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

Reduced white matter maturation in the central auditory system of children living with HIV

Introduction

School-aged children experience crucial developmental changes in white matter (WM) in adolescence. The human immunodeficiency virus (HIV) affects neurodevelopment. Children living with perinatally acquired HIV (CPHIVs) demonstrate hearing and neurocognitive impairments when compared to their uninfected peers (CHUUs), but investigations into the central auditory system (CAS) WM integrity are lacking. The integration of the CAS and other brain areas is facilitated by WM fibers whose integrity may be affected in the presence of HIV, contributing to neurocognitive impairments.

Methods

We used diffusion tensor imaging (DTI) tractography to map the microstructural integrity of WM between CAS regions, including the lateral lemniscus and acoustic radiation, as well as between CAS regions and non-auditory regions of 11-year-old CPHIVs. We further employed a DTI-based graph theoretical framework to investigate the nodal strength and efficiency of the CAS and other brain regions in the structural brain network of the same population. Finally, we investigated associations between WM microstructural integrity outcomes and neurocognitive outcomes related to auditory and language processing. We hypothesized that compared to the CHUU group, the CPHIV group would have lower microstructural in the CAS and related regions.

Results

Our analyses showed higher mean diffusivity (MD), a marker of axonal maturation, in the lateral lemniscus and acoustic radiations, as well as WM between the CAS and non-auditory regions predominantly in frontotemporal areas. Most affected WM connections also showed higher axial and radial diffusivity (AD and RD, respectively). There were no differences in the nodal properties of the CAS regions between groups. The MD of frontotemporal and subcortical WM-connected CAS regions, including the inferior longitudinal fasciculus, inferior fronto-occipital fasciculus, and internal capsule showed negative associations with sequential processing in the CPHIV group but not in the CHUU group.

Discussion

The current results point to reduced axonal maturation in WM, marked by higher MD, AD, and RD, within and from the CAS. Furthermore, alterations in WM integrity were associated with sequential processing, a neurocognitive marker of auditory working memory. Our results provide insights into the microstructural integrity of the CAS and related WM in the presence of HIV and link these alterations to auditory working memory.

Relationship between brain structural network integrity and emotional symptoms in youth with perinatally-acquired HIV

Perinatally acquired HIV infection (PHIV) currently affects approximately 1.7 million children worldwide. Youth with PHIV (YPHIV) are at increased risk for emotional and behavioral symptoms, yet few studies have examined relationships between these symptoms and brain structure. Previous neuroimaging studies in YPHIV report alterations within the salience network (SN), cognitive control network (CCN), and default mode network (DMN). These areas have been associated with social and emotional processing, emotion regulation, and executive function. We examined structural brain network integrity from MRI using morphometric similarity networks and graph theoretical measures of segregation (transitivity), resilience (assortativity), and integration (global efficiency). We examined brain network integrity of 40 YPHIV compared to 214 youths without HIV exposure or infection. Amongst YPHIV, we related structural brain network metrics to the Emotional Symptoms Index of the Behavioral Assessment System for Children, 2nd edition. We also examined the relationship of inflammatory biomarkers in YPHIV to brain network integrity. YPHIV had significantly lower global efficiency in the SN, DMN, and the whole brain network compared to controls. YPHIV also demonstrated lower assortativity or resilience (i.e., network robustness) compared to controls in the DMN and whole brain network. Further, higher emotional symptom score was associated with higher global efficiency in the SN and lower global efficiency in the DMN, signaling more emotional challenges. A significant association was also found between several inflammatory and cardiac markers with structural network integrity. These findings suggest an impact of HIV on developing brain networks, and potential dysfunction of the SN and DMN in relation to network efficiency.

Neurodevelopment among children exposed to HIV and uninfected in sub-Saharan Africa

INTRODUCTION

The population of 16 million children exposed to HIV and uninfected (CHEU) under 15 years of age continues to expand rapidly, and the estimated prevalence of CHEU exceeds 20% in several countries in sub-Saharan Africa with high HIV prevalence. Some evidence suggests that CHEU experience suboptimal neurodevelopmental outcomes compared to children born to women without HIV. In this commentary, we discuss the latest research on biologic and socio-behavioural factors associated with neurodevelopmental outcomes among CHEU.

