Neurometabolite Alterations Associated With Cognitive Performance in Perinatally HIV-Infected Children

Maternal and child immune profiles are associated with neurometabolite measures of early-life neuroinflammation in children who are HIV-exposed and uninfected: a South African birth cohort

Children who are HIV-exposed and uninfected (HEU) are at risk of neurodevelopmental delays, which may be partially due to maternal immune dysregulation during pregnancy. This study investigates associations between maternal and child immune profiles and early neurometabolite profiles in HEU and HIV-unexposed (HU) children from a South African birth cohort. A subgroup of 156 children (66 HEU, 90 HU) from the Drakenstein Child Health Study underwent magnetic resonance spectroscopy at age 2-3 years, and maternal and child serum markers were measured at multiple timepoints via immunoassays. In HEU children, serum concentrations of maternal pro-inflammatory cytokines IL-5 (β = 0.79, p = 0.005) and IL-8 (β = 0.64, p = 0.02) were associated with myo-inositol ratios in parietal grey and white matter regions, respectively, while child serum MMP-9 at two years was associated with myo-inositol ratios in the midline parietal grey matter (β = 1.30, p = 0.03). The association of maternal anti-inflammatory cytokine IL-13 with glutamate ratios in the midline parietal grey matter was negative in HEU (β=-0.41, p = 0.038) and positive in HU children (β = 0.42, p < 0.0001). These findings suggest maternal immune activation may affect neurometabolite profiles in HEU children.

Maternal and child immune profiles are associated with neurometabolite measures of early-life neuroinflammation in children who are HIV-exposed and uninfected: a South African birth cohort

Children who are HIV-exposed and uninfected (HEU) are at risk of neurodevelopmental delays, which may be partially due to maternal immune dysregulation during pregnancy. This study investigates associations between maternal and child immune profiles and early neurometabolite profiles in HEU and HIV-unexposed (HU) children from a South African birth cohort. A subgroup of 156 children (66 HEU, 90 HU) from the Drakenstein Child Health Study underwent magnetic resonance spectroscopy at age 2-3 years, and maternal and child serum markers were measured at multiple timepoints via immunoassays. In HEU children, serum concentrations of maternal pro-inflammatory cytokines IL-5 (β=0.79, p=0.005) and IL-8 (β=0.64, p=0.02) were associated with myo-inositol ratios in parietal grey and white matter regions, respectively, while child serum MMP-9 at two years was associated with myo-inositol ratios in the midline parietal grey matter (β=1.30, p=0.03). The association of maternal anti-inflammatory cytokine IL-13 with glutamate ratios in the midline parietal grey matter was negative in HEU (β=-0.41, p=0.038) and positive in HU children (β=0.42, p<0.0001). These findings suggest maternal immune activation may affect neurometabolite profiles in HEU children.

Whole-brain MR spectroscopic imaging reveals regional metabolite abnormalities in perinatally HIV infected young adults

Perinatally acquired HIV (PHIV) has been associated with brain structural and functional deficiencies, and with poorer cognitive performance despite the advent of antiretroviral therapy (ART). However, investigation of brain metabolite levels in PHIV measured by proton magnetic resonance spectroscopy (MRS) methods, is still limited with often inconclusive or contradictory findings. In general, these MRS-based methods have used a single voxel approach that can only evaluate metabolite concentrations in a few select brain anatomical regions. Additionally, most of the published data have been on children perinatally infected with HIV with only a few studies examining adult populations, though not exclusively. Therefore, this prospective and cross-sectional study aims to evaluate metabolite differences at the whole-brain level, using a unique whole-brain proton magnetic resonance spectroscopy imaging (MRSI) method, in a group of PHIV infected young adults (N = 28) compared to age and gender matched control sample (N = 28), and to find associations with HIV clinical factors and neurocognitive scores. MRSI data were acquired on a 3T scanner with a TE of 70 ms. Brain metabolites levels of total N-acetylaspartate (tNAA), total choline (tCho) and total creatine (tCre), as well as ratios of tNAA/tCre, tCho/tCre, and tNAA/tCho, were obtained from the whole brain level and evaluated at the level of gray matter (GM) and white matter (WM) tissue types and anatomical regions of interest (ROI). Our results indicate extensive metabolic abnormalities throughout the brains of PHIV infected subjects with significantly elevated levels of tCre and tCho, notably in GM regions. Decreases in tNAA and ratios of tNAA/tCre and tNAA/tCho were also found mostly in WM regions. These metabolic alterations indicate increased glial activation, inflammation, neuronal dysfunction, and energy metabolism in PHIV infected individuals, which correlated with a reduction in CD4 cell count, and lower cognitive scores. Our findings suggest that significant brain metabolite alterations and associated neurological complications persist in the brains of those with PHIV on long-term ART, and advocates the need for continued monitoring of their brain health.

