Cross-sectional study of unexplained white matter lesions in HIV positive individuals undergoing brain magnetic resonance imaging

White and Gray Matter Changes are Associated With Neurocognitive Decline in HIV Infection

OBJECTIVE

To investigate the relationship between neurocognitive deficits and structural changes on brain magnetic resonance imaging in people living with HIV (PLWH) with good virological control on combination antiretroviral therapy, compared with socioeconomically matched control participants recruited from the same communities.

METHODS

Brain magnetic resonance imaging scans, and clinical and neuropsychological data were obtained from virologically controlled PLWH (viral load of <50 c/mL and at least 1 year of combination antiretroviral therapy) and socioeconomically matched control participants. Magnetic resonance imaging was carried out on 3 T scanner with 8-channel head coils and segmented using Classification using Derivative-based Features. Multiple regression analysis was performed to examine the association between brain volume and various clinical and neuropsychiatric parameters adjusting for age, race, and sex. To evaluate longitudinal changes in brain volumes, a random coefficient model was used to evaluate the changes over time (age) adjusting for sex and race.

RESULTS

The cross-sectional study included 164 PLWH and 51 controls, and the longitudinal study included 68 PLWH and 20 controls with 2 or more visits (mean 2.2 years, range 0.8-5.1 years). Gray matter (GM) atrophy rate was significantly higher in PLWH compared with control participants, and importantly, the GM and global atrophy was associated with the various neuropsychological domain scores. Higher volume of white matter hyperintensities were associated with increased atherosclerotic cardiovascular disease risk score, and decreased executive functioning and memory domain scores in PLWH.

INTERPRETATION

These findings suggest ongoing neurological damage even in virologically controlled participants, with significant implications for clinical management of PLWH. ANN NEUROL 2024;95:941-950.

Cocaine use is associated with cerebral white matter hyperintensities in HIV disease

BACKGROUND

White matter hyperintensities (WMH), a marker of cerebral small vessel disease and predictor of cognitive decline, are observed at higher rates in persons with HIV (PWH). The use of cocaine, a potent central nervous system stimulant, is disproportionately common in PWH and may contribute to WMH.

METHODS

The sample included of 110 PWH on antiretroviral therapy. Fluid-attenuated inversion recovery (FLAIR) and T1-weighted anatomical MRI scans were collected, along with neuropsychological testing. FLAIR images were processed using the Lesion Segmentation Toolbox. A hierarchical regression model was run to investigate predictors of WMH burden [block 1: demographics; block 2: cerebrovascular disease (CVD) risk; block 3: lesion burden].

RESULTS

The sample was 20% female and 79% African American with a mean age of 45.37. All participants had persistent HIV viral suppression, and the median CD4+ T-cell count was 750. Nearly a third (29%) currently used cocaine regularly, with an average of 23.75 (SD = 20.95) days in the past 90. In the hierarchical linear regression model, cocaine use was a significant predictor of WMH burden (β = .28). WMH burden was significantly correlated with poorer cognitive function (r = -0.27). Finally, higher WMH burden was significantly associated with increased serum concentrations of interferon-γ-inducible protein 10 (IP-10) but lower concentrations of myeloperoxidase (MPO); however, these markers did not differ by COC status.

CONCLUSIONS

WMH burden is associated with poorer cognitive performance in PWH. Cocaine use and CVD risk independently contribute to WMH, and addressing these conditions as part of HIV care may mitigate brain injury underlying neurocognitive impairment.

