Mental Workload in Neuropsychology: An Example With the NASA-TLX in Adults With HIV

A preliminary set of analyses are presented, where workload was examined in 32 adults infected with the human immunodeficiency virus (HIV). Like the current COVID-19 pandemic (caused by the SARS-CoV-2 virus), HIV can produce a wide variety of symptoms, including various levels of cognitive dysfunction. In fact, a recent meta-analysis estimates that of the 39 million adults infected globally with HIV, 42.6% exhibit some form of HIV-associated neurocognitive disorder. A common cognitive symptom in HIV is decline in attention and executive functioning. Though typically examined by clinicians with less precise traditional paper-and-pencil neuropsychological tests, we examined this aspect of cognitive functioning using a more psychometrically sophisticated task as we had HIV-positive adults perform a computerized tracking task in single, dual, and tri-task conditions via the Multi-Attribute Task (MAT) Battery. Also assessed was mental workload, with the NASA-Task Load Index (NASA-TLX), rarely used in neuropsychology but a standard tool in human factors and neuroergonomics research. As expected, tracking performance declined with task condition difficulty (p < 0.001). Although no direct statistical comparisons were made, MAT performance here appeared worse than the MAT performance of various other groups reported in the research literature and in our laboratory. Ratings of workload also tended to increase as a function of task condition difficulty (p < 0.001). Plotting MAT tracking performance against the Mental Demand subscale scores, large individual differences in this aspect of workload were evident in both optimal and sub-optimal tracking performance. To examine likely variables with a potential impact on Mental Demand, a variety of variables (nadir CD4 count, viral load, depression symptoms, diagnosis of AIDS, presence of opportunistic infection, general cognitive status, etc.) were examined in relation to the Mental Demand scale, with age showing a significant association (r = 0.41, p = 0.022) and a diagnosis of AIDS showing trend associations (ps ≥ 0.066). Findings suggesting a deficit in metacognition or insight are also discussed. It is argued that assessment of workload (and its various aspects or components) can provide valuable additional information in neuropsychology.

Association of Immunosuppression and Viral Load With Subcortical Brain Volume in an International Sample of People Living With HIV

IMPORTANCE

Despite more widely accessible combination antiretroviral therapy (cART), HIV-1 infection remains a global public health challenge. Even in treated patients with chronic HIV infection, neurocognitive impairment often persists, affecting quality of life. Identifying the neuroanatomical pathways associated with infection in vivo may delineate the neuropathologic processes underlying these deficits. However, published neuroimaging findings from relatively small, heterogeneous cohorts are inconsistent, limiting the generalizability of the conclusions drawn to date.

OBJECTIVE

To examine structural brain associations with the most commonly collected clinical assessments of HIV burden (CD4+ T-cell count and viral load), which are generalizable across demographically and clinically diverse HIV-infected individuals worldwide.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study established the HIV Working Group within the Enhancing Neuro Imaging Genetics Through Meta Analysis (ENIGMA) consortium to pool and harmonize data from existing HIV neuroimaging studies. In total, data from 1295 HIV-positive adults were contributed from 13 studies across Africa, Asia, Australia, Europe, and North America. Regional and whole brain segmentations were extracted from data sets as contributing studies joined the consortium on a rolling basis from November 1, 2014, to December 31, 2019.

MAIN OUTCOMES AND MEASURES

Volume estimates for 8 subcortical brain regions were extracted from T1-weighted magnetic resonance images to identify associations with blood plasma markers of current immunosuppression (CD4+ T-cell counts) or detectable plasma viral load (dVL) in HIV-positive participants. Post hoc sensitivity analyses stratified data by cART status.

RESULTS

After quality assurance, data from 1203 HIV-positive individuals (mean [SD] age, 45.7 [11.5] years; 880 [73.2%] male; 897 [74.6%] taking cART) remained. Lower current CD4+ cell counts were associated with smaller hippocampal (mean [SE] β = 16.66 [4.72] mm3 per 100 cells/mm3; P < .001) and thalamic (mean [SE] β = 32.24 [8.96] mm3 per 100 cells/mm3; P < .001) volumes and larger ventricles (mean [SE] β = -391.50 [122.58] mm3 per 100 cells/mm3; P = .001); in participants not taking cART, however, lower current CD4+ cell counts were associated with smaller putamen volumes (mean [SE] β = 57.34 [18.78] mm3 per 100 cells/mm3; P = .003). A dVL was associated with smaller hippocampal volumes (d = -0.17; P = .005); in participants taking cART, dVL was also associated with smaller amygdala volumes (d = -0.23; P = .004).

CONCLUSIONS AND RELEVANCE

In a large-scale international population of HIV-positive individuals, volumes of structures in the limbic system were consistently associated with current plasma markers. Our findings extend beyond the classically implicated regions of the basal ganglia and may represent a generalizable brain signature of HIV infection in the cART era.

Randomized, Placebo-Controlled Trial of Targeting Neuroinflammation with Ibudilast to Treat Methamphetamine Use Disorder

Methamphetamine (MA) triggers neuroinflammation and medications that counteract MA-induced neuroinflammation may reduce MA-induced neurodegeneration and improve neurocognition and treatment outcomes in MA use disorder. We performed a randomized, placebo-controlled trial to determine the safety and efficacy of ibudilast (IBUD), a phosphodiesterase inhibitor that reduces neuroinflammation, for the treatment of MA use disorder. Treatment-seeking volunteers with MA use disorder were randomly assigned to receive 12 weeks of IBUD 50 mg twice daily (N = 64) or placebo (N = 61) with medication management counseling. Participants visited the outpatient research clinic twice weekly to provide urine specimens for drug screens and undergo study assessments. The primary outcome was end of treatment MA-abstinence (EOTA) during weeks 11 and 12 of treatment. Serum IBUID levels were measured for IBUD participants during week 3 of treatment. There was no difference in EOTA for IBUD (14%) versus placebo (16%, p > 0.05). There was no correlation between serum IBUD levels and MA use during treatment and mean IBUD levels for participants with (mean = 51.3, SD = 20.3) and without (mean = 54.7, SD = 33.0, p = 0.70) EOTA. IBUD was well tolerated. IBUD did not facilitate MA abstinence in this outpatient trial. Whether targeting neuroinflammation, either with IBUD in other subgroups of MA users or clinical trial designs, or with other anti-inflammatory medications, is an effective strategy for treating MA use disorder is not clear. Graphical Abstract The proportion of urine drug screens negative for methamphetamine (MA) during the two week lead-in period (weeks -2 and - 1) and the 12 week medication treatment period (weeks 1-12) for ibudilast versus placebo.

The joint effect of aging and HIV infection on microstructure of white matter bundles

Recent evidence suggests the aging process is accelerated by HIV. Degradation of white matter (WM) has been independently associated with HIV and healthy aging. Thus, WM may be vulnerable to joint effects of HIV and aging. Diffusion-weighted imaging (DWI) was conducted with HIV-seropositive (n = 72) and HIV-seronegative (n = 34) adults. DWI data underwent tractography, which was parcellated into 18 WM tracts of interest (TOIs). Functional Analysis of Diffusion Tensor Tract Statistics (FADTTS) regression was conducted assessing the joint effect of advanced age and HIV on fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) along TOI fibers. In addition to main effects of age and HIV on WM microstructure, the interactive effect of age and HIV was significantly related to lower FA and higher MD, AD, and RD across all TOIs. The location of findings was consistent with the clinical presentation of HIV-associated neurocognitive disorders. While older age is related to poorer WM microstructure, its detrimental effect on WM is stronger among HIV+ relative to HIV- individuals. Loss of WM integrity in the context of advancing age may place HIV+ individuals at increased risk for brain and cognitive compromise.