DISCUSSION

Some but not all studies have noted that CHEU are at risk of poorer neurodevelopment across multiple cognitive domains, most notably in language and motor skills, in diverse settings, ages and using varied assessment tools. Foetal HIV exposure can adversely influence infant immune function, structural brain integrity and growth trajectories. Foetal exposure to antiretrovirals may also influence outcomes. Moreover, general, non-CHEU-specific risk factors for poor neurodevelopment, such as preterm birth, food insecurity, growth faltering and household violence, are amplified among CHEU; addressing these factors will require multi-factorial solutions. There is a need for rigorous harmonised approaches to identify children at the highest risk of delay. In high-burden HIV settings, existing maternal child health programmes serving the general population could adopt structured early child development programmes that educate healthcare workers on CHEU-specific risk factors and train them to conduct rapid neurodevelopmental screening tests. Community-based interventions targeting parent knowledge of optimal caregiving practices have shown to be successful in improving neurodevelopmental outcomes in children and should be adapted for CHEU.

CONCLUSIONS

CHEU in sub-Saharan Africa have biologic and socio-behavioural factors that may influence their neurodevelopment, brain maturation, immune system and overall health and wellbeing. Multidisciplinary research is needed to disentangle complex interactions between contributing factors. Common environmental and social risk factors for suboptimal neurodevelopment in the general population are disproportionately magnified within the CHEU population, and it is, therefore, important to draw on existing knowledge when considering the socio-behavioural pathways through which HIV exposure could impact CHEU neurodevelopment. Approaches to identify children at greatest risk for poor outcomes and multisectoral interventions are needed to ensure optimal outcomes for CHEU in sub-Saharan Africa.

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.

Shaping the risk for late-life neurodegenerative disease: A systematic review on prenatal risk factors for Alzheimer's disease-related volumetric brain biomarkers

Environmental exposures including toxins and nutrition may hamper the developing brain in utero, limiting the brain's reserve capacity and increasing the risk for Alzheimer's disease (AD). The purpose of this systematic review is to summarize all currently available evidence for the association between prenatal exposures and AD-related volumetric brain biomarkers. We systematically searched MEDLINE and Embase for studies in humans reporting on associations between prenatal exposure(s) and AD-related volumetric brain biomarkers, including whole brain volume (WBV), hippocampal volume (HV) and/or temporal lobe volume (TLV) measured with structural magnetic resonance imaging (PROSPERO; CRD42020169317). Risk of bias was assessed using the Newcastle Ottawa Scale. We identified 79 eligible studies (search date: August 30th, 2020; Ntotal=24,784; median age 10.7 years) reporting on WBV (N = 38), HV (N = 63) and/or TLV (N = 5) in exposure categories alcohol (N = 30), smoking (N = 7), illicit drugs (N = 14), mental health problems (N = 7), diet (N = 8), disease, treatment and physiology (N = 10), infections (N = 6) and environmental exposures (N = 3). Overall risk of bias was low. Prenatal exposure to alcohol, opioids, cocaine, nutrient shortage, placental dysfunction and maternal anemia was associated with smaller brain volumes. We conclude that the prenatal environment is important in shaping the risk for late-life neurodegenerative disease.

Similar cortical morphometry trajectories from 5 to 9 years in children with perinatal HIV who started treatment before age 2 years and uninfected controls

BACKGROUND

Life-long early ART (started before age 2 years), often with periods of treatment interruption, is now the standard of care in pediatric HIV infection. Although cross-sectional studies have investigated HIV-related differences in cortical morphology in the setting of early ART and ART interruption, the long-term impact on cortical developmental trajectories is unclear. This study compares the longitudinal trajectories of cortical thickness and folding (gyrification) from age 5 to 9 years in a subset of children perinatally infected with HIV (CPHIV) from the Children with HIV Early antiRetroviral therapy (CHER) trial to age-matched children without HIV infection.

