HIV infection and cerebral small vessel disease are independently associated with brain atrophy and cognitive impairment

Age-Accelerated Increase of White Matter Hyperintensity Volumes Is Exacerbated by Heavy Alcohol Use in People Living With HIV

BACKGROUND

Antiretroviral treatment has enabled people living with HIV infection to have a near-normal life span. With longevity comes opportunities for engaging in risky behavior, including initiation of excessive drinking. Given that both HIV infection and alcohol use disorder (AUD) can disrupt brain white matter integrity, we questioned whether HIV infection, even if successfully treated, or AUD alone results in signs of accelerated white matter aging and whether HIV+AUD comorbidity further accelerates brain aging.

METHODS

Longitudinal magnetic resonance imaging-FLAIR data were acquired over a 15-year period from 179 control individuals, 204 participants with AUD, 70 participants with HIV, and 75 participants with comorbid HIV+AUD. White matter hyperintensity (WMH) volumes were quantified and localized, and their functional relevance was examined with cognitive and motor testing.

RESULTS

The 3 diagnostic groups each had larger WMH volumes than the control group. Although all 4 groups exhibited accelerating volume increases with aging, only the HIV groups showed faster WMH enlargement than control individuals; the comorbid group showed faster acceleration than the HIV-only group. Sex and HIV infection length, but not viral suppression status, moderated acceleration. Correlations emerged between WMH volumes and attention/working memory and executive function scores of the AUD and HIV groups and between WMH volumes and motor skills in the 3 diagnostic groups.

CONCLUSIONS

Even treated HIV can show accelerated aging, possibly from treatment sequelae or legacy effects, and notably from AUD comorbidity. WMH volumes may be especially relevant for tracking HIV and AUD brain health because each condition is associated with liability for hypertensive processes, for which WMHs are considered a marker.

CSF Extracellular Vesicle Aβ42 and Tau/Aβ42 Ratio Are Associated with Cognitive Impairment in Older People with HIV

HIV-associated neurocognitive disorders (HAND) remain prevalent despite viral suppression on antiretroviral therapy (ART). Older people with HIV (PWH) are also at risk for amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD). β-amyloid (Aβ) and Tau biomarkers are associated with aMCI/AD, but their relationship to HAND is unclear. Given the role of extracellular vesicles (EVs) in age-related neurological disorders, we investigated soluble and EV-associated Aβ42, total Tau, NFL, GFAP, ICAM-1, VCAM-1, and CRP in relation to cognitive impairment in PWH. Plasma and CSF EVs were isolated from 184 participants (98 PWH on ART and 86 HIV- controls). Biomarkers were measured using Meso Scale Discovery assays. The median age of PWH was 53 years, and 52% were diagnosed with mild forms of HAND. PWH had increased plasma NFL (p = 0.04) and CSF Aβ42 (p = 0.0003) compared with HIV- controls but no significant difference in Tau or EV-associated forms of these markers. CSF EV Aβ42 was decreased (p = 0.0002) and CSF EV Tau/Aβ42 ratio was increased (p = 0.001) in PWH with HAND vs. no HAND, while soluble forms of these markers showed no significant differences. Decreased CSF EV Aβ42 (p < 0.0001) and an increased CSF EV Tau/Aβ42 ratio (p = 0.0003) were associated with lower neurocognitive T scores in age-adjusted models; an optimal model included both CSF EV Aβ42 and plasma NFL. Levels of soluble, but not EV-associated, ICAM-1, VCAM-1, and CRP were increased in PWH with HAND vs. no HAND (p < 0.05). These findings suggest that decreased Aβ42 and an increased Tau/Aβ42 ratio in CSF EVs are associated with cognitive impairment in older PWH, and these EV-associated biomarkers may help to distinguish aMCI/AD from HIV-related cognitive disorders in future studies.

Elevated Plasma Protein Carbonyl Concentration Is Associated with More Abnormal White Matter in People with HIV

Structural brain abnormalities, including those in white matter (WM), remain common in people with HIV (PWH). Their pathogenesis is uncertain and may reflect multiple etiologies. Oxidative stress is associated with inflammation, HIV, and its comorbidities. The post-translational carbonylation of proteins results from oxidative stress, and circulating protein carbonyls may reflect this. In this cross-sectional analysis, we evaluated the associations between protein carbonyls and a panel of soluble biomarkers of neuronal injury and inflammation in plasma (N = 45) and cerebrospinal fluid (CSF, n = 32) with structural brain MRI. The volume of abnormal WM was normalized for the total WM volume (nAWM). In this multisite project, all regression models were adjusted for the scanner. The candidate covariates included demographics, HIV disease characteristics, and comorbidities. Participants were PWH on virally suppressive antiretroviral therapy (ART) and were mostly white (64.4%) men (88.9%), with a mean age of 56.8 years. In unadjusted analyses, more nAWM was associated with higher plasma protein carbonyls (p = 0.002) and higher CCL2 (p = 0.045). In the adjusted regression models for nAWM, the association with plasma protein carbonyls remained significant (FDR p = 0.018). Protein carbonyls in plasma may be a valuable biomarker of oxidative stress and its associated adverse health effects, including within the central nervous system. If confirmed, these findings would support the hypothesis that reducing oxidative stress could treat or prevent WM injury in PWH.

Vascular injury markers associated with cognitive impairment in people with HIV on suppressive antiretroviral therapy

OBJECTIVE

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain prevalent despite viral suppression on antiretroviral therapy (ART). Vascular disease contributes to HAND, but peripheral markers that distinguish vascular cognitive impairment (VCI) from HIV-related etiologies remain unclear.

DESIGN

Cross-sectional study of vascular injury, inflammation, and central nervous system (CNS) injury markers in relation to HAND.

METHODS

Vascular injury (VCAM-1, ICAM-1, CRP), inflammation (IFN-γ, IL-1β, IL-6, IL-8, IL-15, IP-10, MCP-1, VEGF-A), and CNS injury (NFL, total Tau, GFAP, YKL-40) markers were measured in plasma and CSF from 248 individuals (143 HIV+ on suppressive ART and 105 HIV- controls).

RESULTS

Median age was 53 years, median CD4 + cell count, and duration of HIV infection were 505 cells/μl and 16 years, respectively. Vascular injury, inflammation, and CNS injury markers were increased in HIV+ compared with HIV- individuals ( P < 0.05). HAND was associated with increased plasma VCAM-1, ICAM-1, and YKL-40 ( P  < 0.01) and vascular disease ( P  = 0.004). In contrast, inflammation markers had no significant association with HAND. Vascular injury markers were associated with lower neurocognitive T scores in age-adjusted models ( P  < 0.01). Furthermore, plasma VCAM-1 correlated with NFL ( r  = 0.29, P  = 0.003). Biomarker clustering separated HAND into three clusters: two clusters with high prevalence of vascular disease, elevated VCAM-1 and NFL, and distinctive inflammation profiles (CRP/ICAM-1/YKL-40 or IL-6/IL-8/IL-15/MCP-1), and one cluster with no distinctive biomarker elevations.