Changes in cognition precede changes in HRQoL among HIV+ males: Longitudinal analysis of the multicenter AIDS cohort study

OBJECTIVES

Despite treatment-related improvements in morbidity and mortality, HIV-1-infected (HIV+) individuals continue to face a wide range of HIV-associated medical and HIV-associated neurocognitive disorders. Little is known about the impact of cognitive impairment on patients' health-related quality of life (HRQoL). To address this, the current study examined the longitudinal relationship between cognitive functioning and HRQoL among HIV+ individuals.

METHOD

The sample consisted of 1,306 HIV+ men enrolled in the Multicenter AIDS Cohort Study. Participants received biannual assessments of cognitive functioning (including tests of processing speed, executive functioning, attention/working memory, motor functioning, learning, and memory) and completed questionnaires assessing HRQoL and depression. Multilevel models were used to examine the longitudinal and cross-lagged relationship between HRQoL and cognition, independent of depression and HIV disease severity.

RESULTS

There was a significant relationship between HRQoL and cognitive functioning both between and within subjects. Specifically, individuals who reported better HRQoL reported better cognitive functioning, and longitudinal change in cognition was positively related to change in HRQoL. There was a significant unidirectional-lagged relationship; cognition predicted HRQoL at subsequent visits, but HRQoL did not predict cognitive functioning at subsequent visits. Furthermore, analyses of severity of neurocognitive impairment revealed that transition to a more severe stage of cognitive impairment was associated with a decline in HRQoL.

CONCLUSIONS

Overall, the current study suggests that changes in HRQoL are partially driven by changes in cognitive functioning. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Intraindividual variability in neuropsychological performance predicts cognitive decline and death in HIV

OBJECTIVE

HIV-associated neurocognitive disorder (HAND) occurs in a significant percentage of HIV-infected (HIV+) adults. Increased intraindividual variability (IIV) in cognitive function may be an early marker of emerging neurocognitive disorder, which suggests that IIV may be a sensitive measure of neurologic compromise in HIV. In the current study, we hypothesize that increased IIV may predict impending morbidity, including future cognitive decline and death.

METHOD

In 708 HIV+ participants followed longitudinally for up to 14 years, we assessed the role of dispersion in forecasting death and cognitive decline. Incident neurocognitive impairment was predicted in a mixed-effects ordinal logistic regression model using age, gender, baseline mean cognitive functioning, CD4+, time followed, years of education, and dispersion at the previous visit. Death before the next visit was predicted in a binomial mixed-effects regression model using age, gender, baseline mean cognitive functioning, CD4+, time followed, years of education, and dispersion.

RESULTS

Point-in-time dispersion and change in dispersion between visits predict future cognitive decline and death in HIV+ individuals. Individuals with greater dispersion at a visit or who had larger changes in dispersion between visits were more likely to demonstrate greater neurocognitive impairment at the subsequent visit. Greater IIV was also associated with an increased risk of death prior to the subsequent visit, even after controlling for HAND severity and global cognitive functioning.

CONCLUSIONS

We conclude that the IIV in cognitive functioning may be more predictive of future disease consequence than mean level of cognitive functioning. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

An augmented aging process in brain white matter in HIV

OBJECTIVE

HIV infection and aging are both associated with neurodegeneration. However, whether the aging process alone or other factors associated with advanced age account for the progression of neurodegeneration in the aging HIV-positive (HIV+) population remains unclear.

METHODS

HIV+ (n = 70) and HIV-negative (HIV-, n = 34) participants underwent diffusion tensor imaging (DTI) and metrics of microstructural properties were extracted from regions of interest (ROIs). A support vector regression model was trained on two independent datasets of healthy adults across the adult life-span (n = 765, Cam-CAN = 588; UiO = 177) to predict participant age from DTI metrics, and applied to the HIV dataset. Predicted brain age gap (BAG) was computed as the difference between predicted age and chronological age, and statistically compared between HIV groups. Regressions assessed the relationship between BAG and HIV severity/medical comorbidities. Finally, correlation analyses tested for associations between BAG and cognitive performance.

RESULTS

BAG was significantly higher in the HIV+ group than the HIV- group F (1, 103) = 12.408, p = .001). HIV RNA viral load was significantly associated with BAG, particularly in older HIV+ individuals (R2  = 0.29, F(7, 70) = 2.66, p = .021). Further, BAG was negatively correlated with domain-level cognitive function (learning: r = -0.26, p = .008; memory: r = -0.21, p = .034).

CONCLUSIONS

HIV infection is associated with augmented white matter aging, and greater brain aging is associated with worse cognitive performance in multiple domains.

Longitudinal intra-individual variability in neuropsychological performance relates to white matter changes in HIV

OBJECTIVES

Recent studies suggest that intraindividual variability (IIV) of neuropsychological performance may be sensitive to HIV-associated neurologic compromise. IIV may be particularly dependent upon the integrity of frontal-subcortical systems, and therefore may be a meaningful phenotype in HIV. We examined the relationship between change in IIV and white matter integrity among HIV seropositive (HIV+) and HIV seronegative (HIV-) individuals.

METHOD

The sample consisted of 38 HIV+ participants and 26 HIV- control participants who underwent neuroimaging and a neuropsychological evaluation at baseline and at 2-year follow-up evaluation.

RESULTS

Among HIV+ participants, increases in IIV (greater dispersion) were related to lower fractional anisotropy (FA) values in the anterior thalamic radiations (ATR) and the superior longitudinal fasciculus (SLF). Changes in mean-level global cognitive functioning were not significantly related to white matter integrity. Additionally, there was a significant Group × IIV interaction effect in the SLF demonstrating that the relationship between IIV and white matter integrity was specific to HIV.

CONCLUSIONS

Overall, findings suggest that IIV may be more sensitive, relative to mean-level global cognitive functioning, in the detection of neurologic compromise among HIV+ individuals. (PsycINFO Database Record

Cortical brain atrophy and intra-individual variability in neuropsychological test performance in HIV disease

To characterize the relationship between dispersion-based intra-individual variability (IIVd) in neuropsychological test performance and brain volume among HIV seropositive and seronegative men and to determine the effects of cardiovascular risk and HIV infection on this relationship. Magnetic Resonance Imaging (MRI) was used to acquire high-resolution neuroanatomic data from 147 men age 50 and over, including 80 HIV seropositive (HIV+) and 67 seronegative controls (HIV-) in this cross-sectional cohort study. Voxel Based Morphometry was used to derive volumetric measurements at the level of the individual voxel. These brain structure maps were analyzed using Statistical Parametric Mapping (SPM2). IIVd was measured by computing intra-individual standard deviations (ISD's) from the standardized performance scores of five neuropsychological tests: Wechsler Memory Scale-III Visual Reproduction I and II, Logical Memory I and II, Wechsler Adult Intelligence Scale-III Letter Number Sequencing. Total gray matter (GM) volume was inversely associated with IIVd. Among all subjects, IIVd -related GM atrophy was observed primarily in: 1) the inferior frontal gyrus bilaterally, the left inferior temporal gyrus extending to the supramarginal gyrus, spanning the lateral sulcus; 2) the right superior parietal lobule and intraparietal sulcus; and, 3) dorsal/ventral regions of the posterior section of the transverse temporal gyrus. HIV status, biological, and cardiovascular disease (CVD) variables were not linked to IIVd -related GM atrophy. IIVd in neuropsychological test performance may be a sensitive marker of cortical integrity in older adults, regardless of HIV infection status or CVD risk factors, and degree of intra-individual variability links with volume loss in specific cortical regions; independent of mean-level performance on neuropsychological tests.