METHODS

75 CHER participants in follow-up care at FAMCRU (Family Centre for Research with Ubuntu), as well as 66 age-matched controls, received magnetic resonance imaging (MRI) on a 3 T Siemens Allegra at ages 5, 7 and/or 9 years. MR images were processed, and cortical surfaces reconstructed using the FreeSurfer longitudinal processing stream. Vertex-wise linear mixed effects (LME) analyses were performed across the whole brain to compare the means and linear rates of change of cortical thickness and gyrification from 5 to 9 years between CPHIV and controls, as well as to examine effects of ART interruption.

RESULTS

Children without HIV demonstrated generalized cortical thinning from 5 to 9 years, with the rate of thinning varying by region, as well as regional age-related gyrification increases. Overall, the means and developmental trajectories of cortical thickness and gyrification were similar in CPHIV. However, at an uncorrected p < 0.005, 6 regions were identified where the cortex of CPHIV was thicker than in uninfected children, namely bilateral insula, left supramarginal, lateral orbitofrontal and superior temporal, and right medial superior frontal regions. Planned ART interruption did not affect development of cortical morphometry.

CONCLUSIONS

Although our results suggest that normal development of cortical morphometry between the ages of 5 and 9 years is preserved in CPHIV who started ART early, these findings require further confirmation with longitudinal follow-up through the vulnerable adolescent period.

Effects of Human Immunodeficiency Virus Infection and Former Cocaine Dependence on Neuroanatomical Measures and Neurocognitive Performance

Evidence from animal research, postmortem analyses, and magnetic resonance imaging (MRI) investigations indicate substantial morphological alteration in brain structure as a function of human immunodeficiency virus (HIV) or cocaine dependence (CD). Although previous research on HIV+ active cocaine users suggests the presence of deleterious morphological effects in excess of either condition alone, a yet unexplored question is whether there is a similar deleterious interaction in HIV+ individuals with CD who are currently abstinent. To this end, the combinatorial effects of HIV and CD history on regional brain volume, cortical thickness, and neurocognitive performance was examined across four groups of participants in an exploratory study: healthy controls (n = 34), HIV-negative individuals with a history of CD (n = 21), HIV+ individuals with no history of CD (n = 20), HIV+ individuals with a history of CD (n = 15). Our analyses revealed no statistical evidence of an interaction between both conditions on brain morphometry and neurocognitive performance. While descriptively, individuals with comorbid HIV and a history of CD exhibited the lowest neurocognitive performance scores, using Principle Component Analysis of neurocognitive testing data, HIV was identified as the primary driver of neurocognitive impairment. Higher caudate volume was evident in CD+ participants relative to CD- participants. Findings indicate no evidence of compounded differences in neurocognitive function or structural measures of brain integrity in HIV+ individuals in recovery from CD relative to individuals with only one condition.

Brain Differences in Adolescents Living With Perinatally Acquired HIV Compared With Adoption Status Matched Controls: A Cross-sectional Study

BACKGROUND AND OBJECTIVES

Despite effective combination antiretroviral therapy (cART), adolescents with perinatally acquired HIV (PHIV) exhibit cognitive impairment, of which structural changes could be the underlying pathophysiologic mechanism. Prior MRI studies found lower brain volumes, higher white matter (WM) hyperintensity (WMH) volume, lower WM integrity, and differences in cerebral blood flow (CBF). However, these findings may be confounded by adoption status, as a large portion of adolescents with PHIV have been adopted. Adoption has been associated with malnutrition and neglect, which, in turn, may have affected brain development. We investigated the long-term effects of PHIV on the brain, while minimizing the confounding effect of adoption status.

METHODS

We determined whole-brain gray matter (GM) and WM volume with 3D T1-weighted scans; total WMH volume with fluid-attenuated inversion recovery; CBF in the following regions of interest (ROIs): WM, GM, and subcortical GM with arterial spin labeling; and whole-brain WM microstructural markers: fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) with diffusion tensor imaging in cART-treated adolescents with PHIV visiting our outpatient clinic in Amsterdam and controls matched for age, sex, ethnic origin, socioeconomic status, and adoption status. We assessed differences in neuroimaging parameters between adolescents with PHIV and controls using linear regression models adjusted for age and sex and applied multiple comparison correction.