CONCLUSIONS

Vascular injury markers are more closely related to HAND and CNS injury in PWH on suppressive ART than inflammation markers and may help to distinguish relative contributions of VCI to HAND.

Low levels of peripheral blood activated and senescent T cells characterize people with HIV-1-associated neurocognitive disorders

Background

HIV infection induces a 75% increase in the risk of developing neurocognitive impairment (NCI), which has been linked to immune activation. We therefore looked for immune activation markers correlating with NCI.

Method

Sixty-five people aged 55-70 years living with controlled HIV-1 infection were enrolled in the study and their neurocognitive ability was assessed according to the Frascati criteria. Fifty-nine markers of T4 cell, T8 cell, NK cell, and monocyte activation, inflammation and endothelial activation were measured in their peripheral blood. White matter hyperintensities (WMH) were identified by magnetic resonance imaging. Double hierarchical clustering was performed for the activation markers and 240 patients including the 65 whose neurocognitive performance had been evaluated.

Results

Thirty-eight percent of volunteers presented NCI. Twenty-four percent of them were asymptomatic and fourteen percent had a mild disorder. Strikingly, activated (HLA-DR+) as well as senescent (CD57+CD28-CD27±) T4 cells and T8 cells were less prevalent in the peripheral blood of participants with NCI than in participants without the disorder. Accordingly, the percentage of HLA-DR+ T4 cells was lower in volunteers with periventricular and deep WMH. The double hierarchical clustering unveiled six different immune activation profiles. The neurocognitive performances of participants with two of these six profiles were poor. Here again, these two profiles were characterized by a low level of T4 and T8 cell activation and senescence.

Conclusion

Our observation of low circulating levels of activated and senescent T cells in HIV-1 patients with NCI raises the interesting hypothesis that these lymphocytes may be recruited into the central nervous system.

Vascular injury markers associated with cognitive impairment in people with HIV on suppressive antiretroviral therapy

Objective

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain prevalent despite viral suppression on antiretroviral therapy (ART). Vascular disease contributes to HAND, but peripheral markers that distinguish vascular cognitive impairment (VCI) from HIV-related etiologies remain unclear.

Design

Cross-sectional study of vascular injury, inflammation, and central nervous system (CNS) injury markers in relation to HAND.

Methods

Vascular injury (VCAM-1, ICAM-1, CRP), inflammation (IFN-γ, IL-1β, IL-6, IL-8, IL-15, IP-10, MCP-1, VEGF-A), and CNS injury (NFL, total Tau, GFAP, YKL-40) markers were measured in plasma and CSF from 248 individuals (143 HIV+ on suppressive ART and 105 HIV- controls).

Results

Median age was 53 years, median CD4 count, and duration of HIV infection were 505 cells/μl and 16 years, respectively. Vascular injury, inflammation, and CNS injury markers were increased in HIV+ compared with HIV- individuals (p<0.05). HAND was associated with increased plasma VCAM-1, ICAM-1, and YKL-40 (p<0.01) and vascular disease (p=0.004). In contrast, inflammation markers had no significant association with HAND. Vascular injury markers were associated with lower neurocognitive T scores in age-adjusted models (p<0.01). Furthermore, plasma VCAM-1 correlated with NFL (r=0.29, p=0.003). Biomarker clustering separated HAND into three clusters: two clusters with high prevalence of vascular disease, elevated VCAM-1 and NFL, and distinctive inflammation profiles (CRP/ICAM-1/YKL-40 or IL-6/IL-8/IL-15/MCP-1), and one cluster with no distinctive biomarker elevations.

Conclusions

Vascular injury markers are more closely related to HAND and CNS injury in PWH on suppressive ART than inflammation markers and may help to distinguish relative contributions of VCI to HAND.

Chronic brain damage in HIV-infected individuals under antiretroviral therapy is associated with viral reservoirs, sulfatide release, and compromised cell-to-cell communication

HIV infection has become a chronic and manageable disease due to the effective use of antiretroviral therapies (ART); however, several chronic aging-related comorbidities, including cognitive impairment, remain a major public health issue. However, these mechanisms are unknown. Here, we identified that glial and myeloid viral reservoirs are associated with local myelin damage and the release of several myelin components, including the lipid sulfatide. Soluble sulfatide compromised gap junctional communication and calcium wave coordination, essential for proper cognition. We propose that soluble sulfatide could be a potential biomarker and contributor to white matter compromise observed in HIV-infected individuals even in the current ART era.

Imaging of Brain Structural and Functional Effects in People With Human Immunodeficiency Virus

Before the introduction of antiretroviral therapy, human immunodeficiency virus (HIV) infection was often accompanied by central nervous system (CNS) opportunistic infections and HIV encephalopathy marked by profound structural and functional alterations detectable with neuroimaging. Treatment with antiretroviral therapy nearly eliminated CNS opportunistic infections, while neuropsychiatric impairment and peripheral nerve and organ damage have persisted among virally suppressed people with HIV (PWH), suggesting ongoing brain injury. Neuroimaging research must use methods sensitive for detecting subtle HIV-associated brain structural and functional abnormalities, while allowing for adjustments for potential confounders, such as age, sex, substance use, hepatitis C coinfection, cardiovascular risk, and others. Here, we review existing and emerging neuroimaging tools that demonstrated promise in detecting markers of HIV-associated brain pathology and explore strategies to study the impact of potential confounding factors on these brain measures. We emphasize neuroimaging approaches that may be used in parallel to gather complementary information, allowing efficient detection and interpretation of altered brain structure and function associated with suboptimal clinical outcomes among virally suppressed PWH. We examine the advantages of each imaging modality and systematic approaches in study design and analysis. We also consider advantages of combining experimental and statistical control techniques to improve sensitivity and specificity of biotype identification and explore the costs and benefits of aggregating data from multiple studies to achieve larger sample sizes, enabling use of emerging methods for combining and analyzing large, multifaceted data sets. Many of the topics addressed in this article were discussed at the National Institute of Mental Health meeting "Biotypes of CNS Complications in People Living with HIV," held in October 2021, and are part of ongoing research initiatives to define the role of neuroimaging in emerging alternative approaches to identifying biotypes of CNS complications in PWH. An outcome of these considerations may be the development of a common neuroimaging protocol available for researchers to use in future studies examining neurological changes in the brains of PWH.

Brief Report: Sex Differences in the Association Between Cerebrovascular Function and Cognitive Health in People Living With HIV in Urban China

BACKGROUND

Cardiometabolic and cerebrovascular disease are strong independent contributors to cognitive impairment in people living with HIV. Data suggest that cardiovascular risk may play a greater role in cognitive health in women than in men with HIV.

METHODS

We performed a cross-sectional study of 104 participants with virologically suppressed HIV from 2 clinics in urban China. Participants underwent neuropsychological testing from which we calculated T scores globally and in 5 cognitive domains. We assessed cerebral vasoreactivity of the middle cerebral arteries in response to breath holding. We constructed linear regression models to determine associations between cerebrovascular and cognitive function overall and stratified by sex.