The effects of HIV and aging on subcortical shape alterations: A 3D morphometric study

Standard volumetric neuroimaging studies have demonstrated preferential atrophy of subcortical structures among individuals with HIV. However, to our knowledge, no study has investigated subcortical shape alterations secondary to HIV and whether advancing age impacts that relationship. This study employed 3D morphometry to examine the independent and interactive effects of HIV and age on shape differences in nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen, and thalamus in 81 participants ranging in age from 24 to 76 including 59 HIV+ individuals and 22 HIV-seronegative controls. T1-weighted MRI underwent a preprocessing pipeline followed by automated subcortical segmentation. Parametric statistical analyses were used to determine independent effects of HIV infection and age on volume and shape in each region of interest (ROI) and the interaction between age and HIV serostatus in predicting volume/shape in each ROI. Significant main effects for HIV were found in the shape of right caudate and nucleus accumbens, left pallidum, and hippocampus. Age was associated with differences in shape in left pallidum, right nucleus accumbens and putamen, and bilateral caudate, hippocampus, and thalamus. Of greatest interest, an age × HIV interaction effect was found in the shape of bilateral nucleus accumbens, amygdala, caudate, and thalamus as well as right pallidum and putamen such that increasing age in HIV participants was associated with greater shape alterations. Traditional volumemetric analyses revealed main effects for both HIV and age but no age × HIV interaction. These findings may suggest that age and HIV infection conferred additional deleterious effects on subcortical shape abnormalities beyond the independent effects of these factors. Hum Brain Mapp 38:1025-1037, 2017. © 2016 Wiley Periodicals, Inc.

HIV DNA Is Frequently Present within Pathologic Tissues Evaluated at Autopsy from Combined Antiretroviral Therapy-Treated Patients with Undetectable Viral Loads

HIV infection treatment strategies have historically defined effectiveness through measuring patient plasma HIV RNA. While combined antiretroviral therapy (cART) can reduce plasma viral load (pVL) to undetectable levels, the degree that HIV is eliminated from other anatomical sites remains unclear. We investigated the HIV DNA levels in 229 varied autopsy tissues from 20 HIV-positive (HIV(+)) cART-treated study participants with low or undetectable plasma VL and cerebrospinal fluid (CSF) VL prior to death who were enrolled in the National Neurological AIDS Bank (NNAB) longitudinal study and autopsy cohort. Extensive medical histories were obtained for each participant. Autopsy specimens, including at least six brain and nonbrain tissues per participant, were reviewed by study pathologists. HIV DNA, measured in tissues by quantitative and droplet digital PCR, was identified in 48/87 brain tissues and 82/142 nonbrain tissues at levels >200 HIV copies/million cell equivalents. No participant was found to be completely free of tissue HIV. Parallel sequencing studies from some tissues recovered intact HIV DNA and RNA. Abnormal histological findings were identified in all participants, especially in brain, spleen, lung, lymph node, liver, aorta, and kidney. All brain tissues demonstrated some degree of pathology. Ninety-five percent of participants had some degree of atherosclerosis, and 75% of participants died with cancer. This study assists in characterizing the anatomical locations of HIV, in particular, macrophage-rich tissues, such as the central nervous system (CNS) and testis. Additional studies are needed to determine if the HIV recovered from tissues promotes the pathogenesis of inflammatory diseases, such as HIV-associated neurocognitive disorders, cancer, and atherosclerosis.

IMPORTANCE

It is well-known that combined antiretroviral therapy (cART) can reduce plasma HIV to undetectable levels; however, cART cannot completely clear HIV infection. An ongoing question is, "Where is HIV hiding?" A well-studied HIV reservoir is "resting" T cells, which can be isolated from blood products and succumb to cART once activated. Less-studied reservoirs are anatomical tissue samples, which have unknown cART penetration, contain a comparably diverse spectrum of potentially HIV-infected immune cells, and are important since <2% of body lymphocytes actually reside in blood. We examined 229 varied autopsy specimens from 20 HIV(+) participants who died while on cART and identified that >50% of tissues were HIV infected. Additionally, we identified considerable pathology in participants' tissues, especially in brain, spleen, lung, lymph node, liver, aorta, and kidney. This study substantiates that tissue-associated HIV is present despite cART and can inform future studies into HIV persistence.

Psychosocial Correlates of Medication Adherence among HIV-Positive, Cognitively Impaired Individuals

Although cognitive impairment has been shown to adversely affect antiviral medication adherence, a subset of cognitively impaired adults nonetheless are able to adequately adhere to their medication regimen. However, little is known about factors that serve as buffers against suboptimal adherence among the cognitively impaired. This study consisted of 160 HIV-positive, cognitively impaired adults (Global Deficit Score ≥ 0.50) whose medication adherence was monitored over 6-months using an electronic monitoring device (MEMS caps). Logistic regressions were run to determine psychosocial variables associated with medication adherence. Higher self-efficacy and treatment related support, a stable medication regimen, stable stress levels, and absence of current stimulant use were predictive of optimal adherence. A distinct array of psychosocial factors was found that buffer against the adverse effects of cognitive impairment on medication adherence. Assessment and interventions targeting these factors may improve adherence rates among cognitively impaired adults.

Increased subcortical neural activity among HIV+ individuals during a lexical retrieval task

BACKGROUND

Deficits in lexical retrieval, present in approximately 40% of HIV+ patients, are thought to reflect disruptions to frontal-striatal functions and may worsen with immunosuppression. Coupling frontal-striatal tasks such as lexical retrieval with functional neuroimaging may help delineate the pathophysiologic mechanisms underlying HIV-associated neurological dysfunction.

OBJECTIVE

We examined whether HIV infection confers brain functional changes during lexical access and retrieval. It was expected that HIV+ individuals would demonstrate greater brain activity in frontal-subcortical regions despite minimal differences between groups on neuropsychological testing. Within the HIV+ sample, we examined associations between indices of immunosuppression (recent and nadir CD4+ count) and task-related signal change in frontostriatal structures. Method16 HIV+ participants and 12 HIV- controls underwent fMRI while engaged in phonemic/letter and semantic fluency tasks. Participants also completed standardized measures of verbal fluency

RESULTS

HIV status groups performed similarly on phonemic and semantic fluency tasks prior to being scanned. fMRI results demonstrated activation differences during the phonemic fluency task as a function of HIV status, with HIV+ individuals demonstrating significantly greater activation in BG structures than HIV- individuals. There were no significant differences in frontal brain activation between HIV status groups during the phonemic fluency task, nor were there significant brain activation differences during the semantic fluency task. Within the HIV+ group, current CD4+ count, though not nadir, was positively correlated with increased activity in the inferior frontal gyrus and basal ganglia.

CONCLUSION

During phonemic fluency performance, HIV+ patients recruit subcortical structures to a greater degree than HIV- controls despite similar task performances suggesting that fMRI may be sensitive to neurocompromise before overt cognitive declines can be detected. Among HIV+ individuals, reduced activity in the frontal-subcortical structures was associated with lower CD4+ count.

HIV-transmission-related risk behavior in HIV+ African American men: Exploring biological, psychological, cognitive, and social factors

OBJECTIVES

To identify factors associated with HIV-transmission-related risk behavior among HIV+ African American men.

METHOD

We examined biological, psychological, cognitive, and social factors and recent HIV-transmission-related risk behavior (i.e., needle sharing, unprotected sex, exchange sex) among a sample of HIV+ African American men.

RESULTS

A binary logistic regression showed that individuals under age 50 (OR=4.2), with clinically-elevated masochism scores (OR=3.9) on the Millon Clinical Multiaxial Inventory-III (MCMI-III), current substance abuse/dependence (OR=2.6), and higher sensation-seeking (OR=1.3) were more likely to report recent risk behavior.

CONCLUSIONS

Reducing substance use, addressing self-defeating attitudes, and improving self-control may be avenues for future prevention and intervention research among HIV+ African American men engaging in HIV-transmission-related risk behavior.

