Do asymptomatic HIV-seropositive individuals show cognitive deficit?

Behavioral, Metabolic, and Immune Consequences of Chronic Alcohol or Cannabinoids on HIV/AIDs: Studies in the Non-Human Primate SIV Model

HIV-associated mortality has been significantly reduced with antiretroviral therapy (ART), and HIV infection has become a chronic disease that frequently coexists with many disorders, including substance abuse (Azar et al. Drug Alcohol Depend 112:178-193, 2010; Phillips et al. J Gen Int Med 16:165, 2001). Alcohol and drugs of abuse may modify host-pathogen interactions at various levels including behavioral, metabolic, and immune consequences of HIV infection, as well as the ability of the virus to integrate into the genome and replicate in host cells. Identifying mechanisms responsible for these interactions is complicated by many factors, such as the tissue specific responses to viral infection, multiple cellular mechanisms involved in inflammatory responses, neuroendocrine and localized responses to infection, and kinetics of viral replication. An integrated physiological analysis of the biomedical consequences of chronic alcohol and drug use or abuse on disease progression is possible using rhesus macaques infected with simian immunodeficiency virus (SIV), a relevant model of HIV infection. This review will provide an overview of the data gathered using this model to show that chronic administration of two of the most commonly abused substances, alcohol and cannabinoids (Δ(9)-Tetrahydrocannabinol; THC), affect host-pathogen interactions.

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.

Cognitive reserve during neuropsychological performance in HIV intravenous drug users

HIV-associated neurocognitive disorders are frequently observed in people with HIV. We aimed to evaluate the influence of cognitive reserve on the neuropsychological performance of seropositive drug users. We carried out a neuropsychological assessment and compared the performance of seropositive drug users (n = 75) with that of a group of seronegative drug users (n = 48). The results showed that a low cognitive reserve makes the seropositive patients neuropsychologically vulnerable. Likewise, we found that a high cognitive reserve has a protective effect in the presence of neuropsychological impairment associated with HIV. In the seronegative group, differences in a small number of tests were found between participants with low and high cognitive reserve. Overall, these data suggest that seropositivity is not sufficient to explain the neuropsychological alterations of seropositive drug users; rather, these alterations are multifactorial.

Tolerance to chronic delta-9-tetrahydrocannabinol (Δ⁹-THC) in rhesus macaques infected with simian immunodeficiency virus

Although Δ⁹-THC has been approved to treat anorexia and weight loss associated with AIDS, it may also reduce well-being by disrupting complex behavioral processes or enhancing HIV replication. To investigate these possibilities, four groups of male rhesus macaques were trained to respond under an operant acquisition and performance procedure, and administered vehicle or Δ⁹-THC before and after inoculation with simian immunodeficiency virus (SIV(mac251), 100 TCID₅₀/ml, i.v.). Prior to chronic Δ⁹-THC and SIV inoculation, 0.032-0.32 mg/kg of Δ⁹-THC produced dose-dependent rate-decreasing effects and small, sporadic error-increasing effects in the acquisition and performance components in each subject. Following 28 days of chronic Δ⁹-THC (0.32 mg/kg, i.m.) or vehicle twice daily, delta-9-THC-treated subjects developed tolerance to the rate-decreasing effects, and this tolerance was maintained during the initial 7-12 months irrespective of SIV infection (i.e., +THC/-SIV, +THC/+SIV). Full necropsy was performed on all SIV subjects an average of 329 days post-SIV inoculation, with postmortem histopathology suggestive of a reduced frequency of CNS pathology as well as opportunistic infections in delta-9-THC-treated subjects. Chronic Δ⁹-THC also significantly reduced CB-1 and CB-2 receptor levels in the hippocampus, attenuated the expression of a proinflammatory cytokine (MCP-1), and did not increase viral load in plasma, cerebrospinal fluid, or brain tissue compared to vehicle-treated subjects with SIV. Together, these data indicate that chronic Δ⁹-THC produces tolerance to its behaviorally disruptive effects on complex tasks while not adversely affecting viral load or other markers of disease progression during the early stages of infection.

Estudo dos transtornos cognitivos decorrentes da infecção pelo HIV-1

A infecção pelo vírus da imunodeficiência humana atinge o Sistema Nervoso Central nos estágios iniciais, causando manifestações neuropsicológicas. Com o objetivo de estudar o desempenho de indivíduos infectados por este vírus em relação às funções cognitivas, foram avaliados 20 pacientes com contagem de linfócitos CD4+ acima de 200 células/mm³, utilizando-se a Escala de Inteligência Wechsler para Adultos. Destes, cinco (25%) eram do sexo masculino e 15 (75%) do sexo feminino, com média de idade de 39,65 desvio-padrão de 10,15 anos. A contagem média de linfócitos CD4+ foi 467,20 desvio-padrão de 215,45 células/mm?. Dentre quatorze pacientes que fizeram uso de terapia antirretroviral de alta atividade foi observado um caso com desempenho das funções cognitivas atenção e aprendizagem muito abaixo da média; os demais (n=13) tiveram desempenho dentro da média. Por meio da Escala de Inteligência Wechsler para Adultos foi possível detectar desempenho abaixo do nível médio do funcionamento cognitivo em indivíduos com resultado positivo para vírus da imunodeficiência humana, mesmo em vigência de terapia antirretroviral de alta atividade.

