Cerebral signal intensity abnormalities on T2-weighted MR images in HIV patients with highly active antiretroviral therapy: relationship with clinical parameters and interval changes

Oscillatory markers of neuroHIV-related cognitive impairment and Alzheimer's disease during attentional interference processing

People with HIV (PWH) frequently experience mild cognitive decline, which is typically attributed to HIV-associated neurocognitive disorder (HAND). However, such declines could also be a sign of early Alzheimer's disease (AD) in older PWH. Distinguishing these two pathologies in PWH is exceedingly difficult, as there is a major knowledge gap regarding their neural and neuropsychological bases. In the current study, we begin to address this knowledge gap by recording magnetoencephalography (MEG) during a flanker interference task in 31 biomarker-confirmed patients on the AD spectrum (ADS), 25 older participants with HAND, and 31 cognitively-normal controls. MEG data was examined in the time-frequency domain using a data-driven approach. Our results indicated that the clinical groups (ADS/HAND) performed significantly worse than controls on the task and exhibited aberrations in interference-related theta and alpha oscillations, some of which were disease-specific. Specifically, patients (ADS/HAND) exhibited weaker interference activity in frontoparietal and cingulate cortices compared to controls, while the ADS group exhibited stronger theta interference than those with HAND in frontoparietal, occipital, and temporal cortices. These results reveal overlapping and distinct patterns of neurophysiological alterations among those with ADS and HAND in attentional processing centers and suggest the existence of unique oscillatory markers of each condition.

Neurologic Complications of Human Immunodeficiency Virus

PURPOSE OF REVIEW

This article reviews the neurologic complications associated with human immunodeficiency virus (HIV) infection.

RECENT FINDINGS

Neurologic complications of HIV may be caused by direct virally mediated pathology, immune-mediated phenomena in response to viral infection, or opportunistic infections secondary to depletion of lymphocytes. These neurologic disorders may be influenced by the degree of immunosuppression (ie, CD4+ T-cell lymphocyte count) and stage of infection (early versus late), as well as use of antiretroviral therapy, and may manifest as a variety of central and peripheral neurologic syndromes, including the more commonly encountered HIV-associated cognitive disorders and length-dependent sensorimotor polyneuropathy, respectively. Immune dysregulation underlies the majority of these neurologic phenomena, as well as other HIV-associated conditions including immune reconstitution inflammatory syndrome (IRIS), CD8 lymphocytosis, and potentially the development of compartmentalized infection within the CSF, also referred to as CSF escape.

SUMMARY

This article reviews a spectrum of clinical syndromes and related neuropathologic states associated with HIV infection.

Association of White Matter Hyperintensities With HIV Status and Vascular Risk Factors

OBJECTIVE

To test the hypothesis that brain white matter hyperintensities (WMH) are more common in people living with HIV (PLWH), even in the setting of well-controlled infection, and to identify clinical measures that correlate with these abnormalities.

METHODS

Research brain MRI scans, acquired within longitudinal studies evaluating neurocognitive outcomes, were reviewed to determine WMH load using the Fazekas visual rating scale in PLWH with well-controlled infection (antiretroviral therapy for at least 1 year and plasma viral load <200 copies/mL) and in sociodemographically matched controls without HIV (CWOH). The primary outcome measure of this cross-sectional analysis was increased WMH load, determined by total Fazekas score ≥2. Multiple logistic regression analysis was performed to evaluate the effect of HIV serostatus on WMH load and to identify MRI, CSF, and clinical variables that associate with WMH in the PLWH group.

RESULTS

The study included 203 PLWH and 58 CWOH who completed a brain MRI scan between April 2014 and March 2019. The multiple logistic regression analysis, with age and history of tobacco use as covariates, showed that the adjusted odds ratio of the PLWH group for increased WMH load is 3.7 (95% confidence interval 1.8-7.5; p = 0.0004). For the PLWH group, increased WMH load was associated with older age, male sex, tobacco use, hypertension, and hepatitis C virus coinfection, and also with the presence of measurable tumor necrosis factor α in CSF.

CONCLUSION

Our results suggest that HIV serostatus affects the extent of brain WMH. This effect is mainly associated with aging and modifiable comorbidities.