Role of non-classical monocytes in HIV-associated vascular cognitive impairment

Despite antiretroviral treatment (cART), people living with HIV (PLWH) are more susceptible to neurocognitive impairment (NCI), probably due to synergistic/additive contribution of traditional cerebrovascular risk factors. Specifically, altered blood brain barrier (BBB) and transmigration of inflammatory monocytes are risk factors for developing cerebral small vessel disease (CSVD). In order to investigate if inflammatory monocytes exacerbate CSVD and cognitive impairment, 110 PLWH on cART and 110 age-, sex- and Reynold’s cardiovascular risk score-matched uninfected individuals were enrolled. Neuropsychological testing, brain magnetic resonance imaging and whole blood analyses to measure platelet-monocyte interaction and monocyte, endothelial activation were performed. Results demonstrated that PLWH exhibited increased levels of platelet-monocyte complexes (PMCs) and higher expression of activation molecules on PMCs. PLWH with CSVD had the poorest cognitive performance and the highest circulating levels of non-classical monocytes which exhibited significant inverse correlation with each other. Furthermore, markers of monocyte and endothelium activation were significantly positively correlated indicating BBB impairment. Our results confirm that interaction with platelets activates and drives monocytes towards an inflammatory phenotype in PLWH. In particular, elevated levels of non-classical monocytes may represent a common pathway to neuroinflammation, CSVD and subsequent cognitive impairment, warranting further longitudinal studies to evaluate responsiveness of this potential biomarker.

Human immunodeficiency virus-related decreases in corpus callosal integrity and corresponding increases in functional connectivity

People living with human immunodeficiency virus (PLWH) often have neurocognitive impairment. However, findings on HIV-related differences in brain network function underlying these impairments are inconsistent. One principle frequently absent from these reports is that brain function is largely emergent from brain structure. PLWH commonly have degraded white matter; we hypothesized that functional communities connected by degraded white matter tracts would show abnormal functional connectivity. We measured white matter integrity in 69 PLWH and 67 controls using fractional anisotropy (FA) in 24 intracerebral white matter tracts. Then, among tracts with degraded FA, we identified gray matter regions connected to these tracts and measured their functional connectivity during rest. Finally, we identified cognitive impairment related to these structural and functional connectivity systems. We found HIV-related decreased FA in the corpus callosum body (CCb), which coordinates activity between the left and right hemispheres, and corresponding increases in functional connectivity. Finally, we found that individuals with impaired cognitive functioning have lower CCb FA and higher CCb functional connectivity. This result clarifies the functional relevance of the corpus callosum in HIV and provides a framework in which abnormal brain function can be understood in the context of abnormal brain structure, which may both contribute to cognitive impairment.

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.

Effect of human immunodeficiency virus on the brain: A review

Thirty million people are infected with human immunodeficiency virus (HIV) worldwide, and HIV-associated neurocognitive disorder (HAND) is one of the most common comorbidities of HIV. However, the effect of HIV on the brain has not been fully investigated. This article aimed to review the changes to the brain due to HIV in terms of atrophy, diffusion changes, and hyperintensities. Studies have observed significant atrophy in subcortical gray matter, as well as in cortical white and gray matter. Moreover, the ventricles enlarge, and the sulci widen. Although HIV causes changes to the white and gray matter of the brain, few diffusion tensor imaging studies have investigated the changes to gray matter integrity. White and gray matter hyperintensities have frequently been observed in HIV-positive individuals, with the subcortical gray matter (caudate nucleus and putamen) and periventricular white matter frequently affected. In conclusion, subcortical gray matter is the first brain region to be affected and is affected most severely. Additionally, this review highlights the gaps in the literature, since the effect of HIV on the brain is not fully known. Future studies should continue to investigate the effect of HIV on the brain in different stages of the disease, and alternate therapies should be developed since highly active antiretroviral therapy is currently ineffective at treating HAND.

