Magnetic resonance imaging morphometric analysis of cerebral volume loss in human immunodeficiency virus infection. The HNRC Group

Brain Volumetric Alterations in Preclinical HIV-Associated Neurocognitive Disorder Using Automatic Brain Quantification and Segmentation Tool

Purpose

This study aimed to determine if people living with HIV (PLWH) in preclinical human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND), with no clinical symptoms and without decreased daily functioning, suffer from brain volumetric alterations and its patterns.

Method

Fifty-nine male PLWH at the HAND preclinical stage were evaluated, including 19 subjects with asymptomatic neurocognitive impairment (ANI), 17 subjects with cognitive abnormality that does not reach ANI (Not reach ANI), and 23 subjects with cognitive integrity. Moreover, 23 healthy volunteers were set as the seronegative normal controls (NCs). These individuals underwent sagittal three-dimensional T₁-weighted imaging (3D T₁WI). Quantified data and volumetric measures of brain structures were automatically segmented and extracted using AccuBrain^®. In addition, the multiple linear regression analysis was performed to analyze the relationship of volumes of brain structures and clinical variables in preclinical HAND, and the correlations of the brain volume parameters with different cognitive function states were assessed by Pearson's correlation analysis.

Results

The significant difference was shown in the relative volumes of the ventricular system, bilateral lateral ventricle, thalamus, caudate, and left parietal lobe gray matter between the preclinical HAND and NCs. Furthermore, the relative volumes of the bilateral thalamus in preclinical HAND were negatively correlated with attention/working memory (left: r = -0.271, p = 0.042; right: r = -0.273, p = 0.040). Higher age was associated with increased relative volumes of the bilateral lateral ventricle and ventricular system and reduced relative volumes of the left thalamus and parietal lobe gray matter. The lower CD4⁺/CD8⁺ ratio was associated with increased relative volumes of the left lateral ventricle and ventricular system. Longer disease course was associated with increased relative volumes of the bilateral thalamus. No significant difference was found among preclinical HAND subgroups in all indices, and the difference between the individual groups (Not reach ANI and Cognitive integrity groups) and NCs was also insignificant. However, there was a significant difference between ANI and NCs in the relative volumes of the bilateral caudate and lateral ventricle.

Conclusion

Male PLWH at the HAND preclinical stage suffer from brain volumetric alterations. AccuBrain^® provides potential value in evaluating HIV-related neurocognitive dysfunction.

Relationships Between Viral Load, Neuroimaging, and NP in Persons Living With HIV

BACKGROUND

This study examined whether recommended viral load (VL) classifications by the Department of Health and Human Services map onto changes in brain integrity observed in people living with HIV (PLWH).

METHODS

Three hundred forty-nine PLWH on combination antiretroviral therapy meeting criteria for virologic suppression (VS) (VL ≤ 20 copies/mL; n = 206), "low-level viremia" (20-200 copies/mL; n = 63), or virologic failure (VF) (>200 copies/mL; n = 80) and 195 demographically similar HIV-negative controls were compared for cognition and brain volumes from 10 regions of interest that are sensitive to HIV. Changes in cognition and brain volumes were examined in a subset of PLWH (n = 132) who completed a follow-up evaluation (mean interval = 28 months) and had no change in treatment regimen.

RESULTS

Significant differences in cognition and brain volumes were observed between the HIV-negative control and VS groups compared with those in the VF groups, with few differences observed between the 3 PLWH subgroups. Longitudinally, PLWH who continued to have VF exhibited a greater decline in cognition and brain volumes compared with PLWH who remained with VS. Observed longitudinal changes in cognition correlated with brain volume changes.

CONCLUSION

PLWH with continued VF (consecutive VL measurements of >200 copies/mL) represent a cause for clinical concern and may benefit from change in treatment in addition to consideration of other potential etiologies of VF to reduce loss of brain integrity.

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.

Systemic Mitochondrial Oxidative Phosphorylation Protein Levels Correlate with Neuroimaging Measures in Chronically HIV-Infected Individuals

Few studies have examined systemic mitochondrial function in conjunction with brain imaging in human immunodeficiency virus (HIV) disease. Oxidative phosphorylation enzyme protein levels of peripheral blood mononuclear cells were measured in association with neuroimaging indices in 28 HIV+ individuals. T1-weighted magnetic resonance imaging yielded volumes of seven brain regions of interest; diffusion tensor imaging determined fractional anisotropy (FA) and mean diffusivity (MD) in the corpus callosum (CC). Higher nicotinamide adenine dinucleotide dehydrogenase levels correlated with lower volumes of thalamus (p = .005) and cerebral white matter (p = .049) and, in the CC, with lower FA (p = .011, body; p = .005, genu; p = .009, total CC) and higher MD (p = .023, body; p = .035, genu; p = .019, splenium; p = .014, total CC). Greater cytochrome c oxidase levels correlated with lower thalamic (p = .034) and cerebellar gray matter (p = .021) volumes. The results indicate that systemic mitochondrial cellular bioenergetics are associated with brain health in HIV.

Language and alexithymia: Evidence for the role of the inferior frontal gyrus in acquired alexithymia

The clinical relevance of alexithymia, a condition associated with difficulties identifying and describing one's own emotion, is becoming ever more apparent. Increased rates of alexithymia are observed in multiple psychiatric conditions, and also in neurological conditions resulting from both organic and traumatic brain injury. The presence of alexithymia in these conditions predicts poorer regulation of one's emotions, decreased treatment response, and increased burden on carers. While clinically important, the aetiology of alexithymia is still a matter of debate, with several authors arguing for multiple 'routes' to impaired understanding of one's own emotions, which may or may not result in distinct subtypes of alexithymia. While previous studies support the role of impaired interoception (perceiving bodily states) in the development of alexithymia, the current study assessed whether acquired language impairment following traumatic brain injury, and damage to language regions, may also be associated with an increased risk of alexithymia. Within a sample of 129 participants with penetrating brain injury and 33 healthy controls, neuropsychological testing revealed that deficits in a non-emotional language task, object naming, were associated with alexithymia, specifically with difficulty identifying one's own emotions. Both region-of-interest and whole-brain lesion analyses revealed that damage to language regions in the inferior frontal gyrus was associated with the presence of both this language impairment and alexithymia. These results are consistent with a framework for acquired alexithymia that incorporates both interoceptive and language processes, and support the idea that brain injury may result in alexithymia via impairment in any one of a number of more basic processes.

Progressive Brain Atrophy Despite Persistent Viral Suppression in HIV Patients Older Than 60 Years

BACKGROUND

Current HIV treatments are successful at suppressing plasma HIV RNA to undetectable levels for most adherent patients. Yet, emerging evidence suggests that viral suppression will inadequately control inflammation and mitigate risk for progressive brain injury. We sought to quantify differences in longitudinal brain atrophy rates among older virally suppressed HIV-infected participants compared with that of healthy aging participants.

METHODS

We examined longitudinal structural brain magnetic resonance imaging atrophy rates using region of interest assessments and voxel-wise tensor-based morphometry in HIV-infected participants older than 60 years (n = 38) compared with age-matched HIV-uninfected healthy and cognitively normal controls (n = 24).

RESULTS

The mean age of participants was 63 years, the mean estimated duration of infection was 21 years, and the median duration of documented viral suppression was 3.2 years. Average proximal and nadir CD4 counts were 550 and 166, respectively; 15/38 (39%) met criteria for HIV-associated neurocognitive disorder. In models adjusting for age and sex, HIV serostatus was associated with more rapid average annualized rates of atrophy in the cerebellum (0.42% vs. 0.02%, P = 0.016), caudate (0.74% vs. 0.03%, P = 0.012), frontal lobe (0.48% vs. 0.01%, P = 0.034), total cortical gray matter (0.65% vs. 0.16%, P = 0.027), brainstem (0.31% vs. 0.01%, P = 0.026), and pallidum (0.73% vs. 0.39%, P = 0.046). Among those with HIV, atrophy rates did not differ statistically by cognitive status.

CONCLUSIONS

Despite persistent control of plasma viremia, these older HIV-infected participants demonstrate more rapid progressive brain atrophy when compared with healthy aging. Either HIV or other factors that differ between older HIV-infected participants and healthy controls could be responsible for these differences.

