberrations and testicular toxicity: A review

The introduction of highly active antiretroviral therapy (HAART) has revolutionized the treatment of HIV/AIDS worldwide. The HAART approach is the combination of two or more antiretroviral drugs of different classes and are responsible for patient's survival and declining death rates from HIV/AIDS and AIDS-related events. However, the severe and persistent reproductive side effect toxicity of HAART regimens is of great concern to patients within the reproductive age. Till date, the underlying pathophysiology of the HAART-induced reproductive toxicity remains unraveled. Nevertheless, preclinical studies show that oxidative stress and inflammation may be involved in HAART-induced sperm-endocrine deficit and reproductive aberrations. Studies are emerging demonstrating the efficacy of plant-based and non-plant products against the molecular alterations and testicular toxicity of HAART. The testicular mechanisms of mitigation by these products are associated with enhancement of testicular steroidogenesis, spermatogenesis, inhibition of oxidative stress and inflammation. This review presents the toxic effects of HAART on spermatogenesis, reproductive hormones and testis integrity. It also provides insights on the molecular mechanisms underlying the mitigation of HAART testicular toxicity by plant-based and non-plant agents. However, effect of repurposing clinical drugs to combat HAART toxicity is unknown, and more mechanistic studies are evidently needed. Altogether, plant-based and non-plant products are potential agents for prevention of rampant endocrine dysfunction and testicular toxicity of HAART.

Chronic and Latent Viral Infections and Leukocyte Telomere Length across the Lifespan of Female and Male Individuals Living with or without HIV

BACKGROUND

Chronic/latent viral infections may accelerate immunological aging, particularly among people living with HIV (PLWH). We characterized chronic/latent virus infections across their lifespan and investigated their associations with leukocyte telomere length (LTL).

METHODS

Participants enrolled in the CARMA cohort study were randomly selected to include n = 15 for each decade of age between 0 and >60 y, for each sex, and each HIV status. Cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 8 (HHV-8), herpes simplex virus 1 (HSV-1), and HSV-2 infection were determined serologically; HIV, hepatitis C (HCV), and hepatitis B (HBV) were self-reported. LTLs were measured using monochrome multiplex qPCR. Associations between the number of viruses, LTL, and sociodemographic factors were assessed using ordinal logistic and linear regression modeling.

RESULTS

The study included 187 PLWH (105 female/82 male) and 190 HIV-negative participants (105 female/84 male), ranging in age from 0.7 to 76.1 years. Living with HIV, being older, and being female were associated with harbouring a greater number of chronic/latent non-HIV viruses. Having more infections was in turn bivariately associated with a shorter LTL. In multivariable analyses, older age, living with HIV, and the female sex remained independently associated with having more infections, while having 3-4 viruses (vs. 0-2) was associated with a shorter LTL.

CONCLUSIONS

Our results suggest that persistent viral infections are more prevalent in PLWH and females, and that these may contribute to immunological aging. Whether this is associated with comorbidities later in life remains an important question.

Disparities in Metabolic Syndrome and Neurocognitive Function Among Older Hispanics/Latinos with Human Immunodeficiency Virus

Neurocognitive impairment and metabolic syndrome (MetS) are prevalent in persons with HIV (PWH). We examined disparities in HIV-associated neurocognitive function between Hispanic and non-Hispanic White older PWH, and the role of MetS in explaining these disparities. Participants included 116 community-dwelling PWH aged 50-75 years enrolled in a cohort study in southern California [58 Hispanic (53% Spanish speaking) and 58 age-comparable non-Hispanic White; overall group: age: M = 57.9, standard deviation (SD) = 5.7; education (years): M = 13, SD = 3.4; 83% male, 58% AIDS, 94% on antiretroviral therapy]. Global neurocognition was derived from T-scores adjusted for demographics (age, education, sex, ethnicity, language) on a battery of 10 cognitive tests. MetS was ascertained via standard criteria that considered central obesity, and fasting elevated triglycerides, low high-density lipoprotein cholesterol and elevated glucose, or medical treatment for these conditions. Covariates examined included sociodemographic, psychiatric, substance use and HIV disease characteristics. Compared with non-Hispanic Whites, Hispanics showed worse global neurocognitive function (Cohen's d = 0.56, p < 0.05) and had higher rates of MetS (38% vs. 56%, p < 0.05). A stepwise regression model including ethnicity and significant covariates showed Hispanic ethnicity was the sole significant predictor of worse global neurocognition (B = -3.82, SE = 1.27, p < 0.01). A model also including MetS showed that both Hispanic ethnicity (B = -3.39, SE = 1.31, p = 0.01) and MetS (B = -2.73, SE = 1.31, p = 0.04) were independently associated with worse neurocognition. In conclusion, findings indicate that increased MetS is associated with worse neurocognitive function in both Hispanic and non-Hispanic White older PWH, but does not explain neurocognitive disparities. MetS remains an important target for intervention efforts to ameliorate neurocognitive dysfunction among diverse older PWH.

A critical role for Macrophage-derived Cysteinyl-Leukotrienes in HIV-1 induced neuronal injury

Macrophages (MΦ) infected with human immunodeficiency virus (HIV)-1 or activated by its envelope protein gp120 exert neurotoxicity. We found previously that signaling via p38 mitogen-activated protein kinase (p38 MAPK) is essential to the neurotoxicity of HIVgp120-stimulated MΦ. However, the associated downstream pathways remained elusive. Here we show that cysteinyl-leukotrienes (CysLT) released by HIV-infected or HIVgp120 stimulated MΦ downstream of p38 MAPK critically contribute to neurotoxicity. SiRNA-mediated or pharmacological inhibition of p38 MAPK deprives MΦ of CysLT synthase (LTC4S) and, pharmacological inhibition of the cysteinyl-leukotriene receptor 1 (CYSLTR1) protects cerebrocortical neurons against toxicity of both gp120-stimulated and HIV-infected MΦ. Components of the CysLT pathway are differentially regulated in brains of HIV-infected individuals and a transgenic mouse model of NeuroHIV (HIVgp120tg). Moreover, genetic ablation of LTC4S or CysLTR1 prevents neuronal damage and impairment of spatial memory in HIVgp120tg mice. Altogether, our findings suggest a novel critical role for cysteinyl-leukotrienes in HIV-associated brain injury.

Underlying Neural Mechanisms of Cognitive Improvement in Fronto-striatal Response Inhibition in People Living with HIV Switching Off Efavirenz: A Randomized Controlled BOLD fMRI Trial

INTRODUCTION

It is unclear whether neurotoxicity due to the antiretroviral drug efavirenz (EFV) results in neurocognitive impairment in people living with HIV (PLWH). Previously, we found that discontinuing EFV was associated with improved processing speed and attention on neuropsychological assessment. In this imaging study, we investigate potential neural mechanisms underlying this cognitive improvement using a BOLD fMRI task assessing cortical and subcortical functioning.

METHODS

Asymptomatic adult PLWH stable on emtricitabine/tenofovirdisoproxil/efavirenz were randomly (1:2) assigned to continue their regimen (n = 12) or to switch to emtricitabine/tenofovirdisoproxil/rilpivirine (n = 28). At baseline and after 12 weeks, both groups performed the Stop-Signal Anticipation Task, which tests reactive and proactive inhibition (indicative of subcortical and cortical functioning, respectively), involving executive functioning, working memory, and attention. Behavior and BOLD fMRI activation levels related to processing speed and attention Z-scores were assessed in 17 pre-defined brain regions.

RESULTS

Both groups had comparable patient and clinical characteristics. Reactive inhibition behavioral responses improved for both groups on week 12, with other responses unchanged. Between-group activation did not differ significantly. For reactive inhibition, positive Pearson coefficients were observed for the change in BOLD fMRI activation levels and change in processing speed and attention Z-scores in all 17 regions in participants switched to emtricitabine/tenofovir disoproxil/rilpivirine, whereas in the control group, negative correlation coefficients were observed in 10/17 and 13/17 regions, respectively. No differential pattern was observed for proactive inhibition.

CONCLUSION

Potential neural mechanisms underlying cognitive improvement after discontinuing EFV in PLWH were found in subcortical functioning, with our findings suggesting that EFV's effect on attention and processing speed is, at least partially, mediated by reactive inhibition.