Biomarkers of Tuberculous Meningitis and Pediatric Human Immunodeficiency Virus on the African Continent

Biomarkers in body fluids are helpful objective tools in diagnosis, prognosis and monitoring of (therapeutic) responses of many neurological diseases. Cerebrospinal fluid (CSF) biomarkers are part of the diagnostic toolbox for infectious neurological diseases. Tuberculous meningitis (TBM) and Human immunodeficiency virus (HIV), are important burdens of disease in Africa and can negatively affect brain health. Two thirds of the world's population of people living with HIV reside in sub-Saharan Africa and 25% of the global burden of tuberculosis (TB) is carried by the African continent. Neuroinflammation and damage of specific neuronal cell types are key constituents in the pathophysiology of these central nervous system (CNS) diseases, and important potential sources of circulating biomarkers. In this review, we summarize current research in the use of biomarkers in TBM and pediatric HIV as case demonstrations for high prevalence neurological diseases in Africa. Inflammatory molecules, primarily when detected in CSF, appear to have diagnostic value in these diseases, especially when measured as profiles. Brain injury molecules, such as S100, Neuron specific enolase and glial fibrillary acidic protein may have prognostic value in TBM, but more studies are needed. There is a need for more cost-economic and high sensitivity technologies to drive further biomarker discoveries and translate into healthcare improvements for these important healthcare problems in a globally fair way.

Plasma Neurofilament Light Is Not Associated with Ongoing Neuroaxonal Injury or Cognitive Decline in Perinatally HIV Infected Adolescents: A Brief Report

Despite combination antiretroviral therapy (cART), adolescents with perinatally acquired human immunodeficiency virus (PHIV) exhibit cerebral injury and cognitive impairment. Plasma neurofilament light (pNfL) is a biomarker identified as a promising marker associated with neuroaxonal injury and cognitive impairment. To investigate whether cerebral injury in cART-treated PHIV adolescents is persistent, we longitudinally measured pNfL. We included 21 PHIV adolescents and 23 controls, matched for age, sex, ethnic origin and socio-economic status. We measured pNfL in both groups and CSF NfL in PHIV adolescents using a highly sensitive Single Molecule Array (Simoa) immunoassay. We compared pNfL between groups over time with a mean follow-up time of 4.6 years and assessed its association with MRI outcomes, cognitive function and HIV-related characteristics using linear mixed models. The median age was 17.5 years (15.5–20.7) and 16.4 years (15.8–19.6) at the second assessment for PHIV adolescents and controls, respectively. We found comparable pNfL (PHIV vs. controls) at the first (2.9 pg/mL (IQR 2.0–3.8) and 3.0 pg/mL (IQR 2.3–3.5), p = 0.499) and second assessment (3.3 pg/mL (IQR 2.5–4.1) and 3.0 pg/mL (IQR 2.5–3.7), p = 0.658) and observed no longitudinal change (coefficient; −0.19, 95% −0.5 to 0.1, p = 0.244). No significant associations were found between pNfL and HIV- or cART-related variables, MRI outcomes or cognitive function. We observed low CSF NfL concentrations at the baseline in PHIV adolescents (100.8 pg/mL, SD = 47.5). Our results suggest that there is no ongoing neuroaxonal injury in cART-treated PHIV adolescents and that the neuroaxonal injury is acquired in the past, emphasizing the importance of early cART to mitigate HIV-related neuroaxonal damage.

A Neurometabolic Pattern of Elevated Myo-Inositol in Children Who Are HIV-Exposed and Uninfected: A South African Birth Cohort Study

Introduction

Exposure to maternal HIV in pregnancy may be a risk factor for impaired child neurodevelopment during the first years of life. Altered neurometabolites have been associated with HIV exposure in older children and may help explain the mechanisms underlying this risk. For the first time, we explored neurometabolic profiles of children who are HIV-exposed and uninfected (CHEU) compared to children who are HIV-unexposed (CHU) at 2-3 years of age.

Methods

The South African Drakenstein Child Health Study enrolled women during pregnancy and is following mother-child pairs through childhood. MRI scans were acquired on a sub-group of children at 2-3 years. We used single voxel magnetic resonance spectroscopy to measure brain metabolite ratios to total creatine in the parietal grey matter, and left and right parietal white matter of 83 children (36 CHEU; 47 CHU). Using factor analysis, we explored brain metabolite patterns in predefined parietal voxels in these groups using logistic regression models. Differences in relative concentrations of individual metabolites (n-acetyl-aspartate, myo-inositol, total choline, and glutamate) to total creatine between CHEU and CHU groups were also examined.