Medication Adherence in HIV-Positive African Americans: The Roles of Age, Health Beliefs, and Sensation Seeking

We examined how two critical constructs, health beliefs and sensation seeking, influence combination antiretroviral therapy adherence in HIV+ African Americans, and whether these factors mediate the association between age and adherence. Two-hundred-and-eighty-six HIV+ African Americans participated in this observational study. Path analyses revealed that higher levels of a specific health belief, perceived utility of treatment, and lower levels of a sensation-seeking component, Thrill and Adventure Seeking, directly predicted optimal adherence. The influence of age on adherence was partially mediated by lower Thrill and Adventure Seeking levels. Depression predicted adherence via perceived utility of treatment and Thrill and Adventure Seeking, whereas current substance abuse and dependence did via Thrill and Adventure Seeking. Poorer neurocognitive function had a direct, adverse effect on adherence. Our findings suggest that supporting the development of more positive perceptions about HIV treatment utility may help increase medication adherence among African Americans. This may be particularly relevant for those with higher levels of depression symptoms, which was directly associated with negative perceptions about treatment. Additionally, clinicians can assess sensation-seeking tendencies to help identify HIV+ African Americans at risk for suboptimal adherence. Compensatory strategies for medication management may help improve adherence among HIV+ individuals with poorer neurocognitive function.

Comparing the unmatched count technique and direct self-report for sensitive health-risk behaviors in HIV+ adults

Researchers often rely on self-report measures to assess sensitive health-risk behaviors in HIV+ individuals, yet the accuracy of self-report has been questioned, particularly when inquiring about behaviors that may be embarrassing, risky, and/or taboo. We compared an anonymous reporting method - the unmatched count technique (UCT) - to direct self-report (DSR) in order to assess reporting differences for several health-risk behaviors related to medication adherence and sexual risk. Contrary to hypotheses, the UCT only produced a significantly higher estimated base rate for one sensitive behavior: reporting medication adherence to one's physician, which may have been contextually primed by our study design. Our results suggest that anonymous reporting methods may not increase disclosure compared to DSR when assessing several health-risk behaviors in HIV+ research volunteers. However, our results also suggest that contextual factors should be considered and investigated further, as they may influence perception of sensitive behavior.

Neuroimaging abnormalities, neurocognitive function, and fatigue in patients with hepatitis C

OBJECTIVE

This study examined neurologic abnormalities (as measured by proton magnetic resonance spectroscopy imaging and diffusion tensor imaging), neurocognitive performance, and fatigue among a sample of adults with hepatitis C virus (HCV). We hypothesized that HCV+ individuals would demonstrate structural brain abnormalities and neurocognitive compromise consistent with frontostriatal dysfunction as well as increased fatigue compared to controls.

METHOD

Participants were 76 individuals diagnosed with HCV and 20 controls who underwent a comprehensive neurocognitive evaluation and clinical assessments. A subset of the HCV+ participants (n = 29) and all controls underwent MRI.

RESULTS

Individuals diagnosed with chronic HCV infection demonstrated greater fractional anisotropy in the striatum as well as greater mean diffusivity in the fronto-occiptal fasciculus and external capsule compared to HCV- controls. HCV+ participants also demonstrated lower levels of N-acetylaspartate in bilateral parietal white matter and elevations in myo-inosital (mI) in bilateral frontal white matter compared to HCV- controls (all p values < 0.05). HCV+ participants also demonstrated significantly poorer neuropsychological performance, particularly in processing speed and verbal fluency. HCV+ patients reported higher levels of fatigue than controls, and fatigue was significantly correlated with diffusivity in the superior fronto-occipital fasciculus, elevations in mI in frontal white matter, and overall cognitive performance.

CONCLUSIONS

Our results suggest that HCV-associated neurologic complications disrupt frontostriatal structures, which may result in increased fatigue and poorer cognitive performance, particularly in those cognitive domains regulated by frontostriatal regions.

Interactive effects of neurocognitive impairment and substance use on antiretroviral non-adherence in HIV disease

While numerous studies have established the adverse independent effects of clinical conditions including neurocognitive dysfunction, psychiatric illness, and substance abuse/dependence on medication adherence among HIV-infected adults, fewer have studied their interactive effects. The current study examined this issue among 204 HIV-infected participants based upon current neurocognitive functioning and DSM-IV-diagnosed psychiatric illness and current substance abuse or dependence. Results confirmed that participants with any of these risk factors demonstrated poorer adherence than individuals with no risk factors. A neurocognitive status × substance abuse/dependence interaction was also identified such that participants with impaired neurocognition and a co-occurring substance abuse/dependence diagnosis demonstrated the poorest adherence. Results confirm the deleterious impact of these risk factors in isolation and also identify a specific interactive effect for individuals with comorbid neurocognitive impairment and a substance abuse/dependence disorder. Findings highlight the need for interventions that simultaneously address these problems.

Mild test anxiety influences neurocognitive performance among African Americans and European Americans: identifying interfering and facilitating sources

The current study examined ethnic/racial differences in test-related anxiety and its relationship to neurocognitive performance in a community sample of African American (n = 40) and European American (n = 36) adults. The authors hypothesized the following: (a) Test-anxiety related to negative performance evaluation would be associated with lower neurocognitive performance, whereas anxiety unrelated to negative evaluation would be associated with higher neurocognitive performance. (b) African American participants would report higher levels of anxiety about negative performance evaluation than European Americans. (c) European Americans would report higher levels of anxiety unrelated to negative performance evaluation. The first two hypotheses were supported: Ethnic/racial differences in test-taking anxiety emerged such that African Americans reported significantly higher levels of negative performance evaluation, which was associated with lower cognitive performance. The third hypothesis was not supported: African Americans and European Americans reported similar levels of test-anxiety unrelated to negative evaluation.

A deconstruction of gambling task performance among HIV+ individuals: the differential contributions of problem solving and risk taking

This study sought to deconstruct gambling task (GT) performance among HIV+ individuals (N = 143) and is intended to capture other cognitive features of task performance (i.e., problem solving and strategy preference). Consistent with our hypotheses, cluster analysis identified three GT groups: a safe/advantageous (AS) strategy group, a risky/disadvantageous (RS) strategy group, and a novel third group who failed to develop a strategy (NS). The NS group performed worst on global neuropsychological performance, processing speed, and executive function. Our results support a novel measure of GT task performance and suggest that failure to develop/implement a strategy reflects cognitive dysfunction.

Apolipoprotein-E genotype and human immunodeficiency virus-associated neurocognitive disorder: the modulating effects of older age and disease severity

BACKGROUND

The apolipoprotein-E (APOE) ε4 allele is a risk factor for vascular dementia and Alzheimer's disease. Recent studies are equivocal with regards to whether or not the ε4 allele confers increased risk for the development of human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND), but suggest that age and/or disease severity may be modulating factors. The aim of this study was to assess the interactions and contributions of APOE genotype, age, and HIV disease severity as risk factors for HAND in HIV-infected adults.

METHODS

Participants were 259 HIV-positive individuals who underwent APOE genotyping, a standardized neurological evaluation, a comprehensive neuropsychological evaluation, and laboratory testing.

RESULTS

Older ε4 carriers showed a higher frequency of HAND compared with age-matched non-ε4 carriers. Analysis by discrete neurocognitive domain revealed that advanced age modulated the effect of the ε4 allele, such that older ε4 allele carriers showed reduced executive functioning and information processing speed. Exploratory analyses assessing the relationship between ε4 and disease severity in the overall sample revealed that disease severity modulated the effect of the ε4 allele on cognition. Lower absolute CD4+ cell count among ε4 allele carriers was associated with poorer working memory ability.

CONCLUSION

Advancing age and degree of immunosuppression may influence the association between APOE ε4 allele status and HAND. These two factors need to be taken into account in future research.