RESULTS

Thirty-five adolescents with PHIV and 38 controls were included with a median age of 14.9 (interquartile range [IQR]: 10.7-18.5) and 15.6 (IQR: 11.1-17.6) years, respectively, with a similar rate of adoption. We found a lower overall FA (beta = -0.012; p < 0.014, -2.4%), a higher MD (beta = 0.014, p = 0.014, 1.3%), and a higher RD (beta = 0.02, p = 0.014, 3.3%) in adolescents with PHIV vs adoption-matched controls, but no differences in AD. We found comparable GM, WM, and WMH volume and CBF in ROIs between adolescents with PHIV and controls. We did not find an association between cognitive profiles and WM microstructural markers in adolescents with PHIV.

DISCUSSION

Irrespective of adoption status, adolescents with PHIV exhibited subtle lower WM integrity. Our findings may point toward early-acquired WM microstructural alterations associated with HIV.

Multimodal magnetic resonance neuroimaging measures characteristic of early cART-treated pediatric HIV: A feature selection approach

Children with perinatally acquired HIV (CPHIV) have poor cognitive outcomes despite early combination antiretroviral therapy (cART). While CPHIV-related brain alterations can be investigated separately using proton magnetic resonance spectroscopy (1 H-MRS), structural magnetic resonance imaging (sMRI), diffusion tensor imaging (DTI), and functional MRI (fMRI), a set of multimodal MRI measures characteristic of children on cART has not been previously identified. We used the embedded feature selection of a logistic elastic-net (EN) regularization to select neuroimaging measures that distinguish CPHIV from controls and measured their classification performance via the area under the receiver operating characteristic curve (AUC) using repeated cross validation. We also wished to establish whether combining MRI modalities improved the models. In single modality analysis, sMRI volumes performed best followed by DTI, whereas individual EN models on spectroscopic, gyrification, and cortical thickness measures showed no class discrimination capability. Adding DTI and 1 H-MRS in basal measures to sMRI volumes produced the highest classification performancevalidation accuracy = 85 % AUC = 0.80 . The best multimodal MRI set consisted of 22 DTI and sMRI volume features, which included reduced volumes of the bilateral globus pallidus and amygdala, as well as increased mean diffusivity (MD) and radial diffusivity (RD) in the right corticospinal tract in cART-treated CPHIV. Consistent with previous studies of CPHIV, select subcortical volumes obtained from sMRI provide reasonable discrimination between CPHIV and controls. This may give insight into neuroimaging measures that are relevant in understanding the effects of HIV on the brain, thereby providing a starting point for evaluating their link with cognitive performance in CPHIV.

Feasibility of FreeSurfer Processing for T1-Weighted Brain Images of 5-Year-Olds: Semiautomated Protocol of FinnBrain Neuroimaging Lab

Pediatric neuroimaging is a quickly developing field that still faces important methodological challenges. Pediatric images usually have more motion artifact than adult images. The artifact can cause visible errors in brain segmentation, and one way to address it is to manually edit the segmented images. Variability in editing and quality control protocols may complicate comparisons between studies. In this article, we describe in detail the semiautomated segmentation and quality control protocol of structural brain images that was used in FinnBrain Birth Cohort Study and relies on the well-established FreeSurfer v6.0 and ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) consortium tools. The participants were typically developing 5-year-olds [n = 134, 5.34 (SD 0.06) years, 62 girls]. Following a dichotomous quality rating scale for inclusion and exclusion of images, we explored the quality on a region of interest level to exclude all regions with major segmentation errors. The effects of manual edits on cortical thickness values were relatively minor: less than 2% in all regions. Supplementary Material cover registration and additional edit options in FreeSurfer and comparison to the computational anatomy toolbox (CAT12). Overall, we conclude that despite minor imperfections FreeSurfer can be reliably used to segment cortical metrics from T1-weighted images of 5-year-old children with appropriate quality assessment in place. However, custom templates may be needed to optimize the results for the subcortical areas. Through visual assessment on a level of individual regions of interest, our semiautomated segmentation protocol is hopefully helpful for investigators working with similar data sets, and for ensuring high quality pediatric neuroimaging data.