Results

Factor analysis revealed four different metabolite patterns, each one characterized by covarying ratios of a single metabolite in parietal grey and white matter. The cross-regional pattern dominated by myo-inositol, a marker for glial reactivity and inflammation, was associated with HIV exposure status (OR 1.63; 95% CI 1.11-2.50) which held after adjusting for child age, sex, and maternal alcohol use during pregnancy (OR 1.59; 95% CI 1.07 -2.47). Additionally, higher relative concentrations of myo-inositol to total creatine were found in left and right parietal white matter of CHEU compared to CHU (p=0.025 and p=0.001 respectively).

Discussion

Increased ratios of myo-inositol to total creatine in parietal brain regions at age 2-3 years in CHEU are suggestive of early and ongoing neuroinflammatory processes. Altered relative concentrations of neurometabolites were found predominantly in the white matter, which is sensitive to neuroinflammation, and may contribute to developmental risk in this population. Future work on the trajectory of myo-inositol over time in CHEU, alongside markers of neurocognitive development, and the potential for specific neurodevelopmental interventions will be useful.

A Longitudinal Analysis of Cerebral Blood Flow in Perinatally HIV Infected Adolescents as Compared to Matched Healthy Controls

Despite effective combination anti-retroviral therapy (cART), perinatally HIV infected (PHIV) adolescents still experience cognitive complications. We previously reported higher cerebral blood flow (CBF) in basal ganglia and white matter (WM) in PHIV children compared to matched controls. In healthy children CBF is associated with cognitive domains. To determine longitudinal changes in CBF and its impact on cognitive complications, we measured CBF—using arterial spin labeling—in 21 PHIV adolescents and 23 controls matched for age, sex and socio-economic status twice with a mean follow-up of 4.6 years. We explored associations between CBF changes and WM micro- and macrostructural markers and cognitive domains using linear mixed models. The median age at follow-up was comparable between PHIV adolescents 17.4y (IQR:15.3–20.7) and controls 16.2y (IQR:15.6–19.1). At baseline, PHIV had higher CBF in the caudate nucleus and putamen. CBF development was comparable in gray matter (GM), WM and subcortical regions in both groups. In our cohort, we found that over time an increase of GM CBF was associated with an increase of visual motor function (p = 0.043) and executive function (p = 0.045). Increase of CBF in the caudate nucleus, putamen and thalamus was associated with an increase processing speed (p = 0.033; 0.036; 0.003 respectively) and visual motor function (p = 0.023; 0.045; 0.003 respectively). CBF development is relatively normal in PHIV adolescents on cART. CBF decline is associated with cognitive impairment, irrespective of HIV status.

Alterations of Brain Metabolites in Adults With HIV: A Systematic Meta-analysis of Magnetic Resonance Spectroscopy Studies

OBJECTIVE

A meta-analysis of proton magnetic resonance spectroscopy studies to investigate alterations in brain metabolites in people with HIV (PWH), the relationship between metabolite alterations and combination antiretroviral therapy (cART), and the relationship between metabolite alterations and cognitive impairment.

METHODS

The PubMed database was searched for studies published from 1997 to 2020. Twenty-seven studies were identified, which included 1255 PWH and 633 controls. Four metabolites (N-acetyl aspartate [NAA], myo-inositol [mI], choline [Cho], and glutamatergic metabolites [Glx]) from 5 brain regions (basal ganglia [BG], frontal gray and white matter [FGM and FWM], and parietal gray and white matter [PGM and PWM]) were pooled separately using random-effects meta-analysis.

RESULTS

During early HIV infection, metabolite alterations were largely limited to the BG, including Cho elevation, a marker of inflammation. cART led to global mI and Cho normalization (i.e., less elevations), but improvement in NAA was negligible. In chronic PWH on cART, there were consistent NAA reductions across brain regions, along with Cho and mI elevations in the FWM and BG, and Glx elevations in the FWM. Cognitive impairment was associated with NAA reduction and to a lesser degree mI elevation.

CONCLUSIONS

The BG are the primary region affected during early infection. cART is successful in partially controlling neuroinflammation (global mI and Cho normalization). However, neuronal dysfunction (NAA reductions) and neuroinflammation (mI and Cho elevations) persist and contribute to cognitive impairment in chronic PWH. Novel compounds targeting NAA signal pathways, along with better neuroinflammation control, may help to reduce cognitive impairment in PWH.