Cerebral white matter Hyperintensities in HIV-positive patients

White matter hyperintensities (WMHs) have been associated with neurological complications including cognitive impairment. WMHs have been often described in HIV positive subjects and they have been linked to neurocognitive impairment, cerebrospinal fluid (CSF) residual viral replication and biomarkers of monocyte activation. Aim of this study was to grade WMHs in HIV-positive individuals using a simple visual scale and to explore their severity with clinical, neurocognitive and biomarker characteristics. Brain MRIs were retrospectively evaluated by two reviewers who rated WMHs following the "age-related white matter changes (ARWMC)" scale. 107 adult HIV-positive patients receiving lumbar punctures for clinical reasons were included. 70 patients (66.6%) were diagnosed with WMHs. Average WMH scores were higher in treated [7 (1-11)] vs. naïve individuals [3 (0-6)] (p = 0.008). Higher WHMs scores were observed in patients with chronic renal impairment along with chronic hepatitis (naïve) and longer HIV duration (treated participants). No consistent associations between plasma, CSF biomarkers and WMHs scores were found. 45 patients underwent full neurocognitive tests and WMHs scores were non-significantly higher in patients diagnosed with HAND [6.5 (0.5-8.3) vs. 1.5 (0-7), p = 0.165]; screening (IHDS and FAB), visuo-spatial (Corsi's) and auditory-verbal memory (disillabic words repetition) tests scored worse in patients with higher WMHs. In our population of HIV-positive patients with low CD4 nadir and partial CD4 cell recovery the burden of WMHs was associated with the duration of HIV infection and with commonly observed comorbidities (such as renal and hepatic impairment). Given the association with worse neurocognition, further studies on tailored interventions are needed.

Differences in location of cerebral white matter hyperintensities in children and adults living with a treated HIV infection: A retrospective cohort comparison

Cerebral white matter hyperintensities (WMH) persist in children and adults living with HIV, despite effective combination antiretroviral therapy (cART). As age and principal routes of transmission differ between children (perinatally) and adults (behaviorally), comparing the characteristics and determinants of WMH between these populations may increase our understanding of the pathophysiology of WMH. From separate cohorts of 31 children (NOVICE) and 74 adults (AGEhIV), we cross-sectionally assessed total WMH volume and number of WMH per location (periventricular vs. deep) using fluid-attenuated inversion recovery (FLAIR) MRI images. WMH were either periventricular when within 10mm of the lateral ventricles, or deep otherwise. We assessed patient- or HIV-related determinants of total WMH volume (adjusted for intracranial volume) and location of WMH using logistic regression, while stratifying on children and adults. At enrollment, median age of participants was 13.8 years (IQR 11.4-15.9) for children and 53.4 years (IQR 48.3-60.8) for adults and 27/31 children (87%) and 74/74 adults (100%) had an HIV RNA viral load <200 copies/mL. WMH were present in 16/27 (52%) children and 74/74 adults (100%). The prevalence of deep WMH was not different between groups, (16/16 [100%] in children vs. 71/74 [96%] in adults, p = 0,999), yet periventricular WMH were more prevalent in adults (74/74 [100%]) compared to children (9/16; 56%) (p<0.001). Median WMH volume was higher in adults compared to children (1182 mm3 [425-2617] vs. 109 mm3 [61.7-625], p<0.001). In children, boys were more likely to have deep WMH compared to girls. In adults, older age was associated with higher total WMH volume, and age, hypertension and lower CD4+ T-lymphocyte nadir with a higher number of periventricular WMH. Our findings suggest that the location of WMH differs between children and adults living with HIV, hinting at a different underlying pathogenesis.

Silent Cerebral Small-Vessel Disease Is Twice as Prevalent in Middle-Aged Individuals With Well-Controlled, Combination Antiretroviral Therapy-Treated Human Immunodeficiency Virus (HIV) Than in HIV-Uninfected Individuals

Background

Silent cerebral small-vessel disease (CSVD) is defined as white matter hyperintensities, silent brain infarction, or microbleeds. CSVD is responsible for future vascular events, cognitive impairment, frailty, and shorter survival. CSVD prevalence among middle-aged people living with well-controlled human immunodeficiency virus (HIV) infection (PLHIV) is unknown.

Methods

The French National Agency for Research on AIDS and Viral Hepatitis (ANRS) EP51 Microvascular Brain Retina and Kidney Study (MicroBREAK; NCT02082574) is a cross-sectional study with prospective enrollment of treated PLHIV, ≥50 years old with viral load controlled for ≥12 months, and frequency age- and sex-matched HIV-uninfected controls (HUCs). It was designed to estimate CSVD prevalence on 3T magnetic resonance imaging (3D fluid-attenuated inversion recovery, transversal T2-weighted gradient-echo imaging and diffusion-weighted imaging), as diagnosed by 2 blinded neuroradiologists. A logistic regression model was used to assess the impact of HIV on CSVD after adjustment for traditional risk factors.