RESULTS

Women were younger than men (48 versus 51 years, P = 0.053), had fewer years of education (9 years versus 12 years, P = 0.004), and fewer cardiometabolic risk factors (0 versus 1 factor, P = 0.008). In a model with all participants, cerebrovascular function was significantly associated with global cognition (2.74 higher T score per 1-point higher cerebral vasoreactivity [SE 1.30], P = 0.037). Cerebrovascular function remained significantly associated with global cognition among women (4.15 higher T score [SE 1.78], P = 0.028) but not men (1.70 higher T score [SE 1.74], P = 0.33). The relationships between cerebrovascular function and specific cognitive domains followed a similar pattern, with significant associations present among women but not men.

CONCLUSIONS

Women with well-controlled HIV may be more vulnerable to the effect of cerebrovascular injury on cognitive health than men. Studies evaluating strategies to protect against cognitive impairment in people living with HIV should include adequate representation of women and stratification of analyses by sex.

Circulating endothelial and angiogenic cells predict hippocampal volume as a function of HIV status

Circulating endothelial cells (CECs) and myeloid angiogenic cells (MACs) have the capacity to stabilize human blood vessels in vivo. Evidence suggests that these cells are depleted in dementia and in persons living with HIV (PWH), who have a higher prevalence of dementia and other cognitive deficits associated with aging. However, the associations of CECs and MACs with MRI-based measures of aging brain health, such as hippocampal gray matter volume, have not been previously demonstrated. The present study examined differences in these associations in 51 postmenopausal women with and without HIV infection. Gray matter volume was quantified using MRI. CECs and MACs were enumerated using fluorescence-activated cell sorting. Analyses examined the association of these cell counts with left and right hippocampal gray matter volume while controlling for age and hypertension status. The main finding was an interaction suggesting that compared to controls, postmenopausal PWH with greater levels of CECs and MACs had significantly greater hippocampus GMV. Further research is necessary to examine potential underlying pathophysiological mechanisms in HIV infection linking morpho-functional circulatory reparative processes with more diminished hippocampal volume in postmenopausal women.

Effects of early human immunodeficiency virus infection on cerebral white matter blood flow autoregulation

Blood flow autoregulation in cerebral white matter was measured before and after acute nicardipine-induced changes in mean arterial pressure of 10-21% in 21 treatment naïve HIV-positive adults and 32 controls. The autoregulatory index (-% cerebral blood flow change/% mean arterial pressure change) was not different at baseline ( P  = 0.71) or after 1 year of treatment ( n  = 11, P  = 0.17). We found no autoregulatory defect to explain the increased stroke risk or the development of cerebral white damage in people with HIV.

White matter hyperintensity distribution differences in aging and neurodegenerative disease cohorts

INTRODUCTION

White matter hyperintensities (WMHs) are common magnetic resonance imaging (MRI) findings in the aging population in general, as well as in patients with neurodegenerative diseases. They are known to exacerbate the cognitive deficits and worsen the clinical outcomes in the patients. However, it is not well-understood whether there are disease-specific differences in prevalence and distribution of WMHs in different neurodegenerative disorders.

METHODS

Data included 976 participants with cross-sectional T1-weighted and fluid attenuated inversion recovery (FLAIR) MRIs from the Comprehensive Assessment of Neurodegeneration and Dementia (COMPASS-ND) cohort of the Canadian Consortium on Neurodegeneration in Aging (CCNA) with eleven distinct diagnostic groups: cognitively intact elderly (CIE), subjective cognitive impairment (SCI), mild cognitive impairment (MCI), vascular MCI (V-MCI), Alzheimer's dementia (AD), vascular AD (V-AD), frontotemporal dementia (FTD), Lewy body dementia (LBD), cognitively intact elderly with Parkinson's disease (PD-CIE), cognitively impaired Parkinson's disease (PD-CI), and mixed dementias. WMHs were segmented using a previously validated automated technique. WMH volumes in each lobe and hemisphere were compared against matched CIE individuals, as well as each other, and between men and women.

RESULTS

All cognitively impaired diagnostic groups had significantly greater overall WMH volumes than the CIE group. Vascular groups (i.e. V-MCI, V-AD, and mixed dementia) had significantly greater WMH volumes than all other groups, except for FTD, which also had significantly greater WMH volumes than all non-vascular groups. Women tended to have lower WMH burden than men in most groups and regions, controlling for age. The left frontal lobe tended to have a lower WMH burden than the right in all groups. In contrast, the right occipital lobe tended to have greater WMH volumes than the left.

CONCLUSIONS

There were distinct differences in WMH prevalence and distribution across diagnostic groups, sexes, and in terms of asymmetry. WMH burden was significantly greater in all neurodegenerative dementia groups, likely encompassing areas exclusively impacted by neurodegeneration as well as areas related to cerebrovascular disease pathology.

Neurological Disorders of Patients Living with HIV Hospitalized in Infectious Departments of the Specialist Hospital in Lower Silesia in Poland

Background and Objectives: Central nervous system (CNS) disorders are estimated to occur in approximately 10–20% of people living with HIV (PLWH). They are more commonly observed in newly diagnosed patients and in previously untreated patients or those refusing to undergo antiretroviral treatment. CNS diseases can also be the first manifestation of HIV/AIDS infection. The most common HIV-related central nervous system diseases (CNS-D) are CNS toxoplasmosis, CNS cryptococcosis, progressive multifocal leukoencephalopathy (PML), and HIV-associated encephalopathy treated as a neurocognitive disorder. Materials and Methods: A retrospective analysis of available medical records was performed on 476 patients hospitalised over a period from 2016 to 2021 and diagnosed with HIV/AIDS infection at the department of infectious diseases at the Provincial Specialist Hospital in Wroclaw. An additional criterion for selecting patients for the analysis was the performance of head imaging using computed tomography or magnetic resonance imaging on prospective patients. Results: Neurotoxoplasmosis, neurocryptococcosis, progressive multifocal leukoencephalopathy (PML), and neurosyphilis were the most common CNS diseases among the analysed group of patients. Based on radiological descriptions, other abnormalities, such as vascular changes or cortical and subcortical atrophy of multifactorial origin, not exclusively related to HIV infection, were also frequently observed. The most common neurological symptoms reported in the study group were headaches, limb paresis, and gait and balance disturbance. Conclusions: The clinical picture and epidemiology of neurological manifestations in the group of HIV-infected patients under assessment were similar to the results of other authors. Given the current epidemiological situation, diagnosis for HIV infection should be considered in patients admitted to neurological departments.