Central Nervous System Impact of Perinatally Acquired HIV in Adolescents and Adults: an Update

Purpose of Review

Perinatally acquired HIV infection (PHIV) can confer neurodevelopmental risk. As children with PHIV increasingly survive through adolescence and into adulthood, understanding its long-term central nervous system (CNS) impacts is critical for maximizing adult outcomes and quality of life.

Recent Findings

Recently published neurocognitive and neuroimaging findings show impacts on the CNS associated with early HIV disease progression that endure into adolescence and young adulthood. Although developmental trajectories in adolescence largely appear stable, further research on maturational processes is indicated.

Summary

Although early antiretroviral therapy in infancy appears to be protective, it is not universally available and current youth largely developed without its benefit. The neurocognitive effects of HIV and the multiple other risks to neurodevelopment experienced by youth with PHIV call for further longitudinal research and a multifaceted approach to prevention and intervention.

Early structural brain development in infants exposed to HIV and antiretroviral therapy in utero in a South African birth cohort

Introduction

There is a growing population of children who are HIV‐exposed and uninfected (HEU) with the successful expansion of antiretroviral therapy (ART) use in pregnancy. Children who are HEU are at risk of delayed neurodevelopment; however, there is limited research on early brain growth and maturation. We aimed to investigate the effects of in utero exposure to HIV/ART on brain structure of infants who are HEU compared to HIV‐unexposed (HU).

Methods

Magnetic resonance imaging using a T2‐weighted sequence was undertaken in a subgroup of infants aged 2–6 weeks enrolled in the Drakenstein Child Health Study birth cohort, South Africa, between 2012 and 2015. Mother–child pairs received antenatal and postnatal HIV testing and ART per local guidelines. We compared subcortical and total grey matter volumes between HEU and HU groups using multivariable linear regression adjusting for infant age, sex, intracranial volume and socio‐economic variables. We further assessed associations between brain volumes with maternal CD4 cell count and ART exposure.

Results

One hundred forty‐six infants (40 HEU; 106 HU) with high‐resolution images were included in this analysis (mean age 3 weeks; 50.7% male). All infants who were HEU were exposed to ART (88% maternal triple ART). Infants who were HEU had smaller caudate volumes bilaterally (5.4% reduction, p < 0.05) compared to HU infants. There were no group differences in other subcortical volumes (all p > 0.2). Total grey matter volume was also reduced in infants who were HEU (2.1% reduction, p < 0.05). Exploratory analyses showed that low maternal CD4 cell count (<350 cells/mm³) was associated with decreased infant grey matter volumes. There was no relationship between timing of ART exposure and grey matter volumes.

Conclusions

Lower caudate and total grey matter volumes were found in infants who were HEU compared to HU in the first weeks of life, and maternal immunosuppression was associated with reduced volumes. These findings suggest that antenatal HIV exposure may impact early structural brain development and improved antenatal HIV management may have the potential to optimize neurodevelopmental outcomes of children who are HEU.

Altered White Matter Tracts in the Somatosensory, Salience, Motor, and Default Mode Networks in 7-Year-Old Children Living with Human Immunodeficiency Virus: A Tractographic Analysis