TRIAL REGISTRATION

Clinicaltrials.gov identifier [NCT02308332].

Autophagy Deregulation in HIV-1-Infected Cells Increases Extracellular Vesicle Release and Contributes to TLR3 Activation

Human immunodeficiency virus type 1 (HIV-1) infection can result in HIV-associated neurocognitive disorder (HAND), a spectrum of disorders characterized by neurological impairment and chronic inflammation. Combined antiretroviral therapy (cART) has elicited a marked reduction in the number of individuals diagnosed with HAND. However, there is continual, low-level viral transcription due to the lack of a transcription inhibitor in cART regimens, which results in the accumulation of viral products within infected cells. To alleviate stress, infected cells can release accumulated products, such as TAR RNA, in extracellular vesicles (EVs), which can contribute to pathogenesis in neighboring cells. Here, we demonstrate that cART can contribute to autophagy deregulation in infected cells and increased EV release. The impact of EVs released from HIV-1 infected myeloid cells was found to contribute to CNS pathogenesis, potentially through EV-mediated TLR3 (Toll-like receptor 3) activation, suggesting the need for therapeutics to target this mechanism. Three HIV-1 TAR-binding compounds, 103FA, 111FA, and Ral HCl, were identified that recognize TAR RNA and reduce TLR activation. These data indicate that packaging of viral products into EVs, potentially exacerbated by antiretroviral therapeutics, may induce chronic inflammation of the CNS observed in cART-treated patients, and novel therapeutic strategies may be exploited to mitigate morbidity.

EcoHIV Infection Modulates the Effects of Cocaine Exposure Pattern and Abstinence on Cocaine Seeking and Neuroimmune Protein Expression in Male Mice

Cocaine use disorders (CUDs) and human immunodeficiency virus (HIV) remain persistent public health dilemmas throughout the world. One major hurdle for treating CUD is the increase in cocaine craving and seeking behavior that occurs over a protracted period of abstinence, an effect known as the incubation of craving. Little is known about how HIV may modulate this process. Thus, we sought to examine the impact of chronic HIV infection on the incubation of cocaine craving and associated changes in the central and peripheral immune systems. Here, mice were inoculated with EcoHIV, which is a chimeric HIV-1 construct that produces chronic HIV infection in mice. EcoHIV- and sham-infected mice were conditioned with cocaine daily or intermittently in a conditioned place preference (CPP) paradigm, followed by 1 or 21 days of forced abstinence prior to assessing preference for the cocaine-paired chamber. Under both conditioning regimens, sham mice exhibited incubation of cocaine CPP after 21 days of abstinence. EcoHIV-infected mice conditioned daily with cocaine showed enhanced cocaine seeking at both abstinence timepoints, whereas infected mice conditioned intermittently showed a reversal of the incubation effect, with higher cocaine seeking after 1 day of abstinence compared to 21 days. Analysis of corticolimbic CX3CL1-CX3CR1 and glutamate receptor expression revealed alterations in medial prefrontal cortex (mPFC) CX3CL1 and nucleus accumbens (NAc) GluN2A receptors that correlated with cocaine seeking following daily cocaine exposure. Moreover, examination of peripheral immune markers showed that the effect of abstinence and EcoHIV infection on these measures depended on the cocaine exposure regimen. Altogether, these results highlight the importance of cocaine abstinence and exposure pattern as critical variables that modulate HIV-associated neuroimmune outcomes and relapse vulnerability.

Associations Between Estimates of Arterial Stiffness and Cognitive Functioning in Adults With HIV

BACKGROUND

Vascular aging, a precursor of arterial stiffness, is associated with neurocognitive impairment (NCI) and cardiovascular disease. Although HIV is associated with rapid vascular aging, it is unknown whether arterial stiffness mediates changes in cognitive function. We explored whether estimated markers of vascular aging were associated with NCI indices in HIV-positive individuals.

METHODS

This study was a secondary analysis of an observational study. Neurocognitive functioning was assessed using a battery of 7 domains (verbal fluency, executive functioning, speed of information processing, attention/working memory, memory [learning and delayed recall], and motor skills). Vascular aging was assessed using estimated markers of arterial stiffness (ie, estimated pulse wave velocity, pulse pressure, and vascular overload index). A multivariable regression adjusted for demographics, cardiovascular disease risk factors, and HIV clinical variables was used to examine the association between vascular aging and NCI outcomes.

RESULTS

Among 165 people with HIV, the mean age was 51.5 ± 6.9 years (62% men and 83% African American/Black or Other). In fully adjusted models, an increase in estimated pulse wave velocity and pulse pressure was associated with lower T scores in learning (-2.95 [-5.13, -0.77]) and working memory (-2.37 [-4.36, -0.37]), respectively. An increase in vascular overload index was associated with lower T scores in working memory (-2.33 [-4.37, -0.29]) and learning (-1.85 [-3.49, -0.21]).

CONCLUSIONS

Estimated markers of arterial stiffness were weakly associated with neurocognitive functioning, suggesting that vascular aging may have a role in cognitive decline among people with HIV.

Neurocognition and its predictors in a linguistically and culturally diverse cohort of people with HIV

Objective: HIV/AIDS disproportionately affects Black and Latino people in the United States, yet there is a lack of research on predictors of neurocognitive outcomes in these groups. We examined neurocognitive performance and its key predictors across White, Black, and Latino people with HIV (PWH). Method: Participants included 586 PWH of White, Black, and Latino (English- and Spanish-speaking) background. Neurocognition was assessed via demographically-adjusted Fluid Cognition Composite T-scores from the NIH-Toolbox cognition battery, and individual tests comprising this composite. Predictors examined included sociodemographic and HIV disease characteristics, and medical, psychiatric and substance comorbidities. Results: Compared to White PWH, English-speaking Latino PWH had lower T-scores on the Fluid Cognition Composite, as well as Flanker Inhibition and Picture Sequence Memory tests. While there were no other significant group differences on Fluid Cognition, both Latino PWH language groups performed worse than Black PWH on Flanker Inhibition, and Black PWH performed worse than White PWH on List Sorting. Separate multivariable linear regression models by ethnic/racial/language group showed that significant correlates of worse Fluid Cognition included depressive symptoms among White PWH; hepatitis C co-infection among Black PWH; hypertension among English-speaking Latino PWH; and higher estimated duration of HIV disease and depressive symptoms in Spanish-speaking Latino PWH. Conclusions: Findings suggest worse neurocognition among English-speaking Latino PWH compared to Whites. Predictors of neurocognitive function among PWH differ across ethnic/racial and language groups. Consideration of these HIV disease characteristics and comorbidities may be valuable in developing targeted culturally-relevant interventions aimed at ameliorating neurocognitive dysfunction among diverse PWH.

Awareness and Knowledge of HIV-Associated Neurocognitive Disorder Among Middle-Aged and Older People Living With HIV/AIDS in Southern Nevada: Implications for HIV/AIDS Community-Based Education Programs

Although a significant amount of biomedical research has been conducted to study HIV-associated neurocognitive disorder (HAND), there has been scant research done to assess the awareness and knowledge of this public health concern among middle-aged and older people living with HIV/AIDS (PLWH). Our qualitative community-based participatory research study sought to address this research gap by examining the awareness and knowledge of HAND among relevant stakeholders in southern Nevada, USA. We conducted 15 semistructured interviews with middle-aged and older PLWH to examine their awareness and knowledge of HAND and access to pertinent resources. After our thematic analysis of our interviews, we identified two overarching themes: (1) limited awareness and knowledge of HAND among PLWH, and (2) southern Nevada social determinants of health. Our findings underscore the importance of raising awareness and knowledge of HAND among PLWH through community-based education programs, and improving access to resources related to social determinants of health.

The clinical utility of three frailty measures in identifying HIV-associated neurocognitive disorders

OBJECTIVE

Frailty measures vary widely and the optimal measure for predicting HIV-associated neurocognitive disorders (HAND) is unclear.

DESIGN

A study was conducted to examine the clinical utility of three widely used frailty measures in identifying HIV-associated neurocognitive disorders.