HIV-associated executive dysfunction in the era of modern antiretroviral therapy: A systematic review and meta-analysis

OBJECTIVE

While some reports suggest that HIV+ individuals continue to display executive function (EF) impairment in the era of cART, findings have been contradictory and appear to differ based on the aspect of EF being measured. To improve the understanding of how discrete executive abilities may be differentially affected or spared in the context of HIV infection, we conducted a systematic review and meta-analysis to (a) determine whether and to what extent HIV+ adults experience deficits in EFs, and (b) understand how demographic and clinical characteristics may modify the associations between HIV infection and executive abilities.

METHOD

Studies comparing HIV+ and HIV-uninfected groups on measures of working memory, set-shifting, inhibition, decision-making, and apathy between 2000 and 2017 were identified from three databases. Effect sizes (Cohen's d) were calculated using inverse variance weighted random effects models. Meta-regression was used to examine the moderating effect of demographic and clinical variables.

RESULTS

Thirty-seven studies (n = 3935 HIV+; n = 2483 HIV-uninfected) were included in the meta-analysis. Pooled effect sizes for deficits associated with HIV infection were small for domains of set-shifting (d = -0.34, 95% CI [-0.47, -0.20]) and inhibition (d = -0.31, 95% CI [-0.40, -0.21]), somewhat larger for measures of decision-making (d = -0.41, 95% CI [-0.53, -0.28]) and working memory (d = -0.42, 95% CI [-0.59, -0.29]), and largest for apathy (d = -0.87, 95% CI [-1.09, -0.66]). Meta-regression demonstrated that age, sex, education, current CD4 count, and substance dependence differentially moderated the effects of HIV infection on specific EFs. However, lower nadir CD4 count was the only variable associated with greater deficits in nearly all EF domains.

CONCLUSIONS

Our results suggest that discrete domains of EF may be differentially affected by HIV infection and moderating demographic and clinical variables. These findings have implications for the development of targeted cognitive remediation strategies.

Heterogeneity of Neuropsychological Impairment in HIV Infection: Contributions from Mild Cognitive Impairment

Despite longstanding acknowledgement of the heterogeneity of HIV-associated neurocognitive disorders (HAND), existing HAND diagnostic methods classify according to the degree of impairment, without regard to the pattern of neuropsychological strengths and weaknesses. Research in mild cognitive impairment (MCI) has demonstrated that classifying individuals into subtypes by both their level and pattern of impairment, using either conventional or statistical methods, has etiologic and prognostic utility. Methods for characterizing the heterogeneity of MCI provide a framework that can be applied to other disorders and may be useful in clarifying some of the current challenges in the study of HAND. A small number of studies have applied these methods to examine the heterogeneity of neurocognitive function among individuals with HIV. Most have supported the existence of multiple subtypes of neurocognitive impairment, with some evidence for distinct clinicodemographic features of these subtypes, but a number of gaps exist. Following a review of diagnostic methods and challenges in the study of HAND, we summarize the literature regarding conventional and empirical subtypes of MCI and HAND and identify directions for future research regarding neurocognitive heterogeneity in HIV infection.

Lower total and regional grey matter brain volumes in youth with perinatally-acquired HIV infection: Associations with HIV disease severity, substance use, and cognition

Despite improved survival due to combination antiretroviral therapy (cART), youth with perinatally-acquired HIV (PHIV) show cognitive deficits and developmental delay at increased rates. HIV affects the brain during critical periods of development, and the brain may be a persistent reservoir for HIV due to suboptimal blood brain barrier penetration of cART. We conducted structural magnetic resonance imaging (sMRI) and cognitive testing in 40 PHIV youth (mean age=16.7years) recruited from the NIH Pediatric HIV/AIDS Cohort Study (PHACS) who are part of the first generation of PHIV youth surviving into adulthood. Historical and current HIV disease severity and substance use measures were also collected. Total and regional cortical grey matter brain volumes were compared to a group of 334 typically-developing, HIV-unexposed and uninfected youth (frequency-matched for age and sex) from the Pediatric Imaging, Neurocognition, and Genetics (PING) study (mean age=16.1years). PHIV youth had smaller (2.8-5.1%) total and regional grey matter volumes than HIV-unexposed and uninfected youth, with smallest volumes seen among PHIV youth with higher past peak viral load (VL) and recent unsuppressed VL. In PHIV youth, worse cognitive performance correlated with smaller volumes. This pattern of smaller grey matter volumes suggests that PHIV infection may influence brain development and underlie cognitive dysfunction seen in this population. Among PHIV youth, smaller volumes were also linked to substance use (alcohol use: 9.0-13.4%; marijuana use: 10.1-16.0%). In this study, collection of substance use information was limited to the PHIV cohort; future studies should also collect substance use information in controls to further address interactions between HIV and substance use on brain volume.

White matter measures are near normal in controlled HIV infection except in those with cognitive impairment and longer HIV duration

The objective of the current study was to quantify the degree of white matter (WM) abnormalities in chronic and virally suppressed HIV-infected (HIV+) persons while carefully taking into account demographic and disease factors. Diffusion tensor imaging (DTI) was conducted in 40 HIV- and 82 HIV+ men with comparable demographics and life style factors. The HIV+ sample was clinically stable with successful viral control. Diffusion was measured across 32 non-colinear directions with a b-value of 1000 s/mm²; fractional anisotropy (FA) and mean diffusivity (MD) maps were quantified with Itrack IDL. Using the ENIGMA DTI protocol, FA and MD values were extracted for each participant and in 11 skeleton regions of interest (SROI) from standard labels in the JHU ICBM-81 atlas covering major striato-frontal and parietal tracks. We found no major differences in FA and MD values across the 11 SROI between study groups. Within the HIV+ sample, we found that a higher CNS penetrating antiretroviral treatment, higher current CD4+ T cell count, and immune recovery from the nadir CD4+ T cell count were associated with increased FA and decreased MD (p < 0.05-0.006), while HIV duration, symptomatic, and asymptomatic cognitive impairment were associated with decreased FA and increased MD (p < 0.01-0.004). Stability of HIV treatment and antiretroviral CNS penetration efficiency in addition to current and historical immune recovery were related to higher FA and lower MD (p = 0.04-p < 0.01). In conclusion, WM DTI measures are near normal except for patients with neurocognitive impairment and longer HIV disease duration.

Topological Organization of Whole-Brain White Matter in HIV Infection

Infection with human immunodeficiency virus (HIV) is associated with neuroimaging alterations. However, little is known about the topological organization of whole-brain networks and the corresponding association with cognition. As such, we examined structural whole-brain white matter connectivity patterns and cognitive performance in 29 HIV+ young adults (mean age = 25.9) with limited or no HIV treatment history. HIV+ participants and demographically similar HIV- controls (n = 16) residing in South Africa underwent magnetic resonance imaging (MRI) and neuropsychological testing. Structural network models were constructed using diffusion MRI-based multifiber tractography and T₁-weighted MRI-based regional gray matter segmentation. Global network measures included whole-brain structural integration, connection strength, and structural segregation. Cognition was measured using a neuropsychological global deficit score (GDS) as well as individual cognitive domains. Results revealed that HIV+ participants exhibited significant disruptions to whole-brain networks, characterized by weaker structural integration (characteristic path length and efficiency), connection strength, and structural segregation (clustering coefficient) than HIV- controls (p < 0.05). GDSs and performance on learning/recall tasks were negatively correlated with the clustering coefficient (p < 0.05) in HIV+ participants. Results from this study indicate disruption to brain network integrity in treatment-limited HIV+ young adults with corresponding abnormalities in cognitive performance.

Deformed Subcortical Structures Are Related to Past HIV Disease Severity in Youth With Perinatally Acquired HIV Infection

BACKGROUND

Combination antiretroviral therapy has led to increased survival among youth with perinatally acquired HIV (PHIV). However, cognitive deficits continue to be common. Histopathological studies in adults have found HIV concentrated in subcortical structures, which are involved in sensory processing, movement, and higher-order cognition that emerges with development.

METHODS

We conducted magnetic resonance imaging and cognitive testing in 40 youth with PHIV at one site of the Adolescent Master Protocol of the Pediatric HIV/AIDS Cohort Study. We collected HIV disease-severity measures and substance-use reports. Subcortical volume and shape deformation were generated with FreeSurfer-Initiated Large Deformation Diffeomorphic Metric Mapping. Inward shape deformation was defined as negative displacement. We evaluated associations of subcortical shape deformation with past HIV severity after adjustment for sex, age at neuroimaging, age at HIV severity marker, and substance use. We examined associations between subcortical deformation and cognitive function.

