Outcome of patients with HIV-1-related cognitive impairment on highly active antiretroviral therapy

Characteristics of refined lymphocyte subsets changes in people living with HIV/AIDS during antiretroviral therapy period: An observation from Wuhan, China

Background

To analyze the changing characteristics of continuous monitoring of refined lymphocyte subsets in people living with HIV/AIDS (PLWHA) during ART period.

Methods

Refined lymphocyte subsets was continuously monitored using flow cytometry for 173 PLWHA, who were hospitalized in Zhongnan Hospital of Wuhan University from August 17, 2021 to September 14, 2022. The effect of ART status and duration of ART on changes of refined lymphocyte subsets were compared in different groups. Then, the levels of refined lymphocyte subsets in PLWHA treated for more than 10 years were compared to those of 1086 healthy individuals.

Results

In addition to conventional CD4⁺ T lymphocytes and CD4⁺/CD8⁺ ratio, gradually increasing in numbers of CD3⁺CD4⁺CD45RO cells, CD3⁺CD4⁺CD45RA cells, CD45RA⁺CD3⁺CD4⁺CD25⁺CD127^low and CD45RO⁺CD3⁺CD4⁺CD25⁺CD127^low cells were found with the increase of ART duration. The number of CD4⁺CD28⁺ cells and CD8⁺CD28⁺ cells were 174/ul and 233/ul at 6 months post-ART, which gradually increased to 616/ul and 461/ul after ART initiation more than 10 years. Moreover, in ART ≤ 6 months, 6 months-3years, 3-10 years and >10 years groups, the percentage of CD3⁺CD8⁺HLA^-DR⁺/CD8 were 79.66%, 69.73%, 60.19% and 57.90%, respectively, and the differences between groups showed statistical significance (F=5.727, P=0.001). For those PLWHA with ART more than 10 years, the levels of CD4⁺ T lymphocytes, CD3⁺CD4⁺CD45RO cells, CD3⁺CD4⁺CD45RA cells, CD4⁺CD28⁺ cells and CD8⁺CD28⁺ cells can increase to levels similar to those of healthy control. However, for those PLWHA with ART more than 10 years, CD4⁺/CD8⁺ ratio was 0.86 ± 0.47, which was lower than that of healthy control (0.86 ± 0.47 vs 1.32 ± 0.59, t=3.611, P=0.003); absolute counts and percentage of CD3⁺CD8⁺HLA^-DR⁺ cells were 547/ul and 57.90%, which were higher than those of healthy control(547/ul vs 135/ul, t=3.612, P=0.003; 57.90% vs 22.38%, t=6.959, P<0.001).

Conclusion

Persistent ART can gradually improve the immune status of PLWHA, which is manifested in the increase of lymphocytes, function recovery of lymphocytes and reduction of aberrant activation status of the immune system. After 10 years of standardized ART, most lymphocytes could return to levels of healthy persons, although it may take longer to complete recovery for CD4⁺/CD8⁺ ratio and CD3⁺CD8⁺HLA^-DR⁺ cells.

Cognitive Assessment of Young Adults Before and After Initiation of Combination Antiretroviral Therapy

Objective

In the determination and monitoring of neurocognitive disorders in human immunodeficiency virus (HIV)-positive individuals, there is a need for significantly more practical methods which provide results in a shorter time than the tests that require challenging and specialized expertise. This study aimed to evaluate cognitive functions and the factors affecting them in naïve HIV-positive patients using by Montreal Cognitive Assessment (MoCA) test before and after the initiation of combination antiretroviral therapy.

Materials and Methods

HIV-positive, treatment-naïve patients monitored between January-June 2017 were included in the study. The MoCA test was performed at the beginning and the sixth month of the treatment.

Results

Forty male patients were included in the study. The mean age was calculated as 29.1±4.0. When the factors affecting the MoCA score were examined, there was a significant relationship between the education level and the MoCA score. Smoking, using alcohol, and substance did not have a significant impact on baseline MoCA values. A significant correlation was found between cluster differentiation 4 (CD4) count and HIV RNA level and attention function. There was a significant increase in the total MoCA score and the MoCA subgroup scores at the end of the sixth month of the treatment.

Conclusion

MoCA test is one of the most practical tests that can be applied in a short time period, and it was found useful in evaluating the changes in the cognitive functions of HIV-positive patients during antiretroviral treatment.

A Dissociation of Attention, Executive Function and Reaction to Difficulty: Development of the MindPulse Test, a Novel Digital Neuropsychological Test for Precise Quantification of Perceptual-Motor Decision-Making Processes

Traditionally, neuropsychological testing has assessed processing speed and precision, closely related to the ability to perform high-order cognitive tasks. An individual making a decision under time pressure must constantly rebalance its speed to action in order to account for possible errors. A deficit in processing speed appears to be afrequent disorder caused by cerebral damage — but it can be hard to pinpoint the exact cause of the slowdown. It is therefore important to separate the perceptual-motor component of processing speed from the decision-time component. We present a technique to isolate Reaction Times (RTs): a short digital test to assess the decision-making abilities of individuals by gauging their ability to balance between speed and precision. Our hypothesis is that some subjects willaccelerate, and others slow down in the face of the difficulty. This pilot study, conducted on 83 neurotypical adult volunteers, used images stimuli. The test was designed to measure RTs and correctness. After learning release gesture, the subjects were presented with three tasks: a simple Reaction Time task, a Go/No-Go, and a complex Go/No-Go with 2 simultaneous Choices. All three tasks have in common a perceptual component and a motor response. By measuring the 3 reference points requiring attentional and executive processing, while progressively increasing the conceptual complexity of the task, we were able to compare the processing times for different tasks — thus calculating the deceleration specific to the reaction time linked to difficulty. We defined the difficulty coefficient of a task as being the ratio of the group average time of this task minus the base time/average time of the unit task minus the base time. We found that RTs can be broken down into three elementary, uncorrelated components: Reaction Time, Executive Speed, and Reaction to Difficulty (RD). We hypothesized that RD reflects how the subject reacts to difficulty by accelerating (RD < 0) or decelerating (RD > 0). Thus we provide here a first proof of concept: the ability to measure four axes of the speed-precision trade-off inherent in a subject’s fundamental decision making: perceptual-motor speed, executive speed, subject accuracy, and reaction to difficulty.

Behavioral and Physical Activity Interventions for HAND

Approximately 30-50% of persons living with HIV manifest some degree of neurocognitive impairment. Even mild-to-moderate forms of HIV-associated neurocognitive disorders (HAND) can result in difficulties with everyday functioning, such as suboptimal medication adherence and impaired driving. Despite the pervasive presence and consequences of HAND, there is a significant unmet need to develop effective behavioral strategies to reduce the incidence and consequences of HAND. Although there is an absence of evidence-based behavioral interventions specific to HAND, the literature reviewed in this chapter suggest the following modifiable lifestyle factors as intervention targets: physical activity, diet, sleep, and antiretroviral medication adherence. Adoption and maintenance of these healthy lifestyle factors may reduce inflammation and oxidative stress, which, in turn, may reduce the incidence and/or severity of HAND.

Incidence of Neurological Disorders Among HIV-Infected Individuals With Universal Health Care in Taiwan From 2000 to 2010

OBJECTIVE

To determine the incidence of and factors associated with neurological disorders in a large Taiwanese cohort of HIV-infected persons with free access to highly active antiretroviral therapy (HAART).