METHODS

The study involved 284 people with HIV (PWH) at least 50 years enrolled at UC San Diego's HIV Neurobehavioral Research Program. Frailty measurements included the Fried Phenotype, the Rockwood Frailty Index, and the Veterans Aging Cohort Study (VACS) Index. HAND was diagnosed according to Frascati criteria. ANOVAs examined differences in frailty severity across HAND conditions. ROC analyses evaluated sensitivity and specificity of each measure to detect symptomatic HAND [mild neurocognitive disorder (MND) and HIV-associated dementia (HAD)] from no HAND.

RESULTS

Across all frailty measures, frailty was found to be higher in HAD compared with no HAND. For Fried and Rockwood (not VACS), frailty was significantly more severe in MND vs. no HAND and in HAD vs. ANI (asymptomatic neurocognitive impairment). For discriminating symptomatic HAND from no HAND, Fried was 37% sensitive and 92% specific, Rockwood was 85% sensitive and 43% specific, and VACS was 58% sensitive and 65% specific.

CONCLUSION

These findings demonstrate that Fried and Rockwood outperform VACS in predicting HAND. However, ROC analyses suggest none of the indices had adequate predictive validity in detecting HAND. The results indicate that the combined use of the Rockwood and Fried indices may be an appropriate alternative.

Methamphetamine Enhancement of HIV-1 gp120-Mediated NLRP3 Inflammasome Activation and Resultant Proinflammatory Responses in Rat Microglial Cultures

Human Immunodeficiency Virus type 1 (HIV-1)-associated neurocognitive disorders (HANDs) remain prevalent in HIV-1-infected individuals despite the evident success of combined antiretroviral therapy (cART). The mechanisms underlying HAND prevalence in the cART era remain perplexing. Ample evidence indicates that HIV-1 envelope glycoprotein protein 120 (gp120), a potent neurotoxin, plays a pivotal role in HAND pathogenesis. Methamphetamine (Meth) abuse exacerbates HANDs, but how this occurs is not fully understood. We hypothesize that Meth exacerbates HANDs by enhancing gp120-mediated neuroinflammation. To test this hypothesis, we studied the effect of Meth on gp120-induced microglial activation and the resultant production of proinflammatory cytokines in primary rat microglial cultures. Our results show that Meth enhanced gp120-induced microglial activation, as revealed by immunostaining and Iba-1 expression, and potentiated gp120-mediated NLRP3 expression and IL-1β processing and release, as assayed by immunoblotting and ELISA. Meth also augmented the co-localization of NLRP3 and caspase-1, increased the numbers of NLRP3 puncta and ROS production, increased the levels of iNOS expression and NO production, and increased the levels of cleaved gasderminD (GSDMD-N; an executor of pyroptosis) in gp120-primed microglia. The Meth-associated effects were attenuated or blocked by MCC950, an NLRP3 inhibitor, or Mito-TEMPO, a mitochondrial superoxide scavenger. These results suggest that Meth enhances gp120-associated microglial NLRP3 activation and the resultant proinflammatory responses via mitochondria-dependent signaling.

HIV-1 Tat and morphine interactions dynamically shift striatal monoamine levels and exploratory behaviors over time

Despite the advent of combination anti-retroviral therapy (cART), nearly half of people infected with HIV treated with cART still exhibit HIV-associated neurocognitive disorders (HAND). HAND can be worsened by co-morbid opioid use disorder. The basal ganglia are particularly vulnerable to HIV-1 and exhibit higher viral loads and more severe pathology, which can be exacerbated by co-exposure to opioids. Evidence suggests that dopaminergic neurotransmission is disrupted by HIV exposure, however, little is known about whether co-exposure to opioids may alter neurotransmitter levels in the striatum and if this in turn influences behavior. Therefore, we assayed motor, anxiety-like, novelty-seeking, exploratory, and social behaviors, and levels of monoamines and their metabolites following 2 weeks and 2 months of Tat and/or morphine exposure in transgenic mice. Morphine decreased dopamine levels, but significantly elevated norepinephrine, the dopamine metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the serotonin metabolite 5-hydroxyindoleacetic acid, which typically correlated with increased locomotor behavior. The combination of Tat and morphine altered dopamine, DOPAC, and HVA concentrations differently depending on the neurotransmitter/metabolite and duration of exposure but did not affect the numbers of tyrosine hydroxylase-positive neurons in the mesencephalon. Tat exposure increased the latency to interact with novel conspecifics, but not other novel objects, suggesting the viral protein inhibits exploratory behavior initiation in a context-dependent manner. By contrast, and consistent with prior findings that opioid misuse can increase novelty-seeking behavior, morphine exposure increased the time spent exploring a novel environment. Finally, Tat and morphine interacted to affect locomotor activity in a time-dependent manner, while grip strength and rotarod performance were unaffected. Together, our results provide novel insight into the unique effects of HIV-1 Tat and morphine on monoamine neurochemistry that may underlie their divergent effects on motor and exploratory behavior.

Auditory neural processing in children living with HIV uncovers underlying central nervous system dysfunction

OBJECTIVE

Central nervous system (CNS) damage from HIV infection or treatment can lead to developmental delays and poor educational outcomes in children living with HIV (CLWH). Early markers of central nervous system dysfunction are needed to target interventions and prevent life-long disability. The frequency following response (FFR) is an auditory electrophysiology test that can reflect the health of the central nervous system. In this study, we explore whether the FFR reveals auditory central nervous system dysfunction in CLWH.

STUDY DESIGN

Cross-sectional analysis of an ongoing cohort study. Data were from the child's first visit in the study.

SETTING

The infectious disease center in Dar es Salaam, Tanzania.

METHODS

We collected the FFR from 151 CLWH and 151 HIV-negative children. To evoke the FFR, three speech syllabi (/da/, /ba/, /ga/) were played monaurally to the child's right ear. Response measures included neural timing (peak latencies), strength of frequency encoding (fundamental frequency and first formant amplitude), encoding consistency (inter-response consistency), and encoding precision (stimulus-to-response correlation).

RESULTS

CLWH showed smaller first formant amplitudes ( P  < 0.0001), weaker inter-response consistencies ( P  < 0.0001) and smaller stimulus to response correlations ( P  < 0.0001) than FFRs from HIV-negative children. These findings generalized across the three speech stimuli with moderately strong effect sizes (partial η2 ranged from 0.061 to 0.094).

CONCLUSION

The FFR shows auditory central nervous system dysfunction in CLWH. Neural encoding of auditory stimuli was less robust, more variable, and less accurate. As the FFR is a passive and objective test, it may offer an effective way to assess and detect central nervous system function in CLWH.

Accelerated neurodegeneration of basal forebrain cholinergic neurons in HIV-1 gp120 transgenic mice: Critical role of the p75 neurotrophin receptor

Human Immunodeficiency Virus-1 (HIV) infection of the brain induces HIV-associated neurocognitive disorders (HAND). The set of molecular events employed by HIV to drive cognitive impairments in people living with HIV are diverse and remain not completely understood. We have shown that the HIV envelope protein gp120 promotes loss of synapses and decreases performance on cognitive tasks through the p75 neurotrophin receptor (p75NTR). This receptor is abundant on cholinergic neurons of the basal forebrain and contributes to cognitive impairment in various neurological disorders. In this study, we examined cholinergic neurons of gp120 transgenic (gp120tg) mice for signs of degeneration. We observed that the number of choline acetyltransferase-expressing cells is decreased in old (12-14-month-old) gp120tg mice when compared to age matched wild type. In the same animals, we observed an increase in the levels of pro-nerve growth factor, a ligand of p75NTR, as well as a disruption of consolidation of extinction of conditioned fear, a behavior regulated by cholinergic neurons of the basal forebrain. Both biochemical and behavioral outcomes of gp120tg mice were rescued by the deletion of the p75NTR gene, strongly supporting the role that this receptor plays in the neurotoxic effects of gp120. These data indicate that future p75NTR-directed pharmacotherapies could provide an adjunct therapy against synaptic simplification caused by HIV.

Cognitive Intra-individual Variability in the Laboratory Is Associated With Greater Executive Dysfunction in the Daily Lives of Older Adults With HIV

BACKGROUND

Executive dysfunction, which is common among persons with HIV (PWH), can have an adverse impact on health behaviors and quality of life. Intra-individual variability (IIV) is a measure of within-person variability across cognitive tests that is higher in PWH and is thought to reflect cognitive dyscontrol.

OBJECTIVE

To assess whether cognitive IIV in the laboratory is associated with self-reported executive dysfunction in daily life among older PWH.