Results

Between June 2013 and May 2016, 456 PLHIV and 154 HUCs were recruited. Median age was 56 and 58 years, respectively (P = .001), among whom 84.9% and 77.3%, respectively (P = .030), were men. CSVD was detected in 51.5% of PLHIV and 36.4% of HUCs with an adjusted odds ratio (aOR) of 2.3. The HIV impact differed according to age, with aOR values of 5.3, 3.7, and 1.0 for age groups <54, 54-60, and >60 years, respectively (P = .022). Older age, hypertension, and lower CD4 cell count nadir were independently associated with a higher risk of CSVD among PLHIV.

Conclusions

HIV is an independent risk factor for CSVD. Despite sustained immunovirological control, the CSVD prevalence was twice as high among middle-aged PLHIV than HUCs.

Clinical Trials Registration

NCT02082574.

Correlates of telomere length shortening in peripheral leukocytes of HIV-infected individuals and association with leukoaraiosis

Telomere length (TL) is a marker of cellular and biological aging. Human immunodeficiency virus (HIV) infection has been reported to be associated with short TLs, which suggests that accelerated biological aging occurs in some cellular compartments of HIV+ individuals. In this study, we measured the TLs of peripheral leukocytes of HIV+ and healthy individuals and examined the biological and environmental correlates of TL. We also investigated the influence of TL on leukoaraiosis, an indicator of cerebral small vessel disease, in HIV+ individuals. Three hundred and twenty-five HIV+ individuals who received stable combination antiretroviral therapy (cART) for >1 year and achieved viral loads of <40 RNA copies/mL were enrolled along with 147 healthy individuals. Relative TLs of leukocytes were estimated by quantitative real-time polymerase chain reaction. Leukoaraiosis was assessed in 184 HIV+ individuals by fluid-attenuated inversion recovery magnetic resonance imaging. We analyzed several covariates, including markers of HIV infection, cART, and social/environmental factors; variables associated with TL length in univariate analyses were incorporated into multivariate models. The TLs of peripheral leukocytes of HIV+ individuals were significantly shorter than those of healthy individuals, and the rate of LT length decline with increasing age was greater. Linear regression analysis showed that in HIV+ individuals, increasing age, cART without integrase-stand transfer inhibitors (INSTI), failure to achieve viral loads of <40 copies/mL within 1 year of initiating cART, and substance use were significantly associated with shorter TLs, even after adjustment for the effects of age. Logistic regression analysis indicated an increasing risk of leukoaraiosis was associated with older age, shorter TLs, hypertension, and carotid artery plaque. Multivariate regression analysis indicated that older age and shorter TLs were significant risk factors for leukoaraiosis. In summary, our data showed that TL shortening in HIV+ individuals was independently associated with leukoaraiosis, and was associated with age, control of viral loads, use of INSTI, and substance use. Our results suggest that effective viral control and less toxic cART can help reduce TL shortening and improve outcomes among HIV+ individuals.

Is treated HIV infection still toxic to the brain?

Clinically apparent HIV infection, accompanied by CNS opportunistic infections and HIV encephalopathy, was often associated with profound structural and functional brain effects prior to the introduction of anti-retroviral therapy (ART). With treatment, HIV structural and functional brain effects are smaller and have not been as easily detected. With near complete elimination of CNS opportunistic infections, the HIV neuroimaging research community now grapples with the problem of detecting subtler structural and functional changes against a background of persisting confounds, such as comorbidities and clinical features common in the HIV infected population. This situation also raises the question of whether imaging measure changes that are reported as HIV brain effects are purely related to viral infection, rather than originating from confounding effects that might include age, substance use, hepatitis C coinfection, cerebrovascular risk factors, ART, premorbid cognitive skills and illness duration. In addition to cohort characteristics, variation in image acquisition and analysis techniques may also contribute to study outcome heterogeneity. We review the potential effects of these confounds on detection of HIV infection effects and discuss strategies to avoid or mitigate the effects of these confounds. We then present a systematic approach to measurement, design and analysis in HIV neuroimaging studies, combining both experimental and statistical control techniques to determine if HIV infection effects persist, fluctuate or worsen in groups achieving viral suppression from ART.