DESIGN

A retrospective population-based cohort study was conducted using the National Health Insurance Research Database for the years 2000-2010.

METHODS

We identified 13,316 HIV-positive persons from 2000 through 2010. We used direct standardization to calculate age-adjusted and sex-adjusted incidence rates based on the 2000 World Health Organization world standard population. Factors associated with neurological disorders were analyzed using a Cox proportional hazards model.

RESULTS

The standardized incidence of neurological disorders among HIV-infected persons increased from 22.16 per 1000 person-years in 2000 to 25.23 per 1000 person-years in 2010. Cognitive disorders increased significantly from 0.36 per 1000 person-years in 2001 to 7.44 per 1000 person-years in 2010 (trend P < 0.001). The rate of neurological disorders increased with age ≥55 years [adjusted hazard ratios (AHRs) 2.54, 95% confidence interval (CI): 1.89 to 3.40], hypertension (AHR 1.41, 95% CI: 1.12 to 1.76), substance abuse (AHR 1.65, 95% CI: 1.36 to 2.02), opportunistic infection (AHR 1.76, 95% CI: 1.47 to 2.11), syphilis (AHR 1.27, 95% CI: 1.10 to 1.47), and emergency department visits >5 (AHR 2.41, 95% CI: 1.96 to 2.97). The incidence of neurological disorders was negatively associated with adherence to HAART (adherence ≥85% AHR: 0.79, 95% CI: 0.64 to 0.97).

CONCLUSIONS

The rising incidence of cognitive disorders among HIV-positive persons highlights the need to provide routine neurological evaluations at clinical visits. Receiving HAART with adherence ≥85% contributes to a reduced risk of neurological disorders.

Lower CSF Aβ is Associated with HAND in HIV-Infected Adults with a Family History of Dementia

BACKGROUND

Both family history of dementia (FHD) and lower levels of Aβ-42 are indepentently associated with worse neurocognitive functioning in HIVinfected patients.

OBJECTIVE

To examine the relationships between cerebrospinal fluid (CSF) Aβ-42 and FHD with HIV-associated neurocognitive disorders (HAND).

METHODS

One hundred eighty-three HIV+ adults underwent neuropsychological and neuromedical assessments, and determination of CSF Aβ-42 concentration and FHD (defined as a self-reported first or second-degree relative with a dementia diagnosis). Univariate analyses and multivariable logistic regressions were used.

RESULTS

FHD was not associated with HAND (p = 0.24); however, CSF Aβ-42 levels were lower (p = 0.03) in the HAND group, but were not associated with FHD (p = 0.89). Multivariable models showed a main effect of CSF Aβ-42 (p = 0.03) and a trend-level (p = 0.06) interaction between FHD and CSF Aβ-42, such that lower CSF Aβ-42 was associated with HAND in those with FHD (p < 0.01) compared to those without FHD (p = 0.83). An analysis in those with follow-up data showed that higher baseline CSF Aβ-42 was associated with lower risk of neurocognitive decline (p = 0.02). While we did not find an FHD X CSF Aβ-42 interaction (p = 0.83), when analyses were stratified by FHD, lower CSF Aβ-42 was associated at the trend-level with neurocognitive decline in the FHD group (p = 0.08) compared to the no FHD group (p = 0.15).

CONCLUSION

FHD moderates the relationship between of CSF Aβ-42 and HAND. The findings highlight the complexities in interpreting the relationships between biomarkers of age-related neurodegeneration and HAND.

Untangling the Gordian knot of HIV, stress, and cognitive impairment

As individuals live longer with HIV, this "graying of the HIV epidemic" has introduced a new set of challenges including a growing number of age and inflammation-related diseases such as cardiovascular disease, type II diabetes, cancer, and dementia. The biological underpinnings of these complex and co-morbid diseases are not fully understood and become very difficult to disentangle in the context of HIV and aging. In the current review we examine the contributions and interactions of HIV, stress, and cognitive impairment and query the extent to which inflammation is the linchpin in these dynamic interactions. Given the inter-relatedness of stress, inflammatory mechanisms, HIV, and cognitive impairment, future work will either need to address multiple dimensions simultaneously or embrace the philosophy that breaking the aberrant cycle at any one point will subsequently remedy the other related systems and processes. Such a single-point intervention may be effective in early disease states, but after perpetuation of an aberrant cycle, adaptations in an attempt to internally resolve the issue will likely lead to the need for multifaceted interventions. Acknowledging that HIV, inflammation, and stress may interact with one another and collectively impact cognitive ability is an important step in fully understanding an individual's complete clinical picture and moving towards personalized medicine.

Executive Dyscontrol of Learning and Memory: Findings from a Clade C HIV-positive South African Sample

OBJECTIVE

Although pre-clinical work suggests there might be differences in neurovirulence across HIV-1 clades, few studies investigate neuropsychological deficits in the globally predominant clade C infection. The purpose of this study was to investigate verbal learning and memory performance in HIV-positive individuals in Cape Town, South Africa, where clade C is the most prevalent subtype of the virus.

METHOD

Using a case-control design, we recruited 53 isiXhosa-speaking, cART-naïve HIV-positive adults and 53 demographically matched HIV-negative controls. Participants were administered a comprehensive neuropsychological test battery. The test of interest was the Hopkins Verbal Learning Test-Revised (HVLT-R); previous studies have used that instrument to identify executive dyscontrol of verbal learning and memory processes in clade B HIV-positive participants.

RESULTS

HIV-positive participants showed only partial impairment on the HVLT-R's learning/memory components (e.g., they recalled significantly fewer words across learning trials, but displayed relatively intact performance on delayed recall trials). They also displayed little executive dyscontrol over encoding and retrieval processes (e.g., there were no significant between-group differences on measures of semantic or serial clustering).

CONCLUSIONS

Post-cART era studies suggest that verbal learning and memory performance is impaired in clade B samples, at least partially due to executive dyscontrol over encoding and retrieval processes. We found few such impairments in the current clade C sample. These preliminary findings suggest different CNS vulnerability across clades that would have implications for delineating clade-specific neuropathological and neurocognitive clinical features.

Reward, attention, and HIV-related risk in HIV+ individuals

Human immunodeficiency virus (HIV) is often contracted through engaging in risky reward-motivated behaviors such as needle sharing and unprotected sex. Understanding the factors that make an individual more vulnerable to succumbing to the temptation to engage in these risky behaviors is important to limiting the spread of HIV. One potential source of this vulnerability concerns the degree to which an individual is able to resist paying attention to irrelevant reward information. In the present study, we examine this possible link by characterizing individual differences in value-based attentional bias in a sample of HIV+ individuals with varying histories of risk-taking behavior. Participants learned associations between experimental stimuli and monetary reward outcome. The degree of attentional bias for these reward-associated stimuli, reflected in their ability to capture attention when presented as task-irrelevant distractors, was then assessed both immediately and six months following reward learning. Value-driven attentional capture was related to substance abuse history and non-planning impulsiveness during the time leading up to contraction of HIV as measured via self-report. These findings suggest a link between the ability to ignore reward-associated information and prior HIV-related risk-taking behavior. Additionally, particular aspects of HIV-associated neurocognitive disorders were related to attentional bias, including motor deficits commonly associated with HIV-induced damage to the basal ganglia.

Proteinuria is associated with neurocognitive impairment in antiretroviral therapy treated HIV-infected individuals

BACKGROUND

Proteinuria is a marker of vascular dysfunction that predicted increased cardiovascular mortality and is associated with neurocognitive impairment (NCI) in population-based studies. We examined associations between proteinuria and HIV-associated NCI.