METHOD

Participants included 71 PWH aged ≥50 years who completed six subtests from the Cogstate battery and two subscales from the Frontal Systems Behavior Scale (FrSBe; self-report version). Cognitive IIV was calculated from the Cogstate as the coefficient of variation derived from age-adjusted normative T scores.

RESULTS

Cognitive IIV as measured by the Cogstate showed a significant, positive, medium-sized association with current FrSBe ratings of executive dysfunction but not disinhibition.

CONCLUSION

Higher cognitive IIV in the laboratory as measured by the Cogstate may be related to the expression of HIV-associated symptoms of executive dysfunction in daily life for older PWH.

Elevated homocysteine levels may moderate and mediate the association between HIV and cognitive impairment among middle-aged and older adults in an underserved population in Baltimore, Maryland

Background: In the antiretroviral therapy (ART) era, HIV-associated neurocognitive disorders (HAND) remain a considerable challenge for people with HIV, yet not all such disorders can be attributed to HIV alone. This study aimed to: (1) identify factors influencing neurocognitive impairment (NCI) utilizing the NIH Toolbox Cognition Battery (NIHTB-CB) as per the revised research criteria for HAND; (2) ascertain the moderating role of high homocysteine levels in the association between NCI and HIV; and (3) assess the mediating effect of elevated homocysteine levels on this association.Methods: We analyzed data from 788 adults (≥45 years) participating in a study on HIV-related comorbidities in underserved Baltimore communities, using NIHTB-CB to gauge neurocognitive performance. Special attention was given to results from the Dimensional Change Card Sort (DCCS) test within the executive function domain during causal mediation analysis.Results: Overall, HIV was not associated with NCI presence. However, HIV was associated with NCI among individuals with homocysteine >14 μmol/L. Furthermore, HIV was both directly and indirectly associated with NCI in DCCS test scores. Notably, the mediating role of elevated homocysteine in DCCS scores was only observable among individuals who had never used cocaine or had used it for ≤ 10 years, suggesting that extended cocaine use may have a substantial influence on cognitive performance.Conclusions: The findings from this study suggest elevated homocysteine levels may moderate and mediate the association between HIV and neurocognitive impairment.

Frontal cortical volume deficits as enduring evidence of childhood abuse in community adults with AUD and HIV infection comorbidity

Background

Childhood abuse is an underappreciated source of stress, associated with adverse mental and physical health consequences. Childhood abuse has been directly associated with risky behavior thereby increasing the likelihood of alcohol misuse and risk of HIV infection, conditions associated with brain structural and functional deficits. Here, we examined the neural and behavioral correlates of childhood trauma history in alcohol use disorder (AUD), HIV infection (HIV), and their comorbidity (AUD+HIV).

Methods

Occurrence of childhood trauma was evaluated by retrospective interview. Cortical (frontal, temporal, parietal, and occipital), subcortical (hippocampus, amygdala), and regional frontal volumes were derived from structural MRI, adjusted for intracranial volume and age. Test scores of executive functioning, attention/working memory, verbal/visual learning, verbal/visual memory, and motor speed functional domains were standardized on age and education of a laboratory control group.

Results

History of childhood abuse was associated with smaller frontal lobe volumes regardless of diagnosis. For frontal subregional volumes, history of childhood abuse was selectively associated with smaller orbitofrontal and supplementary motor volumes. In participants with a child abuse history, poorer verbal/visual memory performance was associated with smaller orbitofrontal and frontal middle volumes, whereas in those without childhood abuse, poorer verbal/visual memory performance was associated with smaller orbitofrontal, frontal superior, and supplemental motor volumes.

Conclusions

Taken together, these results comport with and extend the findings that childhood abuse is associated with brain and behavioral sequelae in AUD, HIV, and AUD+HIV comorbidity. Further, these findings suggest that sequelae of abuse in childhood may be best conceptualized as a spectrum disorder as significant deficits may be present in those who may not meet criteria for a formal trauma-related diagnosis yet may be suffering enduring stress effects on brain structural and functional health.

Acute Effects of Monoacylglycerol Lipase Inhibitor ABX1431 on Neuronal Hyperexcitability, Nociception, Locomotion, and the Endocannabinoid System in HIV-1 Tat Male Mice

Background: Evidence suggests that monoacylglycerol lipase (MAGL) inhibitors can potentially treat HIV symptoms by increasing the concentration of 2-arachidonoylglycerol (2-AG). We examined a selective MAGL inhibitor ABX1431 in the context of neuroHIV. Methods: To assess the effects of ABX1431, we conducted in vitro and in vivo studies. In vitro calcium imaging on frontal cortex neuronal cultures was performed to evaluate the role of ABX1431 (10, 30, 100 nM) on transactivator of transcription (Tat)-induced neuronal hyperexcitability. Following in vitro experiments, in vivo experiments were performed using Tat transgenic male mice. Mice were treated with 4 mg/kg ABX1431 and assessed for antinociception using tail-flick and hot plate assays followed by locomotor activity. After the behavioral experiments, their brains were harvested to quantify endocannabinoids (eCB) and related lipids through mass spectrometry, and cannabinoid type-1 and -2 receptors (CB1R and CB2R) were quantified through western blot. Results: In vitro studies revealed that adding Tat directly to the neuronal cultures significantly increased intracellular calcium concentration, which ABX1431 completely reversed at all concentrations. Preincubating the cultures with CB1R and CB2R antagonists showed that ABX1431 exhibited its effects partially through CB1R. In vivo studies demonstrated that acute ABX1431 increased overall total distance traveled and speed of mice regardless of their genotype. Mass spectrometry and western blot analyses revealed differential effects on the eCB system based on Tat expression. The 2-AG levels were significantly upregulated following ABX1431 treatment in the striatum and spinal cord. Arachidonic acid (AA) was also upregulated in the striatum of vehicle-treated Tat(+) mice. No changes were noted in CB1R expression levels; however, CB2R levels were increased in ABX1431-treated Tat(-) mice only. Conclusion: Findings indicate that ABX1431 has potential neuroprotective effects in vitro partially mediated through CB1R. Acute treatment of ABX1431 in vivo shows antinociceptive effects, and seems to alter locomotor activity, with upregulating 2-AG levels in the striatum and spinal cord.

Clinical markers of HIV predict redox-regulated neural and behavioral function in the sensorimotor system

Even in the modern era of combination antiretroviral therapy, aberrations in motor control remain a predominant symptom contributing to age-related functional dependencies (e.g., neurocognitive impairment) in people with HIV (PWH). While recent evidence implicates aberrant mitochondrial redox environments in the modulation of neural oscillatory activity serving motor control in PWH, the contribution of important clinical and demographic factors on this bioenergetic-neural-behavioral pathway is unknown. Herein, we evaluate the predictive capacity of clinical metrics pertinent to HIV (e.g., CD4 nadir, time with viremia) and age on mitochondrial redox-regulated sensorimotor brain-behavior dynamics in 69 virally-suppressed PWH. We used state-of-the-art systems biology and neuroscience approaches, including Seahorse analyzer of mitochondrial energetics, EPR spectroscopy of intracellular oxidant levels, antioxidant activity assays pertinent to superoxide and hydrogen peroxide (H2O2) redox environments, and magnetoencephalographic (MEG) imaging to quantify sensorimotor oscillatory dynamics. Our results demonstrate differential effects of redox systems on the neural dynamics serving motor function in PWH. In addition, measures of immune stability and duration of compromise due to HIV had dissociable effects on this pathway, above and beyond the effects of age alone. Moreover, peripheral measures of antioxidant activity (i.e., superoxide dismutase) fully mediated the relationship between immune stability and current behavioral performance, indicative of persistent oxidative environments serving motor control in the presence of virologic suppression. Taken together, our data suggest that disease-related factors, in particular, are stronger predictors of current redox, neural and behavioral profiles serving motor function, which may serve as effective targets for alleviating HIV-specific alterations in cognitive-motor function in the future.