Multivariate approach for longitudinal analysis of brain metabolite levels from ages 5-11 years in children with perinatal HIV infection

Treatment guidelines recommend that children with perinatal HIV infection (PHIV) initiate antiretroviral therapy (ART) early in life and remain on it lifelong. As part of a longitudinal study examining the long-term consequences of PHIV and early ART on the developing brain, 89 PHIV children and a control group of 85 HIV uninfected children (HIV-) received neuroimaging at ages 5, 7, 9 and 11 years, including single voxel magnetic resonance spectroscopy (MRS) in three brain regions, namely the basal ganglia (BG), midfrontal gray matter (MFGM) and peritrigonal white matter (PWM). We analysed age-related changes in absolute metabolite concentrations using a multivariate approach traditionally applied to ecological data, the Correlated Response Model (CRM) and compared these to results obtained from a multilevel mixed effect modelling (MMEM) approach. Both approaches produce similar outcomes in relation to HIV status and age effects on longitudinal trajectories. Both methods found similar age-related increases in both PHIV and HIV- children in almost all metabolites across regions. We found significantly elevated GPC+PCh across regions (95% CI=[0.033; 0.105] in BG; 95% CI=[0.021; 0.099] in PWM; 95% CI=[0.059; 0.137] in MFGM) and elevated mI in MFGM (95% CI=[0.131; 0.407]) among children living with PHIV compared to HIV- children; additionally the CRM model also indicated elevated mI in BG (95% CI=[0.008; 0.248]). These findings suggest persistent inflammation across the brain in young children living with HIV despite early ART initiation.

Mitochondrial toxicity before and after combination antiretroviral therapy, a Magnetic Resonance Spectroscopy study

The aim of this study was to quantify, via Magnetic Resonance Spectroscopy (MRS), the effect of combination antiretroviral therapy (cART) on brain metabolites and characterize any possible associations between changes in metabolites, age, blood biomarkers of neuronal damage, functional connectivity and cognitive performance. As cART has dramatically increased the life expectancy of HIV-infected (HIV + ) individuals and unmasked an increase in HIV-associated neurocognitive disorders, it is still not clear whether cART neurotoxicity contributes to these disorders. We hypothesized a bimodal effect, with early cART treatment of HIV infection decreasing inflammation as measured by MRS metabolites and improving cognitive performance, and chronic exposure to cART contributing to persistence of cognitive impairment via its effect on mitochondrial function. Basal ganglia metabolites, functional connectivity, cognitive scores, as well as plasma levels of neurofilament light chain (NfL) and tau protein were measured before and after 12 weeks, 1 year and 2 years of cART in a cohort of 50 cART-naïve HIV + subjects and 72 age matched HIV- healthy controls. Glutamate (Glu) levels were lower in the cART naïve patients than in healthy controls and were inversely correlated with plasma levels of NfL. There were no other significant metabolite differences between HIV + and uninfected individuals. Treatment improved Glu levels in HIV+, however, no associations were found between Glu, functional connectivity and cognitive performance. Stable brain metabolites and plasma levels of NfL and Tau over two-years of follow-ups suggest there are no signs of cART neurotoxicity in this relatively young cohort of HIV + individuals.

Health-related quality of life of perinatally HIV-infected young people: a longitudinal study

Young people perinatally infected with HIV (pHIV) are at risk of a lowered health-related quality of life (HRQOL). Previous evaluation of the NeurOlogical, VIsual and Cognitive performance in HIV-infected Children (NOVICE)-cohort showed no difference in HRQOL between pHIV and matched HIV-uninfected controls (HIV-), yet a higher percentage of pHIV had impaired HRQOL. The aim of this study is to compare the change over time in HRQOL of pHIV to HIV- over a 5-year period. We used the Pediatric Quality of Life Inventory (PedsQL)™ 4.0 to repeat HRQOL assessment. High PedsQL scores indicate good HRQOL. Fifteen/33 (45.5%) pHIV and 17/37 (45.9%) HIV- completed both assessments. At the first assessment, the mean age was 13.1 years (range 8.0-18.4). PHIV scored higher than HIV- on Emotional functioning and on Total scale score. After five years, the mean age was 17.6 years (range 12.1-22.8). PHIV scored higher than HIV- on all scales, except Social functioning. PHIV did not differ significantly from the Dutch norm on either time-point. LMEM showed no difference in change over time for any of the PedsQL scales. In this study, young people with pHIV receiving high-quality health care, including monitoring of HRQOL, remain to experience a good HRQOL.