METHODS

Multivariable logistic regression was used to examine associations between NCI at the first neurocognitive assessment (baseline) and simultaneous, clinically significant proteinuria [as random spot urine protein-to-creatinine ratios (UP/Cr) ≥200 mg/g] in a prospective multicenter observational cohort study. Generalized estimating equations were used to examine associations between baseline proteinuria and subsequent NCI among subjects without NCI at baseline. NCI was defined as a Z-score, derived from the combination of normalized scores from the Trailmaking A and B and the Wechsler Adult Intelligence Scale-Revised Digit Symbol tests.

RESULTS

A total of 1972 subjects were included in this analysis. Baseline proteinuria was associated with increased odds of NCI [odds ratio (OR): 1.41, 95% confidence interval (CI): 1.08 to 1.85; P = 0.01] and with subsequent NCI among subjects without NCI at baseline (OR: 1.39, 95% CI: 1.01 to 1.93; P = 0.046) in multivariable models adjusted for risk factors and potential confounders. Similar associations were evident when these analyses were limited to visits at which time study subjects maintained plasma HIV RNA levels <200 copies per milliliter.

CONCLUSIONS

The association between proteinuria and NCI observed in this study adds to a growing body of evidence implicating contributions by vascular disease to NCI in antiretroviral treated individuals. Studies examining interventions that improve vascular function are warranted.

Memory Performance in HIV/AIDS - A Prospective Case Control Study

Background:

Memory impairment, usually impaired retrieval of information, has been described in HIV/AIDS, especially among those with severe illness. Neuro-cognitive disturbances in HIV/AIDS have been linked to poor quality of life and medication adherence. This prospective, case-control study was designed to assess the verbal and non-verbal memory as well as the attention abilities of Nigerian Africans with HIV/AIDS and correlate their performances with their CD4+ T lymphocytes (CD4+) counts.

Methods:

A total of 288 randomly selected subjects, comprising 96 HIV-positive symptomatic patients, 96 HIV-positive asymptomatic patients and 96 HIV-negative controls, participated in the study. The subjects were age-, sex-, and level of education matched. The Recognition Memory Test and Choice Reaction Time tasks, components of the computer-assisted neuropsychological tests battery- the Iron Psychology ‘FePsy’ were used for cognitive assessments.

Results:

The mean memory scores of the HIV-positive asymptomatic subjects did not differ significantly from the controls (p>0.05) but the HIV-positive symptomatic subjects' scores were significantly lower than the controls (p<0.05). Both HIV-positive groups had psychomotor slowing and impaired attention (p<0.05). The HIV-positive subjects with CD4+ counts <200/μl and between 200 and 499/μl had significant memory impairment (p<0.001 and p<0.001 respectively) but there was no significant impairment among those with count ≥500/μl. Impaired ability for sustained attention was however present irrespective of the CD4+ level relative to controls (p<0.001).

Conclusions:

We concluded that there was no significant memory disturbance among HIV-positive asymptomatic subjects despite the presence of impaired attention and psychomotor slowing, and that the severity of immune suppression (as indicated by the CD4+ T lymphocytes count) is a strong determinant of cognitive decline in HIV/AIDS.

Regional cerebral blood flow and FDG uptake in asymptomatic HIV-1 men

Despite advances in the treatment of patients with human immunodeficiency virus (HIV), HIV-associated neurocognitive disorder occurs in 15-50% of HIV-infected individuals, and may become more apparent as ageing advances. In the present study we investigated regional cerebral blood flow (rCBF) and regional cerebral metabolic rate of glucose uptake (rCMRglc) in medically and psychiatrically stable HIV-1-infected participants in two age-groups. Positron emission tomography (PET) and magnetic resonance imaging (MRI)-based arterial spin labeling (ASL) were used to measure rCMRglc and rCBF, respectively, in 35 HIV-infected participants and 37 HIV-negative matched controls. All participants were currently asymptomatic with undetectable HIV-1 viral loads, without medical or psychiatric comorbidity, alcohol or substance misuse, stable on medication for at least 6 months before enrolment in the study. We found significant age effects on both ASL and PET with reduced rCBF and rCMRglc in related frontal brain regions, and consistent, although small, reductions in rCBF and rCMRglc in the anterior cingulate cortex (ACC) in HIV, a finding of potential clinical significance. There was no significant interaction between HIV status and the ageing process, and no significant HIV-related changes elsewhere in the brain on PET or ASL. This is the first paper to combine evidence from ASL and PET method in HIV participants. These finding provide evidence of crossvalidity between the two techniques, both in ageing and a clinical condition (HIV).

Does antiretroviral therapy improve HIV-associated cognitive impairment? A quantitative review of the literature

The development of antiretroviral therapy (ART) has dramatically improved survival for those living with human immunodeficiency virus (HIV), but whether ART improves cognitive functioning remains unclear. The aim of the present review was to examine systematically the extent to which ART improves cognition among individuals with HIV using meta-analytic methods. Twenty-three studies were included in the quantitative review. ART was associated with modest improvements in attention (mean d = .17; p < .001; 95% confidence interval [CI], .09/.25), executive function (mean d = .18; p < .001; 95% CI, .10/.26), and motor function (mean d = .24; p < .001; 95% CI, .16/.32). ART did not improve language, verbal memory, visual memory or visuospatial function. The extent to which cognition improved was correlated with the change in CD4 cell count following ART, suggesting a link between cognitive outcome and immune system integrity. Together, the present findings indicate that the neuropsychological test performance of most HIV patients taking ART is comparable to those not taking ART. Development of pharmaceutical treatments and rehabilitation strategies that target the cognitive effects of HIV infection is needed.

Regional cortical thinning associated with detectable levels of HIV DNA

High levels of human immunodeficiency virus (HIV) DNA in peripheral blood mononuclear cells (PBMCs), and specifically within CD14+ blood monocytes, have been found in HIV-infected individuals with neurocognitive impairment and dementia. The failure of highly active antiretroviral therapy (HAART) to eliminate cognitive dysfunction in HIV may be secondary to persistence of HIV-infected PBMCs which cross the blood-brain barrier, leading to perivascular inflammation and neuronal injury. This study assessed brain cortical thickness relative to HIV DNA levels and identified, we believe for the first time, a neuroimaging correlate of detectable PBMC HIV DNA in subjects with undetectable HIV RNA. Cortical thickness was compared between age- and education-matched groups of older (>40 years) HIV-seropositive subjects on HAART who had detectable (N = 9) and undetectable (N = 10) PBMC HIV DNA. Statistical testing revealed highly significant (P < 0.001) cortical thinning associated with detectable HIV DNA. The largest regions affected were in bilateral insula, orbitofrontal and temporal cortices, right superior frontal cortex, and right caudal anterior cingulate. Cortical thinning correlated significantly with a measure of psychomotor speed. The areas of reduced cortical thickness are key nodes in cognitive and emotional processing networks and may be etiologically important in HIV-related neurological deficits.

Effects of highly active antiretroviral therapy on cognitive functions in severely immune-compromised HIV-seropositive patients

OBJECTIVE

This study assessed the effects of highly active antiretroviral therapy on the cognitive performances of HIV seropositive patients with severe immune depression.