Effect of Human Immunodeficiency Virus on Trace Elements in the Brain

Comorbidities of human immunodeficiency virus (HIV) include HIV-associated neurocognitive disorder (HAND). Changes in the brain due to HIV include atrophy, hyperintensities, and diffusion changes. However, no research has focused on trace elements concentration changes in the brain due to HIV, as seen in other neurodegenerative diseases. Therefore, the aim of this study was to determine the concentration of several trace elements in the brains of individuals with and without HIV infection. Prior to formalin embalming, blood was drawn and tested in triplicate with Determine HIV-1/2 rapid tests and confirmed with a SD HIV Device 1/2 3.0 rapid HIV Kit. After embalming, tissue was sampled from the caudate nucleus and analyzed using inductively coupled plasma mass spectrometry. A Kruskal-Wallis test was used to determine statistically significant differences between the two groups (p < 0.05). Fifteen HIV-positive and 14 HIV-negative male cadavers were included (mean age 44, range 22 to 61). Cadmium was marginally decreased, possibly due to malnutrition or utilization by the HIV nucleocapsid. Nickel was marginally increased, perhaps due to a reduced capability to remove metals from the body. In conclusion, this article provides the first information on trace element levels in the brains from HIV-infected individuals and postulates that cadmium and nickel may play a role in the pathophysiology of HAND. This information can contribute to finding a treatment for HAND, other than the use of antiretroviral drugs. Future studies should asses the levels of cadmium and nickel in a larger cohort of HIV-infected individuals.

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.

Human immunodeficiency virus-related cerebral white matter disease in children

The human immunodeficiency virus (HIV) epidemic seems largely controlled by anti-retroviral treatment with resultant large numbers of children growing up with the disease on long-term treatment, placing them at higher risk to develop HIV-related brain injury, ongoing cognitive impairment and treatment-related neurological complications. Cerebral white matter involvement is a common radiologic finding in HIV infection and the causes of this have overlapping appearances, ranging from diffuse widespread involvement to focal lesions. The varied pathophysiology is broadly grouped into primary effects of HIV, opportunistic infection, vascular disease and neoplasms. White matter changes in children can be different from those in adults. This review provides guidance to radiologists with the diagnostic dilemma of nonspecific cerebral white matter lesions in children with HIV. The authors discuss common causes of HIV-related cerebral white matter disease as well as the role of neuroimaging in the management of these children.

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.

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.

Characteristics of Resting-State Functional Connectivity in HIV-Associated Neurocognitive Disorder

BACKGROUND

HIV-associated neurocognitive disorder (HAND) can occur in patients without prior AIDS defining illness and can be debilitating. This study aimed to evaluate the difference in the patterns of intrinsic brain activity between patients with or without HAND for deepening our understanding of HAND.

METHODS

We evaluated 24 HIV-infected individuals, 12 with previously diagnosed HAND and 12 previously diagnosed without HAND, and 11 seronegative individuals. These individuals then underwent repeat NP testing and a functional brain MRI scan. For functional MRI analysis, seed-based analysis with bilateral precuneus cortex seed was applied.

RESULTS

Among the 12 individuals with previously diagnosed HAND, 3 showed improvement of their neurocognitive function and 1 was excluded for worsening liver disease. Among the 12 patients who previously had normal neurocognitive function, 2 showed neurocognitive impairment. Overall, the HAND group, who had impaired cognitive function at the time of MRI scan, showed significant decrease of resting status functional connectivity between bilateral precuneus and prefrontal cortex (PFC) compared with nonHAND group, those who had normal neurocognitive function (Corrected P<0.05). The functional connectivity with the right inferior frontal operculum and right superior frontal gyrus was positively correlated with memory and learning ability.

CONCLUSIONS

This cross-sectional study found a significant difference in fMRI patterns between patients with and without HAND. Decreased functional connectivity between precuneus and PFC could be possible functional substrate for cognitive dysfunction in HIV patients, which should be characterized in a longitudinal study.

Neurocognitive decline in HIV patients is associated with ongoing T-cell activation in the cerebrospinal fluid

Objective

HIV-associated neurocognitive disorders (HAND) remain a challenge despite combination antiretroviral therapy (cART). Immune cell activation has been implicated to play a major role in the development of HAND.

Methods

In this study, we used multicolor flow cytometry on peripheral blood (PB) and cerebrospinal fluid (CSF) samples to determine the expression of HLA-DR and programmed death-1 (PD-1) on CD4+ and CD8+ T cells in patients with chronic HIV infection. Expression levels were correlated with HI virus load in PB and CSF, classification of HAND and severity of magnetic resonance imaging (MRI) signal abnormalities.

Results

In a cohort of 86 HIV patients we found that the grade of neurocognitive impairment and the severity of MRI signal abnormalities correlated with decreasing CD4/CD8-ratios and increased frequencies of HLA-DR expressing CD4+ and CD8+ T cells reaching the highest values in the CSF samples. Importantly, HLA-DR upregulation was still detectable in virologically suppressed HIV patients. Further, T-cell subpopulation analysis of 40 HIV patients showed a significant shift from naïve to effector memory (EM) T cells that was negatively correlated with the grade of neurocognitive impairment in the PB samples. Moreover, PD-1 was significantly increased on CD4+ memory T cells with highest levels on EM T cells in HIV patients with mild or severe neurocognitive alterations.