RESULTS

Negative correlations between shape deformation and peak HIV viral load (VL) were found in clusters in the caudate tail, globus pallidus, lateral putamen, and anterior and medial thalamus. Positive correlations between shape deformation and nadir CD4-positive T-lymphocyte percentage (CD4%) were found in clusters in the medial and posterior thalamus. Inward deformation in caudate and thalamic clusters correlated with worse cognition.

CONCLUSIONS

Youth with PHIV have demonstrable subcortical shape deformation related to past HIV severity and cognition; inward deformation was associated with higher peak VL, lower nadir CD4%, and worse cognition. Identifying subcortical deformation may inform clinical practice for early intervention to help improve cognitive outcomes and assess the neuroefficacy of combination antiretroviral therapy in youth with PHIV.

Neurocognitive Complications of HIV Disease

Neurocognitive complications are the most common sequelae of HIV infection if the full spectrum of HIV disease—from initial seroconversion to death from advanced AIDS—is considered. Though resembling subcortical neurological disorders from a neuropsychological standpoint, the presentation is variable, and almost any pattern can be seen. Although neuropsychological impairment is often subtle, it can affect day-to-day life and is associated with earlier mortality. It is not clear if milder forms of neurocognitive disturbance necessarily presage advanced dementia, and current data suggest a two-factor model: a subacute relapsing-remitting condition that can occur at any stage of HIV disease and a progressive, more fulminant dementia. The pathological substrates of these conditions are not well characterized, although recent data support the notion that synaptodendritic damage underlies the neuropsychological impairment, and may precede the neuronal loss and other pathological features more characteristic of HIV encephalitis. Some reversibility of neurocognitive disturbance has been reported with zidovudine therapy, though the data are not consistent. New regimens involving protease inhibitors need to be evaluated in terms of benefit to the central nervous system because many drugs of this class do not penetrate the blood-brain barrier efficiently. Finally, studies utilizing experimental treatments that may affect the putative mechanisms of neural injury are in progress.

Effects of HIV and childhood trauma on brain morphometry and neurocognitive function

A wide spectrum of neurocognitive deficits characterises HIV infection in adults. HIV infection is additionally associated with morphological brain abnormalities affecting neural substrates that subserve neurocognitive function. Early life stress (ELS) also has a direct influence on brain morphology. However, the combined impact of ELS and HIV on brain structure and neurocognitive function has not been examined in an all-female sample with advanced HIV disease. The present study examined the effects of HIV and childhood trauma on brain morphometry and neurocognitive function. Structural data were acquired using a 3T Magnetom MRI scanner, and a battery of neurocognitive tests was administered to 124 women: HIV-positive with ELS (n = 32), HIV-positive without ELS (n = 30), HIV-negative with ELS (n = 31) and HIV-negative without ELS (n = 31). Results revealed significant group volumetric differences for right anterior cingulate cortex (ACC), bilateral hippocampi, corpus callosum, left and right caudate and left and right putamen. Mean regional volumes were lowest in HIV-positive women with ELS compared to all other groups. Although causality cannot be inferred, findings also suggest that alterations in the left frontal lobe, right ACC, left hippocampus, corpus callosum, left and right amygdala and left caudate may be associated with poorer neurocognitive performance in the domains of processing speed, attention/working memory, abstraction/executive functions, motor skills, learning and language/fluency with these effects more pronounced in women living with both HIV and childhood trauma. This study highlights the potential contributory role of childhood trauma to brain alterations and neurocognitive decline in HIV-infected individuals.

Conditional Tat protein brain expression in the GT-tg bigenic mouse induces cerebral fractional anisotropy abnormalities

Cerebral white matter changes including tissue water diffusion abnormalities detected with diffusion tensor magnetic resonance imaging (DTI) are commonly found in humans with Human Immunodeficiency Virus (HIV) infection, as well as in animal models of the disorder. The severities of some of these abnormalities have been reported to correlate with measures of disease progression or severity, or with the degree of cognitive dysfunction. Accordingly, DTI may be a useful translational biomarker. HIV-Tat protein appears to be an important factor in the viral pathogenesis of HIV-associated neurotoxicity. We previously reported cerebral gray matter density reductions in the GT-tg bigenic mouse treated with doxycycline (Dox) to conditionally induce Tat protein expression. Presently, we administered intraperitoneal (i.p.) Dox (100 mg/kg/day) for 7 days to GT-tg mice to determine whether induction of conditional Tat expression led to the development of cerebral DTI abnormalities. Perfused and fixed brains from eight GT-tg mice administered Dox and eight control mice administered saline i.p. were extracted and underwent DTI scans on a 9.4 Tesla scanner. A whole brain analysis detected fractional anisotropy (FA) reductions in several areas including insular and endopiriform regions, as well as within the dorsal striatum. These findings suggest that exposure to Tat protein is sufficient to induce FA abnormalities, and further support the use of the GT-tg mouse to model some effects of HIV.

Human immunodeficiency virus has similar effects on brain volumetrics and cognition in males and females

Most studies that have examined neuropsychological impairments associated with human immunodeficiency virus (HIV) have focused on males, yet females represent one of the largest groups of newly infected patients. Further, few studies have examined neuropsychological performance and neuroimaging outcomes among females compared to males in the modern era of highly active anti-retroviral therapy (HAART). The present study investigated neuropsychological performance and brain volumetrics among HIV+ males (n = 93) and females (n = 44) on stable HAART compared to HIV seronegative (HIV-) males (n = 42) and females (n = 49). Results revealed a significant effect of HIV on neuropsychological performance and neuroimaging measures. An effect of gender, independent of HIV status, was also observed for neuroimaging measures but not neuropsychological performance. Additionally, no significant differences in neuropsychological performance or brain volumetrics were seen between HIV+ males and females. No significant interaction was observed between HIV and gender on either neuropsychological or neuroimaging indices. Our results suggest that both HIV+ males and females treated with HAART experience similar outcomes in terms of brain integrity.

HIV infection is associated with attenuated frontostriatal intrinsic connectivity: a preliminary study

HIV-associated cognitive impairments are prevalent, and are consistent with injury to both frontal cortical and subcortical regions of the brain. The current study aimed to assess the association of HIV infection with functional connections within the frontostriatal network, circuitry hypothesized to be highly vulnerable to HIV infection. Fifteen HIV-positive and 15 demographically matched control participants underwent 6 min of resting-state functional magnetic resonance imaging (RS-fMRI). Multivariate group comparisons of age-adjusted estimates of connectivity within the frontostriatal network were derived from BOLD data for dorsolateral prefrontal cortex (DLPFC), dorsal caudate and mediodorsal thalamic regions of interest. Whole-brain comparisons of group differences in frontostriatal connectivity were conducted, as were pairwise tests of connectivity associations with measures of global cognitive functioning and clinical and immunological characteristics (nadir and current CD4 count, duration of HIV infection, plasma HIV RNA). HIV - associated reductions in connectivity were observed between the DLPFC and the dorsal caudate, particularly in younger participants (<50 years, N=9). Seropositive participants also demonstrated reductions in dorsal caudate connectivity to frontal and parietal brain regions previously demonstrated to be functionally connected to the DLPFC. Cognitive impairment, but none of the assessed clinical/immunological variables, was also associated with reduced frontostriatal connectivity. In conclusion, our data indicate that HIV is associated with attenuated intrinsic frontostriatal connectivity. Intrinsic connectivity of this network may therefore serve as a marker of the deleterious effects of HIV infection on the brain, possibly via HIV-associated dopaminergic abnormalities. These findings warrant independent replication in larger studies.