Incomplete recovery of the CD4+/CD8+ ratio is associated with the late introduction of antiretroviral therapy among people living with HIV infection

Despite being subject to lower AIDS-related mortality rates and having a higher life expectancy, patients with HIV are more prone to develop non-AIDS events. A low CD4+/CD8+ ratio during antiretroviral therapy identifies people with heightened immune senescence and increased risk of mortality. In clinical practice, finding determinants of a low CD4+/CD8+ ratio may be useful for identifying patients who require close monitoring due to an increased risk of comorbidities and death. We performed a prospective study on the evolution of the CD4+/CD8+ ratio in 60 patients infected with HIV (80% males), who were subjected to two different antiretroviral regimens: early and deferred therapy. The initial CD4+/CD8+ ratio was ≤1 for 70% of the patients in both groups. Older age, CD4+ cell count at inclusion, Nadir CD8+T-cell count, and Initial CD4+/CD8+ ratio ≤ 1 were risk factors for lack of ratio recovery. In the multivariate analysis, a CD4+/CD8+ ratio > 1 at the start of the treatment was found to be a determinant factor in maintaining a CD4+/CD8+ ratio > 1. The nadir CD4+T-cell count was lower in the deferred therapy group (p=0.004), and the last CD4+/CD8+ ratio ≤1 was not associated with comorbidities. Ratio recovery was not associated with the duration of HIV infection, time without therapy, or absence of AIDS incidence. A greater improvement was observed in patients treated early (p=0.003). In contrast, the slope of increase was slower in patients who deferred treatment. In conclusion, the increase in the CD4+/CD8+ ratio occurred mostly for patients undergoing early strategy treatment and its extension did not seem to be related to previous HIV-related factors.

HIV-1 mRNA knockdown with CRISPR/CAS9 enhances neurocognitive function

Mixed glia are infiltrated with HIV-1 virus early in the course of infection leading to the development of a persistent viral reservoir in the central nervous system. Modification of the HIV-1 genome using gene editing techniques, including CRISPR/Cas9, has shown great promise towards eliminating HIV-1 viral reservoirs; whether these techniques are capable of removing HIV-1 viral proteins from mixed glia, however, has not been systematically evaluated. Herein, the efficacy of adeno-associated virus 9 (AAV9)-CRISPR/Cas9 gene editing for eliminating HIV-1 messenger RNA (mRNA) from cortical mixed glia was evaluated in vitro and in vivo. In vitro, a within-subjects experimental design was utilized to treat mixed glia isolated from neonatal HIV-1 transgenic (Tg) rats with varying doses (0, 0.9, 1.8, 2.7, 3.6, 4.5, or 5.4 µL corresponding to a physical titer of 0, 4.23 × 109, 8.46 × 109, 1.269 × 1010, 1.692 × 1010, 2.115 × 1010, and 2.538 × 1010 gc/µL) of CRISPR/Cas9 for 72 h. Dose-dependent decreases in the number of HIV-1 mRNA, quantified using an innovative in situ hybridization technique, were observed in a subset (i.e., n = 5 out of 8) of primary mixed glia. In vivo, HIV-1 Tg rats were retro-orbitally inoculated with CRISPR/Cas9 for two weeks, whereby treatment resulted in profound excision (i.e., approximately 53.2%) of HIV-1 mRNA from the medial prefrontal cortex. Given incomplete excision of the HIV-1 viral genome, the clinical relevance of HIV-1 mRNA knockdown for eliminating neurocognitive impairments was evaluated via examination of temporal processing, a putative neurobehavioral mechanism underlying HIV-1-associated neurocognitive disorders (HAND). Indeed, treatment with CRISPR/Cas9 protractedly, albeit not permanently, restored the developmental trajectory of temporal processing. Proof-of-concept studies, therefore, support the susceptibility of mixed glia to gene editing and the potential of CRISPR/Cas9 to serve as a novel therapeutic strategy for HAND, even in the absence of full viral eradication.

Central auditory test performance predicts future neurocognitive function in children living with and without HIV

Tests of the brain's ability to process complex sounds (central auditory tests) correlate with overall measures of neurocognitive performance. In the low- middle-income countries where resources to conduct detailed cognitive testing is limited, tests that assess the central auditory system may provide a novel and useful way to track neurocognitive performance. This could be particularly useful for children living with HIV (CLWH). To evaluate this, we administered central auditory tests to CLWH and children living without HIV and examined whether central auditory tests given early in a child's life could predict later neurocognitive performance. We used a machine learning technique to incorporate factors known to affect performance on neurocognitive tests, such as education. The results show that central auditory tests are useful predictors of neurocognitive performance and perform as well or in some cases better than factors such as education. Central auditory tests may offer an objective way to track neurocognitive performance in CLWH.

Identifying and distinguishing cognitive profiles among virally suppressed people with HIV

OBJECTIVE

Cognitive deficits are common among people with HIV (PWH), even when virally suppressed. We identified cognitive profiles among virally suppressed PWH and determined how sociodemographic, clinical/behavioral, and HIV disease characteristics distinguish profile membership.

METHOD

Participants included 704 virally suppressed PWH (Mage = 43.9 [SD = 10.2], 88% male, 58.9% non-Hispanic White) from the HIV Neurobehavioral Research Program. Demographically adjusted T scores were derived from a neuropsychological evaluation comprised of 13 tests. We implemented a pipeline involving dimension reduction and clustering to identify profiles of cognitive performance. Random forest models on a 70/30 training/testing set with internal cross-validation were used to identify sociodemographic, clinical/behavioral, and HIV disease correlates of profile membership.

RESULTS

Six cognitive profiles were identified: (a) "unimpaired" (19.9%); (b) weakness in verbal learning and memory (15.5%); (c) weakness in executive function and learning (25.8%); (d) weakness in motor, processing speed, and executive function (8.1%); (e) impaired learning and recall with weak-to-impaired motor, processing speed, and executive function (13.1%); (f) global deficits (17.6%). The most discriminative sociodemographic, clinical/behavioral, and HIV disease characteristics varied by profile with self-reported mood symptoms and cognitive/functional difficulties (e.g., language/communication, memory, and overall everyday function complaints) most consistently associated with profile membership.

CONCLUSIONS

Cognitive profiles and their associated factors among PWH are heterogeneous, but learning/memory deficits were most common and self-reported mood, and cognitive/functional difficulties were most consistently related to profile membership. This heterogeneity in cognitive profiles and their correlates in PWH suggests that differing mechanisms contribute to cognitive deficits and, thus, underscores the need for personalized risk reduction and therapeutic strategies among PWH. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Latent Profile Analysis of Cognitive Performance and Depressive Symptoms Among People with HIV

Depression and cognitive impairment are prevalent conditions among people with HIV (PWH), likely attributable to shared causes and common risk factors. Identifying subtypes of PWH with similar patterns of neurocognitive impairment (NCI) and depressive symptoms may inform development of patient-centered interventions that target-specific profiles. This study aimed to (1) classify PWH based on patterns of domain-specific NCI and depression; and (2) determine the relationship between latent class membership and pertinent clinical characteristics. PWH (N = 580, 86.2% male, 57.1% non-Hispanic White, 69.2% unemployed) completed a comprehensive neuropsychological test battery assessing global and domain-specific cognition. Domain-specific NCI was classified as deficit score >0.5. Participants completed the Beck Depression Inventory-II (BDI-II), and domain-specific BDI-II scores reflecting cognitive, affective, and somatic symptoms were computed. Latent profile analysis (LPA) was used to determine latent subgroups of NCI and depression. The optimal LPA solution consisted of five classes: minimal NCI and minimal depression (Class 1), amnestic and minimal depression (Class 2), severe multi-domain NCI and moderate depression (somatic and affective; Class 3), mild NCI and mild depression (Class 4), and moderate multi-domain NCI and severe depression (Class 5). Despite similar levels of functional impairment, Class 5 had a significant psychiatric profile, whereas Class 3 had a complex medical profile (i.e., higher frailty index, higher medications, greater proportion of AIDS diagnosis). In contrast, Class 1 had the lowest medication use and frailty index, with similar HIV disease characteristics to Classes 3 and 5. Our results suggest there are multiple pathways to cognitive and functional impairment among PWH with co-occurring depression and cognitive impairment, and these groups may respond differently to interventions. Of note, our sample was majority non-Hispanic White and male, which is nonrepresentative of the US population of PWH. Future interventions should consider a more integrated, person-centered approach that addresses cognitive and emotional health to optimize health outcomes in PWH.