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

OBJECTIVE

The objective of this study is to investigate whether cerebral small vessel disease (CSVD) is more common in virologically suppressed HIV-positive participants compared with HIV-negative controls and examine the potential synergistic effects of HIV and CSVD on brain structure and cognition.

DESIGN

Cross-sectional analysis of 119 treated, virologically suppressed HIV-positive and 55 HIV-negative participants. Forty-six HIV-positive and 30 HIV-negative participants had follow-up 2 years later. All participants underwent MRI and neuropsychological testing.

METHODS

Volume of white matter hyperintensities (WMH) was used as a surrogate measure of CSVD severity. Tensor-based morphometry and cortical modeling estimated brain volumes and cortical thickness, respectively. Rasch measurement theory was applied to neuropsychological test scores to estimate overall cognition. Linear models compared WMH loads, brain volumes, and cognition between groups; evaluated the association of WMH loads with brain volumes and cognition; and tested the interaction between HIV and WMH loads on brain volumes and cognition. Mixed-effects models compared the change in WMH loads between groups.

RESULTS

WMH loads and change in WMH loads were similar between the groups. HIV-positive participants had poorer cognition, thinner cortex and reduced subcortical volumes compared with HIV-negative controls. Higher WMH loads were associated with reduced cortical thickness and subcortical volumes and worse cognition, regardless of HIV serostatus. No significant interactions were observed between HIV and WMH loads with regards to brain volumes or cognition.

CONCLUSION

These findings suggest that the contributions of HIV and CSVD on brain atrophy and cognitive impairment are independent but additive processes. This argues that optimizing vascular health may mitigate brain injury and cognitive decline, especially in treated, virologically suppressed HIV-positive individuals.

Brain MRI findings related to Alzheimer's disease in older African American adults

Although a substantial body of research has identified brain MRI measures as important markers of Alzheimer's disease (AD) risk, progression, and treatment response, most of that research has been performed in non-Hispanic white American populations, leading to questions about the utility of the brain MRI measures among individuals of other races or ethnicities. African American individuals in particular are under-represented in AD research, and may exhibit differences in prevalence of AD risk factors, prevalence of AD, incidence of AD, the clinical course of cognitive decline, and AD neuropathology, each of which could influence the utility of brain MRI markers. Unfortunately, while current evidence suggests that African Americans exhibit poorer brain health late in life based on brain MRI measurements, several other aspects of brain MRI markers in this population are unclear, including trajectories of brain MRI markers leading up to old age, relationships between traditional brain health risk factors and brain MRI findings, and the status of brain MRI markers as correlates of cognitive impairment. This unclear state of affairs highlights the urgency of future research in which large numbers of older African American adults contribute longitudinal brain MRI measurements concurrent with clinical, cognitive, and molecular biomarker measurements, ideally in the context of AD preventive or therapeutic trials.

Clinical research cerebral MRI findings in HIV-positive subjects and appropriate controls

: Abnormalities in cerebral MRI are frequently reported in persons living with HIV (PLWH). We compared clinical cerebral MRI reports in 59 PLWH and 29 lifestyle matched controls. Although clinical abnormalities were highly prevalent (47.7%), and included white-matter lesions (46.6%), microvascular disease (22.7%) and cerebral volume loss (11.4%), no differences were apparent between PLWH and controls, with abnormalities being associated with age and hypertension rather than HIV serostatus.

Brain MRI Features of CSF Human Immunodeficiency Virus Escape

BACKGROUND AND PURPOSE

HIV infection of the central nervous system (CNS) is a nearly universal feature of untreated systemic HIV infection. While combination antiretroviral therapy (ART) that suppresses systemic infection usually suppresses CNS (CNS) HIV infection, exceptions have been reported with discordance between CSF and blood HIV RNA concentrations such that CSF demonstrates higher HIV concentrations than blood, referred to as CSF HIV escape. Rarely, CSF HIV escape presents with neurological symptoms, called neurosymptomatic escape.

METHODS

In this report, we describe the MRI findings in 6 patients with neurosymptomatic escape who were identified at our institution.