Impact of human immunodeficiency virus on neurocognition and risky behaviors in young adults

Previous studies have identified cognitive impairments due to human immunodeficiency virus (HIV) in adults. However, few studies have examined the impact of HIV on cognition in young adults (18-24 years old). Yet, this group is one of the largest populations of individuals with new HIV infection. Young adulthood is also an important developmental window because the brain has not fully matured and individuals are prone to engage in risky behavior. The purpose of the present study was to examine the impact of HIV on neurocognition and risky behaviors. We hypothesized that HIV+ young adults (n = 23) would exhibit greater cognitive impairment and risky behaviors compared to seronegative controls (n = 21). In addition, we predicted that self-reported risky behavior as assessed by the Risk Assessment Battery (RAB) would covary with cognitive performances. Results revealed poorer executive function in HIV+ young adults compared to seronegative (HIV-) controls. HIV+ young adults exhibited significantly greater risk scores on the RAB (p < 0.01) compared to HIV- young adults. However, there were no relationships between risky behavior and cognitive performance. Overall, our results suggest that HIV is associated with poorer cognition and increased risky behaviors in young adults.

Cognitive reserve protects against apathy in individuals with human immunodeficiency virus

Apathy is associated with impaired neuropsychological functioning in individuals with HIV. While cognitive reserve (CR) delays neurocognitive decline, CR's relationship with apathy has never been studied. We examined CR's association with apathy in 116 HIV-positive individuals recruited from an urban AIDS center and assessed whether this relationship is moderated by age and/or disease severity. Participants completed the Wechsler Test of Adult Reading and Apathy Evaluation Scale. A CR-composite, combining years of education and word-reading ability, significantly predicted apathy (t = -2.37, p = .02). CR's relationship with apathy was not moderated by age, but participants with nadir CD4 levels ≤ 200 demonstrated a stronger association (t = -3.25, p = .002) than those with nadir CD4 levels > 200 (t = -0.61, p = .55). These findings suggest a protective effect of CR against apathy in HIV-infected individuals across the age span, particularly after a certain threshold of disease severity.

Disrupted cerebral metabolite levels and lower nadir CD4 + counts are linked to brain volume deficits in 210 HIV-infected patients on stable treatment

Cognitive impairment and brain injury are common in people with HIV/AIDS, even when viral replication is effectively suppressed with combined antiretroviral therapies (cART). Metabolic and structural abnormalities may promote cognitive decline, but we know little about how these measures relate in people on stable cART. Here we used tensor-based morphometry (TBM) to reveal the 3D profile of regional brain volume variations in 210 HIV + patients scanned with whole-brain MRI at 1.5 T (mean age: 48.6 ± 8.4 years; all receiving cART). We identified brain regions where the degree of atrophy was related to HIV clinical measures and cerebral metabolite levels assessed with magnetic resonance spectroscopy (MRS). Regional brain volume reduction was linked to lower nadir CD4 + count, with a 1–2% white matter volume reduction for each 25-point reduction in nadir CD4 +. Even so, brain volume measured by TBM showed no detectable association with current CD4 + count, AIDS Dementia Complex (ADC) stage, HIV RNA load in plasma or cerebrospinal fluid (CSF), duration of HIV infection, antiretroviral CNS penetration-effectiveness (CPE) scores, or years on cART, after controlling for demographic factors, and for multiple comparisons. Elevated glutamate and glutamine (Glx) and lower N-acetylaspartate (NAA) in the frontal white matter, basal ganglia, and mid frontal cortex — were associated with lower white matter, putamen and thalamus volumes, and ventricular and CSF space expansion. Reductions in brain volumes in the setting of chronic and stable disease are strongly linked to a history of immunosuppression, suggesting that delays in initiating cART may result in imminent and irreversible brain damage.

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We mapped the 3D pattern of brain abnormalities in 210 HIV patients on stable cART.

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Brain atrophy was linked to MRS metabolite disturbances reflecting neuronal injury.

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Lower nadir CD4 + count was associated with greater white matter atrophy.

Evaluation of emotion processing in HIV-infected patients and correlation with cognitive performance

BACKGROUND

Facial emotion recognition depends on cortical and subcortical networks. HIV infection of the central nervous system can damage these networks, leading to impaired facial emotion recognition.

METHODS

We performed a cross-sectional single cohort study consecutively enrolling HIV + subjects during routine outpatient visits. Age, gender and education-matched HIV-negative healthy individuals were also selected. Subjects were submitted to a Facial Emotion Recognition Test, which assesses the ability to recognize six basic emotions (disgust, anger, fear, happiness, surprise, sadness). The score for each emotion and a global score (obtained by summing scores for each emotion) were analyzed. General cognitive status of patients was also assessed.

RESULTS

A total of 49 HIV + and 20 HIV - subjects were enrolled. On the Facial Emotion Recognition Test, ANOVA revealed a significantly lower performance of HIV + subjects than healthy controls in recognizing fear. Moreover, fear facial emotion recognition was directly correlated with Immediate Recall of Rey Words. The lower the patients' neurocognitive performance the less accurate they were in recognizing happiness. AIDS-defining events were negatively related to the correct recognition of happiness.

CONCLUSIONS

Fear recognition deficit in HIV + patients might be related to the impaired function of neural networks in the frontostriatal system. AIDS events, including non-neurological ones, may have a negative effect on this system. Inclusion of an emotion recognition test in the neuropsychological test battery could help clinicians during the long term management of HIV-infected patients, to better understand the cognitive mechanisms involved in the reduction of emotion recognition ability and the impact of this impairment on daily life.

An update on diagnostic imaging studies for viral encephalitis

Viral encephalitis is still a life-threatening disease occurring at any age. It is critical to make a rapid and correct diagnosis for a better outcome of the disease. Accumulating evidence has suggested that MRI is a powerful tool for the detection of any lesion of the CNS caused by viral infections and helps to initiate the timely treatment. In this review, we summarize the current understanding of MRI findings of viral encephalitis, especially related to HSV, HIV, varicella zoster, Japanese encephalitis, John Cunningham, and influenza viruses. With these considerations, we learnt that the inclusion of diffusion-weighted image sequences on routine MRI examination would have a significant value in detecting the pathologic changes that occur following viral invasion of the CNS.

Effects of HIV and early life stress on amygdala morphometry and neurocognitive function

Both HIV infection and high levels of early life stress (ELS) have been related to abnormalities in frontal-subcortical structures, yet the combined effects of HIV and ELS on brain structure and function have not been previously investigated. In this study we assessed 49 non-demented HIV-seropositive (HIV+) and 47 age-matched HIV-seronegative healthy control (HC) adults. Levels of ELS exposure were quantified and used to define four HIV-ELS groups: HC Low-ELS (N = 20); HC High-ELS (N = 27); HIV+ Low-ELS (N = 24); HIV+ High-ELS (N = 25). An automated segmentation tool measured volumes of brain structures known to show HIV-related or ELS-related effects; a brief neurocognitive battery was administered. A significant HIV-ELS interaction was observed for amygdala volumes, which was driven by enlargements in HIV+ High-ELS participants. The HIV+ High-ELS group also demonstrated significant reductions in psychomotor/processing speed compared with HC Low-ELS. Regression analyses in the HIV+ group revealed that amygdala enlargements were associated with higher ELS, lower nadir CD4 counts, and reduced psychomotor/processing speed. Our results suggest that HIV infection and high ELS interact to increase amygdala volume, which is associated with neurocognitive dysfunction in HIV+ patients. These findings highlight the lasting neuropathological influence of ELS and suggest that high ELS may be a significant risk factor for neurocognitive impairment in HIV-infected individuals.

Early microstructural white matter changes in patients with HIV: a diffusion tensor imaging study

BACKGROUND

Previous studies have reported white matter (WM) brain alterations in asymptomatic patients with human immunodeficiency virus (HIV).

METHODS

We compared diffusion tensor imaging (DTI) derived WM fractional anisotropy (FA) between HIV-patients with and without mild macroscopic brain lesions determined using standard magnetic resonance imaging (MRI). We furthermore investigated whether WM alterations co-occurred with neurocognitive deficits and depression. We performed structural MRI and DTI for 19 patients and 19 age-matched healthy controls. Regionally-specific WM integrity was investigated using voxel-based statistics of whole-brain FA maps and region-of-interest analysis. Each patient underwent laboratory and neuropsychological tests.

RESULTS

Structural MRI revealed no lesions in twelve (HIV-MRN) and unspecific mild macrostructural lesions in seven patients (HIV-MRL). Both analyses revealed widespread FA-alterations in all patients. Patients with HIV-MRL had FA-alterations primarily adjacent to the observed lesions and, whilst reduced in extent, patients with HIV-MRN also exhibited FA-alterations in similar regions. Patients with evidence of depression showed FA-increase in the ventral tegmental area, pallidum and nucleus accumbens in both hemispheres, and patients with evidence of HIV-associated neurocognitive disorder showed widespread FA-reduction.