Interpretation

The CD4/CD8 ratio, the proportion of EM to naïve T cells and the immune activation profile of CD4+ and CD8+ T cells in PB and CSF might be useful parameters to monitor the efficacy of cART and to identify HIV patients at risk of further neurocognitive deterioration.

[HIV 1-associated neurocognitive disorder: current epidemiology, pathogenesis, diagnosis and management]

By restoring the immunological function the modern antiretroviral treatment of human immunodeficiency virus (HIV-1) infection has considerably lowered the incidence of opportunistic infections. As opposed to the classical manifestations of HIV-induced immunosuppression the incidence and prevalence of HIV-associated neurocognitive disorders (HAND) has not noticeably decreased and HAND continues to be relevant in daily clinical practice. At present, HAND occurs in earlier stages of HIV infection, and the clinical course differs from that before the introduction of combination antiretroviral treatment (cART). The predominant clinical manifestation is a subcortical dementia with deficits in the domains attention, concentration and memory. Signs of central motor pathway lesions have become less frequent and less prominent. Prior to the advent of cART the cerebral dysfunction could at least partially be explained by the viral load and by virus-associated histopathological findings. In patients with at least partially successfully treated infections, this relationship no longer exists, but a plethora of poorly understood immunological and probably toxic phenomena are under discussion.This consensus paper summarizes the progress made in the last 12 years in the field of HAND and provides suggestions for the diagnostic and therapeutic management.

Neuropathological sequelae of Human Immunodeficiency Virus and apathy: A review of neuropsychological and neuroimaging studies

Apathy remains a common neuropsychiatric disturbance in the Human Immunodeficiency Virus (HIV-1) despite advances in anti-retroviral treatment (ART). The goal of the current review is to recapitulate findings relating apathy to the deleterious biobehavioral effects of HIV-1 in the post-ART era. Available literatures demonstrate that the emergence of apathy with other neurocognitive and neuropsychiatric symptoms may be attributed to neurotoxic effects of viral proliferation, e.g., aggregative effect of Tat and gp120 on apoptosis, transport and other enzymatic reactions amongst dopaminergic neurons and neuroglia. An assortment of neuroimaging modalities converge on the severity of apathy symptoms associated with the propensity of the virus to replicate within frontal-striatal brain circuits that facilitate emotional processing. Burgeoning research into functional brain connectivity also supports the effects of microvascular and neuro-inflammatory injury linked to aging with HIV-1 on the presentation of neuropsychiatric symptoms. Summarizing these findings, we review domains of HIV-associated neurocognitive and neuropsychiatric impairment linked to apathy in HIV. Taken together, these lines of research suggest that loss of affective, cognitive and behavioral inertia is commensurate with the neuropathology of HIV-1.

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

OBJECTIVES

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Cognitive impairment in HIV infection is associated with MRI and CSF pattern of neurodegeneration

BACKGROUND AND PURPOSE

Biomarkers as indicators for the progression of human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain still elusive. We performed a cross-sectional study to analyze the correlation between cognitive impairment, abnormalities in magnetic resonance imaging (MRI), and cerebrospinal fluid (CSF) markers of neurodegeneration in HIV-infected patients.

METHODS

We enrolled 94 patients (82 men and 12 women; mean age 45 ± 10 years) with HIV infection, but without opportunistic infections of the CNS. All patients underwent MRI and CSF analysis. The global pattern of white matter signal intensity abnormalities, the index of atrophy, the severity of periventricular white matter abnormalities, and the severity of basal ganglia signal changes were analyzed. We measured CSF markers of neurodegeneration (total tau, phospho-tau, beta-amyloid). The findings of this evaluation were correlated with demographic and infection parameters of the patients in blood and CSF.

RESULTS

We found a highly significant correlation between the severity of global brain atrophy, basal ganglia signal changes, and cognitive impairment in HIV-infected patients. Furthermore, cognitive impairment was significantly correlated with total tau, but not with phospho-tau or A-beta-amyloid in CSF analysis.

CONCLUSIONS

Our results confirm the significant correlation between MRI changes and cognitive impairment in HIV infection. Furthermore, we could show that global brain atrophy and signal changes in basal ganglia are the typical MRI pattern in HAND. The correlation between cognitive impairment and total tau, but not phospho-tau, supports the hypothesis that HAND are not a subtype of Alzheimer's dementia.