RESULTS

MR imaging suggests an encephalitis possibly evolving from a distinct HIV subpopulation within the CNS. A major difference between primary HIV infection and the current case series is that untreated HIV encephalitis usually occurs in the setting of late disease and a low CD4 whereas CSF Escape develops in setting of a higher CD4, as well as more robust immune and inflammatory responses. Our findings show a burden and distribution of white matter signal abnormalities atypical for patients adherent to ART and that differs from that seen in untreated HIV encephalitis and leukoencephalopathy. Moreover, these patients may also demonstrate perivascular enhancement, a finding not previously reported in the CSF HIV escape literature.

CONCLUSION

Recognition of these imaging characteristics-patchy subcortical white matter intensities and a perivascular pattern of enhancement-may be helpful in recognition and, along with other clinical information and CSF findings, in diagnosis of neurosymptomatic escape.

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

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

Neural response to working memory demand predicts neurocognitive deficits in HIV

Human immunodeficiency virus (HIV) continues to have adverse effects on cognition and the brain in many infected people, despite a reduced incidence of HIV-associated dementia with combined antiretroviral therapy (cART). Working memory is often affected, along with attention, executive control, and cognitive processing speed. Verbal working memory (VWM) requires the interaction of each of the cognitive component processes along with a phonological loop for verbal repetition and rehearsal. HIV-related functional brain response abnormalities during VWM are evident in functional MRI (fMRI), though the neural substrate underlying these neurocognitive deficits is not well understood. The current study addressed this by comparing 24 HIV+ to 27 demographically matched HIV-seronegative (HIV-) adults with respect to fMRI activation on a VWM paradigm (n-back) relative to performance on two standardized tests of executive control, attention and processing speed (Stroop and Trail Making A-B). As expected, the HIV+ group had deficits on these neurocognitive tests compared to HIV- controls, and also differed in neural response on fMRI relative to neuropsychological performance. Reduced activation in VWM task-related brain regions on the 2-back was associated with Stroop interference deficits in HIV+ but not with either Trail Making A or B performance. Activation of the posterior cingulate cortex (PCC) of the default mode network during rest was associated with Hopkins Verbal Learning Test-2 (HVLT-2) learning in HIV+. These effects were not observed in the HIV- controls. Reduced dynamic range of neural response was also evident in HIV+ adults when activation on the 2-back condition was compared to the extent of activation of the default mode network during periods of rest. Neural dynamic range was associated with both Stroop and HVLT-2 performance. These findings provide evidence that HIV-associated alterations in neural activation induced by VWM demands and during rest differentially predict executive-attention and verbal learning deficits. That the Stroop, but not Trail Making was associated with VWM activation suggests that attentional regulation difficulties in suppressing interference and/or conflict regulation are a component of working memory deficits in HIV+ adults. Alterations in neural dynamic range may be a useful index of the impact of HIV on functional brain response and as a fMRI metric in predicting cognitive outcomes.

Cerebral blood flow and cognitive function in HIV-infected men with sustained suppressed viremia on combination antiretroviral therapy

OBJECTIVE

To assess if HIV-infected patients on long-term successful combination antiretroviral therapy show cerebral blood flow (CBF) alterations in comparison with HIV-uninfected, otherwise similar controls. To explore whether such alterations are associated with HIV-associated cognitive impairment and to explore potential determinants of CBF alterations in HIV.

DESIGN

Cross-sectional comparison of CBF in an observational cohort study.

METHODS

Clinical, cognitive and MRI data of 100 middle-aged aviremic HIV-infected men on combination antiretroviral therapy and 69 HIV-uninfected controls were collected and compared. From pseudocontinuous arterial spin labeling MRI data, CBF-maps were calculated. The associations of mean gray matter CBF with clinical and cognitive parameters were explored in regression models, followed by a spatial delineation in a voxel-based analysis.

RESULTS

CBF was decreased in HIV-infected patients compared with HIV-uninfected controls (P = 0.02), adjusted for age, ecstasy use and waist circumference. Spatially distinct and independent effects of total gray matter volume and HIV-serostatus on CBF were found. Within the HIV-infected group, decreased CBF was associated with increased triglyceride levels (P = 0.005) and prior clinical AIDS (P = 0.03). No association between CBF and cognitive impairment was found.