Introduction: Even with the increased access and early initiation of combination antiretroviral therapy, children with perinatally acquired human immunodeficiency virus (CPHIV) continue to demonstrate white matter alterations. Children perinatally HIV-exposed, but uninfected (CHEU) alike show differences in white matter integrity compared with children who are HIV-unexposed and uninfected (CHUU). Objectives: Mapping white matter connections that link gray matter regions that form resting-state (RS) functional networks may demonstrate whether structural and functional connectivity alterations in HIV infection and exposure may be related. We hypothesized reduced structural connectivity in CPHIV within the default mode network (DMN), visual, ventral DMN (vDMN), somatosensory, salience, auditory, motor, executive, basal ganglia, and posterior DMN (pDMN). We also hypothesized that CHEU will have increased structural connectivity compared with CHUU in the vDMN, somatosensory, pDMN, dorsal attention, salience, auditory, motor and basal ganglia. Methods: Study participants were 61 seven-year-old CPHIV and 46 age-matched children who are HIV uninfected (CHU) (19 CHEU). We used diffusion tensor imaging-based tractography to investigate white matter connections that link gray matter regions within RS functional networks. Results: We found altered white matter integrity in the somatosensory, salience, default mode, and motor networks of CPHIV compared with CHU. The superior temporal cortex, superior frontal cortex, and putamen were affected in all four networks and have also been reported to demonstrate morphological alterations in the same cohort. In CHEU, white matter integrity was higher in the visual network, pDMN, and motor network compared with CHUU. Conclusion: Our results suggest that altered white matter integrity may influence gray matter morphology and functional network alterations. Impact statement The long-term effects of human immunodeficiency virus (HIV) and exposure on the developing brain in the combination antiretroviral therapy era are still not well known. We use diffusion tensor imaging-based tractography to explore these effects on white matter connections that link gray matter regions within functional networks. Our findings provide a context for HIV-associated white matter and connectivity abnormalities.

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.

Cortical structural changes related to early antiretroviral therapy (ART) interruption in perinatally HIV-infected children at 5 years of age

ART interruption in children can occur especially in resource-limited settings for reasons including poor adherence, stock-outs, ART intolerance of non-pediatric formulas and pill size, as well as ultimately to test for HIV remission. Although early ART initiation is now standard of care in pediatric HIV management, very little is known on the effect of early ART initiation or subsequent interruption on brain development. This study aimed to investigate the effect of ART interruption on brain cortical thickness (CT) and folding in a subset of children from the Children with HIV Early antiRetroviral therapy (CHER) trial cohort who all started ART before 18 months of age. CHER participants in the neuroimaging follow-up study had magnetic resonance (MRI) scans on a 3T Siemens Allegra brain scanner at age 5.44 ± 0.37 years. MR images were processed using the automated cross-sectional stream in FreeSurfer v6.0 and vertex wise comparisons of CT and local gyrification indices (LGIs) were performed between HIV+ children and HIV- controls, as well as between HIV+ children on interrupted or continuous ART and controls. HIV+ children (n = 46) showed thicker cortex than HIV- children (n = 29) in bilateral frontal and left temporo-insular regions but lower LGIs in left superior and bilateral medial orbitofrontal cortex extending into rostral anterior cingulate. Children on interrupted ART (n = 21) had thicker cortex than HIV- controls in left frontal and right insular regions, but children on continuous treatment (n = 25) showed no difference from controls. Children on both interrupted and continuous ART showed region-specific alterations in LGI relative to controls. Cortical folding appears more sensitive than CT to early life events including early ART and interruption. However, immune health resilience in children can translate to long term preservation of morphometric brain development, especially for those on early and continuous treatment.

Effects of perinatal HIV-infection on the cortical thickness and subcortical gray matter volumes in young adulthood