Executive function in HIV-affected children and adolescents: a systematic review and meta-analyses

This review aimed to determine: whether EF is affected in children and adolescents (2-24-years-old) with perinatal HIV infection, perinatal HIV exposure without infection, and behaviourally acquired HIV. A systematic review (PROSPERO number: CRD42017067813) was conducted using 11 electronic databases (01.01.1981-09.07.2019) and 8 conference websites. Primary quantitative studies with EF scores on cognitive tasks and/or behavioural report measures were included. Meta-analyses were performed by EF subtype and subpopulations compared. 1789 records were found. Sixty-one studies were included in the narrative synthesis; 32 (N = 7884 participants) were included in meta-analyses. There was a distinct pattern of reduced EF in those with perinatal HIV infection on antiretroviral therapy compared to controls: pooled effect sizes were largest for verbal and visuospatial working memory, with smaller effects on planning, inhibitory control and set-shifting. Data were limited for other HIV-affected subpopulations. Perinatal HIV infection is associated with reduced EF with varying effect sizes for the different EF subtypes.

Neurocognitive Development in Perinatally Human Immunodeficiency Virus-infected Adolescents on Long-term Treatment, Compared to Healthy Matched Controls: A Longitudinal Study

BACKGROUND

A cross-sectional analysis of the Neurological, cOgnitive and VIsual performance in hiv-infected Children cohort showed significant cognitive impairment in combination antiretroviral therapy (cART)-treated, perinatally human immunodeficiency virus (HIV)-infected adolescents (PHIV+) compared to age-, sex-, ethnicity- and socioeconomic status (SES)-matched HIV-negative controls (HIV-). In this longitudinal study, we compared cognitive development in the same adolescents over time.

METHODS

We repeated the standardized cognitive test battery after a mean of 4.6 years (standard deviation 0.3). In participants who completed both assessments, we compared cognitive trajectories between groups in the domains of intelligence quotient (IQ), processing speed, working memory, executive functioning, learning ability, and visual-motor function, using linear mixed models. We explored associations with disease- and treatment-related factors and used multivariate normative comparison (MNC) to determine the prevalence of cognitive impairment.

RESULTS

There were 21 PHIV+ and 23 HIV- participants that completed 2 assessments and were similar concerning age, sex, ethnicity, and SES. Compared to HIV- participants, in PHIV+ participants the IQ score increased significantly more over time (group*time 6.01, 95% confidence interval [CI] 1.5-10.50; P = .012), whereas executive functioning decreased significantly more (group*time -1.43 z score, 95% CI -2.12 to -0.75; P < .001), resulting in the disappearance and appearance of significant differences. Processing speed, working memory, learning ability, and visual-motor function trajectories were not statistically different between groups. Univariately, those who had started cART at an older age deviated more in executive functioning (-0.13 z score, 95% CI -0.24 to -0.02; P = .043). The prevalence of cognitive impairments by MNC was similar in both groups, at both time points.

CONCLUSIONS

The cART-treated PHIV+ adolescents appeared to have similar global cognitive development, compared to their healthy peers. Executive functioning trajectory appears to deviate, potentially explained by earlier brain damage.

MRS suggests multi-regional inflammation and white matter axonal damage at 11 years following perinatal HIV infection

The neurological changes in children living with perinatal HIV (PHIV) on antiretroviral therapy (ART) can be studied at a metabolic level through proton magnetic resonance spectroscopy. While previous studies in children have largely focused on individual metabolite changes, investigating patterns within and across regions of interest can aid in identifying metabolic markers of HIV infection. In this study 76 children with PHIV from the Children with HIV Early AntiRetroviral (CHER) trial, 30 children who were HIV-exposed-uninfected (HEU) and 30 children who were HIV-unexposed (HU), were scanned at the age of 11.6 (sd = 0.3) years using a 3 T Skyra scanner. Metabolite concentrations were quantified within the basal ganglia (BG), midfrontal gray matter (MFGM) and peritrigonal white matter (PWM), comparing levels between HIV status groups using linear regression. Factor analysis and logistic regression were performed to identify metabolic patterns characteristic of HIV infection within and across the regions of interest. In the BG region we observed restored metabolic activity in children with PHIV and children who were HEU, despite differences being previously observed at younger ages, suggesting that treatment may effectively reduce the effects of HIV infection and exposure. Elevated MFGM choline levels in children with PHIV are indicative of inflammation. Further, we observed reduced N-acetyl-aspartate (NAA) in the PWM of children with PHIV and children who were HEU, indicating possible axonal damage. Lower levels of PWM creatine in children with PHIV suggest that this may not be a valid reference metabolite in HIV studies. Finally, factor scores for a cross-regional inflammatory factor and a PWM axonal factor, driven by PWM NAA and creatine levels, distinguished children with PHIV from children without HIV (HEU and HU) at 11 years. Therefore, the effects of perinatal HIV infection and exposure continue to be seen at 11 years despite early treatment.