CONCLUSION

These results show that patients with HIV-MRN have evidence of FA-alterations in similar regions that are lesioned in HIV-MRL patients, suggesting common neuropathological processes. Furthermore, they suggest a biological rather than a reactive origin of depression in HIV-patients.

Functional interactions of HIV-infection and methamphetamine dependence during motor programming

Methamphetamine (METH) dependence is frequently comorbid with HIV infection and both have been linked to alterations of brain structure and function. In a previous study, we showed that the brain volume loss characteristic of HIV infection contrasts with METH-related volume increases in striatum and parietal cortex, suggesting distinct neurobiological responses to HIV and METH (Jernigan et al., 2005). Functional magnetic resonance imaging (fMRI) has the potential to reveal functional interactions between the effects of HIV and METH. In the present study, 50 participants were studied in four groups: an HIV+ group, a recently METH-dependent group, a dually affected group, and a group of unaffected community comparison subjects. An fMRI paradigm consisting of motor sequencing tasks of varying levels of complexity was administered to examine blood oxygenation level dependent (BOLD) changes. Within all groups, activity increased significantly with increasing task complexity in large clusters within sensorimotor and parietal cortex, basal ganglia, cerebellum, and cingulate. The task complexity effect was regressed on HIV status, METH status, and the HIV×METH interaction term in a simultaneous multiple regression. HIV was associated with less complexity-related activation in striatum, whereas METH was associated with less complexity-related activation in parietal regions. Significant interaction effects were observed in both cortical and subcortical regions; and, contrary to expectations, the complexity-related activation was less aberrant in dually affected than in single risk participants, in spite of comparable levels of neurocognitive impairment among the clinical groups. Thus, HIV and METH dependence, perhaps through their effects on dopaminergic systems, may have opposing functional effects on neural circuits involved in motor programming.

Independent effects of HIV, aging, and HAART on brain volumetric measures

BACKGROUND

Neurocognitive impairment remains prevalent in HIV-infected (HIV+) individuals despite highly active antiretroviral therapy (HAART). We assessed the impact of HIV, HAART, and aging using structural neuroimaging.

METHODS

Seventy-eight participants [HIV- (n = 26), HIV+ on stable HAART (HIV+/HAART+; n = 26), HIV+ naive to HAART (HIV+/HAART-; n = 26)] completed neuroimaging and neuropsychological testing. A subset of HIV+ subjects (n = 12) performed longitudinal assessments before and after initiating HAART. Neuropsychological tests evaluated memory, psychomotor speed, and executive function, and a composite neuropsychological score was calculated based on normalized performances (neuropsychological summary Z score, NPZ-4). Volumetrics were evaluated for the amygdala, caudate, thalamus, hippocampus, putamen, corpus callosum, and cerebral gray and white matter. A 3-group 1-way analysis of variance assessed differences in neuroimaging and neuropsychological indices. Correlations were examined between NPZ-4 and volumetrics. Exploratory testing using a broken-stick regression model evaluated self-reported duration of HIV infection on brain structure.

RESULTS

HIV+ individuals had significant reductions in brain volumetrics within select subcortical regions (amygdala, caudate, and corpus callosum) compared with HIV- participants. However, HAART did not affect brain structure as regional volumes were similar for HIV+/HAART- and HIV+/HAART+. No association existed between NPZ-4 and volumetrics. HIV and aging were independently associated with volumetric reductions. Exploratory analyses suggest caudate atrophy due to HIV slowly occurs after self-reported seroconversion.

CONCLUSIONS

HIV associated volumetric reductions within the amygdala, caudate, and corpus callosum occurs despite HAART. A gradual decline in caudate volume occurs after self-reported seroconversion. HIV and aging independently increase brain vulnerability. Additional longitudinal structural magnetic resonance imaging studies, especially within older HIV+ participants, are required.

Substance Abuse, Hepatitis C, and Aging in HIV: Common Cofactors that Contribute to Neurobehavioral Disturbances

Although the prevalence of neurocognitive disturbances among individuals with HIV has decreased in recent years, rates of impairment still remain high. This review presents findings from comorbid conditions that may contribute to further neurocognitive impairments in this already vulnerable population. We will focus on three co-factors that have received substantial attention in the neuroAIDS literature: drug use, hepatitis C co-infection (HCV), and aging. All three conditions commonly co-occur with HIV and likely interact with HIV in complex ways. Collectively, the extant literature suggests that drug use, HCV, and aging serve to worsen the neurocognitive profile of HIV through several overlapping mechanisms. A better understanding of how specific comorbidities interact with HIV may reveal specific phenotypes of HIV-associated neurocognitive disorder that may aid in the development of more targeted behavioral and pharmacological treatment efforts.

Neurocognitive effects of HIV, hepatitis C, and substance use history

HIV-associated neurocognitive dysfunction persists in the highly active antiretroviral therapy (HAART) era and may be exacerbated by comorbidities, including substance use and hepatitis C virus (HCV) infection. However, the neurocognitive impact of HIV, HCV, and substance use in the HAART era is still not well understood. In the current study, 115 HIV-infected and 72 HIV-seronegative individuals with significant rates of lifetime substance dependence and HCV infection received comprehensive neuropsychological assessment. We examined the effects of HIV serostatus, HCV infection, and substance use history on neurocognitive functioning. We also examined relationships between HIV disease measures (current and nadir CD4, HIV RNA, duration of infection) and cognitive functioning. Approximately half of HIV-infected participants exhibited neurocognitive impairment. Detectable HIV RNA but not HIV serostatus was significantly associated with cognitive functioning. HCV was among the factors most consistently associated with poorer neurocognitive performance across domains, while substance use was less strongly associated with cognitive performance. The results suggest that neurocognitive impairment continues to occur in HIV-infected individuals in association with poor virologic control and comorbid conditions, particularly HCV coinfection.

Clinical contributors to cerebral white matter integrity in HIV-infected individuals

HIV-infected people frequently exhibit brain dysfunction characterized by preferential damage to the cerebral white matter. Despite suppressed viral load and reconstituted immune function afforded by combination antiretroviral therapy (CART), brain dysfunction continues to be observed even in medically stable individuals. To provide insight into the etiology of HIV-associated brain dysfunction in the CART era, we examined the effects of HIV disease markers, antiretroviral treatment, hepatitis C (HCV) coinfection, and age on DTI measures of white matter integrity in a cohort of 85 individuals aged 23 to 65 years with chronic HIV infection. Fractional anisotropy and mean diffusivity were derived from 29 cerebral white matter regions, which were segmented on each individual brain using a high-resolution T1-weighted image and registered to diffusion images. Significant effects of clinical variables were found on white matter abnormalities in nearly all brain regions examined. Most notably, HCV coinfection and older age were associated with decreased anisotropy or increased diffusivity in the majority of brain regions. Individuals with higher current CD4 levels exhibited higher anisotropy in parietal lobe regions, while those undergoing antiretroviral treatment exhibited higher anisotropy in temporal lobe regions. The observed diffuse pattern of white matter injury suggests that future neuroimaging studies should employ methodologies that are not limited to circumscribed regions of interest. The current findings underline the multifactorial nature of HIV-associated brain dysfunction in the CART era, and the importance of examining the effects of HIV disease in the context of other comorbidities, in particular HCV coinfection and aging.

Relationship of ethnicity, age, education, and reading level to speed and executive function among HIV+ and HIV- women: the Women's Interagency HIV Study (WIHS) Neurocognitive Substudy

Use of neuropsychological tests to identify HIV-associated neurocognitive dysfunction must involve normative standards that are well suited to the population of interest. Norms should be based on a population of HIV-uninfected individuals as closely matched to the HIV-infected group as possible and must include examination of the potential effects of demographic factors on test performance. This is the first study to determine the normal range of scores on measures of psychomotor speed and executive function among a large group of ethnically and educationally diverse HIV-uninfected, high-risk women, as well as their HIV-infected counterparts. Participants (n = 1,653) were administered the Trail Making Test Parts A and B (Trails A and Trails B), the Symbol Digit Modalities Test (SDMT), and the Wide Range Achievement Test-3 (WRAT-3). Among HIV-uninfected women, race/ethnicity accounted for almost 5% of the variance in cognitive test performance. The proportions ofvariance in cognitive test performance accounted for by age (13.8%), years of school (4.1%), and WRAT-3 score (11.5%) were each significant, but did not completely account for the effect of race (3%). HIV-infected women obtained lower scores than HIV-uninfected women on time to complete Trails A and B, SDMT total correct, and SDMT incidental recall score, but after adjustment for age, years of education, racial/ethnic classification, and reading level, only the difference on SDMT total correct remained significant. Results highlight the need to adjust for demographic variables when diagnosing cognitive impairment in HIV-infected women. Advantages of demographically adjusted regression equations developed using data from HIV-uninfected women are discussed.