ABSTRACT

Brain atrophy has been observed in perinatally HIV-infected patients (PHIV) despite initiation on combined antiretroviral treatment (cART), but neuroimaging studies are limited. We aimed to evaluate cortical thickness (CT) and subcortical gray matter (GM) volumes of PHIV youths with stable immunovirological situation and with a normal daily performance.A prospective cross-sectional study was conducted. A total of 25 PHIV patients on cART and 25 HIV-negative (HIV-) controls matched by age, sex, level of education, and socioeconomic status underwent a magnetic resonance imaging scan. CAT12 toolbox was used to extract CT values from T1w images using parcellations from Desikan-Killiany atlas (DK40). To measure regional brain volumes, native segmented images were parceled in regions of interest according to the Neuromorphometrics Atlas. Neuropsychological assessment and psychopathological symptoms were documented.Fifty participants were included (60% females, median age 20 years [interquartile range, IQR 19-23], 64% Whites). No differences regarding neuropsychological tests or psychopathological symptoms were found between groups (all P > .05). All participants presented an average performance in the Fluid Intelligence (FI) test (PHIV mean: -0.12, HIV- mean: 0.24), When comparing CT, PHIV-infected patients showed thinner cortices compared with their peers in fusiform gyrus (P = .000, P = .009), lateral-orbitofrontal gyrus (P = .006, P = .0024), and right parsobitalis gyrus (P = .047). Regarding subcortical GM volumes, PHIV patients showed lower right amygdala (P = .014) and left putamen (P = .016) volumes when compared with HIV- controls. Within the PHIV group, higher CD4 count was associated with higher volumes in right putamen (B = 0.00000038, P = .045). Moreover, increased age at cART initiation and lower nadir CD4 count was associated with larger volumes in left accumbens (B = 0.0000046, P = .033; B = -0.00000008, P = .045, respectively).PHIV patients showed thinner cortices of areas in temporal, orbito-frontal and occipital lobes and lower volumes of subcortical GM volumes when compared with the HIV- control group, suggesting cortical and subcortical brain alterations in otherwise neuroasymptomatic patients. Nevertheless, larger and longitudinal studies are required to determine the impact of HIV on brain structure in PHIV patients and to further identify risk and protective factors that could be implicated.

Neuroimaging young children and associations with neurocognitive development in a South African birth cohort study

Magnetic resonance imaging (MRI) is an indispensable tool for investigating brain development in young children and the neurobiological mechanisms underlying developmental risk and resilience. Sub-Saharan Africa has the highest proportion of children at risk of developmental delay worldwide, yet in this region there is very limited neuroimaging research focusing on the neurobiology of such impairment. Furthermore, paediatric MRI imaging is challenging in any setting due to motion sensitivity. Although sedation and anesthesia are routinely used in clinical practice to minimise movement in young children, this may not be ethical in the context of research. Our study aimed to investigate the feasibility of paediatric multimodal MRI at age 2–3 years without sedation, and to explore the relationship between cortical structure and neurocognitive development at this understudied age in a sub-Saharan African setting. A total of 239 children from the Drakenstein Child Health Study, a large observational South African birth cohort, were recruited for neuroimaging at 2–3 years of age. Scans were conducted during natural sleep utilising locally developed techniques. T1-MEMPRAGE and T2-weighted structural imaging, resting state functional MRI, diffusion tensor imaging and magnetic resonance spectroscopy sequences were included. Child neurodevelopment was assessed using the Bayley-III Scales of Infant and Toddler Development. Following 23 pilot scans, 216 children underwent scanning and T1-weighted images were obtained from 167/216 (77%) of children (median age 34.8 months). Furthermore, we found cortical surface area and thickness within frontal regions were associated with cognitive development, and in temporal and frontal regions with language development (beta coefficient ≥0.20). Overall, we demonstrate the feasibility of carrying out a neuroimaging study of young children during natural sleep in sub-Saharan Africa. Our findings indicate that dynamic morphological changes in heteromodal association regions are associated with cognitive and language development at this young age. These proof-of-concept analyses suggest similar links between the brain and cognition as prior literature from high income countries, enhancing understanding of the interplay between cortical structure and function during brain maturation.

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MRI data are challenging to acquire in the early years of life.

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Paediatric MRI without sedation is feasible in sub-Saharan Africa, with 77% success.

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The Drakenstein Child Health study has novel MRI data of South African children.

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Morphological features of the cortex associate with neurocognitive development.

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Structure-cognition relationships in heteromodal association regions at 2–3 years.

Brain morphometric differences in youth with and without perinatally-acquired HIV: A cross-sectional study

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We performed vertex-wise analyses comparing grey matter in youth with and without perinatally-acquired HIV (PHIV).

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PHIV youth had reduced cortical thickness, surface area, and gyrification compared to control youth.

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PHIV youth did not exhibit the same pattern of inverse grey matter-age relationships that were observed in control youth.