The impact of neurobehavioral features on medication adherence in HIV: evidence from longitudinal models

Effective antiretroviral therapy has led to substantial improvements in health-related outcomes among individuals with HIV. Despite advances in HIV pharmacotherapy, suboptimal medication adherence remains a significant barrier to successful treatment. Although several factors have been associated with medication adherence in the extant literature, study assessing the effects of some of the neurobehavioral features specific to HIV has been limited. Moreover, although there is a growing body of literature measuring medication adherence in HIV prospectively, few employ advanced statistical methodologies suited to handle advanced models with multiple predictors that would strengthen our understanding of medication adherence trajectories in HIV. This study sought to integrate traditionally assessed predictors of medication adherence with neurobehavioral features of HIV in a longitudinal study of medication adherence to combined antiretroviral therapy (cART). The current study used multilevel modeling to examine a wide arrangement of categories of factors - demographic, medication related, psychosocial, and neurobehavioral - on medication adherence. The sample consisted of 235 HIV+ individuals whose medication adherence was monitored over the course of six months using electronic monitoring devices. After controlling for the effects of demographic, medication, and psychosocial factors, neurobehavioral features added predictive validity to the model. In the final model, simultaneously controlling for the effects of each of the predictors within all the categories, age, self-efficacy, executive functioning, apathy, and frequency of stimulant use emerged as unique individual predictors of average medication adherence across the 6-month study. Self-efficacy and irritability predicted changes in medication adherence over time. Adherence behavior is multidetermined. Adequate assessment of these factors, combined with timely intervention, appears to be warranted in order to boost adherence rates.

The aggregate effects of multiple comorbid risk factors on cognition among HIV-infected individuals

This study developed and then cross-validated a novel weighting algorithm based on multiple comorbid risk factors (stimulant use, vascular disease, hepatitis C, HIV disease severity, cognitive reserve) to predict cognitive functioning among 366 HIV+ adults. The resultant "risk severity score" was used to differentially weight, as a function of age, the impact and magnitude of multiple risk factors on cognition. Among older adults (≥50 years) the risk severity index was differentially predictive of learning/memory and verbal fluency, whereas among younger adults it was linked to working memory and executive function. Cognitive reserve was found to be the most robust predictor of neurocognition.

Systems analysis of human brain gene expression: mechanisms for HIV-associated neurocognitive impairment and common pathways with Alzheimer's disease

Background

Human Immunodeficiency Virus-1 (HIV) infection frequently results in neurocognitive impairment. While the cause remains unclear, recent gene expression studies have identified genes whose transcription is dysregulated in individuals with HIV-association neurocognitive disorder (HAND). However, the methods for interpretation of such data have lagged behind the technical advances allowing the decoding genetic material. Here, we employ systems biology methods novel to the field of NeuroAIDS to further interrogate extant transcriptome data derived from brains of HIV + patients in order to further elucidate the neuropathogenesis of HAND. Additionally, we compare these data to those derived from brains of individuals with Alzheimer’s disease (AD) in order to identify common pathways of neuropathogenesis.

Methods

In Study 1, using data from three brain regions in 6 HIV-seronegative and 15 HIV + cases, we first employed weighted gene co-expression network analysis (WGCNA) to further explore transcriptome networks specific to HAND with HIV-encephalitis (HIVE) and HAND without HIVE. We then used a symptomatic approach, employing standard expression analysis and WGCNA to identify networks associated with neurocognitive impairment (NCI), regardless of HIVE or HAND diagnosis. Finally, we examined the association between the CNS penetration effectiveness (CPE) of antiretroviral regimens and brain transcriptome. In Study 2, we identified common gene networks associated with NCI in both HIV and AD by correlating gene expression with pre-mortem neurocognitive functioning.

Results

Study 1: WGCNA largely corroborated findings from standard differential gene expression analyses, but also identified possible meta-networks composed of multiple gene ontology categories and oligodendrocyte dysfunction. Differential expression analysis identified hub genes highly correlated with NCI, including genes implicated in gliosis, inflammation, and dopaminergic tone. Enrichment analysis identified gene ontology categories that varied across the three brain regions, the most notable being downregulation of genes involved in mitochondrial functioning. Finally, WGCNA identified dysregulated networks associated with NCI, including oligodendrocyte and mitochondrial functioning. Study 2: Common gene networks dysregulated in relation to NCI in AD and HIV included mitochondrial genes, whereas upregulation of various cancer-related genes was found.

Conclusions

While under-powered, this study identified possible biologically-relevant networks correlated with NCI in HIV, and common networks shared with AD, opening new avenues for inquiry in the investigation of HAND neuropathogenesis. These results suggest that further interrogation of existing transcriptome data using systems biology methods can yield important information.

Visuospatial and Attentional Abilities Predict Driving Simulator Performance Among Older HIV-infected Adults

OBJECTIVES

To examine the effects of aging and neuropsychological (NP) impairment on driving simulator performance within a human immunodeficiency virus (HIV)-infected cohort.

METHODS

Participants included 79 HIV-infected adults (n = 58 > age 50, n = 21 ≤ 40) who completed a NP battery and a personnel computer-based driving simulator task. Outcome variables included total completion time (time) and number of city blocks to complete the task (blocks).

RESULTS

Compared to the younger group, the older group was less efficient in their route finding (blocks over optimum: 25.9 [20.1] vs 14.4 [16.9]; P = .02) and took longer to complete the task (time: 1297.6 [577.6] vs 804.4 [458.5] seconds; P = .001). Regression models within the older adult group indicated that visuospatial abilities (blocks: b = -0.40, P <.001; time: b = -0.40, P = .001) and attention (blocks: b = -0.49, P = .001; time: b = -0.42, P = .006) independently predicted simulator performance. The NP-impaired group performed more poorly on both time and blocks, compared to the NP normal group.

CONCLUSIONS

Older HIV-infected adults may be at risk of driving-related functional compromise secondary to HIV-associated neurocognitive decline.

Functional disability in medication management and driving among individuals with HIV: a 1-year follow-up study

Approximately 50% of individuals with HIV report cognitive deficits that can affect social or occupational functioning. The present study used a longitudinal design (1 year) to examine the relationship between cognitive factors and incidental functional deficits in medication management and driving ability among a cohort of 101 HIV+ participants. Participants were classified into groups of functionally "stable" and "disabled" for each laboratory-based functional task (i.e., Medication Management Task-Revised, MMT-R, and PC-based driving simulator). We hypothesized that participants who exhibited a functional deficit in either MMT-R or driving at follow-up assessment would demonstrate significantly poorer baseline cognitive performance at study entry than participants who remained functionally stable. As hypothesized, participants who demonstrated significantly lower baseline performance in learning/memory and executive functioning also demonstrated functional disability on the MMT-R at follow-up when compared to functionally stable participants. Poor baseline performance in speed of information processing was associated with a deficit in driving ability at follow-up assessment. Our results suggest that lower baseline cognitive functioning predicts downstream functional disability, and that deficits in learning/memory and information processing speed are particularly predictive of deficits in medication management and driving ability.

Differential predictors of medication adherence in HIV: findings from a sample of African American and Caucasian HIV-positive drug-using adults

Modest or even occasional nonadherence to combined antiretroviral therapy (cART) can result in adverse clinical outcomes. African Americans demonstrate lower rates of adherence than Caucasians or Latinos. Identifying factors that influence medication adherence among African Americans is a critical step toward reducing HIV/AIDS disease progression and mortality. In a sample of 181 African American (n=144) and Caucasian (n=37) HIV-positive drug-using individuals [age (M=42.31; SD=6.6) education (M=13.41; SD=2.1)], we examined the influence of baseline drug use, literacy, neurocognition, depression, treatment-specific social support, and patient satisfaction with health care provider on medication adherence averaged over the course of 6 months (study dates 2002-2006). Our findings suggest differential baseline predictors of medication adherence for African Americans and Caucasians, such that patient satisfaction with provider was the strongest predictor of follow-up medication adherence for African Americans whereas for Caucasians depressive symptoms and treatment-specific social support were predictive of medication adherence (after controlling for duration of drug use).