Lower IQ and poorer cognitive profiles in treated perinatally HIV-infected children is irrespective of having a background of international adoption

Background

HIV-associated cognitive deficiency in perinatally HIV-infected (PHIV) children has been studied in Western countries in a population of which an increasing proportion has been internationally adopted. Studies often lack an appropriate internationally adopted HIV-uninfected control group, potentially confounding the relationship between HIV and cognitive functioning. This study aims to further elucidate the association between treated HIV infection and cognitive development by addressing the background of international adoption.

Methods

We cross-sectionally studied the impact of HIV on cognition by comparing PHIV children and HIV- uninfected controls, matched for age-, sex-, ethnicity-, socioeconomic status (SES)- and adoption status. We used a standardized neuropsychological test battery to measure intelligence (IQ), and the cognitive domains of processing speed, working memory, executive function, learning ability and visual-motor function and compared outcomes using lineair regression models, adjusted for IQ. We determined cognitive profiles and cognitive impairment by using multivariate normative comparison (MNC) and explored associations with HIV disease- and treatment-related factors.

Results

We enrolled fourteen PHIV children (mean age 10.45 years [1.73 SD], 93% adopted from sub-Saharan Africa at a median age of 3.3 years [IQR 2.1–4.2]) and fifteen HIV- uninfected controls. Groups did not clinically nor statistically differ in age, sex, ethnicity, SES, region of birth, adoption status and age at adoption. PHIV scored consistently lower on all cognitive domains and MNC outcomes. Compared to controls, PHIV children had a significant lower IQ (mean 81 [SD 11] versus mean 97 [SD 15], p = 0.005), and a poorer cognitive profile by MNC (Hotelling’s T² mean -4.36 [SD 5.6] versus mean 0.16 [SD 4.5], p = 0.021), not associated with HIV disease- and treatment-related factors. Two PHIV (14%) and one control (7%) were classified as cognitively impaired (p = 0.598).

Conclusions

Findings indicate treated HIV-infection to be independently associated with lower IQ and poorer cognitive profiles in PHIV children, irrespective of a background of international adoption.

Systemic and intrathecal immune activation in association with cerebral and cognitive outcomes in paediatric HIV

Despite treatment, immune activation is thought to contribute to cerebral injury in children perinatally infected with human immunodeficiency virus (HIV). We aimed to characterize immune activation in relation to neuroimaging and cognitive outcomes. We therefore measured immunological, coagulation, and neuronal biomarkers in plasma and cerebrospinal fluid (CSF) samples of 34 perinatally HIV-infected children aged 8–18 years, and in plasma samples of 37 controls of comparable age, sex, ethnicity, and socio-economic status. We then compared plasma biomarker levels between groups, and explored associations between plasma/CSF biomarkers and neuroimaging and cognitive outcomes using network analysis. HIV-infected children showed higher plasma levels of C-reactive protein, interferon-gamma, interferon-gamma-inducible protein-10, and monocyte chemoattractant protein-1 than controls. In HIV-infected participants, plasma soluble CD14 was positively associated with microstructural white matter (WM) damage, and plasma D-dimer was negatively associated with WM blood flow. In CSF, IL-6 was negatively associated with WM volume, and neurofilament heavy-chain (NFH) was negatively associated with intelligence quotient and working memory. These markers of ongoing inflammation, immune activation, coagulation, and neuronal damage could be used to further evaluate the pathophysiology and clinical course of cerebral and cognitive deficits in perinatally acquired HIV.

Brain structure of perinatally HIV-infected patients on long-term treatment: A systematic review

Objective

We aim to give an overview of the available evidence on brain structure and function in PHIV-infected patients (PHIV+) using long-term combination antiretroviral therapy (cART) and how differences change over time.

Methods

We conducted an electronic search using MEDLINE, Embase, and PsycINFO. We used the following selection criteria: cohort and cross-sectional studies that reported on brain imaging differences between PHIV+ of all ages who used cART for at least six months before neuroimaging and HIV-negative controls. Two reviewers independently selected studies, performed data extraction, and assessed quality of studies.