Youth with perinatally-acquired HIV (PHIV) experience specific and global cognitive deficits at increased rates compared to typically-developing HIV-uninfected youth. In youth with PHIV, HIV infects the brain early in development. Neuroimaging studies have demonstrated altered grey matter morphometry in youth with PHIV compared to typically-developing youth. This study examined cortical thickness, surface area, and gyrification of grey matter in youth (age 11–20 years old) with PHIV (n = 40) from the Pediatric HIV/AIDS Cohort Study (PHACS) compared to typically-developing presumed HIV uninfected and unexposed youth (n = 80) from the Pediatric Imaging, Neurocognition and Genetics Study (PING) using structural magnetic resonance imaging. This study also examined the relationship between grey matter morphometry and age. Youth with PHIV had reduced cortical thickness, surface area, and gyrification compared to typically-developing youth. In addition, an inverse relationship between age and grey matter volume was found in typically-developing youth, but was not observed in youth with PHIV. Longitudinal studies are necessary to understand the neurodevelopmental trajectory of youth with PHIV.

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.

Neuroanatomical Changes Underlying Vertical HIV Infection in Adolescents

Purpose: The aim of this study was to investigate how human immunodeficiency virus (HIV) affects brain development in adolescents, what are susceptible brain regions, and how these brain structural changes correlate with cognitive abilities. Methods: We used structural magnetic resonance imaging to examine gray matter volume and cortical thickness in 16 HIV-infected children (mean age = 13.63 years) and 25 HIV-exposed uninfected children (mean age = 13.32 years), 12 of them were subjected to a 1-year repetitive magnetic resonance scan of the brain. Five neurocognitive tests were performed on each subject to assess cognitive performance in different areas. Results: Cross-sectional studies showed that the gray matter volume of HIV-infected children was widely reduced (mainly in the bilateral frontal, temporal, and insular regions, and cerebellum). The changes in cortical thickness were mainly due to thinning of the right temporal lobe and thickening of the left occipital lobe. Longitudinal studies showed that the gray matter volume reduction of HIV-infected children after 1 year mainly occurs in the advanced functional area of the right prefrontal, parietal lobe and the motor area, cortical thinning of brain regions were sensorimotor cortex and the limbic system. The gray matter volume of the bilateral cerebellum was positively correlated with the performance of the Wisconsin Card Sorting Test, while the cortical thickness of the right dorsolateral prefrontal cortex was negatively correlated with this test. Conclusion: This study found that HIV-infected pubertal children showed a delayed cortical maturation with atrophy. This abnormal pattern of cortical development may be the structural basis for cognitive impairment in HIV-infected children.

Initiation of antiretroviral therapy after the critical neuronal developmental period of the second postnatal year affects white matter microstructure in adolescents living with HIV

Rapid maturation of major white matter pathways occurs in the first 2 years of life, indicating a critical neuronal developmental period. The impact of initiating antiretroviral therapy (ART) in children perinatally infected with HIV-1, after the age of 2 years on neurocognitive functioning and white matter development in adolescence has not been studied. Forty-six adolescents who initiated ART during the first 2 years of life (< 2 years) and 79 adolescents who initiated ART after 2 years of age (> 2 years), with perinatally acquired HIV were enrolled in the Cape Town Adolescent Antiretroviral Cohort. Adolescents completed a comprehensive neurocognitive battery testing a number of cognitive domains. Diffusion tensor imaging (DTI) was done to determine fractional anisotropy (FA), mean diffusivity (MD), axial diffusion (AD), and radial diffusion (RD) in a region of interest analysis. Neurocognitive performance was similar between adolescents who initiated ART < 2 years or > 2 years. There was a trend towards attention (p = .07) and working memory (p = .05) being poorer in the group who initiated ART > 2 years. FA was lower in the > 2-year group in the superior corona radiata (p = .03), and the external capsule (p = .04). MD was higher in the > 2-year group in the cerebral peduncle (p = .02), the superior corona radiata (p = .01), and the superior fronto-occipital fasciculus (p = .03). RD was higher in the > 2-year group in the superior corona radiata (p = .02), the cerebral peduncle (p = .01), and the superior fronto-occipital fasciculus (p = .01). However, the higher AD in the > 2-year group in the superior corona radiata was not in the expected direction (p = .01). Initiation of ART after the neuronal development period of the second postnatal year is associated with white matter alterations on neuroimaging.