Exploring HIV-Associated Neurocognitive Impairment in the Era of Effective Antiretroviral Therapy: A Primary Healthcare Perspective

The prevalence of HIV-associated neurocognitive impairment (H-NCI) is concerning. Individuals on effective antiretroviral therapy (ART) may still be at risk for H-NCI as they experience longer life expectancies. There are, however, few professionals with knowledge and skills to identify H-NCI, in low- and middle-income countries. We explored qualitatively, primary healthcare workers' knowledge and views of H-NCI, in the era of effective ART, particularly their views toward task-sharing of H-NCI screening from specialists to mid-level or lay healthcare providers. The first phase of data collection involved two focus group discussions (FGDs) 23 primary healthcare workers from two facilities in the Western Cape participated in the FGDs. In the second phase of data collection12 individual, in-depth interviews were conducted in KwaZulu-Natal. Using thematic analysis, several key themes emerged. Although healthcare providers were unable to specifically identify H-NCI, they described several HIV disease and treatment related or mental health comorbidities that could be responsible for the symptoms. Despite healthcare workers reporting low frequencies of H-NCI, they favoured receiving training to screen for H-NCI with a view toward providing holistic care.

The Role of Pannexin-1 Channels in HIV and NeuroHIV Pathogenesis

The human immunodeficiency virus-1 (HIV) enters the brain shortly after infection, leading to long-term neurological complications in half of the HIV-infected population, even in the current anti-retroviral therapy (ART) era. Despite decades of research, no biomarkers can objectively measure and, more importantly, predict the onset of HIV-associated neurocognitive disorders. Several biomarkers have been proposed; however, most of them only reflect late events of neuronal damage. Our laboratory recently identified that ATP and PGE₂, inflammatory molecules released through Pannexin-1 channels, are elevated in the serum of HIV-infected individuals compared to uninfected individuals and other inflammatory diseases. More importantly, high circulating ATP levels, but not PGE₂, can predict a decline in cognition, suggesting that HIV-infected individuals have impaired ATP metabolism and associated signaling. We identified that Pannexin-1 channel opening contributes to the high serological ATP levels, and ATP in the circulation could be used as a biomarker of HIV-associated cognitive impairment. In addition, we believe that ATP is a major contributor to chronic inflammation in the HIV-infected population, even in the anti-retroviral era. Here, we discuss the mechanisms associated with Pannexin-1 channel opening within the circulation, as well as within the resident viral reservoirs, ATP dysregulation, and cognitive disease observed in the HIV-infected population.

White matter lesions may be an early marker for age-related cognitive decline

BACKGROUND

Research suggests that cerebral small vessel disease (CSVD), amyloid, and pTau contribute to age-related cognitive decline. It remains unknown how these factors relate to one another and how they jointly contribute to cognitive decline in normal aging. This project examines the association between these factors and their relationship to cognitive decline in cognitively unimpaired older adults without subjective cognitive decline.

METHODS

A total of 230 subjects with cerebrospinal fluid (CSF) Aß42, CSF pTau181, white matter lesions (WMLs) used as a proxy of CSVD, and cognitive scores from the Alzheimer's Disease Neuroimaging Initiative were included. Associations between each factor and cognitive score were investigated using regression models. Furthermore, relationships between the three pathologies were also examined using regression models.

RESULTS

At baseline, there was an inverse association between WML load and Aß42 (t = -4.20, p <.001). There was no association between WML load and pTau (t = 0.32, p = 0.75), nor with Aß42 and pTau (t = 0.51, p =.61). Correcting for age, sex and education, baseline WML load was associated with baseline ADAS-13 scores (t = 2.59, p =.01) and lower follow-up executive functioning (t = -2.84, p =.005). Baseline Aß42 was associated with executive function at baseline (t = 3.58, p<.004) but not at follow-up (t = 1.05, p = 0.30), nor with ADAS-13 at baseline (t = -0.24, p = 0.81) or follow-up (t = 0.09, p = 0.93). Finally, baseline pTau was not associated with any cognitive measure at baseline or follow-up.

CONCLUSION

Both baseline Aß42 and WML load are associated with some baseline cognition scores, but only baseline WML load is associated with follow-up executive functioning. This finding suggests that WMLs may be one of the earliest clinical manifestations that contributes to future cognitive decline in cognitively healthy older adults. Given that healthy older adults with WMLs exhibit declines in cognitive functioning, they may be less resilient to future pathology increasing their risk for cognitive impairment due to dementia than those without WMLs.

Brain aging and cardiovascular factors in HIV: a longitudinal volume and shape MRI study

OBJECTIVE

We aimed to examine the relative contributions of HIV infection, age, and cardiovascular risk factors to subcortical brain atrophy in people with HIV (PWH).

DESIGN

Longitudinal observational study.

METHODS

Virally suppressed PWH with low neuropsychological confounds (n  = 75) and demographically matched HIV-negative controls (n = 31) completed baseline and 18-month follow-up MRI scans, neuropsychological evaluation, cardiovascular assessments, and HIV laboratory tests. PWH were evaluated for HIV-associated neurocognitive disorder (HAND). Subcortical volumes were extracted with Freesurfer after removal of white matter hyperintensities. Volumetric and shape analyses were conducted using linear mixed-effect models incorporating interactions between age, time, and each of HIV status, HAND status, HIV disease factors, and cardiovascular markers.

RESULTS

Across baseline and follow-up PWH had smaller volumes of most subcortical structures compared with HIV-negative participants. In addition, over time older PWH had a more rapid decline in caudate volumes (P  = 0.041), predominantly in the more severe HAND subgroups (P = 0.042). Higher CD4+ cell counts had a protective effect over time on subcortical structures for older participants with HIV. Increased cardiovascular risk factors were associated with smaller volumes across baseline and follow-up for most structures, although a more rapid decline over time was observed for striatal volumes. There were no significant shape analyses findings.

CONCLUSION

The study demonstrates a three-hit model of general (as opposed to localized) subcortical injury in PWH: HIV infection associated with smaller volumes of most subcortical structures, HIV infection and aging synergy in the striatum, and cardiovascular-related injury linked to early and more rapid striatal atrophy.

Intracranial vascular imaging detects arterial wall abnormalities in persons with treated HIV infection

OBJECTIVE

Although a substantial proportion of ischemic strokes in persons with HIV infection (PWH) is related to large artery disease, studies evaluating elevated cerebrovascular risk in PWH have focused primarily on microvascular disease. We compared the burden of intracranial large artery disease on vessel wall MRI (VW-MRI) in PWH and HIV-uninfected individuals.

DESIGN

Cross-sectional study.

METHODS

We recruited antiretroviral therapy-treated PWH with undetectable plasma viral load and HIV-uninfected individuals. All participants were at least 40 years of age and at moderate-to-high cardiovascular risk. We used Poisson and mixed effects logistic regression models to compare the number and associated characteristics of enhancing intracranial arteries on VW-MRI by HIV status.

RESULTS

Of 46 participants (mean age 59 years), 33 were PWH. PWH had nearly four-fold as many enhancing intracranial arteries on VW-MRI than HIV-uninfected individuals (rate ratio 3.94, 95% CI 1.57-9.88, P = 0.003). The majority of wall enhancement was eccentric (76%) and short-segment (93%), suggestive of intracranial atherosclerotic disease (ICAD). Sixty-nine percent of enhancing arteries were not associated with luminal narrowing on magnetic resonance angiography (MRA). None of these characteristics differed significantly by HIV status.