METHODS

It is a prospective longitudinal interventional study of 69 anti-retroviral naïve HIV-seropositive adult patients with CD4 levels ≤ 350/μl. The cognitive assessment was done at initiation and 12 months after anti-retroviral treatment using the Community Screening Instrument for Dementia (CSID) and the computer-assisted Iron Psychology (FePsy). The impact of therapy on CD4 levels and cognitive scores of the patients before and after therapy were compared and tested for statistical significance using Student t test and one-way ANOVA.

RESULTS

The mean age of the patients was 36.6 ± 8.8 years. There was a significant increase in CD4 levels of the patients from 144.75 ± 88.92 at baseline to 295.91 ± 148.79 after 12 months of HAART (p<0.0001). There were significant improvements in their cognitive scores (p<0.05) in all cognitive domains tested but the finger tapping task (motor speed) did not show any improvement (p>0.05). Combination ARV drugs with efavirenz did not significantly improve attention and choice reaction time.

CONCLUSION

Highly active antiretroviral therapy significantly improved the CD4 levels and cognitive performances of treated HIV positive patients in all tested domains with the exception of motor speed.

Impact of social support on cognitive symptom burden in HIV/AIDS

As many as 50% of people living with HIV/AIDS report cognitive difficulties, which can be associated with objective neuropsychological impairments and depression. A number of studies have demonstrated an association between higher social support and lower rates of depression. Using a cross-sectional design, we examined the role social support may play in attenuating the effects of both neuropsychological status and depression on cognitive difficulties. A total of 357 participants completed a battery of neuropsychological tests, questionnaires about cognitive difficulties and depression, and an interview that included an assessment of perceived level of social support. A multivariate linear regression analysis revealed that higher levels of cognitive symptom burden were significantly associated with depression (P<0.05) while lower levels of cognitive symptom burden were significantly associated with greater social support (P<0.01) and higher level of education (P<0.05). There was a significant interaction between neuropsychological status and depression (P<0.001); the presence of neuropsychological impairment with depression was associated with higher levels of cognitive symptom burden. There was also a significant interaction between social support and depression (P<0.05). Interestingly, social support was also associated with a lower cognitive symptom burden for non-depressed individuals living with HIV/AIDS. These findings have important clinical implications for promoting psychological well-being in persons living with HIV/AIDS. To improve quality of life, it is important to screen for and identify individuals with HIV/AIDS who may be depressed and to intervene appropriately. Further research should examine the potential role of social support interventions in modifying the effects of both depression and neuropsychological status on cognitive symptom burden.

Insulin resistance in treated HIV infection

Insulin resistance (IR) was one of the first metabolic complications reported with highly active antiretroviral therapy for HIV infection. It continues to be of concern despite the introduction of newer antiretrovirals with safer metabolic profiles and is associated with inflammation and the development of diabetes mellitus. As the HIV-infected population ages, the prevalence of IR is likely to rise. Specific antiretrovirals can increase insulin resistance through two principal mechanisms, either directly by interfering with insulin signalling at the cellular level or indirectly as a consequence of defects in lipid metabolism (lipotoxocity) arising from antiretroviral toxicities such as the IR observed in those with HIV-associated lipodystrophy. There is considerable overlap between different antiretrovirals in their propensity to cause IR making it more difficult to attribute development of IR to a particular antiretroviral medication. In addition, in the setting of a generalised epidemic of obesity that exists in many populations worldwide, HIV-infected patients may be more prone to the consequences of antiretroviral-induced insulin resistance and diabetes mellitus. Optimal screening and treatment strategies for IR in treated HIV infection have not been established. In this article we review current opinion on insulin resistance in HIV and identify potential areas for future research.

The relationship between indoleamine 2,3-dioxygenase activity and post-stroke cognitive impairment

BACKGROUND

Activation of indoleamine 2,3-dioxygenase (IDO) and higher concentrations of several kynurenine metabolites have been observed post-stroke, where they have been associated with increased mortality. While lower tryptophan or a higher ratio of kynurenine/tryptophan (K/T) in peripheral blood have been associated with dementia and the severity of cognitive symptoms in Alzheimer's disease, the association between K/T ratios and post-stroke cognitive impairment (PSCI) has not been investigated.

METHODS

Patients were recruited from the acute stroke unit of a general hospital within 1 month post-stroke. Assessments included the Standardized Mini-Mental State Examination (sMMSE) for cognition, the National Institutes of Health Stroke Scale (NIHSS) for stroke severity, and the Center for Epidemiological Studies-Depression Scale (CES-D) for depressive symptoms. Tryptophan and kynurenine concentrations were determined by high-performance liquid chromatography.

RESULTS

A total of 41 patients with ischemic stroke ([mean ± SD] age 72.3 ± 12.2 years, 53.7% male, sMMSE 25.6 ± 4.1, NIHSS 7.27 ± 5.55) were recruited. Higher K/T ratios were associated with lower post-stroke global cognition (i.e. sMMSE scores; β = -.327, P = .037). A backward stepwise elimination linear regression (F1,40=6.15, P=.005, adjusted R2=.205) showed that the highest K/T ratio tertile (β = -.412, P = .006) predicted lower sMMSE scores, controlling for age (β = -.253, p = .081), with NIHSS (β = -.027, P = 0.859), and lesion volume (β = -.066, P = 0.659) removed from the model. In receiver operating characteristic analysis, a K/T ratio of 78.3 μmol/mmol (top tertile) predicted significant cognitive impairment (sMMSE score ≤ 24) with 67% sensitivity and 86% specificity (area under the curve = 0.730, p = .022).

CONCLUSIONS

These data suggest an inflammatory response characterized by IDO activation may be relevant to the development of PSCI. Since the neuroactivity of kynurenine metabolites may be amenable to pharmacotherapeutic intervention, the K/T ratio may be a clinically important biomarker.

Family history of dementia predicts worse neuropsychological functioning among HIV-infected persons

HIV-negative individuals with a family history of dementia (FHD) are more likely to develop dementia than those without FHD. Whether FHD increases risk for neuropsychological (NP) impairment in HIV+ persons is unknown. As part of a multisite study into HIV-associated neurocognitive disorders (HAND), the authors captured FHD with a free-response, self-report question, and assessed NP performance with a comprehensive battery of tests. The authors examined HIV+ persons with (N=190) and without (N=916) self-reported FHD. Despite the fact that the FHD group had factors typically associated with better NP performance (e.g., higher CD4 counts and estimated verbal IQ), persons with FHD had significantly worse NP ability than those without FHD as measured by a Global Deficit Score. Thus, FHD appears to be a risk factor for HAND; the mechanism(s) underlying how FHD contributes to NP impairment among HIV+ persons warrants study.

Does highly active antiretroviral therapy improve neurocognitive function? A systematic review

Highly active antiretroviral therapy (HAART) reduces the incidence of human immunodeficiency virus (HIV) dementia (HAD), whereas the overall prevalence appears to have increased. Recent changes to diagnostic nosology have emphasized the presence of neurocognitive deficits. Uniform methods of ascertaining neuropsychological impairment and excluding confounding causes are critical to between-study comparison. We conducted a systematic review on all studies that use single-cohort prospective treatment effect design that reported on the neurocognitive or neuropsychological profile of individuals commencing HAART. Fifteen 15 relevant studies were included. A large number of studies using observational or cross-sectional designs were excluded, as these do not allow for a within-subject description of pre- and post-HAART predictive factors. Eleven studies reported a significant improvement in neurocognitive status or neuropsychological profile over an average study period of 6 months. Variable or nonreporting of HAART regimens in these studies did not allow for an analysis of individual agent or regimen effectiveness. The results show that although HAART does improve cognition, it does not appear to fully eradicate impairments. The methods used in this research differ widely and therefore comparison across studies is difficult. Studies examining the long-term effects of HAART on HIV-associated neurocognitive disorders (HANDs) using uniform methods of data collection are needed, together with clear reporting of HAART regimens.