Cognitive reserve as a protective factor in older HIV-positive patients at risk for cognitive decline

The present study examined the impact of cognitive reserve in maintaining intact neuropsychological (NP) function among older HIV-positive individuals, a uniquely at-risk subgroup. Participants included 129 individuals classified by HIV serostatus, age group, and NP impairment. A three-way analysis of variance (ANOVA) followed by a series of within-group ANOVA and multiple regression analyses were conducted to investigate the pattern of cognitive reserve (vs. other protective) influence among groups with varying risks of NP impairment. Results indicated a significant age × HIV status interaction, with older HIV-positive individuals demonstrating higher cognitive reserve than subgroups with less risk for NP compromise (younger age and/or HIV-negative). Results demonstrated higher cognitive reserve specific to NP-intact older HIV-positive individuals. Within this group, the interaction of younger age and higher cognitive reserve independently contributed to cognitive status when controlling for psychiatric, immunological, and psychosocial protective mechanisms, suggesting the importance of cognitive reserve beyond other protective mechanisms in maintaining optimal NP functioning in those individuals most at risk. Alongside younger age, factors contributing to cognitive reserve (i.e., education and estimated premorbid intelligence) may provide substantial benefit for older HIV-positive adults who are at high risk for NP compromise.

The role of HIV infection, cognition, and depression in risky decision-making

The authors examined the impact of HIV, cognitive dysfunction, and depression on decision-making. HIV+ (N=100) and HIV- (N=26) participants were administered a comprehensive neuropsychological battery, a modified version of the Iowa Gambling Task, and a measure of depressive symptoms. HIV+ participants demonstrated more difficulties in learning the gambling task than did HIV- participants. Executive functioning and depression emerged as strong predictors of gambling task performance. Depression partially mediated the relationship between executive functioning and gambling performance. Our findings suggest that HIV infection, executive dysfunction, and depression place individuals at risk for poor decision-making.

Basal ganglia structures differentially contribute to verbal fluency: evidence from Human Immunodeficiency Virus (HIV)-infected adults

BACKGROUND

The basal ganglia (BG) are involved in executive language functions (i.e., verbal fluency) through their connections with cortical structures. The caudate and putamen receive separate inputs from prefrontal and premotor cortices, and may differentially contribute to verbal fluency performance. We examined BG integrity in relation to lexico-semantic verbal fluency performance among older HIV infected adults.

METHOD

20 older (50+ years) HIV+ adults underwent MRI and were administered measures of semantic and phonemic fluency. BG (caudate, putamen) regions of interest were extracted.

RESULTS

Performance on phonemic word generation significantly predicted caudate volume, whereas performance on phonemic switching predicted putamen volume.

CONCLUSIONS

These findings suggest a double dissociation of BG involvement in verbal fluency tasks with the caudate subserving word generation and the putamen associated with switching. As such, verbal fluency tasks appear to be selective to BG function.

Multi-dimensional MR spectroscopy: towards a better understanding of hepatic encephalopathy

Hepatic encephalopathy (HE) is normally diagnosed by neuropsychological (NP) tests. The goals of this study were to quantify cerebral metabolites, separate glutamate (Glu) from glutamine (Gln) in patients with minimal hepatic encephalopathy (MHE) as well as healthy subjects using the prior-knowledge fitting (ProFit) algorithm on data acquired by two-dimensional (2D) localized correlated spectroscopy (L-COSY) on two different MR scanners, and to correlate the metabolite changes with neuropsychological (NP) tests. We studied 14 MHE patients and 18 healthy controls using a GE 1.5 T Signa MR scanner. Another group of 16 MHE patients and 18 healthy controls were studied using a Siemens 1.5 T Avanto MR scanner. The following parameters were used for L-COSY: TR/TE = 2 s/30 ms, 3 × 3 × 3 cm(3) voxel size, 96 Δt(1) increments with 8 averages per Δt(1). Using the ProFit algorithm, we were able to differentiate Gln from Glu on the GE 1.5 T data in the medial frontal white/gray matter. The ratios of myo-inositol (mI), Glu, total choline, scyllo-inositol (sI), phosphoethanolamine (PE), and total N-acetyl aspartate (NAA) showed statistically significant decline in HE patients compared to healthy controls, while the ratio of Gln was significantly increased. Similar trend was seen in the ProFit quantified Siemens 1.5 T data in the frontal and occipito-parietal white/gray regions. Among the NP domain scores, motor function, cognitive speed, executive function and the global scores showed significant differences. Excellent correlations between various NP domains and metabolite ratios were also observed. ProFit based cerebral metabolite quantitation enhances the understanding and basis of the current hypothesis of MHE.

Depression, cognition, and self-appraisal of functional abilities in HIV: an examination of subjective appraisal versus objective performance

Depression frequently co-occurs with HIV infection and can result in self-reported overestimates of cognitive deficits. Conversely, genuine cognitive dysfunction can lead to an under-appreciation of cognitive deficits. The degree to which depression and cognition influence self-report of capacity for instrumental activities of daily living (IADLs) requires further investigation. This study examined the effects of depression and cognitive deficits on self-appraisal of functional competence among 107 HIV-infected adults. As hypothesized, higher levels of depression were found among those who over-reported problems in medication management, driving, and cognition when compared to those who under-reported or provided accurate self-assessments. In contrast, genuine cognitive dysfunction was predictive of under-reporting of functional deficits. Together, these results suggest that over-reliance on self-reported functional status poses risk for error when diagnoses require documentation of both cognitive impairment and associated functional disability in everyday life.

A comparison of screening batteries in the detection of neurocognitive impairment in HIV-infected Spanish speakers

BACKGROUND

A substantial number of Spanish-speaking individuals from Mexico and Central America are now living in the United States. These individuals are at heightened risk for HIV infection and, due to late diagnosis and limited resources, for HIV-associated neurocognitive disorders (HAND). Early detection is key, yet adequate methods for detecting HAND in Spanish speakers, especially in resource-poor areas, remains problematic. Therefore, it is necessary to identify accurate yet efficient neurocognitive screening tools that are appropriate for use in resource-limited AIDS clinics serving Spanish-speaking patients.

METHODS

Twenty-one Spanish-speaking, HIV-positive adults who migrated from Mexico or Central America underwent neuromedical and neurocognitive evaluation in Spanish. The concordance of three neurocognitive screening measures (the HIV Dementia Scale [HDS], the Mini-Mental State Examination [MMSE], and the NEUROPSI) with a comprehensive neuropsychological battery was examined. In addition, accuracy in detecting neurocognitive impairment using standard and alternative cutoff scores was examined.

RESULTS

The HDS and the NEUROPSI showed high correlation with the comprehensive neuropsychological battery. The HDS and the NEUROPSI also had the highest sensitivity (67% and 75%, respectively) and specificity (50% and 38%, respectively). Both measures also showed greater sensitivity than the MMSE to very mild forms of HAND.

CONCLUSION

In this small sample of HIV-positive Spanish speakers from Mexico and Central America living in the United States, the HDS and the NEUROPSI demonstrated reasonable accuracy in detecting neurocognitive impairment, while the MMSE demonstrated very poor accuracy. The HDS and the NEUROPSI were equally sensitive in detecting mild HAND. Continued test development is required to capture this disorder, especially in resource-limited settings.

Antiretroviral adherence and the nature of HIV-associated verbal memory impairment

The authors investigated the relationship between antiretroviral adherence and HIV-associated verbal memory impairment. HIV-positive participants demonstrated poorer verbal memory than HIV-negative participants. Both good (≥90%) and poor (<90%) adherers displayed encoding deficits as compared with controls, but only poor adherers exhibited retrieval deficits. Encoding deficits primarily accounted for reduced delayed recall in good adherers, but both encoding and retrieval deficits accounted for reduced delayed recall in poor adherers. The retrieval difference between the adherence groups might be explained by a neuroprotective effect of good antiretroviral adherence or preexisting HIV-related retrieval deficits that result in poorer adherence.