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

RATIONALE AND OBJECTIVES

The aim of this study was to assess the relationship between immune state and cerebral signal intensity abnormalities (SIAs) on T2-weighted magnetic resonance images in subjects with human immunodeficiency virus type 1 infection and highly active antiretroviral therapy.

MATERIALS AND METHODS

Thirty-two subjects underwent a total of 109 magnetic resonance studies. The presence of human immunodeficiency virus-associated neurocognitive disorder, categorized CD4(+) T lymphocyte count, and plasma viral load were assessed for relationship with the severity and interval change of SIAs for different anatomic locations of the brain.

RESULTS

Subjects with multifocal patterns of SIAs had CD4(+) cell counts < 200 cells/μL in 66.0%, whereas subjects with diffuse patterns of SIAs had CD4(+) cell counts < 200 cells/μL in only 31.4% (P < .001). Subjects without SIAs in the basal ganglia had CD4(+) cell counts < 200 cells/μL in 37.0%, whereas subjects with minor and moderate SIAs in the basal ganglia had CD4(+) cell counts < 200 cells/μL in 78.3% and 80.0%, respectively (P < .005). The percentage of subjects with CD4(+) cell counts < 200 cells/μL was 85.7% when there were progressive periventricular SIA changes and 45.5% when periventricular SIA changes were stable in follow-up (P < .05).

CONCLUSIONS

The presence and progression of cerebral SIAs on T2-weighted magnetic resonance images reflecting cerebral infection with human immunodeficiency virus are significantly related to impaired immune state as measured by CD4(+) cell count.

Impact of HIV and a history of marijuana dependence on procedural learning among individuals with a history of substance dependence

Marijuana (MJ) use and HIV infection are both associated with neurocognitive deficits, yet there is little research to date examining their interactions, specifically how they pertain to procedural learning (PL). We examined a sample of 86 individuals with a history of dependence for multiple substances who underwent a comprehensive evaluation including measures of mental health, substance use history, and three measures of PL: the photoelectric Rotary Pursuit Task (RPT), the Star Mirror Tracing Task (SMT), and the Weather Prediction Task (WPT). We found that a positive HIV serostatus and a history of marijuana dependence were both independently associated with overall poorer performance on the SMT and RPT in this sample of individuals with a history of dependence for multiple substances. Rate of improvement across trial blocks did not differ as a function of HIV serostatus or history of marijuana dependence. Although we found no significant HIV × MJ interaction for any of the PL tasks, we did observe evidence of additive negative effects from HIV and a history of marijuana dependence on overall performance on the SMT and RPT, but not the WPT. The findings suggest that complex motor skills are adversely affected among abstinent polysubstance users with a history of marijuana dependence and that such deficits are compounded by HIV.

Clinical factors related to brain structure in HIV: the CHARTER study

Despite the widening use of combination antiretroviral therapy (ART), neurocognitive impairment remains common among HIV-infected (HIV+) individuals. Associations between HIV-related neuromedical variables and magnetic resonance imaging indices of brain structural integrity may provide insight into the neural bases for these symptoms. A diverse HIV+ sample (n = 251) was studied through the CNS HIV Antiretroviral Therapy Effects Research initiative. Multi-channel image analysis produced volumes of ventricular and sulcal cerebrospinal fluid (CSF), cortical and subcortical gray matter, total cerebral white matter, and abnormal white matter. Cross-sectional analyses employed a series of multiple linear regressions to model each structural volume as a function of severity of prior immunosuppression (CD4 nadir), current CD4 count, presence of detectable CSF HIV RNA, and presence of HCV antibodies; secondary analyses examined plasma HIV RNA, estimated duration of HIV infection, and cumulative exposure to ART. Lower CD4 nadir was related to most measures of the structural brain damage. Higher current CD4, unexpectedly, correlated with lower white and subcortical gray and increased CSF. Detectable CSF HIV RNA was related to less total white matter. HCV coinfection was associated with more abnormal white matter. Longer exposure to ART was associated with lower white matter and higher sulcal CSF. HIV neuromedical factors, including lower nadir, higher current CD4 levels, and detectable HIV RNA, were associated with white matter damage and variability in subcortical volumes. Brain structural integrity in HIV likely reflects dynamic effects of current immune status and HIV replication, superimposed on residual effects associated with severe prior immunosuppression.

Longitudinal psychomotor speed performance in human immunodeficiency virus-seropositive individuals: impact of age and serostatus

Older human immunodeficiency virus-seropositive (HIV+) individuals (greater than age 50 years) are twice as likely to develop HIV dementia compared to younger HIV+ individuals. The objective of this study was to examine the impact of both age and serostatus on longitudinal changes in psychomotor speed/executive functioning performance among HIV+ and HIV− individuals. Four hundred and seventy-seven HIV+ and 799 HIV− individuals from the Multicenter AIDS Cohort Study (MACS) were subdivided into three age groups: (1) <40 years, (2) 40-50 years, and (3) >50 years. Psychomotor speed/executive functioning test performance was measured by the Symbol Digit Modalities Test (SDMT) and the Trail Making (TM) Test Parts A and B. Changes in performance were compared among the three age groups for both HIV+ and HIV− individuals. Among HIV+ individuals, on the TM Test Part B the younger group demonstrated improvement in performance over time (P = .007). The older and middle age groups demonstrated decline in performance over time (P = .041 and .030). The older group had a significantly different trajectory relative to the younger group (P = .046). Among the HIV− individuals, there was no effect of age on longitudinal performance. In conclusion, older HIV+ individuals show greater decline over time than younger HIV+ individuals on the TM Test Part B. Our results suggest that both HIV serostatus and age together may impact longitudinal performance on this test. Mild neurocognitive changes over time among older HIV+ individuals are likely to reflect age associated pathophysiological mechanisms including cerebrovascular risk factors.

Peripheral biomarkers do not correlate with cognitive impairment in highly active antiretroviral therapy-treated subjects with human immunodeficiency virus type 1 infection

Neuropsychological (NP) impairments in human immunodeficiency virus (HIV)-infected individuals remain high despite the introduction of highly active antiretroviral therapy (HAART). We sought to determine whether or not a monocyte gene expression profile along with other peripheral factors would correlate with neuropsychological impairment among HIV-infected individuals. Forty-four HIV-1-seropositive subjects (HIV+) on HAART and 11 HIV-1-seronegative controls (HIV-) had NP testing and blood drawn for monocyte gene expression analysis. All HIV+ subjects were assessed for CD4 counts, apolipoprotein E (ApoE) genotype, viral load, and plasma lipopolysaccharide (LPS) and soluble CD14 (sCD14). NP scores were normalized to age, gender, and education. Twenty-five percent of HIV+ individuals showed abnormal NP testing results (> 1.5 SD below normal in two domains). HIV+ individuals had deficits in attention/working memory, verbal learning, and information processing speed compared to HIV- controls. There was no correlation between overall NP impairment and plasma viral load, level of education, age, ethnic diversity, sCD14, plasma LPS, CD4 cell count, ApoE genotype, or years of infection. However, greater years of infection had worse visual learning performance. sCD14 and CD4 nadir positively correlated with information processing speed and fine motor skills, respectively. LPS correlated with viral load but not cognitive impairment. Monocyte gene expression confirmed a chronic inflammatory profile that correlated with viral load but not cognition. No blood index or profile was associated with overall NP impairment.