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.

Depression and symptomatic response among HIV-infected drug users enrolled in a randomized controlled trial of directly administered antiretroviral therapy

BACKGROUND

Depression is highly prevalent among HIV-infected injection drug users (IDUs) and has been associated with poor adherence to antiretroviral therapy and increased morbidity and mortality. Factors associated with changes in depressive symptoms among this group receiving antiretroviral treatment that have not been extensively evaluated.

METHODS

This post-hoc analysis of prospective clinical trial analyzes the factors associated with changes in depressive symptomatology using the Center for Epidemiologic Studies of Depression Scale (CES-D) among HIV-infected IDUs enrolled in a prospective, six months randomized controlled trial of directly administered antiretroviral therapy (DAART) versus self-administered therapy.

RESULTS

Of the 127 evaluable IDUs enrolled in the study, 89 subjects (70%) had complete six-month follow-up data. Of these, 58 (63%) met baseline criteria for severe or major depressive disorder (MDD) using the CES-D. CES-D scores improved significantly from baseline to six months overall for the 89 subjects (p=0.01) and for the 58 who had MDD with six-month data (p=0.001). Using multiple regression, an improvement in CES-D score was independently associated with: (1) increase in CD4 count; (2) increase in adherence; (3) non-Caucasian race; and (4) older age. Worsening in CES-D score was associated with: (1) increase in HIV-1 RNA levels; (2) homelessness; (3) poor self-efficacy; (4) active drug use; and (5) male gender. Factors not correlated with changes in CES-D were receipt of DAART, engagement in drug treatment, use of antidepressant medication, and employment. Using generalized estimating equation modeling, factors that remained positively associated with improvements in CES-D score were absence of drug use at six months, having housing, higher self-efficacy, increase in CD4 count and increases in adherence.

CONCLUSION

Improvements in depressive symptoms could occur with improvement of alterable factors that are associated with strengthening adherence such as linkages to case management, mental health and substance abuse treatment services as well as through enhancement of social stabilization factors through social support and supportive housing.

[Neurocognitive disorders related to human immunodeficiency virus infection]

Disruption of neurocognitive functioning is one of most frequent complications in patients with HIV infection nowadays. The Highly Active Antiretroviral Therapy (HAART) has demonstrated an improvement associated with its use, although there are different works that show this improvement is achieved in a low proportion of individuals who initiate therapy. The most known characterization of neurocognitive dysfunction is the HIV-associated Dementia (HAD), yet there may also exist the asymptomatic neurocognitive impairment (ANI) or the Minor Cognitive-Motor Disorder (MCMD). This review describes the disorders related to HIV infection, and comments on possible interventions focused on the protection of neurocognitive functioning in HIV-infected people.

Functional consequences of HIV-associated neuropsychological impairment

This review focuses on the "real world" implications of infection with HIV/AIDS from a neuropsychological perspective. Relevant literature is reviewed which examines the relationships between HIV-associated neuropsychological impairment and employment, driving, medication adherence, mood, fatigue, and interpersonal functioning. Specifically, the relative contributions of medical, cognitive, psychosocial, and psychiatric issues on whether someone with HIV/AIDS will be able to return to work, adhere to a complicated medication regimen, or safely drive a vehicle will be discussed. Methodological issues that arise in the context of measuring medication adherence or driving capacity are also explored. Finally, the impact of HIV/AIDS on mood state, fatigue, and interpersonal relationships are addressed, with particular emphasis on how these variables interact with cognition and independent functioning. The purpose of this review is to integrate neuropsychological findings with their real world correlates of functional behavior in the HIV/AIDS population.

Neuropsychological functioning and antiretroviral treatment in HIV/AIDS: a review

This article presents a review of studies that have investigated the neuropsychological effects of antiretroviral treatment (ART) for HIV-1 infection. It provides a brief overview of the era of monotherapy, dual-therapy, and an extended overview of the current era of combination antiretroviral therapy (CART). This review highlights that while CART has had a dramatic effect on the incidence and the severity of HIV-associated neurocognitive disorders (HAND), HAND, in its mild form, still remains prevalent. New causes of this sustained prevalence are poor CNS penetration of some antiretroviral agents, drug resistance, poor adherence, potential neurotoxicity, co-morbidities such as the long-term CART side effects in relation to cardio-vascular disease, and chronic HIV brain infection that may facilitate the expression of new forms of neurodegenerative processes. The review emphasizes the need to address methodological limitations of published studies and the need for large and representative cross-disciplinary longitudinal investigations across the HIV illness span.

Aging, neurocognition, and medication adherence in HIV infection

OBJECTIVE

To evaluate the hypothesis that poor adherence to highly active antiretroviral treatment (HAART) would be more strongly related to cognitive impairment among older than among younger HIV-seropositive adults.

SETTING AND PARTICIPANTS

A volunteer sample of 431 HIV-infected adult patients prescribed self-administered HAART was recruited from community agencies and university-affiliated infectious disease clinics in the Los Angeles area.

MEASUREMENTS

Neurocognitive measures included tests of attention, information processing speed, learning/memory, verbal fluency, motor functioning, and executive functioning. Medication adherence was measured using microchip-embedded pill bottle caps (Medication Event Monitoring System) and self-report. Latent/structural analysis techniques were used to evaluate factor models of cognition and adherence.

RESULTS

Mean adherence rates were higher among older (>or=50 years) than younger (<50 years) HIV-positive adults. However, latent/structural modeling demonstrated that neurocognitive impairment was associated with poorer medication adherence among older participants only. When cognitive subdomains were examined individually, executive functioning, motor functioning, and processing speed were most strongly related to adherence in this age group. CD4 count and drug problems were also more strongly associated with adherence among older than younger adults.

CONCLUSIONS

Older HIV-positive individuals with neurocognitive impairment or drug problems are at increased risk of suboptimal adherence to medication. Likewise, older adults may be especially vulnerable to immunological and neurocognitive dysfunction under conditions of suboptimal HAART adherence. These findings highlight the importance of optimizing medication adherence rates and evaluating neurocognition in the growing population of older HIV-infected patients.

Kynurenine pathway metabolites in humans: disease and healthy States

Tryptophan is an essential amino acid that can be metabolised through different pathways, a major route being the kynurenine pathway. The first enzyme of the pathway, indoleamine-2,3-dioxygenase, is strongly stimulated by inflammatory molecules, particularly interferon gamma. Thus, the kynurenine pathway is often systematically up-regulated when the immune response is activated. The biological significance is that 1) the depletion of tryptophan and generation of kynurenines play a key modulatory role in the immune response; and 2) some of the kynurenines, such as quinolinic acid, 3-hydroxykynurenine and kynurenic acid, are neuroactive. The kynurenine pathway has been demonstrated to be involved in many diseases and disorders, including Alzheimer's disease, amyotrophic lateral sclerosis, Huntington's disease, AIDS dementia complex, malaria, cancer, depression and schizophrenia, where imbalances in tryptophan and kynurenines have been found. This review compiles most of these studies and provides an overview of how the kynurenine pathway might be contributing to disease development, and the concentrations of tryptophan and kynurenines in the serum, cerebrospinal fluid and brain tissues in control and patient subjects.