CONCLUSION

Decreased CBF was observed among HIV-infected patients, which was associated with both vascular risk factors as well as with measures of past immune deficiency. These results provide support for increased vascular disease in HIV-infected patients as represented by hemodynamic alteration, but without overt cognitive consequences within the current cohort of patients on long-term successful treatment.

Psychiatric symptom burden in older people living with HIV with and without cognitive impairment: the UCSF HIV over 60 cohort study

Psychiatric comorbidities are common in people living with HIV (PLWH) and adversely affect life satisfaction, treatment adherence and disease progression. There are few data to inform the burden of psychiatric symptoms in older PLWH, a rapidly growing demographic in the U.S. We performed a cross-sectional analysis to understand the degree to which symptom burden was associated with cognitive disorders in PLWH over age 60. Participants completed a standardized neuropsychological battery and were assigned cognitive diagnoses using Frascati criteria. We captured psychiatric symptom burden using the Geriatric Depression Scale (GDS) and proxy-informed Neuropsychiatric Inventory-Questionnaire (NPI-Q). Those diagnosed with HIV-associated neurocognitive disorders (HAND, n = 39) were similar to those without HAND (n = 35) by age (median = 67 years for each group, p = 0.696), education (mean = 16 years vs. 17 years, p = 0.096), CD4+ T-lymphocyte counts (mean = 520 vs. 579, p = 0.240), duration of HIV (median = 21 years for each group, p = 0.911) and sex (92% male in HAND vs. 97% in non-HAND, p = 0.617). Our findings showed similarities in HAND and non-HAND groups on both NPI-Q (items and clusters) and GDS scores. However, there was a greater overall symptom burden in HIV compared to healthy elder controls (n = 236, p < 0.05), with more frequent agitation, depression, anxiety, apathy, irritability and nighttime behavior disturbances (p < 0.05). Our findings demonstrate no differences in psychiatric comorbidity by HAND status in older HIV participants; but confirm a substantial neurobehavioral burden in this older HIV-infected population.

White matter hyperintensities correlate to cognition and fiber tract integrity in older adults with HIV

Our aim was to examine the clinical relevance of white matter hyperintensities (WMH) in HIV. We used an automated approach to quantify WMH volume in HIV seropositive (HIV+; n = 65) and HIV seronegative (HIV-; n = 29) adults over age 60. We compared WMH volumes between HIV+ and HIV- groups in cross-sectional and multiple time-point analyses. We also assessed correlations between WMH volumes and cardiovascular, HIV severity, cognitive scores, and diffusion tensor imaging variables. Serostatus groups did not differ in WMH volume, but HIV+ participants had less cerebral white matter (mean: 470.95 [43.24] vs. 497.63 [49.42] mL, p = 0.010). The distribution of WMH volume was skewed in HIV+ with a high proportion (23%) falling above the 95th percentile of WMH volume defined by the HIV- group. Serostatus groups had similar amount of WMH volume growth over time. Total WMH volume directly correlated with measures of hypertension and inversely correlated with measures of global cognition, particularly in executive functioning, and psychomotor speed. Greater WMH volume was associated with poorer brain integrity measured from diffusion tensor imaging (DTI) in the corpus callosum and sagittal stratum. In this group of HIV+ individuals over 60, WMH burden was associated with cardiovascular risk and both worse diffusion MRI and cognition. The median total burden did not differ by serostatus; however, a subset of HIV+ individuals had high WMH burden.

An Overview of Human Immunodeficiency Virus Type 1-Associated Common Neurological Complications: Does Aging Pose a Challenge?