The association of depression and anxiety symptoms to three different types of activities of daily living in persons with and without HIV

Mood disorders are highly prevalent in people living with HIV (PLWH) and represent a potential contributor to functional impairment in activities of daily living. We aimed to determine if (1) Anxiety and depression symptoms were independently associated with impairments in basic self-care, role functioning, and social functioning and (2) PLWH differentially experienced impairments due to mood symptoms compared to those without HIV. Data for this study were obtained from 150 individuals (87 PLWH, 61% male, mean age = 44) via a cross-sectional study on alcohol and HIV-associated brain dysfunction. The Beck Anxiety Inventory (BAI) and the Center for Epidemiologic Studies Depression Scale (CES-D) were used to assess anxiety and depressive symptoms. Higher anxiety symptoms were associated with role functioning impairment, while higher depressive and anxiety symptoms were each associated with social functioning impairment. As depressive symptoms increased, PLWH were 3x more likely to have impairments in role functioning compared to those without HIV. HIV status did not interact with mood symptoms to affect basic self-care or social functioning. Overall, mood symptoms are associated with different types of functional impairment, and improved management of mood symptoms could lead to improved role and social functioning.

Human iPSC-derived neurons reveal NMDAR-independent dysfunction following HIV-associated insults

The central nervous system encounters a number of challenges following HIV infection, leading to increased risk for a collection of neurocognitive symptoms clinically classified as HIV-associated neurocognitive disorders (HAND). Studies attempting to identify causal mechanisms and potential therapeutic interventions have historically relied on primary rodent neurons, but a number of recent reports take advantage of iPSC-derived neurons in order to study these mechanisms in a readily reproducible, human model. We found that iPSC-derived neurons differentiated via an inducible neurogenin-2 transcription factor were resistant to gross toxicity from a number of HIV-associated insults previously reported to be toxic in rodent models, including HIV-infected myeloid cell supernatants and the integrase inhibitor antiretroviral drug, elvitegravir. Further examination of these cultures revealed robust resistance to NMDA receptor-mediated toxicity. We then performed a comparative analysis of iPSC neurons exposed to integrase inhibitors and activated microglial supernatants to study sub-cytotoxic alterations in micro electrode array (MEA)-measured neuronal activity and gene expression, identifying extracellular matrix interaction/morphogenesis as the most consistently altered pathways across HIV-associated insults. These findings illustrate that HIV-associated insults dysregulate human neuronal activity and organization even in the absence of gross NMDA-mediated neurotoxicity, which has important implications on the effects of these insults in neurodevelopment and on the interpretation of primary vs. iPSC in vitro neuronal studies.

Effects of acute Δ9-tetrahydrocannabinol on behavior and the endocannabinoid system in HIV-1 Tat transgenic female and male mice

Cannabis use is highly prevalent especially among people living with HIV (PLWH). Activation of the anti-inflammatory and neuroprotective endocannabinoid system by phytocannabinoids, i.e. Δ9-tetrahydrocannabinol (THC), has been proposed to reduce HIV symptoms. However, THC's effects on HIV-related memory deficits are unclear. Using HIV-1 Tat transgenic mice, the current study investigates acute THC effects on various behavioral outcomes and the endocannabinoid system. For the rodent tetrad model, THC doses (1, 3, 10 mg/kg) induced known antinociceptive effects, with Tat induction increasing antinociceptive THC effects at 3 and 10 mg/kg doses. Only minor or no effects were noted for acute THC on body temperature, locomotor activity, and coordination. Increased anxiety-like behavior was found for females compared to males, but acute THC had no effect on anxiety. Object recognition memory was diminished by acute THC in Tat(-) females but not Tat(+) females, without affecting males. The endocannabinoid system and related lipids were not affected by acute THC, except for THC-induced decreases in CB1R protein expression levels in the spinal cord of Tat(-) mice. Female sex and Tat induction was associated with elevated 2-AG, AEA, AA, CB1R, CB2R, FAAH and/or MAGL expression in various brain regions. Further, AEA levels in the prefrontal cortex of Tat(+) females were negatively associated with object recognition memory. Overall, findings indicate that acute THC exerts differential effects on antinociception and memory, dependent on sex and HIV Tat expression, potentially in relation to an altered endocannabinoid system, which may be of relevance in view of potential cannabis-based treatment options for PLWH.

Mitochondrial DNA mutation pathogenicity score and neurocognitive performance in persons with HIV

BACKGROUND

Mitochondrial DNA (mtDNA) genetic variation is associated with neurocognitive (NC) impairment (NCI) in people with HIV (PWH). Other approaches use sequence conservation and protein structure to predict the impact of mtDNA variants on protein function. We examined predicted mtDNA variant pathogenicity in the CHARTER study using MutPred scores, hypothesizing that persons with higher scores (greater predicted pathogenicity) have more NCI.

METHODS

CHARTER included NC testing in PWH from 2003 to 2007. MutPred scores were assigned to CHARTER participants with mtDNA sequence; any score > 0.5 was considered potentially deleterious. Outcomes at cohort entry were NCI, defined by global and seven NC domain deficit scores, and by mean global and domain NC performance T-scores. Univariate and multivariable regression analyses assessed associations between having a deleterious variant and NCI. Additional models included estimated peripheral blood cell mtDNA copy number.

RESULTS

Data were available for 744 PWH (357 African ancestry; 317 European; 70 Hispanic). In the overall cohort, PWH having any potentially deleterious variant were less likely to have motor impairment (16 vs. 25 %, p = 0.001). In multivariable analysis, having a deleterious variant remained associated with lower likelihood of motor impairment (adjusted odds ratio 0.59 [95 % CI 0.41-0.88]; p = 0.009), and better motor performance by T-score (β 1.71 [0.31-3.10], p = 0.02). Associations persisted after adjustment for estimated mtDNA quantity.

CONCLUSIONS

In these PWH, having a potentially deleterious mtDNA variant was associated with less motor impairment. These unexpected findings suggest that potentially deleterious mtDNA variations may confer protection against impaired motor function by as yet unknown mechanisms.

Neurological Complications Caused by Human Immunodeficiency Virus (HIV) and Associated Opportunistic Co-infections: A Review on their Diagnosis and Therapeutic Insights

Neurocognitive disorders associated with human immunodeficiency virus (HIV) infected individuals increase the risk of mortality and morbidity that remain a prevalent clinical complication even in the antiretroviral therapy era. It is estimated that a considerable number of people in the HIV community are developing neurological complications at their early stages of infection. The daily lives of people with chronic HIV infections are greatly affected by cognitive declines such as loss of attention, learning, and executive functions, and other adverse conditions like neuronal injury and dementia. It has been found that the entry of HIV into the brain and subsequently crossing the blood-brain barrier (BBB) causes brain cell damage, which is the prerequisite for the development of neurocognitive disorders. Besides the HIV replication in the central nervous system and the adverse effects of antiretroviral therapy on the BBB, a range of opportunistic infections, including viral, bacterial, and parasitic agents, augment the neurological complications in people living with HIV (PLHIV). Given the immuno-compromised state of PLHIV, these co-infections can present a wide range of clinical syndromes with atypical manifestations that pose challenges in diagnosis and clinical management, representing a substantial burden for the public health system. Therefore, the present review narrates the neurological complications triggered by HIV and their diagnosis and treatment options. Moreover, coinfections that are known to cause neurological disorders in HIV infected individuals are highlighted.

HIV and COVID-19: two pandemics with significant (but different) central nervous system complications

Human immunodeficiency virus (HIV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cause significant neurologic disease. Central nervous system (CNS) involvement of HIV has been extensively studied, with well-documented invasion of HIV into the brain in the initial stage of infection, while the acute effects of SARS-CoV-2 in the brain are unclear. Neuropathologic features of active HIV infection in the brain are well characterized whereas neuropathologic findings in acute COVID-19 are largely non-specific. On the other hand, neuropathologic substrates of chronic dysfunction in both infections, as HIV-associated neurocognitive disorders (HAND) and post-COVID conditions (PCC)/long COVID are unknown. Thus far, neuropathologic studies on patients with HAND in the era of combined antiretroviral therapy have been inconclusive, and autopsy studies on patients diagnosed with PCC have yet to be published. Further longitudinal, multidisciplinary studies on patients with HAND and PCC and neuropathologic studies in comparison to controls are warranted to help elucidate the mechanisms of CNS dysfunction in both conditions.