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.

Cognitive performance and the thymus among HIV-infected subjects receiving HAART

OBJECTIVE

To evaluate the impact of alcohol use, which is widespread in human immunodeficiency virus (HIV)+ individuals, on highly active antiretroviral therapy (HAART)-associated immune and cognitive improvements and the relationship between those two responses.

METHODS

In a case-control longitudinal study, thymic volume, cognition, and immune responses were evaluated at baseline and after 6 months therapy in HIV+ and HIV- controls. Cognitive performance was evaluated using the HIV Dementia Score (HDS) and the California Verbal Learning Test (CVLT).

RESULTS

Prior to HAART, thymic volume varied considerably from 2.7 to 29.3 cm(3) (11 +/- 7.2 cm(3)). Thymic volume at baseline showed a significantly inverse correlation with the patient's number of years of drinking (r(2) = 0.207; p < 0.01), as well as HDS and the CVLT scores in both HIV-infected (r(2) = 0.37, p = 0.03) and noninfected (r(2) = 0.8, p < 0.01). HIV-infected individuals with a small thymic volume scored in the demented range, as compared with those with a larger thymus (7 +/- 2.7 vs. 12 +/- 2.3, p = 0.005). After HAART, light/moderate drinkers exhibited thymus size twice that of heavy drinkers (14.8 +/- 10.4 vs. 6.9 +/- 3.3 cm(3)).

CONCLUSIONS

HAART-associated increases of thymus volume appear to be negatively affected by alcohol consumption and significantly related to their cognitive status. This result could have important clinical implications.

Neurocognitive disturbances in HIV

HIV infection is associated with disturbances in brain function which reflect themselves in HIV associated neurocognitive disorder (HAND). Neurocognitive examination is a sensitive and relevant approach to detecting and monitoring HAND. The approaches to evaluating the various neurocognitive disturbances are reviewed, along with consideration of cofactors that may influence expression of these disorders.

HIV suppression by HAART preserves cognitive function in advanced, immune-reconstituted AIDS patients

INTRODUCTION

HIV can damage neurons leading to cognitive impairment. Epidemiological observations suggest that neuropsychological impairment might progress despite successful HAART therapy, but available prevalence estimates are based on populations that were selected for impairment.

METHODS

Of 433 advanced AIDS patients with documented immune reconstitution (CD4 lymphocyte counts < 50 before and > 100 cells/microl after HAART), 286 had brief assessments of cognition (Trailmaking A/B and Digit Symbol Tests) at least once, no confounding neurological conditions, and available neuropsychological norms with comprehensive demographic corrections. At entry, most were immune reconstituted on HAART (median CD4 cell count 230 cells/microl) and HIV was suppressed (65% < 500; only 14% > 20 000 RNA copies/ml).

RESULTS

Over one quarter (27%) of participants exhibited impairment at their initial neuropsychological assessment, a rate nearly twice that expected in a normal (HIV-uninfected) reference population (14%). These impaired participants did not differ from the unimpaired group with respect to age, sex, education, race, CD4 lymphocyte counts, or HIV-RNA levels. Improved performance on neuropsychological tests was documented over a 2-year period 3-5 years after initiating HAART. This improvement was marginally associated with the continued or improving control of plasma HIV-RNA levels, but not with concurrent levels of immune recovery (CD4 lymphocyte counts).

CONCLUSION

Most advanced AIDS patients responding to HAART for prolonged periods have stable or improving cognition, but remain more likely to be impaired than the general population. During HAART, improving test performance probably reflects both practice effects and continuing neurological recovery after more than 3 years of HAART.

HIV and antiretroviral therapy in the brain: neuronal injury and repair

Approximately 40 million people worldwide are infected with human immunodeficiency virus (HIV). Despite HIV's known propensity to infect the CNS and cause neurological disease, HIV neurocognitive disorders remain under-recognized. Although combination antiretroviral therapy has improved the health of millions of those living with HIV, the penetration into the CNS of many such therapies is limited, and patients' quality of life continues to be diminished by milder, residual neurocognitive impairment. Synaptodendritic neuronal injury is emerging as an important mediator of such deficits in HIV. By carefully selecting specific antiretrovirals and supplementing them with neuroprotective agents, physicians might be able to facilitate innate CNS repair, promoting enhanced synaptodendritic plasticity, neural function and clinical neurological status.

Effects of highly active antiretroviral therapy (HAART) on psychomotor performance in children with HIV disease

OBJECTIVE

This study assesses the effects of HAART on psychomotor performance of symptomatic HIV-infected children. It is one of the first studies to look at neurobehavioral functioning in children infected with HIV in resource-limited countries.

DESIGN

A longitudinal pilot study of vertically HIV-infected children at the HIV Netherlands Australia Thailand Research Collaboration Center in Bangkok, Thailand.

METHODS

A total of 34 children participated in the study of whom 16 had never received antiretroviral (ARV) therapy and were about to start HAART (Newly treated children), 7 did not receive antiretroviral therapy (Untreated children) and 11 had been treated with HAART for more than one year (HAART experienced children). All children were administered 4 psychomotor tasks at baseline and after 4 months. The Newly treated and the Untreated children were also evaluated after 12 months.

RESULTS

In general, the children performed similarly on all psychomotor tasks at baseline. After 12 months of HAART, there was a significant increase in CD4% in the Newly treated group. Overall, psychomotor performance did not change at the 4-month evaluation in all groups. At the 12-month evaluation psychomotor performance had deteriorated substantially on all tasks in both the Newly treated and the Untreated children.

CONCLUSIONS

There was no significant difference in psychomotor functioning between children newly treated, previously treated and untreated with HAART over the course of one year. Psychomotor performance deteriorated after 12 months of HAART, which provides important indications concerning the lack of benefits of HAART on psychomotor functions in children despite immunologic reconstitution. Further research with larger sample sizes is needed to confirm these findings.

Neurocognitive aspects of medication adherence in HIV-positive injecting drug users

Cognitive deficits are associated with nonadherence to HIV medications. HIV-positive injecting drug users (IDUs) are at particular risk for nonadherence and cognitive barriers to adherence specific to this population should therefore be identified. The present study assessed the relation of three domains of cognitive functioning, executive functions, memory, and psychomotor speed, to self-reported antiretroviral adherence in a sample of HIV-positive IDUs. Depression, use of alcohol, heroin, cocaine/crack, or marijuana in the last week were also included in the models. Logistic regression analyses showed that only psychomotor slowing was significantly associated with nonadherence. Executive functions, memory, depression, and active alcohol and substance use were unrelated to adherence. No other studies to date have exclusively linked psychomotor slowing to nonadherence in HIV infection. Psychomotor slowing among our study sample was severe and suggests that when evident, such slowing may be a valuable determinant for antiretroviral adherence among IDUs.