With increasing survival of patients infected with human immunodeficiency virus type 1 (HIV-1), the manifestation of heterogeneous neurological complications is also increasing alarmingly in these patients. Currently, more than 30% of about 40 million HIV-1 infected people worldwide develop central nervous system (CNS)-associated dysfunction, including dementia, sensory, and motor neuropathy. Furthermore, the highly effective antiretroviral therapy has been shown to increase the prevalence of mild cognitive functions while reducing other HIV-1-associated neurological complications. On the contrary, the presence of neurological disorder frequently affects the outcome of conventional HIV-1 therapy. Although, both the children and adults suffer from the post-HIV treatment-associated cognitive impairment, adults, especially depending on the age of disease onset, are more prone to CNS dysfunction. Thus, addressing neurological complications in an HIV-1-infected patient is a delicate balance of several factors and requires characterization of the molecular signature of associated CNS disorders involving intricate cross-talk with HIV-1-derived neurotoxins and other cellular factors. In this review, we summarize some of the current data supporting both the direct and indirect mechanisms, including neuro-inflammation and genome instability in association with aging, leading to CNS dysfunction after HIV-1 infection, and discuss the potential strategies addressing the treatment or prevention of HIV-1-mediated neurotoxicity.

White matter hyperintensities in relation to cognition in HIV-infected men with sustained suppressed viral load on combination antiretroviral therapy

OBJECTIVES

The objective of this study was to assess whether HIV-infected patients on long-term successful combination antiretroviral therapy (cART) have more extensive white matter hyperintensities (WMH) of presumed vascular origin compared with uninfected controls and whether these intensities are associated with cognitive impairment. Furthermore, we explored potential determinants of increased WMH load long-term suppressed HIV infection.

DESIGN

A cross-sectional comparison of WMH in an observational cohort.

METHODS

Clinical, cognitive, and MRI data were collected from 103 middle-aged, aviremic HIV-infected men on cART, and 70 HIV-uninfected, otherwise similar controls. In the MRI data, WMH load was quantified by automated approaches and qualitatively reviewed by an experienced neuroradiologist using the Fazekas scale.

RESULTS

HIV-infected men had an increased WMH load. Among HIV-infected patients, increased WMH load was independently associated with older age, higher DBP, higher D-dimer levels, and longer time spent with a CD4 cell count below 500 cells/μl. HIV-associated cognitive deficits were associated with increased WMH load.

CONCLUSIONS

WMH are more extensive and associated with cognitive deficits in middle-aged, aviremic cART-treated HIV-infected men. The extent of WMH load was associated with both cardiovascular risk factors and past immune deficiency. As cognitive impairment in these same patients is also associated with these risk factors, this may suggest that in the setting of HIV, WMH, and cognitive deficits share a common cause. This supports the importance of optimizing cardiovascular risk management, and early, effective treatment of HIV infection.

Neuroretinal Degeneration in HIV Patients Without Opportunistic Ocular Infections in the cART Era

Subtle structural and functional retinal abnormalities, termed 'HIV-associated Neuroretinal Disorder (HIV-NRD)', have been reported in HIV patients receiving combination antiretroviral therapy (cART), without infectious retinitis or any apparent fundus abnormalities otherwise. In this review, we provide an overview of studies investigating HIV-NRD in HIV patients without opportunistic ocular infections in the cART era, and try to elucidate underlying mechanisms and associated risk factors. Most studies focused on patients with severe immune-deficiency and demonstrated that patients with nadir CD4 counts<100 cells/μL are most at risk for neuroretinal damage, with a thinner retinal nerve fiber layer, subtle loss of color vision and/or contrast sensitivity, visual field deficits, and subnormal electrophysiological responses. In contrast, alterations in retinal vascular calibers and retinal blood flow were not associated with nadir CD4 counts, but instead with detectable viremia, suggesting a role for (chronic) inflammation in microvascular damage. Although the alterations in visual function are subtle, they can lead to difficulties in activities, such as reading or driving, thereby affecting quality of life. Since HIV has become a chronic disease, its long-term effects with respect to visual function loss become more important, as is recently emphasized by a longitudinal study, reporting that AIDS patients with HIV-NRD have higher risks of developing bilateral visual impairment and even blindness than patients without HIV-NRD. The question remains whether patients with high (>350 cells/μL) nadir CD4 counts and well-suppressed HIV infection on cART remain at risk for HIV-NRD, as this group constitutes a growing part of the aging HIV-infected population.