Facial emotion recognition impairments in individuals with HIV

Characterized by frontostriatal dysfunction, human immunodeficiency virus (HIV) is associated with cognitive and psychiatric abnormalities. Several studies have noted impaired facial emotion recognition abilities in patient populations that demonstrate frontostriatal dysfunction; however, facial emotion recognition abilities have not been systematically examined in HIV patients. The current study investigated facial emotion recognition in 50 nondemented HIV-seropositive adults and 50 control participants relative to their performance on a nonemotional landscape categorization control task. We examined the relation of HIV-disease factors (nadir and current CD4 levels) to emotion recognition abilities and assessed the psychosocial impact of emotion recognition abnormalities. Compared to control participants, HIV patients performed normally on the control task but demonstrated significant impairments in facial emotion recognition, specifically for fear. HIV patients reported greater psychosocial impairments, which correlated with increased emotion recognition difficulties. Lower current CD4 counts were associated with poorer anger recognition. In summary, our results indicate that chronic HIV infection may contribute to emotion processing problems among HIV patients. We suggest that disruptions of frontostriatal structures and their connections with cortico-limbic networks may contribute to emotion recognition abnormalities in HIV. Our findings also highlight the significant psychosocial impact that emotion recognition abnormalities have on individuals with HIV.

Cerebral metabolite abnormalities in human immunodeficiency virus are associated with cortical and subcortical volumes

Cerebral metabolite disturbances occur among human immunodeficiency virus (HIV)-infected people, and are thought to reflect neuropathology, including proinflammatory processes, and neuronal loss. HIV-associated cortical atrophy continues to occur, though its basis is not well understood, and the relationship of cerebral metabolic disturbance to structural brain abnormalities in HIV has not been well delineated. We hypothesized that metabolite disturbances would be associated with reduced cortical and subcortical volumes. Cerebral volumes were measured in 67 HIV-infected people, including 10 people with mild dementia (acquired immunodeficiency syndrome [AIDS] dimentia complex [ADC] stage >1) via automated magnetic resonance imaging (MRI) segmentation. Magnetic resonance spectroscopy (MRS) was used to measure levels of cerebral metabolites N-acetylaspartate (NAA), myo-inositol (MI), choline-containing compounds (Cho), glutamate/glutamine (Glx), and creatine (Cr) from three brain regions (frontal gray matter, frontal white matter, basal ganglia). Analyses were conducted to examine the associations between MRS and cerebral volumetric measures using both absolute and relative metabolite concentrations. NAA in the mid-frontal gray matter was most consistently associated with cortical (global, frontal, and parietal), ventricular, and caudate volumes based on analysis of absolute metabolite levels, whereas temporal lobe volume was associated with basal ganglia NAA and Glx, and Cho concentrations in the frontal cortex and basal ganglia. Hippocampal volume was associated with frontal white matter NAA, whereas thalamic volume was associated with both frontal white matter NAA and basal ganglia Glx. Analyses of relative metabolite concentrations (referenced to Cr) yielded weaker effects, although more metabolites were retained as significant predictors in the models than the analysis of absolute concentrations. These findings demonstrate that reduced cortical and subcortical volumes, which have been previously found to be linked to HIV status and history, are also strongly associated with the degree of cerebral metabolite disturbance observed via MRS. Reduced cortical and hippocampal volumes were most strongly associated with decreased NAA, though reduced Glx also tended to be associated with reduced cortical and subcortical volumes (caudate and thalamus) as well, suggesting both neuronal and glial disturbances. Interestingly, metabolite-volumetric relationships were not limited to the cortical region from which MRS was measured, possibly reflecting shared pathophysiological processes. The relationships between Cho and volumetric measures suggest a complicated relationship possibly related to the effects of inflammatory processes on brain volume. The findings demonstrate the relationship between MRI-derived measures of cerebral metabolite disturbances and structural brain integrity, which has implication in understanding HIV-associated neuropathological mechanisms.

Evidence for ongoing brain injury in human immunodeficiency virus-positive patients treated with antiretroviral therapy

Treatment with antiretroviral therapy (ART) has greatly reduced the incidence of dementia. The goal of this longitudinal study was to determine if there are ongoing macrostructural brain changes in human immunodeficiency virus-positive (HIV + ) individuals treated with ART. To quantify brain structure, three-dimensional T1-weighted magnetic resonance imaging (MRI) scans were performed at baseline and again after 24 months in 39 HIV+ patients on ART and 30 HIV- controls. Longitudinal changes in brain volume were measured using tissue segmentation within regions of interest and deformation morphometry. Measured by tissue segmentation, HIV+ patients on ART had significantly (all P<.05) greater rates of white matter volume loss than HIV- control individuals. Compared with controls, the subgroup of HIV+ individuals on ART with viral suppression also had significantly greater rates of white matter volume loss. Deformation morphometry confirmed these results with more specific spatial localization. Deformation morphometry also detected greater rates of gray matter and white matter loss in the subgroup of HIV+ individuals with detectable viral loads. These results provide evidence of ongoing brain volume loss in HIV+ individuals on stable ART, possibly suggesting ongoing cerebral injury. The presence of continuing injury raises the possibility that HIV+ individuals-even in the presence of viral suppression in the periphery-are at greater risk for future cognitive impairments and dementia and possibly faster cognitive decline. Therefore, HIV+ individuals on ART should be monitored for cognitive decline, and treatments that reduce ongoing neurological injury should be considered.

Effects of nadir CD4 count and duration of human immunodeficiency virus infection on brain volumes in the highly active antiretroviral therapy era

Cerebral atrophy is a well-described, but poorly understood complication of human immunodeficiency virus (HIV) infection. Despite reduced prevalence of HIV-associated dementia in the highly active antiretroviral therapy (HAART) era, HIV continues to affect the brains of patients with chronic infection. In this study we examine patterns of brain volume loss in HIV-infected patients on HAART, and demographic and clinical factors contributing to brain volume loss. We hypothesized that nadir CD4+ lymphocyte count, duration of HIV infection, and age would be associated with reduced cortical volumes. Volumes of cortical and subcortical regions in 69 HIV-infected neuroasymptomatic (NA) individuals and 13 with at least mild acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) were measured using voxel-based morphometry. Demographic and clinical factors (age, plasma HIV RNA level, current and nadir CD4 counts, duration of infection, central nervous system [CNS] penetration of antiretroviral regimen) along with their interactions were entered into a regression model selection algorithm to determine the final models that best described regional brain volumes. Relative to NA, individuals with ADC exhibited decreased total gray matter and parietal cortex volumes and increased total ventricular volumes. Final regression models showed overall cerebral volume, including gray and white matter volume and volumes of the parietal, temporal, and frontal lobes and the hippocampus, were most strongly associated with disease history factors (nadir CD4 and duration of infection). In contrast, basal ganglia volumes were related most strongly to current disease factors, most notably plasma HIV RNA. These findings indicate that individuals with a history of chronic HIV infection with previous episodes of severely impaired immune function, as reflected by reduced nadir CD4+ lymphocyte count, may be at greatest risk for cerebral atrophy. The pattern of HIV-associated brain loss may be changing from a subcortical to a cortical disease among patients who are largely asymptomatic on HAART.

Neurocognitive correlates of alexithymia in asymptomatic individuals with HIV

Alexithymia, an impairment of affective and cognitive emotional processing, is often associated with human immunodeficiency virus (HIV) and may reflect effects of the virus on brain areas that are also important for multiple cognitive functions, such as the prefrontal and anterior cingulate cortices. We hypothesized that there would be a correlation between extent of alexithymia and cognitive performance associated with these brain areas, including attention, executive function, and visuospatial processing. Thirty-four asymptomatic HIV+ participants and 34 matched healthy HIV- volunteers were administered the Toronto Alexithymia Scale, a series of neuropsychological tests, and measures of apathy, depression, and quality of life (QoL). The HIV+ participants had significantly higher levels of alexithymia, depression and apathy than the HIV- group. The extent of alexithymia and two of its processing components (Difficulty Describing Feelings [DDF] and Externally Oriented Thinking), but not depression, correlated with performance on measures of executive and visuospatial abilities, consistent with dysfunction of the frontostriatal circuits and their cortical projections. Apathy was related to alexithymia and two processing components (Difficulty Identifying Feelings and DDF) but to only one cognitive measure. The higher rate of alexithymia, as well as cognitive dysfunction, in HIV may be a consequence of the infection on the frontostriatal system and its cortical connections. Our findings also demonstrated a dissociation of apathy and alexithymia in HIV, pointing to overlapping but distinct neural substrates within frontostriatal circuits. Alexithymia correlated strongly with QoL ratings, underscoring the importance of assessment and treatment of HIV-associated emotional and cognitive processing deficits.