Changing patterns in the neuropathogenesis of HIV during the HAART era

Rapid progress in the development of highly active antiretroviral therapy has changed the observed patterns in HIV encephalitis and AIDS-related CNS opportunistic infections. Early in the AIDS epidemic, autopsy studies pointed to a high prevalence of these conditions. With the advent of nucleoside reverse transcriptase inhibitors, the prevalence at autopsy of opportunistic infections, such as toxoplasmosis and progressive multifocal leukoencephalopathy, declined while that of HIV encephalitis increased. After the introduction of protease inhibitors, a decline in both HIV encephalitis and CNS opportunistic infections was observed. However, with the increasing resistance of HIV strains to antiretrovirals, there has been a resurgence in the frequency of HIV encephalitis and HIV leukoencephalopathy. HIV leukoencephalopathy in AIDS patients failing highly active antiretroviral therapy is characterized by massive infiltration of HIV infected monocytes/macrophages into the brain and extensive white matter destruction. This condition may be attributable to interactions of anti-retrovirals with cerebrovascular endothelium, astroglial cells and white matter of the brain. These interactions may lead to cerebral ischemia, increased blood-brain barrier permeability and demyelination. Potential mechanisms of such interactions include alterations in host cell signaling that may result in trophic factor dysregulation and mitochondrial injury. We conclude that despite the initial success of combined anti-retroviral therapy, more severe forms of HIV encephalitis appear to be emerging as the epidemic matures. Factors that may contribute to this worsening include the prolonged survival of HIV-infected patients, thereby prolonging the brain's exposure to HIV virions and proteins, the use of increasingly toxic combinations of poorly penetrating drugs in highly antiretroviral-experienced AIDS patients, and selection of more virulent HIV strains with higher replication rates and greater virulence in neural tissues.

Molecular mechanisms of HIV-1 associated neurodegeneration

Since identification of the human immunodeficiency virus-1 (HIV-1), numerous studies suggest a link between neurological impairments, in particular dementia, with acquired immunodeficiency syndrome (AIDS) with alarming occurrence worldwide. Approximately, 60% of HIV-infected people show some form of neurological impairment, and neuropathological changes are found in 90% of autopsied cases. Approximately 30% of untreated HIV-infected persons may develop dementia. The mechanisms behind these pathological changes are still not understood. Mounting data obtained by in vivo and in vitro experiments suggest that neuronal apoptosis is a major feature of HIV associated dementia (HAD), which can occur in the absence of direct infection of neurons. The major pathway of neuronal apoptosis occurs indirectly through release of neurotoxins by activated cells in the central nervous system (CNS) involving the induction of excitotoxicity and oxidative stress. In addition a direct mechanism induced by viral proteins in the pathogenesis of HAD may also play a role. This review focuses on the molecular mechanisms of HIV-associated dementia and possible therapeutic strategies.

Monitoring tryptophan metabolism in chronic immune activation

The essential amino acid tryptophan is a constituent of proteins and is also a substrate for two important biosynthetic pathways: the generation of neurotransmitter 5-hydroxytryptamine (serotonin) by tryptophan 5-hydroxylase, and the formation of kynurenine derivatives and nicotinamide adenine dinucleotides. The latter pathway is initiated by the enzymes tryptophan pyrrolase (tryptophan 2,3-dioxygenase, TDO) and indoleamine 2,3-dioxygenase (IDO). TDO is located in liver cells, whereas IDO is expressed in a variety of cells including monocyte-derived macrophages and dendritic cells and is preferentially induced by Th1-type cytokine interferon-gamma. Tryptophan depletion via IDO is part of the cytostatic and antiproliferative activity mediated by interferon-gamma in cells. In vivo tryptophan concentration can be measured by HPLC by monitoring its natural fluorescence (285 nm excitation and 365 nm emission wavelength). IDO activity is characterized best by the kynurenine to tryptophan ratio which correlates with concentrations of immune activation markers such as neopterin. Low serum/plasma tryptophan concentration is observed in infectious, autoimmune, and malignant diseases and disorders that involve cellular (Th1-type) immune activation as well as during pregnancy due to accelerated tryptophan conversion. Thus, in states of persistent immune activation, low tryptophan concentration may contribute to immunodeficiency. Decreased serum tryptophan can also effect serotonin biosynthesis and thus contribute to impaired quality of life and depressive mood. As such, monitoring tryptophan metabolism in chronic immunopathology provides a better understanding of the association between immune activation and IDO and its role in the development of immunodeficiency, anemia and mood disorders.

Arthritic pain, aging, and psychomotor decline in people with HIV

Arthritic pain and subsequent immobility are common in people with Human Immunodeficiency Virus (HIV) and in persons of older ages. It is hypothesized that such pain may contribute to psychomotor impairment commonly observed with HIV and aging. Empirical evaluation of this hypothesis among older persons with HIV and consideration of treatment should be undertaken.

Histopathological and cognitive defects induced by Nef in the brain

Complex mechanisms of human immunodeficiency virus type-1 (HIV-1) brain pathogenesis suggest the contribution of individual HIV-1 gene products. Among them, the Nef protein has been reported to harbor a major determinant of pathogenicity in AIDS-like disease. The goal of the present study was to determine whether Nef protein expressed in vivo by primary macrophages could induce a brain toxicity also affecting the behavior of the rat. To achieve this goal we grafted Nef-transduced macrophages into the rat hippocampus. Two months post-transplantation, we observed that Nef induces monocyte/macrophage recruitment, expression of TNF-alpha, and astrogliosis. No apoptotic event was detected. We further demonstrated that Nef neurotoxicity is associated with cognitive deficits.

Prevalence and pattern of neuropsychological impairment in human immunodeficiency virus-infected/acquired immunodeficiency syndrome (HIV/AIDS) patients across pre- and post-highly active antiretroviral therapy eras: a combined study of two cohorts

The objective of this study was to assess the prevalence and pattern of neuropsychological impairment in cohorts of human immunodeficiency virus (HIV)-infected individuals across pre- and post-HAART (highly active antiretroviral therapy) eras. Two cohorts of HIV-infected individuals attending tertiary referral hospital outpatient clinics were studied. The cohorts represented two eras of antiretroviral medication: monotherapy (n = 51) and HAART (n = 90). Each was compared in nine neuropsychological domains in regard to the prevalence as well as pattern of neuropsychological impairment. Because the authors intended to characterize the prevalence and pattern of neuropsychological deficits in nondemented advanced HIV-infected individuals, patients with a current diagnosis of acquired immunodeficiency syndrome (AIDS) dementia complex were not included. The prevalence of impairment was not significantly different across pre-HAART and HAART eras using a standard criterion to define impairment: -2 SD in two neuropsychological measures (41.1%/38.8%). Prevalence of deficits was not significantly reduced in patients with undetectable plasma viral load. The pattern of neuropsychological impairment was different across pre-HAART and HAART eras, with an improvement in attention, verbal fluency, visuoconstruction deficits, but a deterioration in learning efficiency and complex attention. This change remained even in patients with an undetectable plasma viral load, although the severity was partially diminished. Neuropsychological deficits remain common in the HAART era, essentially uninfluenced by HAART. The finding that some neuropsychological functions are improving while other are deteriorating indicates that these deficits do not reflect "burnt out" damage but rather that there is an active intracerebral process occurring, the nature of which is still to be determined.

Cortical and subcortical dynamics of aging with HIV infection

Given pharmaceutical advancements, more people with HIV will be living to old age. Cognitive declines have been observed both during normal aging and in people with HIV; whether there are cumulative cognitive declines in adults aging with HIV remains unknown. Based on current literature, adults aging with HIV may be at risk for psychomotor declines that resemble parkinsonianism.