CONCLUSION

In persons at moderate-to-high cardiovascular risk, HIV infection, even when well controlled, may be associated with a greater burden of intracranial large artery disease and, specifically, of ICAD. Studies of the mechanisms underlying higher rates of ischemic stroke in PWH should include evaluation for intracranial large artery disease. VW-MRI provides added value as an adjunct to traditional luminal imaging when evaluating cerebrovascular risk in PWH.

White matter hyperintensities are associated with grey matter atrophy and cognitive decline in Alzheimer's disease and frontotemporal dementia

White matter hyperintensities (WMHs) are commonly assumed to represent non-specific cerebrovascular disease comorbid to neurodegenerative processes, rather than playing a synergistic role. We compared the impact of WMHs on grey matter (GM) atrophy and cognition in normal aging (n = 571), mild cognitive impairment (MCI, n = 551), Alzheimer's dementia (AD, n = 212), fronto-temporal dementia (FTD, n = 125), and Parkinson's disease (PD, n = 271). Longitudinal data were obtained from ADNI, FTLDNI, and PPMI datasets. Mixed-effects models were used to compare WMHs and GM atrophy between patients and controls and assess the impact of WMHs on GM atrophy and cognition. MCI, AD, and FTD patients had significantly higher WMH loads than controls. WMHs were related to GM atrophy in insular and parieto-occipital regions in MCI/AD, and frontal regions and basal ganglia in FTD. In addition, WMHs contributed to more severe cognitive deficits in AD and FTD compared to controls, whereas their impact in MCI and PD was not significantly different from controls. These results suggest potential synergistic effects between WMHs and proteinopathies in the neurodegenerative process in MCI, AD and FTD.

The Longitudinal Effects of Blood Pressure and Hypertension on Neurocognitive Performance in People Living With HIV

BACKGROUND

Hypertension (HTN) and HIV are salient risk factors for cerebral small vessel disease and neurocognitive (NC) impairment, yet the effects of HTN on NC performance in persons living with HIV remain poorly understood. This is the first study to examine the longitudinal associations between blood pressure (BP), HTN, and pulse pressure (PP) with NC performance in persons living with HIV.

SETTING

New York City.

METHODS

Analysis of medical, NC, and virologic data from 485 HIV+ participants was collected by the Manhattan HIV Brain Bank, a prospective, observational, longitudinal study of neuroHIV. A series of multilevel linear growth curve models with random intercepts and slopes were estimated for BP, HTN status, and PP to predict the change in NC performance.

RESULTS

The baseline prevalence of HTN was 23%. Longitudinal changes in diastolic and systolic pressure were associated with a 10.5-second and 4-second increase in the Grooved Pegboard Test nondominant hand performance, respectively. A longitudinal change in diastolic BP was also associated with a 0.3-point decline in correct categories and 3-point increase in perseverative responses and total errors on the Wisconsin Card Sorting Test. Increasing odds of prevalent and/or incident HTN were associated with a 0.1-point decrease in correct categories and a 0.8-point increase in total errors on the Wisconsin Card Sorting Test. There was no association between PP and NC performance.

CONCLUSIONS

The results indicate linear longitudinal relations for BP and HTN with poorer NC test performance, particularly in psychomotor and executive functions in persons with HIV.

Cerebrovascular Disease Correlates With Longitudinal Brain Atrophy in Virally Suppressed Older People Living With HIV

BACKGROUND

Mild cognitive difficulties and progressive brain atrophy are observed in older people living with HIV (PLWH) despite persistent viral suppression. Whether cerebrovascular disease (CVD) risk factors and white matter hyperintensity (WMH) volume correspond to the observed progressive brain atrophy is not well understood.

METHODS

Longitudinal structural brain atrophy rates and WMH volume were examined among 57 HIV-infected participants and 40 demographically similar HIV-uninfected controls over an average (SD) of 3.4 (1.7) years. We investigated associations between CVD burden (presence of diabetes, hypertension, hyperlipidemia, obesity, smoking history, and atrial fibrillation) and WMH with atrophy over time.

RESULTS

The mean (SD) age was 64.8 (4.3) years for PLWH and 66.4 (3.2) years for controls. Participants and controls were similar in age and sex (P > 0.05). PLWH were persistently suppressed (VL <375 copies/mL with 93% <75 copies/mL). The total number of CVD risk factors did not associate with atrophy rates in any regions of interests examined; however, body mass index independently associated with progressive atrophy in the right precentral gyrus (β = -0.30; P = 0.023), parietal lobe (β = -0.28; P = 0.030), and frontal lobe atrophy (β = -0.27; P = 0.026) of the HIV-infected group. No associations were found in the HIV-uninfected group. In both groups, baseline WMH was associated with progressive atrophy rates bilaterally in the parietal gray in the HIV-infected group (β = -0.30; P = 0.034) and the HIV-uninfected participants (β = -0.37; P = 0.033).

CONCLUSIONS

Body mass index and WMH are associated with atrophy in selective brain regions. However, CVD burden seems to partially contribute to progressive brain atrophy in older individuals regardless of HIV status, with similar effect sizes. Thus, CVD alone is unlikely to explain accelerated atrophy rates observed in virally suppressed PLWH. In older individuals, addressing modifiable CVD risk factors remains important to optimize brain health.

Gray matter volumes discriminate cognitively impaired and unimpaired people with HIV

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HIV-associated neurocognitive disorders (HAND) are common in people with HIV.

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HAND is typically diagnosed using a neuropsychological assessment battery.

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We examined whether gray matter volumes can be used to identify HAND cases.

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Gray matter volumes accurately discriminated people with and without HAND.

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Stratifying by sex improved discriminability, revealing sex differences in HAND.

Background

Current diagnostic criteria of HIV-associated neurocognitive disorders (HAND) rely on neuropsychological assessments. The aim of this study was to evaluate if gray matter volumes (GMV) can distinguish people with HAND, neurocognitively unimpaired people with HIV (unimpaired PWH), and uninfected controls using linear discriminant analyses.

Methods

A total of 231 participants, including 110 PWH and 121 uninfected controls, completed a neuropsychological assessment and an MRI protocol. Among PWH, HAND (n = 48) and unimpaired PWH (n = 62) designations were determined using the widely accepted Frascati criteria. We then assessed the extent to which GMV, corrected for intracranial volume, could accurately distinguish the three groups using linear discriminant analysis. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, area under the curve (AUC), and accuracy were computed for each model using the classification results based on GMV compared to the neuropsychological assessment.

Results

The best performing model was comprised of bilaterally combined GMV and was stratified by sex. Among males, sensitivity was 85.2% (95% CI: 66.3%–95.8%), specificity was 97.0% (95% CI: 91.6%-99.4%), and the AUC was 0.91 (95% CI: 0.83–0.99). Among females, sensitivity was 100.0% (95% CI: 83.9%–100.0%), specificity was 98.8% (95% CI: 93.4%-100.0%), and the AUC was 0.99 (95% CI: 0.98–1.00).