Influence of procedural learning on Iowa Gambling Task performance among HIV+ individuals with history of substance dependence

HIV+ individuals have been shown to demonstrate deficits on the Iowa Gambling Task (IGT), a complex measure of "decision-making." Little remains known about what other neurocognitive processes may account for variability in IGT performance among HIV+ samples or the role of procedural learning (PL) in IGT performance. A sample of 49 HIV+ individuals with a history of substance use disorders was examined to explore the relationship between IGT performance and three measures of PL: The Rotary Pursuit, Mirror Star Tracing, and Weather Prediction tasks. We found no statistically significant relationships between IGT performance and any of the PL tasks, despite finding significant correlations among the PL tasks. This pattern of results persisted when analyzing IGT performance in various ways (e.g., performance on earlier trial blocks or impairment classifications). Although other nondeclarative processes (e.g., somatic markers) may be important for IGT performance, these findings do not support PL as an important component neurocognitive process for the IGT. Similarly, these results suggest that differences in PL performance does not account for the decision-making deficits or variability in performances observed on the IGT among HIV+ individuals with a history of substance dependence.

Cognitive neuropsychology of HIV-associated neurocognitive disorders

Advances in the treatment of the human immunodeficiency virus (HIV) have dramatically improved survival rates over the past 10 years, but HIV-associated neurocognitive disorders (HAND) remain highly prevalent and continue to represent a significant public health problem. This review provides an update on the nature, extent, and diagnosis of HAND. Particular emphasis is placed on critically evaluating research within the realm of cognitive neuropsychology that aims to elucidate the component processes of HAND across the domains of executive functions, motor skills, speeded information processing, episodic memory, attention/working memory, language, and visuoperception. In addition to clarifying the cognitive mechanisms of HAND (e.g., impaired cognitive control), the cognitive neuropsychology approach may enhance the ecological validity of neuroAIDS research and inform the development of much needed novel, targeted cognitive and behavioral therapies.

Human immunodeficiency virus type 1 in the central nervous system leads to decreased dopamine in different regions of postmortem human brains

Human immunodeficiency virus type 1 (HIV-1) invades the central nervous system (CNS) shortly after infection and becomes localized in varying concentrations in different brain regions, the most vulnerable is the basal ganglia (BG). It is hypothesized that HIV-1-mediated neuropathogenesis involves degeneration of dopaminergic neurons in the substantia nigra and the loss of dopaminergic terminals in the BG, leading to deficits in the central dopaminergic activity, resulting in progressive impairment of neurocognitive and motor functions. In the era of highly active antiretroviral therapy (HAART), although the incidence of HIV-associated dementia (HAD) has decreased, the neurocognitive and neuropsychological deficits continue to persist after HAART. In this study, We investigated the impact of HIV-1 on dopaminergic activity with respect to concentrations of dopamine (DA) and homovanillic acid (HVA) in different regions of postmortem human brains of HIV-1-negative and HIV-1+ individuals and their relationship to neurocognitive impairment. We found that in HIV-1+ as well as HIV-negative cases, dopamine and HVA concentrations in ranged widely in different brain regions. In HIV-negative brain regions, the highest concentration of DA was found in putamen, caudate, substantia nigra, and the basal ganglia. In HIV-1+ cases, there was a significant decrease in DA levels in caudate nucleus, putamen, globus pallidus, and substantia nigra compared to that in HIV-negative cases. In HIV-1+ cases, a strong correlation was found between DA levels in substantia nigra and other brain regions. Concentration of HVA in HIV-negative cases was also highest in the regions containing high dopamine levels. However, no significant decrease in regional HVA levels was found in HIV-1+ cases. HIV-1 RNA load (nondetectable [ND] to log10 6.9 copies/g tissue) also ranged widely in the same brain regions of HIV-1+ cases. Interestingly, the brain regions having the highest HIV-1 RNA had the maximum decrease in DA levels. Age, gender, ethnicity, and postmortem interval were not correlated with decrease in DA levels. Profile of DA, HVA, and HIV-1 RNA levels in the brain regions of HIV-1+ individuals treated with HAART was similar to those not treated with HAART. A majority of HIV-1+ individuals had variable degrees of neurocognitive impairments, but no specific relationship was found between the regional DA content and severity of neurocognitive deficits. These findings suggest widespread deficits in dopamine in different brain regions of HIV-1-infected cases, and that these deficits may be the results of HIV-1-induced neurodegeneration in the subcortical regions of human brain.

Deficits in complex motor functions, despite no evidence of procedural learning deficits, among HIV+ individuals with history of substance dependence

Human immunodeficiency virus (HIV) and drugs of abuse affect common neural systems underlying procedural memory, including the striatum. The authors compared performance of 48 HIV seropositive (HIV+) and 48 HIV seronegative (HIV-) participants with history of cocaine and/or heroin dependence across multiple Trial Blocks of three procedural learning (PL) tasks: Rotary Pursuit (RP), Mirror Star Tracing (MST), and Weather Prediction (WP). Groups were well matched on demographic, psychiatric, and substance use parameters, and all participants were verified abstinent from drugs. Mixed model analyses of variance revealed that the individuals in the HIV+ group performed more poorly across all tasks, with a significant main effect of HIV serostatus observed on the Mirror Star Tracing and a trend toward significance obtained for the Rotary Pursuit task. No significant differences were observed on the Weather Prediction task. Both groups demonstrated significant improvements in performance across all three procedural learning tasks. It is important to note that no significant Serostatus x Trial Block interactions were observed on any task. Thus, the individuals in the HIV+ group tended to perform worse than those in the HIV- group across all trial blocks of procedural learning tasks with motor demands, but showed no differences in their rate of improvement across all tasks. These findings are consistent with HIV--associated deficits in complex motor skills, but not in procedural learning.

HIV-associated alterations in normal-appearing white matter: a voxel-wise diffusion tensor imaging study

OBJECTIVE

There are conflicting reports of adverse HIV-associated alterations in white matter integrity as measured by diffusion tensor imaging (DTI). We sought to address these conflicting reports by assessing, on a voxel-by-voxel basis, HIV-associated regional changes in radiologically defined normal-appearing white matter (NAWM) integrity using high-resolution DTI.

METHODS

30 HIV-seropositive (SP) and 30 HIV-seronegative (SN) nondemented, community-dwelling participants underwent DTI to derive whole-brain measures of white matter integrity (fractional anisotropy [FA] and mean diffusivity [MD]). For each participant, the white matter T2 volume was thresholded to remove regions of abnormal signal, resulting in a NAWM mask, which was then applied to the FA and MD volumes to extract voxel-wise NAWM measures of white matter integrity. Voxel-wise group comparisons of FA and MD were conducted (P < 0.005, extent threshold 5 voxels) while controlling for age and substance-abuse history.

RESULTS

There were no significant differences between the groups for demographic or cognitive performance variables. Summary whole-brain measures of FA and MD were equivalent between the SP and SN samples. Among the SP sample, history of substance abuse was associated with significantly increased whole-brain NAWM MD, and coinfection with hepatitis C virus (HCV) was associated with a trend for increased MD. Correlations between whole-brain NAWM FA and MD with cognitive performance measures were not significant. Regional analyses of DTI measures revealed variable differences in NAWM FA in the SP sample, with findings of both decreased and increased FA. Differences in NAWM MD were more consistent, with widespread increases noted in the SP sample compared to the SN sample. Eight of the 10 regions displaying significantly increased FA in the SP sample were also found to have significantly increased MD compared to the SN sample.

CONCLUSIONS

Decreased white matter integrity is present even in radiologically defined NAWM in nondemented, community-dwelling patients with HIV. The decrease in NAWM integrity is best seen in increases in MD, a measure of generalized tissue breakdown. Indications of NAWM axonal integrity (FA) present a more complicated picture, with both decreased FA and increased FA in the SP sample. Our findings of variable HIV-associated FA changes in NAWM may account for previous conflicting reports of changes in DTI parameters in this population. The results of our study suggest that HIV infection contributes to variable changes in DTI values, reflecting both direct loss of axonal integrity and a loss of complexity to the underlying axonal matrix.