Impaired performance on a rhesus monkey neuropsychological testing battery following simian immunodeficiency virus infection

Infection with simian immunodeficiency virus (SIV) in macaques provides an excellent model of AIDS including HIV-induced central nervous system (CNS) pathology and cognitive/behavioral impairment. Recently a behavioral test battery has been developed for macaques based on the CANTAB human neuropsychological testing battery. As with human neuropsychological batteries, different tasks are thought to involve different neural substrates, and therefore performance profiles may assess function in particular brain regions. Ten rhesus monkeys were infected with SIV after being trained on two or more of the battery tasks addressing memory (delayed nonmatching to sample, DNMS), spatial working memory (using a self-ordered spatial search task, SOSS), motivation (progressive-ratio, PR), reaction time (RT), and/or fine motor skills (bimanual motor skill, BMS). Performance was compared to that of 9 uninfected monkeys. Overall, some aspect of performance was impaired in all 10 monkeys following infection. Consistent with results in human AIDS patients, individual performance was impaired most often on battery tasks thought to be sensitive to frontostriatal dopaminergic functioning such as SOSS, RT, and BMS. These results further demonstrate the similarity of behavioral impairment produced by SIV and HIV on homologous behavioral tests, and establish the utility of the testing battery for further investigations into the CNS mechanisms of the reported behavioral changes.

Neurocognitive performance and quality of life in patients with HIV infection

We examined the relationship of HIV-related cognitive impairment and health-related quality of life (QoL). Subjects were administered measures of cognitive function (a battery of 17 neuropsychological tests) and of QoL (the MOS-HIV questionnaire). Study measures also included comprehensive clinical and neurological evaluation, laboratory testing, and brain imaging studies in patients with impaired neuropsychological evaluation. One-hundred and eleven subjects were examined. Cognitively impaired patients (33.3%) reported poorer QoL scores in all domains (p < 0.05): physical health summary score (PHS) (44.6 vs. 49.9), mental health summary score (MHS) (37.7 vs. 44.4), pain (67.6 vs. 79.4), physical functioning (75.9 vs. 87.7), role functioning (32.4 vs. 41.5), social functioning (70.3 vs. 83.5), mental health (48.2 vs. 61.0), energy (53.1 vs. 63.0), health distress (60.8 vs. 75.5), cognitive functioning (CF) (60.5 vs. 71.8), general health perceptions (29.2 vs. 43.4), and QoL (36.5 vs. 47.0). The number of altered neuropsychological tests correlated significantly with MHS (p < 0.001), PHS (p < 0.03), CF (p < 0.02), and QoL (p < 0.02) scores. A correlation between seven of seven neuropsychological measures exploring speed of mental processing, three of four exploring mental flexibility, four of six exploring memory, and two of two exploring fine motor functioning and MHS, PHS, CF, or QoL scores was also found. Poor performance on the Digit Symbol test was most strongly associated with poor MHS (OR 1.04, 95% CI 1.01-1.08, p < 0.009) and PHS (OR 1.04, 95% CI 1.01-1.08, p < 0.01) scores, controlling for CD4 count, previous AIDS diagnosis, receiving HAART, and drug abuse. Cognitive impairment is associated with poor QoL. People with more severe cognitive impairment have the highest probability of having a poor QoL. Cognitive impairment in any cognitive domain explored in our battery is also associated with poor QoL. Poor performance on the Digit Symbol Test is the strongest predictor of poor QoL.

Central nervous system correlates of behavioral deficits following simian immunodeficiency virus infection

Despite the high incidence of cognitive and motor impairment in acquired immunodeficiency syndrome (AIDS) patients, the mechanisms of AIDS-related central nervous system (CNS) pathology are not completely understood. Infection with simian immunodeficiency virus (SIV) in macaques provides an excellent model of AIDS, including human immunodeficiency virus (HIV)-induced CNS pathology and cognitive/behavioral impairment. Co-inoculation with two SIV strains, SIV/17E-Fr and SIV/DeltaB670, accelerates SIV CNS disease, producing SIV encephalitis in over 90% of pig-tailed macaques within 3 months. In the present study, this SIV model was employed to identify cellular and viral correlates of behavioral impairment following SIV infection. Measures of psychomotor speed (simple reaction time), fine motor control (bimanual motor task), and general motor activity (home cage movement) were all adversely affected by SIV disease. Prior to euthanasia, performance was significantly impaired in both a simple reaction time task in 6 of 12 monkeys and a bimanual motor task in 5 of 6 monkeys. All monkeys evaluated (11 of 11) showed significant reductions in spontaneous motor activity. Significant correlations were found between impaired performance on the bimanual motor test and axonal damage (accumulation of beta-amyloid precursor protein in the corpus callosum) as well as increased microglial activation and macrophage infiltration (levels of CD68 and Ham56 immunostaining). These results suggest that axonal damage is related to the behavioral impairment induced by infection with SIV. The axonal damage may result from neuroimmune responses, including microglial and macrophage activation. Therefore, axonal damage may be a morphologic manifestation of neuronal dysfunction that underlies development of behavioral impairment in HIV/SIV CNS infection.

Neurologic aspects of HIV infection in infants and children: therapeutic approaches and outcome

Central nervous system (CNS) HIV-related disorders frequently have devastating consequences. Significant progress has been made in the early diagnosis and treatment of the HIV-infected patient. As a result, the prevalence and natural history of neurologic illnesses have changed. This paper reviews the epidemiology, clinical manifestations, and neuropathogenesis of HIV-related CNS disorders. Advances in antiretroviral therapy, neuroprophylaxis, and neuroprotective strategies are also discussed.

Assessing the efficacy of highly active antiretroviral therapy in the brain

The devastating effects of HIV infection have been documented for the last 2 decades. Since the 1980s over 60 million people have been infected and at present 40 million people globally are living with HIV. HIV infects the central nervous system (CNS) early in the disease process. Indeed, numerous studies document the presence of HIV within the cerebrospinal fluid (CSF). Direct infection of the brain by HIV ultimately results in HIV associated dementia (HAD), which (prior to the advent of antiretroviral therapy) affected 20% of patients. An increasing number of drugs have been developed to treat this infection and delay the development of AIDS. Current treatment is aimed at inhibiting viral replication, and thus, lowering the viral load. However a subsequent increase in viral load can occur as patients become resistant to drug therapy. In the era of HAART, the incidence of HAD has been reduced, whereas the prevalence rate is increasing as people with HIV survive longer. However, in a study of initial AIDS defining illnesses, the proportion with HIV related dementia did not decline following introduction of HAART. In a separate study, no decrease was found in the incidence of dementia per se, although there was a decrease in the incidence of all AIDS-defining illnesses during this time period. It is evident from most studies that since the introduction of HAART, its effect on HAD is not entirely clear, although the majority of findings indicate that it is beneficial. Here we will outline the issues relevant to preventing HAD by HAART.

Effective antiretroviral therapy reduces degradation of tryptophan in patients with HIV-1 infection

Activation of indoleamine-(2,3)-dioxygenase (IDO), an enzyme converting tryptophan to N-formyl-kynurenine, was found to be critical for induction of T-cell tolerance. In 45 HIV-seropositive patients we measured plasma tryptophan and kynurenine before and 6 months post-initiation of ART. Before ART, patients had decreased tryptophan and increased kynurenine levels compared to controls. During ART, average tryptophan concentrations increased, kynurenine decreased. Tryptophan degradation correlated with neopterin levels and with viral load but not with CD4 cell counts. The data support the concept that immune activation is the common background of IDO activation and could represent an important factor underlying T-cell hyporesponsiveness in HIV infection.