Conclusions

GMV accurately discriminated HAND from unimpaired PWH and controls. Measures of GMV may be highly sensitive to HAND, and revisions to the Frascati criteria should consider including GMV in conjunction with a neuropsychological assessment to diagnose HAND.

Role of Brain Arterial Remodeling in HIV-Associated Cerebrovascular Outcomes

As the life expectancy of people living with HIV (PLWH) on combination antiretroviral therapy (cART) increases, so does morbidity from cerebrovascular disease and neurocognitive disorders. Brain arterial remodeling stands out as a novel investigational target to understand the role of HIV in cerebrovascular and neurocognitive outcomes. We therefore conducted a review of publications in PubMed, EMBASE, Web of Science and Wiley Online Library, from inception to April 2021. We included search terms such as HIV, cART, brain, neuroimmunity, arterial remodeling, cerebrovascular disease, and neurocognitive disorders. The literature shows that, in the post-cART era, PLWH continue to experience an increased risk of stroke and neurocognitive disorders (albeit milder forms) compared to uninfected populations. PLWH who are immunosuppressed have a higher proportion of hemorrhagic strokes and strokes caused by opportunistic infection and HIV vasculopathy, while PLWH on long-term cART have higher rates of ischemic strokes, compared to HIV-seronegative controls. Brain large artery atherosclerosis in PLWH is associated with lower CD4 nadir and higher CD4 count during the stroke event. HIV vasculopathy, a form of non-atherosclerotic outward remodeling, on the other hand, is associated with protracted immunosuppression. HIV vasculopathy was also linked to a thinner media layer and increased adventitial macrophages, suggestive of non-atherosclerotic degeneration of the brain arterial wall in the setting of chronic central nervous system inflammation. Cerebrovascular architecture seems to be differentially affected by HIV infection in successfully treated versus immunosuppressed PLWH. Brain large artery atherosclerosis is prevalent even with long-term immune reconstitution post-cART. HIV-associated changes in brain arterial walls may also relate to higher rates of HIV-associated neurocognitive disorders, although milder forms are more prevalent in the post-cART era. The underlying mechanisms of HIV-associated pathological arterial remodeling remain poorly understood, but a role has been proposed for chronic HIV-associated inflammation with increased burden on the vasculature. Neuroimaging may come to play a role in assessing brain arterial remodeling and stratifying cerebrovascular risk, but the data remains inconclusive. An improved understanding of the different phenotypes of brain arterial remodeling associated with HIV may reveal opportunities to reduce rates of cerebrovascular disease in the aging population of PLWH on cART.

Beware of white matter hyperintensities causing systematic errors in FreeSurfer gray matter segmentations!

Volumetric estimates of subcortical and cortical structures, extracted from T1-weighted MRIs, are widely used in many clinical and research applications. Here, we investigate the impact of the presence of white matter hyperintensities (WMHs) on FreeSurfer gray matter (GM) structure volumes and its possible bias on functional relationships. T1-weighted images from 1,077 participants (4,321 timepoints) from the Alzheimer's Disease Neuroimaging Initiative were processed with FreeSurfer version 6.0.0. WMHs were segmented using a previously validated algorithm on either T2-weighted or Fluid-attenuated inversion recovery images. Mixed-effects models were used to assess the relationships between overlapping WMHs and GM structure volumes and overall WMH burden, as well as to investigate whether such overlaps impact associations with age, diagnosis, and cognitive performance. Participants with higher WMH volumes had higher overlaps with GM volumes of bilateral caudate, cerebral cortex, putamen, thalamus, pallidum, and accumbens areas (p < .0001). When not corrected for WMHs, caudate volumes increased with age (p < .0001) and were not different between cognitively healthy individuals and age-matched probable Alzheimer's disease patients. After correcting for WMHs, caudate volumes decreased with age (p < .0001), and Alzheimer's disease patients had lower caudate volumes than cognitively healthy individuals (p < .01). Uncorrected caudate volume was not associated with ADAS13 scores, whereas corrected lower caudate volumes were significantly associated with poorer cognitive performance (p < .0001). Presence of WMHs leads to systematic inaccuracies in GM segmentations, particularly for the caudate, which can also change clinical associations. While specifically measured for the Freesurfer toolkit, this problem likely affects other algorithms.

Reductions in Gray Matter Linked to Epigenetic HIV-Associated Accelerated Aging

A growing literature suggests a relationship between HIV-infection and a molecular profile of age acceleration. However, despite the widely known high prevalence of HIV-related brain atrophy and HIV-associated neurocognitive disorder (HAND), epigenetic age acceleration has not been linked to HIV-related changes in structural MRI. We applied morphological MRI methods to study the brain structure of 110 virally suppressed participants with HIV infection and 122 uninfected controls age 22-72. All participants were assessed for cognitive impairment, and blood samples were collected from a subset of 86 participants with HIV and 83 controls to estimate epigenetic age. We examined the group-level interactive effects of HIV and chronological age and then used individual estimations of epigenetic age to understand the relationship between age acceleration and brain structure. Finally, we studied the effects of HAND. HIV-infection was related to gray matter reductions, independent of age. However, using epigenetic age as a biomarker for age acceleration, individual HIV-related age acceleration was associated with reductions in total gray matter. HAND was associated with decreases in thalamic and hippocampal gray matter. In conclusion, despite viral suppression, accentuated gray matter loss is evident with HIV-infection, and greater biological age acceleration specifically relates to such gray matter loss.

HIV, Vascular Risk Factors, and Cognition in the Combination Antiretroviral Therapy Era: A Systematic Review and Meta-Analysis

OBJECTIVES

Mounting evidence indicates that vascular risk factors (VRFs) are elevated in HIV and play a significant role in the development and persistence of HIV-associated neurocognitive disorder. Given the increased longevity of people living with HIV (PLWH), there is a great need to better elucidate vascular contributions to neurocognitive impairment in HIV. This systematic review and meta-analysis examine relationships between traditional VRFs, cardiovascular disease (CVD), and cognition in PLWH in the combination antiretroviral therapy era.

METHODS

For the systematic review, 44 studies met inclusion criteria and included data from 14,376 PLWH and 6,043 HIV-seronegative controls. To better quantify the contribution of VRFs to cognitive impairment in HIV, a robust variance estimation meta-analysis (N = 11 studies) was performed and included data from 2139 PLWH.

RESULTS

In the systematic review, cross-sectional and longitudinal studies supported relationships between VRFs, cognitive dysfunction, and decline, particularly in the domains of attention/processing speed, executive functioning, and fine motor skills. The meta-analysis demonstrated VRFs were associated with increased odds of global neurocognitive impairment (odds ratio [OR ]= 2.059, p = .010), which remained significant after adjustment for clinical HIV variables (p = .017). Analyses of individual VRFs demonstrated type 2 diabetes (p = .004), hyperlipidemia (p = .043), current smoking (p = .037), and previous CVD (p = .0005) were significantly associated with global neurocognitive impairment.