Two-dimensional MR spectroscopy of minimal hepatic encephalopathy and neuropsychological correlates in vivo

PURPOSE

To evaluate regional cerebral metabolic and structural changes in patients with minimal hepatic encephalopathy (MHE) using two-dimensional (2D) MR spectroscopy (MRS) and T( (1) )-weighted MRI, to correlate the observed MR changes with neuropsychological (NP) test scores, and to compare the diagnostic accuracy of MRI, 2D MRS, and NP tests in discriminating between patients and healthy subjects.

MATERIALS AND METHODS

Thirty-three MHE patients and 30 healthy controls were investigated. The 2D localized correlated spectroscopy (L-COSY) was performed in the frontal and occipital brain on a 1.5 Tesla (T) MR scanner. The NP test battery included 15 tests, grouped into 6 cognitive domains. Globus pallidus signal intensities were calculated from T(1)-weighted images.

RESULTS

The 2D MRS showed significant differences in ratios of the following metabolite(s) peaks with respect to creatine (Cr): decreased myo-inositol (mI), choline (Ch), mICh, and increased (glutamate plus glutamine) (Glx) in patients compared with healthy subjects in both occipital and frontal lobes. Frontal lobe taurine also showed a decline in patients. The NP test results revealed declines in cognitive speed, motor function, executive function, and global cognitive status. Significant correlations were found between the altered metabolites and NP tests. Alteration in the mICh/Cr ratio was noted as a powerful discriminant between healthy subjects and the patients.

CONCLUSION

The study demonstrates that relative metabolite levels determined by 2D MRS, in particular mICh/Cr, provide the best diagnostic prediction for MHE. The results suggest that depletions of myo-inositol, choline and taurine with respect to creatine correlate with measures of neuropsychological impairment.

Reaction time variability in HIV-positive individuals

Progression of HIV/AIDS is frequently associated with frontal/subcortical dysfunction and mean reaction time (RT) slowing. Beyond group means, within-subject variability of RT has been found to be particularly sensitive to frontal/subcortical dysfunction in other populations. However, the possible relevance of RT variability to HIV/AIDS patients remains unknown. This study evaluated the relationships between RT variability and indicators such as neurocognitive, behavioral, and immunological status. A total of 46 HIV-positive adults on antiretroviral medication regimens were included in this study. Overall performance of this sample was poorer than normative means on measures of RT latency, RT variability, and traditional neurocognitive domains. Results demonstrated that the measures of RT variability were associated with global cognition, medication adherence rates, and peak immunological dysfunction, above and beyond the effects of RT latency. These preliminary findings suggest that measures of RT variability may provide enhanced sensitivity to neurocognitive disease burden in HIV/AIDS relative to more traditional measures of mean RT or cognitive function.

Medication and finance management among HIV-infected adults: the impact of age and cognition

This study examined the effects of aging and cognitive impairment on medication and finance management in an HIV sample. We observed main effects of age (older < younger) and neuropsychological impairment on functional task performance. Interactions between age and cognition demonstrated that older impaired individuals performed significantly more poorly than all other comparison groups. There were no relationships between laboratory performance and self-reported medication and finance management. The interaction of advancing age and cognitive impairment may confer significant functional limitations for HIV individuals that may be better detected by performance-based measures of functional abilities rather than patient self-report.

Reciprocal prediction of medication adherence and neurocognition in HIV/AIDS

BACKGROUND

Antiretroviral medications have been shown to benefit neurocognition in HIV/AIDS, and neurocognitive deficits are a risk factor for poor adherence to these medications. However, little is known about the predictive pathways linking medication adherence with cognitive ability.

METHODS

In the current 6-month cohort study, antiretroviral medication adherence was tracked prospectively among 91 HIV-positive adults using electronic monitoring. Comprehensive neuropsychological evaluations were performed at baseline and 6 months.

RESULTS

Multivariate path analyses provided evidence that antiretroviral adherence and cognitive ability are reciprocally related, although the neurocognitive pathways of this relationship appear to vary by predictive direction. Executive function and learning/memory were most strongly predictive of levels of medication adherence achieved, whereas higher levels of adherence were predictive of relative improvements in a wide range of frontostriatal brain functions including processing speed, attention, executive functions, and motor functioning.

CONCLUSIONS

These data provide evidence that cognition and adherence are reciprocally related in HIV/AIDS. In particular, executive dysfunction may play a key role in this relationship. Interventions aimed at improving or preserving executive functions could hold promise for interrupting progressive declines in adherence and neurocognitive ability in HIV/AIDS.

Neurocognitive functioning in HIV-1 infection: effects of cerebrovascular risk factors and age

This study examined the interactive effects of cerebrovascular risks, advancing age, and HIV infection on neurocognition, and explored whether pharmacological treatment of cerebrovascular risk factors attenuated neurocognitive dysfunction. Participants included 98 HIV-seropositive adults (cerebrovascular risk: 23.5%; age > 50: 27.6%). Cerebrovascular risk was associated with slower processing speed even after controlling for age effects (b = -2.071; p =.04), and the interaction of age and cerebrovascular risk was associated with poorer verbal fluency (b = 1.276, p =.002). Participants with pharmacologically untreated cerebrovascular risk demonstrated reduced processing speed, learning/memory, and executive functioning relative to those on medication. Poor cerebrovascular health confers significant risk for HIV+ individuals, and this effect may be of greater consequence than advancing age. The cognitive impact of risk appears to be more pronounced in the absence of adequate pharmacological treatment.

CCL3 genotype and current depression increase risk of HIV-associated dementia

BACKGROUND: The prevalence of Human immunodeficiency virus (HIV)-associated dementia (HAD) has continued to rise even as incidence has fallen. Several host genetic variants have been identified that modify risk for HAD. However, the findings have not been replicated consistently and most studies did not consider the multitude of factors that might themselves confer risk for HAD. In the current study, we sought to replicate the findings of previous studies in a neurologically and behaviorally well-characterized cohort. METHODS: The sample consisted of 143 HIV+ individuals enrolled in the National NeuroAIDS Tissue Consortium (NNTC). Based on consensus diagnosis, 117 were considered neurologically normal upon study entry, and 26 had HAD. Seven single-nucleotide polymorphisms (SNPs) were genotyped within seven genes (CCL2, CCL3, CCL5, interleukin-1α [IL-1α], IL-10, stromal cell-derived factor 1, and tumor necrosis factor-α). Logistic regression analysis was used to predict group membership (normal vs HAD), with predictor variables including length of infection, age, current drug dependence, current depression, and genotype. RESULTS: The two groups were statistically similar with regards to demographic characteristics, current drug use, and disease factors. The HAD group had significantly greater number of individuals with current depression. Only one SNP, rs1130371 within the gene for CCL3, was entered into the analysis as the others showed symmetric distribution between groups. Logistic regression indicated that current depression and CCL3 genotype were significant predictors of HAD. Depression conferred a fivefold greater risk of HAD, while the TT genotype for CCL3 SNP (rs1130371) was associated with twofold risk for HAD. CONCLUSION: Depression and CCL3 genotype predicted HAD. The fact that SNPs previously found to be associated with HAD were not in our analysis, and that rs1130371 is in high linkage disequilibrium with neighboring genes indicates that more dense genotyping in significantly larger cohorts is required to further characterize the relationship between genotype and risk for HAD.

The Item-Specific Deficit Approach to evaluating verbal memory dysfunction: rationale, psychometrics, and application

In the current study, we introduce the Item-Specific Deficit Approach (ISDA), a novel method for characterizing memory process deficits in list-learning data. To meet this objective, we applied the ISDA to California Verbal Learning Test (CVLT) data collected from a sample of 132 participants (53 healthy participants and 79 neurologically compromised participants). Overall, the ISDA indices measuring encoding, consolidation, and retrieval deficits demonstrated advantages over some traditional indices and indicated acceptable reliability and validity. Currently, the ISDA is intended for experimental use, although further research may support its utility for characterizing memory impairments in clinical assessments.