CD4 dim CD8 bright T cells are inversely associated with neuro-inflammatory markers among people with HIV

OBJECTIVE

HIV-associated neuroinflammation persists in the brain despite suppressive combination antiretroviral therapy (cART). We evaluated associations between a subset of CD8 + T cells, termed CD4 dim CD8 bright T cells, and soluble markers of immune activation and/or neuroinflammation in the cerebrospinal fluid (CSF) and plasma of people with HIV (PWH).

DESIGN

Fifteen cART-naive PWH were enrolled and underwent blood draw, lumbar puncture for CSF collection, and neuropsychological tests at week 0 (pre-cART) and 24 weeks after cART initiation.

METHODS

CSF and peripheral blood T cells were evaluated with flow cytometry and soluble markers of immune activation were measured by multiplex and singleplex assays. Spearman bootstrap correlation coefficients with 10 000 resamples were computed and reported with corresponding 95% confidence intervals (CIs) for each marker of interest and T-cell type.

RESULTS

The frequency of CSF CD4 dim CD8 bright T cells at week 0 was inversely related with CSF neopterin. In contrast, at week 24, CSF CD4 - CD8 + T cells were positively correlated with CSF s100β, a marker of brain injury. In the blood, at week 0, CD4 dim CD8 bright T cells were inversely correlated with MCP-1, IP-10, IL-8, IL-6, G-CSF, and APRIL and positively correlated with plasma RANTES and MMP1. At week 0, the frequency of blood CD4 - CD8 + were positively correlated with CRP and BAFF.

CONCLUSION

CD4 dim CD8 bright T cells are associated with some anti-inflammatory properties, whereas CD4 - CD8 + T cells may contribute to inflammation and injury. Assessing the contrast between these two cell populations in neuroHIV may inform targeted therapeutic intervention to reduce neuroinflammation and associated neurocognitive impairment.

HIV-1 infection of genetically engineered iPSC-derived central nervous system-engrafted microglia in a humanized mouse model

IMPORTANCE

Our mouse model is a powerful tool for investigating the genetic mechanisms governing central nervous system (CNS) human immunodeficiency virus type-1 (HIV-1) infection and latency in the CNS at a single-cell level. A major advantage of our model is that it uses induced pluripotent stem cell-derived microglia, which enables human genetics, including gene function and therapeutic gene manipulation, to be explored in vivo, which is more challenging to study with current hematopoietic stem cell-based models for neuroHIV. Our transgenic tracing of xenografted human cells will provide a quantitative medium to develop new molecular and epigenetic strategies for reducing the HIV-1 latent reservoir and to test the impact of therapeutic inflammation-targeting drug interventions on CNS HIV-1 latency.

Methamphetamine enhancement of HIV-1 gp120-mediated NLRP3 inflammasome activation and resultant proinflammatory responses in rat microglial cultures

Background

Human Immunodeficiency Virus type 1 (HIV-1)-associated neurocognitive disorders (HAND) remain prevalent in HIV-1-infected individuals despite the evident success of combined antiretroviral therapy (cART). The mechanisms under HAND prevalence in the cART era remain perplexing. Ample evidence indicates that HIV-1 envelope glycoprotein protein 120 (gp120), a potent neurotoxin, plays a pivotal role in the HAND pathogenesis. Methamphetamine (Meth) abuse exacerbates HAND. How Meth exacerbates HAND is not fully understood. This study was to test the hypothesis that Meth exacerbates HAND by enhancing gp120-mediated proinflammatory responses in the brain, worsening the pathogenesis of HAND.

Methods

Experiments were carried out on primary microglial cultures prepared from neonatal SD rats. The purity of microglia was determined by staining with anti-CD11b. Meth and gp120 were applied to microglial cultures. Microglial activation was revealed by immunostaining and Iba-1 expression. The protein expression levels of Pro-IL-1β, Il-1β, Iba-1, iNOS, NLRP3, GSDMD and GSDMD-N were detected by western blotting analyses. The levels of proinflammatory cytokine and NO production in the microglia culture supernatants were assayed by ELISA and Griess reagent systems, respectively. NLRP3 activation was uncovered by fluorescent microscopy images displaying NLRP3 puncta labeled by anti-NLRP3 antibody. NLRP3 co-localization with caspase-1 was labeled with antibodies. One-way ANOVA with post hoc Tukey's multiple comparison tests was employed for statistical analyses.

Results

Meth enhanced gp120-induced microglia activation revealed by immunostaining and Iba-1 expression, and potentiated gp120-mediated NLRP3 expression, IL-1β processing and release assayed by immunoblot and ELISA. Meth also augmented the co-localization of NLRP3 and caspase-1, increased the numbers of NLRP3 puncta and ROS production, elevated levels of iNOS expression and NO production, and enhanced levels of cleaved gasderminD (GSDMD-N, an executor of pyroptosis) in gp120-primed microglia. The Meth-associated effects were attenuated or blocked by MCC950, an NLRP3 inhibitor, or Mito-TEMPO, a mitochondrial superoxide scavenger, indicating the involvement of mitochondria in Meth enhancement of NLRP3 inflammasome activation in gp120-primed microglia.

Conclusions

These results suggest that Meth enhanced gp120-associated microglial NLRP3 activation and resultant proinflammatory responses via mitochondria-dependent signaling.

Behavioral and histological assessment of a novel treatment of neuroHIV in humanized mice

Neurocognitive deficits are prevalent among people living with HIV, likely due to chronic inflammation and oxidative stress in the brain. To date, no pharmaceutical treatments beyond antiretroviral therapy (ARV) has been shown to reduce risk for, or severity of, HIV-associated neurocognitive disorder. Here we investigate a novel compound, CDDO-Me, with documented neuroprotective effects via activation of the nrf2 and inhibition of the NFkB pathways.

Methods

We conducted three studies to assess the efficacy of CDDO-Me alone or in combination with antiretroviral therapy in humanized mice infected with HIV; behavioral, histopathological, and immunohistochemical.

Results

CDDO-Me in combination with ARV rescued social interaction deficits; however, only ARV was associated with preserved functioning in other behaviors, and CDDO-Me may have attenuated those benefits. A modest neuroprotective effect was found for CDDO-Me when administered with ARV, via preservation of PSD-95 expression; however, ARV alone had a more consistent protective effect. No significant changes in antioxidant enzyme expression levels were observed in CDDO-Me-treated animals. Only ARV use seemed to affect some antioxidant levels, indicating that it is ARV rather than CDDO-Me that is the major factor providing neuroprotection in this animal model. Finally, immunohistochemical analysis found that several cellular markers in various brain regions varied due to ARV rather than CDDO-Me.

Conclusion

Limited benefit of CDDO-Me on behavior and neuroprotection were observed. Instead, ARV was shown to be the more beneficial treatment. These experiments support the future use of this chimeric mouse for behavioral experiments in neuroHIV research.

Inhibition of lipid synthesis by the HIV integrase strand transfer inhibitor elvitegravir in primary rat oligodendrocyte cultures

Combined antiretroviral therapy (cART) has greatly decreased mortality and morbidity among persons with HIV; however, neurologic impairments remain prevalent, in particular HIV-associated neurocognitive disorders (HANDs). White matter damage persists in cART-treated persons with HIV and may contribute to neurocognitive dysfunction as the lipid-rich myelin membrane of oligodendrocytes is essential for efficient nerve conduction. Because of the importance of lipids to proper myelination, we examined the regulation of lipid synthesis in oligodendrocyte cultures exposed to the integrase strand transfer inhibitor elvitegravir (EVG), which is administered to persons with HIV as part of their initial regimen. We show that protein levels of genes involved in the fatty acid pathway were reduced, which correlated with greatly diminished de novo levels of fatty acid synthesis. In addition, major regulators of cellular lipid metabolism, the sterol regulatory element-binding proteins (SREBP) 1 and 2, were strikingly altered following exposure to EVG. Impaired oligodendrocyte differentiation manifested as a marked reduction in mature oligodendrocytes. Interestingly, most of these deleterious effects could be prevented by adding serum albumin, a clinically approved neuroprotectant. These new findings, together with our previous study, strengthen the possibility that antiretroviral therapy, at least partially through lipid dysregulation, may contribute to the persistence of white matter changes observed in persons with HIV and that some antiretrovirals may be preferable as life-long therapy.