CONCLUSIONS

VRFs and CVD are associated with worse cognitive performance and decline, and neurocognitive impairment in PLWH. Future studies are needed to examine these relationships in older adults with HIV, and investigate how race/ethnicity, gender, medical comorbidities, and psychosocial factors contribute to VRF-associated cognitive dysfunction in HIV.

Neuroimaging and Cognitive Evidence for Combined HIV-Alcohol Effects on the Central Nervous System: A Review

Alcohol use disorder (AUD) among people living with HIV (PLWH) is a significant public health concern. Despite the advent of effective antiretroviral therapy, up to 50% of PLWH still experience worsened neurocognition, which comorbid AUD exacerbates. We report converging lines of neuroimaging and neuropsychological evidence linking comorbid HIV/AUD to dysfunction in brain regions linked to executive function, learning and memory, processing speed, and motor control, and consequently to impairment in daily life. The brain shrinkage, functional network alterations, and brain metabolite disruption seen in individuals with HIV/AUD have been attributed to several interacting pathways: viral proteins and EtOH are directly neurotoxic and exacerbate each other's neurotoxic effects; EtOH reduces antiretroviral adherence and increases viral replication; AUD and HIV both increase gut microbial translocation, promoting systemic inflammation and HIV transport into the brain by immune cells; and HIV may compound alcohol's damaging effects on the liver, further increasing inflammation. We additionally review the neurocognitive effects of aging, Hepatitis C coinfection, obesity, and cardiovascular disease, tobacco use, and nutritional deficiencies, all of which have been shown to compound cognitive changes in HIV, AUD, and in their comorbidity. Finally, we examine emerging questions in HIV/AUD research, including genetic and cognitive protective factors, the role of binge drinking in HIV/AUD-linked cognitive decline, and whether neurocognitive and brain functions normalize after drinking cessation.

Pathomechanisms of HIV-Associated Cerebral Small Vessel Disease: A Comprehensive Clinical and Neuroimaging Protocol and Analysis Pipeline

Rationale: We provide an in-depth description of a comprehensive clinical, immunological, and neuroimaging study that includes a full image processing pipeline. This approach, although implemented in HIV infected individuals, can be used in the general population to assess cerebrovascular health.

Aims: In this longitudinal study, we seek to determine the effects of neuroinflammation due to HIV-1 infection on the pathomechanisms of cerebral small vessel disease (CSVD). The study focuses on the interaction of activated platelets, pro-inflammatory monocytes and endothelial cells and their impact on the neurovascular unit. The effects on the neurovascular unit are evaluated by a novel combination of imaging biomarkers.

Sample Size: We will enroll 110 HIV-infected individuals on stable combination anti-retroviral therapy for at least three months and an equal number of age-matched controls. We anticipate a drop-out rate of 20%.

Methods and Design: Subjects are followed for three years and evaluated by flow cytometric analysis of whole blood (to measure platelet activation, platelet monocyte complexes, and markers of monocyte activation), neuropsychological testing, and brain MRI at the baseline, 18- and 36-month time points. MRI imaging follows the recommended clinical small vessel imaging standards and adds several advanced sequences to obtain quantitative assessments of brain tissues including white matter microstructure, tissue susceptibility, and blood perfusion.

Discussion: The study provides further understanding of the underlying mechanisms of CSVD in chronic inflammatory disorders such as HIV infection. The longitudinal study design and comprehensive approach allows the investigation of quantitative changes in imaging metrics and their impact on cognitive performance.

Cerebral alterations in West African HIV and non-HIV adults aged ≥50: An MRI study

Objectives:

To cross-sectionally describe brain alterations in PLHIV aged above 50 years old, receiving antiretroviral treatment (ART) and living in Senegal compared to HIV-negative subjects.

Methods:

Twenty PLHIV and 26 HIV-negative subjects with comparable socio-demographic and clinical characteristics underwent an MRI exam (3D-T1 and FLAIR sequences). Global atrophy and White Matter Hyperintensities (WMH) were evaluated. After assessing the feasibility and acceptability of MRI scans in this population, we described atrophy and WHM prevalence and associated factors using logistic regressions.

Results:

Overall, 43.5% of the study sample were aged ≥60 years, 58.7% were women, and 28.3% had hypertension. The overall prevalence of atrophy and WMH was 19.6% [95% CI: 8.1–31.1] and 30.4% [95% CI: 17.1–43.7]. HIV status had no significant effect on atrophy or WMH. Unemployment and hypertension were significantly associated with atrophy, whereas women were less likely to present atrophy. Aged ≥60 years was the only factor associated with WMH.

Conclusions:

A high prevalence of atrophy and WMH was observed in West African adults aged over 50 years without a clear HIV impact. As brain MRI studies are critical to better understand cognitive and emotional outcomes, we encourage those studies in older PLHIV in West Africa.

The temporal relationships between white matter hyperintensities, neurodegeneration, amyloid beta, and cognition

Introduction

Cognitive decline in Alzheimer's disease is associated with amyloid beta (Aβ) accumulation, neurodegeneration, and cerebral small vessel disease, but the temporal relationships among these factors is not well established.

Methods

Data included white matter hyperintensity (WMH) load, gray matter (GM) atrophy and Alzheimer's Disease Assessment Scale‐Cognitive‐Plus (ADAS13) scores for 720 participants and cerebrospinal fluid amyloid (Aβ1–42) for 461 participants from the Alzheimer's Disease Neuroimaging Initiative. Linear regressions were used to assess the relationships among baseline WMH, GM, and Aβ1–42 to changes in WMH, GM, Aβ1–42, and cognition at 1‐year follow‐up.

Results

Baseline WMHs and Aβ1–42 predicted WMH increase and GM atrophy. Baseline WMHs and Aβ1–42 predicted worsening cognition. Only baseline Aβ1–42 predicted change in Aβ1–42.

Discussion

Baseline WMHs lead to greater future GM atrophy and cognitive decline, suggesting that WM damage precedes neurodegeneration and cognitive decline. Baseline Aβ1–42 predicted WMH increase, suggesting a potential role of amyloid in WM damage.

The regional pattern of abnormal cerebrovascular reactivity in HIV-infected, virally suppressed women

The purpose of this study was to assess whole brain and regional patterns of cerebrovascular reactivity (CVR) abnormalities in HIV-infected women using quantitative whole brain arterial spin labeling (ASL). We hypothesized that HIV-infected women would demonstrate decreased regional brain CVR despite viral suppression. This cross-sectional study recruited subjects from the Bay Area Women's Interagency Health Study (WIHS)-a cohort study designed to investigate the progression of HIV disease in women. In addition to conventional noncontrast cerebral MRI sequences, perfusion imaging was performed before and after the administration of intravenous acetazolamide. CVR was measured by comparing quantitative ASL brain perfusion before and after administration of intravenous acetazolamide. In order to validate and corroborate ASL-based whole brain and regional perfusion, phase-contrast (PC) imaging was also performed through the major neck vessels. FLAIR and susceptibility weighted sequences were performed to assess for white matter injury and microbleeds, respectively. Ten HIV-infected women and seven uninfected, age-matched controls were evaluated. Significant group differences were present in whole brain and regional CVR between HIV-infected and uninfected women. These regional differences were significant in the frontal lobe and basal ganglia. CVR measurements were not significantly impacted by the degree of white matter signal abnormality or presence of microbleeds. Despite complete viral suppression, dysfunction of the neurovascular unit persists in the HIV population. Given the lack of association between CVR and traditional imaging markers of small vessel disease, CVR quantification may provide an early biomarker of pre-morbid vascular disease.