Emerging issues in the neuropsychology of HIV infection

Neurocognitive compromise, a common sequela of HIV infection, ranges in severity from minor motor and information-processing speed decrements to severely incapacitating symptoms that affect functional independence. However, with the emergence of highly active antiretroviral therapy (HAART), neurocognitive phenotypes have become highly heterogeneous and increasingly fail to resemble pre-HAART presentations. This article provides an overview of our current knowledge of HIV-associated neuropsychological abnormalities, with an emphasis on the most recent attempts to classify cognitive impairment within Western and developing societies, the emergence of diverse cognitive presentations in the post-HAART era, factors that moderate the development or impact of HIV-related neurocognitive and functional deficits, and the neurophysiologic consequences of infection.

Sensation seeking and visual selective attention in adults with HIV/AIDS

The association between sensation seeking and visual selective attention was examined in 31 adults with the Human Immunodeficiency Virus (HIV). Sensation seeking was measured with Zuckerman's Sensation Seeking Scale Form V (SSS-V). Selective attention was assessed with a perceptual span task, where a target letter-character must be identified in a quickly presented array of nontarget letter-characters. As predicted, sensation seeking was strongly associated (R(2) = .229) with perceptual span performance in the array size 12 condition, where selective attention demands were greatest, but not in the easier conditions. The Disinhibition, Boredom Susceptibility, and Experience Seeking subscales of the SSS-V were associated with span performance. It is argued that personality factors such as sensation seeking may play a significant role in selective attention and related cognitive abilities in HIV positive adults. Furthermore, sensation seeking differences might explain certain inconsistencies in the HIV neuropsychology literature.

An exploratory study of long-term neurocognitive outcomes following recovery from opportunistic brain infections in HIV+ adults

Central nervous system opportunistic infections (CNS-OI) are a significant cause of morbidity and mortality in AIDS. While current interventions are increasingly successful in treating CNS-OI, little information exists regarding long-term behavioral outcomes among survivors. In this exploratory study we examined neurocognitive data among three groups of adults with different AIDS-related CNS-OI: 15 with past cryptococcal meningitis (CM), 8 with toxoplasmosis encephalitis (TE), and 8 with progressive multifocal leukoencephalopathy (PML). A group of 61 individuals with AIDS, but without CNS-OI, was used as a comparison group. A battery of standardized neuropsychological tests assessing a variety of cognitive domains was administered upon entry. Results indicate that individuals with a history of CNS-OI were most impaired on measures of cognitive and psychomotor speed relative to the HIV+ comparison group. Among the CNS-OI groups, individuals with history of TE had the most severe and varied deficits. The results are discussed in relation to what is known about the neuropathological consequences of the various CNS-OIs. While this is the first systematic group study of residual CNS-OI effects on neurocognitive function, future studies employing more participants, perhaps focusing on specific CNS-OIs, will further characterize the long-term outcomes in AIDS-related CNS-OI.

Discrepancies between self-report and objective measures for stimulant drug use in HIV: cognitive, medication adherence and psychological correlates

While it has long been recognized that self-reported drug use may be at variance with objectively obtained evidence such as urine toxicology assays, few studies have explored the behavioral correlates of such discrepancies. Here we compared self-reported and objective measures of stimulant drug use for 162 HIV infected individuals and identified a sub-group with discrepancies between data obtained via the two methods. Results showed poorer neurocognitive performance (attention, learning/memory) and lower medication adherence rates for the discrepant group as compared to those who either acknowledged their drug use or accurately denied recent stimulant use. Using the Millon Clinical Multiaxial Inventory-III, it was also found that those in the discrepant group were more hesitant to reveal psychopathology. Comparisons of self-reported and objectively measured medication adherence data are also discussed.

The generalizability of neurocognitive test/retest data derived from a nonclinical sample for detecting change among two HIV+ cohorts

Objective methods for determining clinically relevant neurocognitive change are useful for clinicians and researchers, but the utility of such methods requires validation studies in order to assess their accuracy among target populations. We examined the generalizability of regression equations and reliable change indexes (RCI) derived from a healthy sample to two HIV-infected samples, one similar in demographic makeup to the normative group and the other dissimilar. Measures administered at baseline and follow-up included the Trail Making Test, Controlled Oral Word Association Test (COWAT), Grooved Pegboard, and Digit Span. Frequencies of decline, improvement, or stability were determined for each measure. Among the demographically similar clinical cohort, elevated rates of decline among more immunologically impaired participants were indicated by simple regression method on measures of psychomotor speed and attention, while RCI addressing practice effects (RCI-PE) indicated improvement on most measures regardless of immunostatus. Conversely, among the demographically dissimilar cohort, simple regression indicated high rates of decline across all measures, while RCI-PE indicated elevated rates of decline on psychomotor and attention measures. Thus, the accuracy of the two methods examined for determining clinically significant change among HIV+ cohorts differs depending upon their similarity with the normative sample.

Relationship between psychiatric status and frontal-subcortical systems in HIV-infected individuals

Human immunodeficiency virus (HIV)-infected adults frequently evidence both neurocognitive and psychiatric dysfunction. It was hypothesized that apathy and irritability, but not anxiety and depression, are related to HIV effects on frontal-subcortical systems. This hypothesis was evaluated by determining the degree to which these psychiatric features are associated with neurocognitive functioning that is dependent upon frontal-subcortical circuitry and, therefore, thought to be sensitive to the central nervous system effects of HIV. Rating scales assessing irritability, apathy, depression, and anxiety and a dual-task paradigm were administered to 189 HIV-seropositive (HIV+) and 53 HIV-seronegative participants. Deficits in dual-task performance and greater anxiety, depression, apathy, and irritability were observed in HIV+ participants. Simultaneous multivariate regression and communality analyses revealed that only apathy and irritability were associated with dual-task performance in HIV+ participants. Thus, these findings suggest that apathy and irritability, but not depression and anxiety, are likely associated with the effects of HIV on frontal-subcortical circuitry.

Neuropsychological exploration of alleged mold neurotoxicity

Cognitive and emotional correlates of toxic mold exposure and potential dose-response effects for both outcomes were investigated. Self-reported length of exposure, time since last exposure, and serum immunoglobulin (IgG) levels were assessed. Despite CNS complaints often seen with mold exposed individuals, overall results did not uncover concomitant cognitive deficits suggested in previous studies or a significant reduction in intellectual functioning. Fewer subjects were excluded as result of failing effort/motivation assessment than expected. Correlations of IgG and cognitive function are discussed. A dose-effect for self-reported length of exposure and cognitive outcome was not seen. The sample's overall Minnesota Multiphasic Personality Inventory II (MMPI-2) profile indicated elevations on scales 1, 2, 3, 7 and 8. MMPI-2 clinical scales 1 and 3 were significantly correlated with length of exposure. The MMPI-2 may be sensitive to increasing physical and emotional sequelae as length of exposure increases. A potential subgroup of cognitively impaired outliers within mold exposure litigants is explored. Limitations of self-reported and objective measurements for mold exposure and exploratory statistical methodology are discussed.

Elements of attention in HIV-infected adults: evaluation of an existing model

Because of the multifactorial nature of neuropsychological tests, attention remains poorly defined from a neuropsychological perspective, and conclusions made regarding attention across studies may be limited due to the different nature of the measures used. Thus, a more definitive schema for this neurocognitive domain is needed. We assessed the applicability of Mirsky and Duncan's (2001) neuropsychological model of attention to a cohort of 104 HIV+ adults. Our analysis resulted in a five-factor structure similar to that of previous studies, which explained 74.5% of the variance. However, based on the psychometric characteristics of the measures comprising each factor, we offer an alternative interpretation of the factors. Findings also indicate that one factor, which is generally not assessed in clinical neuropsychology settings, may be more predictive of real-world behaviors (such as medication adherence) than those composed of traditional measures. Suggestions for further research in this important area are discussed.