Is the Central Nervous System Reservoir a Hurdle for an HIV Cure?

There is currently no cure for HIV infection although adherence to effective antiretroviral therapy (ART) suppresses replication of the virus in blood, increases CD4+ T-cell counts, reverses immunodeficiency, and increases life expectancy. Despite these substantial advances, ART is a lifelong treatment for people with HIV (PWH) and upon cessation or interruption, the virus quickly rebounds in plasma and anatomic sites, including the central nervous system (CNS), resulting in disease progression. With recent advances in quantifying viral burden, detection of genetically intact viral genomes, and isolation of replication-competent virus from brain tissues of PWH receiving ART, it has become apparent that the CNS viral reservoir (largely comprised of macrophage type cells) poses a substantial challenge for HIV cure strategies. Other obstacles impacting the curing of HIV include ageing populations, substance use, comorbidities, limited antiretroviral drug efficacy in CNS cells, and ART-associated neurotoxicity. Herein, we review recent findings, including studies of the proviral integration sites, reservoir decay rates, and new treatment/prevention strategies in the context of the CNS, together with highlighting the next steps for investigations of the CNS as a viral reservoir.

Predictors of hippocampal tauopathy in people with and at risk for human immunodeficiency virus infection

Combination antiretroviral therapy (cART) has extended lifespans of people living with HIV (PWH), increasing both the risk for age-related neuropathologies and the importance of distinguishing effects of HIV and its comorbidities from neurodegenerative disorders. The accumulation of hyperphosphorylated tau (p-tau) in hippocampus is a common degenerative change, with specific patterns of hippocampal subfield vulnerability observed in different disease contexts. Currently, associations between chronic HIV, its comorbidities, and p-tau burden and distribution in the hippocampus are unexplored. We used immunohistochemistry with antibody AT8 to analyze hippocampal p-tau in brain tissues of PWH (n = 71) and HIV negative controls (n = 25), for whom comprehensive clinical data were available. Using a morphology-based neuroanatomical segmentation protocol, we annotated digital slide images to measure percentage p-tau areas in the hippocampus and its subfields. Factors predicting p-tau burden and distribution were identified in univariate analyses, and those with significance at p ≤ 0.100 were advanced to multivariable regression. The patient sample had a mean age of 61.5 years. Age predicted overall hippocampal p-tau burden. Subfield p-tau predictors were for Cornu Ammonis (CA)1, age; for CA2 and subiculum, seizure history; for CA3, seizure history and head trauma; and for CA4/dentate, history of hepatitis C virus (HCV) infection. In this autopsy sample, hippocampal p-tau burden and distribution were not predicted by HIV, viral load, or immunologic status, with viral effects limited to associations between HCV and CA4/dentate vulnerability. Hippocampal p-tau pathologies in cART-era PWH appear to reflect age and comorbidities, but not direct effects of HIV infection.

HIV chronicity as a predictor of hippocampal memory deficits in daily cannabis users living with HIV

Background

Antiretroviral medications have increased the lifespan of persons living with HIV (PLWH) thereby unmasking memory decline that may be attributed to chronological age, HIV symptomatology, HIV disease chronicity, and/or substance use (especially cannabis use which is common among PLWH). To date, few studies have attempted to disentangle these effects. In a sample of daily cannabis-using PLWH, we investigated whether hippocampal memory function, assessed via an object-location associative learning task, was associated with age, HIV chronicity and symptom severity, or substance use.

Methods

48 PLWH (12.9 ± 9.6 years since HIV diagnosis), who were 44 years old on average (range: 24-64 years; 58 % male) and reported daily cannabis use (recent use confirmed by urinalysis) completed the study. We assessed each participant's demographics, substance use, medical history, current HIV symptoms, and hippocampal memory function via a well-validated object-location associative learning task.

Results

Multiple regression analyses found that living more years since HIV+ diagnosis predicted significantly worse associative learning total score (r=-0.40) and learning rate (r=-0.34) whereas chronological age, cannabis-use characteristics, and recent HIV symptom severity were not significantly related to hippocampal memory function.

Conclusions

In daily cannabis-using PLWH, HIV chronicity was related to worse hippocampal memory function independent from cannabis use, age, and HIV symptomatology. Object-location associative learning performance could serve as an 'early-warning' metric of cognitive decline among PLWH. Future research should examine longitudinal changes in associative learning proficiency and evaluate interventions to prevent hippocampal memory decline among PLWH. ClinicalTrials.gov: NCT01536899.

An overview of neurocognitive impairment in older people living with HIV

Background

With improved survival among People Living with HIV (PLHIV), many are confronted with age associated comorbidities and geriatric syndromes. Neurocognitive impairment is one of the three most frequent conditions that affects quality of life of PLHIV despite achieving viral suppression. Healthcare providers face challenges in early identification of neurocognitive impairment, performing comprehensive assessment and managing older PLHIV.

Objectives

This paper aims to review available evidence regarding aetiology and management of older PLHIV who develop neurocognitive impairment, suggest improvements on current management and postulate future study direction.

Methods

A PubMed search for original articles and Clinical Guidelines was conducted from September 2021 to August 2022 using a combination of keywords related to neurocognitive impairment in PLHIV. The citations from all selected articles were reviewed for additional studies.

Results

Older PLHIV tend to be frailer than their uninfected counterparts, are plagued with multi-morbidity and are at increased risk of cognitive impairment. The aetiologies for neurocognitive impairment are multifactorial, multi-dimensional and complex. The management of neurocognitive impairment in older PLHIV involves identifying and optimizing predisposing factors, physical function, social and psychological health with appropriate care navigation.

Conclusion

Identification and management of neurocognitive impairment in older PLHIV through interdisciplinary collaboration among stakeholders is important. This exemplifies an integrated model of care for older PLHIV and promotes the notion of living well beyond viral suppression.

A reappraisal on amyloid cascade hypothesis: the role of chronic infection in Alzheimer's disease

Alzheimer disease (AD) is a progressive neurological disorder that accounted for the most common cause of dementia in the elderly population. Lately, 'infection hypothesis' has been proposed where the infection of microbes can lead to the pathogenesis of AD. Among different types of microbes, human immunodeficiency virus-1 (HIV-1), herpes simplex virus-1 (HSV-1), Chlamydia pneumonia, Spirochetes and Candida albicans are frequently detected in the brain of AD patients. Amyloid-beta protein has demonstrated to exhibit antimicrobial properties upon encountering these pathogens. It can bind to microglial cells and astrocytes to activate immune response and neuroinflammation. Nevertheless, HIV-1 and HSV-1 can develop into latency whereas Chlamydia pneumonia, Spirochetes and Candida albicans can cause chronic infections. At this stage, the DNA of microbes remains undetectable yet active. This can act as the prolonged pathogenic stimulus that over-triggers the expression of Aβ-related genes, which subsequently lead to overproduction and deposition of Aβ plaque. This review will highlight the pathogenesis of each of the stated microbial infection, their association in AD pathogenesis as well as the effect of chronic infection in AD progression. Potential therapies for AD by modulating the microbiome have also been suggested. This review will aid in understanding the infectious manifestations of AD.

The relationship between synaptodendritic neuropathology and HIV-associated neurocognitive disorders is moderated by cognitive reserve

We examined whether cognitive reserve moderated the relationship between neurodegeneration and cognition in 67 postmortem persons with HIV (PWH) who were cognitively assessed within 1 year of death. Cognitive reserve was measured via the Wide Range Achievement Test-4 reading subtest (WRAT4). Synaptodendritic neurodegeneration was based on densities of synaptophysin and microtubule-associated protein 2 immunohistochemical reactivity in frontal cortex, and categorized as minimal, moderate, or severe (tertile-split). T-Scores from 15 cognitive tests were averaged into a global cognitive T-score. Among those with low cognitive reserve (based on WRAT4 median split), the moderate neurodegeneration group showed cognition that was poorer than the minimal neurodegeneration group and comparable to the severe neurodegeneration group. Among those with high cognitive reserve, the moderate neurodegeneration group showed cognition comparable to the minimal neurodegeneration group and better than the severe neurodegeneration group. High cognitive reserve may buffer against cognitive impairment among PWH with moderate, but not severe, neurodegeneration.