Results

After screening 1500 abstracts and 343 full-text articles, we identified 19 eligible articles. All included studies had a cross-sectional design and used MRI with different modalities: structural MRI (n = 7), diffusion tensor imaging (DTI) (n = 6), magnetic resonance spectroscopy (n = 5), arterial spin labeling (n = 1), and resting-state functional neuroimaging (n = 1). Studies showed considerable methodological limitations and heterogeneity, preventing us to perform meta-analyses. DTI data on white matter microstructure suggested poorer directional diffusion in cART-treated PHIV+ compared with controls. Other modalities were inconclusive.

Conclusion

Evidence may suggest brain structure and function differences in the population of PHIV+ on long-term cART compared with the HIV-negative population. Because of a small study population, and considerable heterogeneity and methodological limitations, the extent of brain structure and function differences on neuroimaging between groups remains unknown.

CNS penetration of ART in HIV-infected children

Background

Paediatric data on CNS penetration of antiretroviral drugs are scarce.

Objectives

To evaluate CNS penetration of antiretroviral drugs in HIV-infected children and explore associations with neurocognitive function.

Patients and methods

Antiretroviral drug levels were measured in paired CSF and blood samples of clinically stable HIV-infected children between 8 and 18 years old on long-term combined ART. Plasma drug concentrations were corrected for protein binding. We evaluated CNS penetration using CSF/plasma ratios and compared CSF concentrations with the IC50 as a surrogate marker for effectiveness. Blood-brain barrier permeability was assessed for possible confounding. Associations with neurocognitive function were explored using linear regression analysis.

Results

Median CSF/plasma ratios (IQR) were: lopinavir 0.059 (0.024-0.157, n = 7), efavirenz 0.681 (0.555-0.819, n = 12), tenofovir 0.021 (0.020-0.024, n = 4), lamivudine 0.464 (0.331-0.607, n = 17), emtricitabine 0.365 (0.343-0.435, n = 3), nevirapine 1.203 (n = 1), zidovudine 0.718 (0.711-1.227, n = 5) and abacavir 1.344 (0.670-2.450, n = 10). CSF concentrations were below the IC50 for tenofovir (100%), emtricitabine (100%), abacavir (50%) and zidovudine (17%). Lamivudine, lopinavir, efavirenz and nevirapine concentrations were all above the IC50. All participants were virologically suppressed in blood and CSF. CSF drug concentrations were not associated with blood-brain barrier permeability or neurocognitive function.

Conclusions

We showed adequate CSF concentrations of lamivudine, lopinavir, efavirenz and nevirapine, and potential suboptimal CSF concentrations of tenofovir, abacavir and emtricitabine in long-term treated HIV-infected children. None the less, the use of combined antiretroviral drugs led to adequate viral suppression.

Altered brain morphometry in 7-year old HIV-infected children on early ART

Even with the increased roll out of combination antiretroviral therapy (cART), paediatric HIV infection is associated with neurodevelopmental delays and neurocognitive deficits that may be accompanied by alterations in brain structure. Few neuroimaging studies have been done in children initiating ART before 2 years of age, and even fewer in children within the critical stage of brain development between 5 and 11 years. We hypothesized that early ART would limit HIV-related brain morphometric deficits at age 7. Study participants were 7-year old HIV-infected (HIV+) children from the Children with HIV Early Antiretroviral Therapy (CHER) trial whose viral loads were supressed at a young age, and age-matched uninfected controls. We used structural magnetic resonance imaging (MRI) and FreeSurfer ( http://www.freesurfer.net/ ) software to investigate effects of HIV and age at ART initiation on cortical thickness, gyrification and regional brain volumes. HIV+ children showed reduced gyrification compared to controls in bilateral medial parietal regions, as well as reduced volumes of the right putamen, left hippocampus, and global white and gray matter and thicker cortex in small lateral occipital region. Earlier ART initiation was associated with lower gyrification and thicker cortex in medial frontal regions. Although early ART appears to preserve cortical thickness and volumes of certain brain structures, HIV infection is nevertheless associated with reduced gyrification in the parietal cortex, and lower putamen and hippocampus volumes. Our results indicate that in early childhood gyrification is more sensitive than cortical thickness to timing of ART initiation. Future work will clarify the implications of these morphometric effects for neuropsychological function.

HIV-associated neurocognitive disorder

PURPOSE OF REVIEW

HIV-associated neurocognitive disease is the most active topic for neuroAIDS investigations at present. Although impairment is mild in patients successfully treated with modern antiviral regimens, it remains an ongoing problem for HIV patients. It is important to update the emerging research concerning HIV-associated neurocognitive disease.