Cerebral atrophy in amyotrophic lateral sclerosis parallels the pathological distribution of TDP43

Amyotrophic lateral sclerosis is a neurodegenerative disease characterized by a preferential involvement of both upper and lower motor neurons. Evidence from neuroimaging and post-mortem studies confirms additional involvement of brain regions extending beyond the motor cortex. The aim of this study was to assess the extent of cerebral disease in amyotrophic lateral sclerosis cross-sectionally and longitudinally and to compare the findings with a recently proposed disease-staging model of amyotrophic lateral sclerosis pathology. Deformation-based morphometry was used to identify the patterns of brain atrophy associated with amyotrophic lateral sclerosis and to assess their relationship with clinical symptoms. Longitudinal T₁-weighted MRI data and clinical measures were acquired at baseline, 4 months and 8 months, from 66 patients and 43 age-matched controls who participated in the Canadian Amyotrophic Lateral Sclerosis Neuroimaging Consortium study. Whole brain voxel-wise mixed-effects modelling analysis showed extensive atrophy patterns differentiating patients from the normal controls. Cerebral atrophy was present in the motor cortex and corticospinal tract, involving both grey matter and white matter, and to a lesser extent in non-motor regions. More specifically, the results showed significant bilateral atrophy in the motor cortex and corticospinal tract (including the internal capsule and brainstem) and ventricular enlargement, along with significant longitudinal atrophy in precentral gyrus, frontal and parietal white matter, accompanied by ventricular and sulcal enlargement. Atrophy in the precentral gyrus was significantly associated with greater disability as quantified with the Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (P < 0.0001). The pattern of atrophy observed using deformation-based morphometry was consistent with the Brettschneider’s four-stage pathological model of the disease. Deformation-based morphometry provides a sensitive indicator of atrophy in Amyotrophic lateral sclerosis and has potential as a biomarker of disease burden, in both grey matter and white matter.

Metabolic Syndrome and Cardiovascular Disease Impacts on the Pathophysiology and Phenotype of HIV-Associated Neurocognitive Disorders

Evidence from epidemiological studies on the general population suggests that midlife cardiovascular disease (CVD) and/or metabolic syndrome (MetS) are associated with an increased risk of cognitive impairment and dementia later in life. In the modern combined antiretroviral therapy (cART) era, as in the general population, CVD and MetS were strongly and independently associated with poorer cognitive performances of sustained immunovirologically controlled persons living with human immunodeficiency viruses (PLHIVs). Those findings suggest that CV/metabolic comorbidities could be implicated in the pathogenesis of HIV-associated neurocognitive disorders (HAND) and might be more important than factors related to HIV infection or its treatment, markers of immunocompetence, or virus replication. The association between CVD/MetS and cognition decline is driven by still not well-understood mechanisms, but risk might well be the consequence of increased brain inflammation and vascular changes, notably cerebral small-vessel disease. In this review, we highlight the correspondences observed between the findings concerning CVD and MetS in the general population and virus-suppressed cART-treated PLHIVs to evaluate the real brain-aging processes. Indeed, incomplete HIV control mainly reflects HIV-induced brain damage described during the first decades of the pandemic. Given the growing support that CVD and MetS are associated with HAND, it is crucial to improve early detection and assure appropriate management of these conditions.

White Matter Abnormalities Linked to Interferon, Stress Response, and Energy Metabolism Gene Expression Changes in Older HIV-Positive Patients on Antiretroviral Therapy

Neurocognitive impairment (NCI) remains a significant cause of morbidity in human immunodeficiency virus (HIV)-positive individuals despite highly active antiretroviral therapy (HAART). White matter abnormalities have emerged as a key component of age-related neurodegeneration, and accumulating evidence suggests they play a role in HIV-associated neurocognitive disorders. Viral persistence in the brain induces chronic inflammation associated with lymphocytic infiltration, microglial proliferation, myelin loss, and cerebrovascular lesions. In this study, gene expression profiling was performed on frontal white matter from 34 older HIV+ individuals on HAART (18 with NCI) and 24 HIV-negative controls. We used the NanoString nCounter platform to evaluate 933 probes targeting inflammation, interferon and stress responses, energy metabolism, and central nervous system-related genes. Viral loads were measured using single-copy assays. Compared to HIV- controls, HIV+ individuals exhibited increased expression of genes related to interferon, MHC-1, and stress responses, myeloid cells, and T cells and decreased expression of genes associated with oligodendrocytes and energy metabolism in white matter. These findings correlated with increased white matter inflammation and myelin pallor, suggesting interferon (IRFs, IFITM1, ISG15, MX1, OAS3) and stress response (ATF4, XBP1, CHOP, CASP1, WARS) gene expression changes are associated with decreased energy metabolism (SREBF1, SREBF2, PARK2, TXNIP) and oligodendrocyte myelin production (MAG, MOG), leading to white matter dysfunction. Machine learning identified a 15-gene signature predictive of HIV status that was validated in an independent cohort. No specific gene expression patterns were associated with NCI. These findings suggest therapies that decrease chronic inflammation while protecting mitochondrial function may help to preserve white matter integrity in older HIV+ individuals.

CROI 2019: neurologic complications of HIV disease

Investigators reported many new neuroHIV research findings at the 2019 Conference on Retroviruses and Opportunistic Infections (CROI). These findings included confirmation that HIV-associated neurocognitive disorder (HAND) remains common with an increasingly recognized role for comorbidities (eg, obesity) and neurodegenerative conditions (eg, Alzheimer's disease), especially as persons living with HIV (PLWH) advance into their seventh decade of life and beyond. HAND is increasingly recognized as a heterogeneous disorder that differs between individuals (eg, by sex) in the trajectory of specific neurocognitive abilities (eg, executive functioning). A more recent focus at this year's conference was toxicity of combination antiretroviral therapy: neurocognitive performance and neuroimaging data from several studies were presented but did not consistently support that integrase strand transfer inhibitors are associated with worse neurologic outcomes. Neuroimaging studies found that white matter changes reflect a combination of the effects of HIV and comorbidities (including cerebrovascular small vessel disease) and best correlate with blood markers of inflammation. The pathogenesis of HIV in the central nervous system (CNS) was the focus of a plenary lecture and numerous presentations on HIV compartmentalization in the CNS and cerebrospinal fluid viral escape. Novel findings were also presented on associations between HIV-associated neurologic complications and glycomics, neuron-derived exosomes, and DNA methylation in monocytes. This summary will review findings from CROI and identify new research and clinical opportunities.