RECENT FINDINGS

The virus enters the brain during acute infection, with evidence for abnormal functioning that may occur early and often persists. Direct relationships with ongoing viral infection continue to be monitored, but chronic inflammation often associated with monocytes and macrophages appears to be the most likely driver of cognitive dysfunction. Appreciation for cerebrovascular disease as a significant comorbidity that is associated with cognitive deficits is increasing. Neuroimaging is actively being developed to address detection and measurement of changes in the brain. Optimal combined antiretroviral treatment therapy has vastly improved neurologic outcomes, but so far has not been demonstrated to reverse the remaining mild impairment. Inflammatory and vascular mechanisms of cerebral dysfunction may need to be addressed to achieve better outcomes.

SUMMARY

Ongoing research is required to improve neurological outcomes for persons living with HIV. It is likely that interventions beyond antiviral approaches will be required to control or reverse HIV-associated neurocognitive disease.

Higher subcortical and white matter cerebral blood flow in perinatally HIV-infected children

This study aimed to evaluate cerebral blood flow (CBF) in pediatric human immunodeficiency virus (HIV)-infection, and its role in HIV-related cerebral injury and cognitive impairment.This cross-sectional observational study compared 28 perinatally HIV-infected children (8-18 years) to 34 healthy controls matched for age, sex, ethnicity, and socio-economic status. All participants underwent 3-Tesla magnetic resonance imaging, using arterial spin labeling to assess CBF in gray matter (GM), white matter (WM), basal ganglia, and thalamus. We used linear regression analysis to evaluate group differences and associations with HIV disease and treatment characteristics, macrostructural (volume loss, WM lesions) or microstructural injury (increased WM diffusivity, neurometabolite alterations), or poorer cognitive performance.HIV-infected children had higher CBF in WM (+10.2%; P = 0.042), caudate nucleus (+4.8%; P = 0.002), putamen (+3.6%; P = 0.017), nucleus accumbens (+3.9%; P = 0.031), and thalamus (+5.5%; P = 0.032). Thalamus CBF was highest in children with a Centers for Disease Control and Prevention stage B (Coef. = 6.45; P = 0.005) or C (Coef. = 8.52; P = 0.001) diagnosis. Lower GM CBF was associated with higher WM lesion volume in HIV-infected children (Coef. = -0.053; P = 0.001). No further associations with HIV-related cognitive impairment or cerebral injury were found.CBF was higher in WM, basal ganglia, and thalamus in combination antiretroviral therapy (cART)-treated perinatally HIV-infected children, but this was not associated with cerebral injury or cognitive impairment. HIV-infected children with lower GM CBF had a higher volume of WM lesions, which could reflect vascular disease as potential contributing factor to white matter injury. Lifelong exposure to HIV and cART in this population warrants longitudinal assessment of CBF and how it relates to (neuro)inflammation, vascular dysfunction, and cerebral injury in pediatric HIV.

HIV-Associated Cognitive Impairment in Perinatally Infected Children: A Meta-analysis

CONTEXT

Research shows, conclusively, that perinatal HIV infection has negative effects on cognitive functioning of children and adolescents. However, the extent of these cognitive impairments is unknown. Current literature does not document specific cognitive domains most affected in HIV-infected children and adolescents.

OBJECTIVE

To systematically review and meta-analyze the degree of cognitive impairment, and the specific cognitive domains affected, in children and adolescents with perinatally acquired HIV infection.

DATA SOURCES

We systematically searched 5 electronic bibliographic databases, namely: PubMed, PsychINFO, Academic Search Premier, Scopus, and WorldCat, by using a search protocol specifically designed for this study.

STUDY SELECTION

Studies were selected on the basis of set a priori eligibility criteria. Titles, abstracts, and full texts were assessed by 2 independent reviewers.

DATA EXTRACTION

Data from included studies were extracted into Microsoft Excel by 2 independent reviewers.

RESULTS

Twenty-two studies were identified for inclusion in the systematic review and of this, 6 studies were included in the meta-analysis. Results from the meta-analysis indicated that working memory and executive function were the domains most affected by the HIV virus.

LIMITATIONS

Only 27% of the included studies were suitable to enter into the meta-analysis. There was significant geographic bias in published studies, with only 32% (7/22) of included studies from sub-Saharan Africa.

CONCLUSIONS

The evidence supports an association between HIV infection in children and adolescents and cognitive impairment in the domains of working memory, executive function and processing speed, with effect size estimates also providing some support for deficits in visual memory and visual-spatial ability.