Neuropsychological impairment and gender differences in HIV-1 infection

AIMS

Research into neuropsychological consequences of HIV has focused mainly on male subjects, and therefore very little is known about the disease in female subjects and, of course, about gender differences. The aim of the present research was therefore to investigate neuropsychological impairment rates and pattern in HIV male and female patients, with regard to the study of gender differences in tasks assessing attention, memory for texts, digits and words, psychomotor speed, verbal intelligence and abstract reasoning.

METHODS

A clinical sample was recruited consisting of 122 subjects, divided into four groups: (i) 57 HIV+ men; (ii) 31 HIV+ women; (iii) 18 HIV- men and (iv) 16 HIV- women. All the subjects had more than 18 years, being the average of age of 34.08 for men and 33.35 for women. The evaluation of each subject consisted of a semistructured interview investigating sociodemographic, clinical and toxicological aspects and a neuropsychological assessment, with a battery of tests specifically selected for this study and chosen for their validity and because they have been shown to be sensitive to neuropsychological impairment in HIV-infected patients in other studies.

RESULTS

None of HIV- male and female groups fulfilled impairment criteria. Regarding the HIV+ group, a rate of neuropsychological impairment of 51.9% was obtained for the men and 54.8% for the women, but there were no significant differences between groups. Nevertheless, were detected significant differences in neuropsychological impairment rates between HIV+ and HIV- women, and also between HIV+ and HIV- men. Although HIV+ women presented multiple factors that could increase their neuropsychological vulnerability to the effects of HIV, HIV+ men had the same probability of having neuropsychological impairment as HIV+ women.

CONCLUSIONS

A different neuropsychological impairment pattern was detected between genders: while HIV+ men had greater impairment in visual memory, attention, psychomotor speed and abstract reasoning, HIV+ women had greater impairment on attention, psychomotor speed and verbal memory for texts.

Neuropsychological Impairment Among Asymptomatic HIV-Positive Former Intravenous Drug Users

OBJECTIVE

To evaluate the influence of human immunodeficiency virus (HIV) infection and situation of drug consumption on neuropsychological impairment in asymptomatic HIV-positive (HIV+) former intravenous drug users (IVDUs) of Spanish nationality.

BACKGROUND

Currently, we have no data about neuropsychological impairment in asymptomatic HIV+ IVDUs taking into account different situations of drug consumption.

METHOD

A neuropsychological evaluation was made of four groups of IVDUs: 33 abstinent HIV+ IVDUs, 21 methadone-maintained HIV+ IVDUs, 27 abstinent HIV-negative (HIV-) IVDUs, and 21 methadone-maintained HIV- IVDUs. Their neuropsychological impairment rates were determined taking as a reference the performance of 23 HIV- subjects without history of drug abuse.

RESULTS

The rate of neuropsychological impairment of methadone-maintained HIV+ patients (48%) and that of those in abstinence (24%) is greater than that of HIV- subjects in a similar condition (19% and 11%). The impairment rate of the methadone-maintained HIV+ group is significantly greater than that of the abstinent HIV+. Methadone-maintained HIV+ subjects with neuropsychological impairment have fewer education years than those not impaired; likewise, the percentages of subjects with significant immunodepression, detectable viral load, and without antiretroviral treatments are higher among methadone-maintained subjects with neuropsychological impairment.

CONCLUSIONS

This study emphasizes the association of asymptomatic HIV infection with neuropsychological impairment in IVDUs and reveals the importance of the drug consumption situation in relation to this risk, being methadone-maintained IVDUs more likely to suffer from it. This fact seems to be related to the worsening of the infection and its treatment and to educational level.

The neuropsychological profile of symptomatic AIDS and ADC patients in the pre-HAART era: a meta-analysis

It remains essential to document the neuropsychological profile of acquired immunodeficiency syndrome (AIDS) dementia complex (ADC) and minor forms human immunodeficiency virus (HIV)-associated neurocognitive impairment by quantifying the magnitude of impairment across eras of treatment. Indeed, with the introduction of the highly active antiretroviral therapy (HAART), there is evidence of changes in aspects of ADC. To allow quantitative and qualitative comparisons with the HAART era studies, we developed a summary of neuropsychological performance acquired in pre-HAART era studies in advanced HIV infection and ADC. Using a meta-analytical procedure and a test nomenclature that accounts for task complexity, we found that individuals with symptomatic infection (but no AIDS) demonstrated a global mild level of cognitive impairment, except for the domains complex attention/psychomotor speed, motor coordination, and learning, which showed moderate impairment. Individuals with AIDS demonstrated a global moderate level of cognitive impairment with a predominance of deficits in attention, complex attention/psychomotor speed, learning, motor coordination, with additional deficits in verbal memory and reasoning. Individuals with ADC demonstrated the most severe cognitive disturbances in domains of learning, motor coordination, with additional deficits in veibal fluency and verbal memory. Moderate impairment was evidenced in domains of complex attention/psychomotor speed, whereas naming and visuospatial functions were relatively preserved. The profile of deficits in ADC suggests that it may not be only interpreted as a worsening form of the impairment that is seen in the AIDS and symptomatic stages of HIV disease but that there are also additional deficits suggestive of an alternate pathogenetic process(es).

The hypothalamic-pituitary-adrenal axis and viral infection

The hypothalamic-pituitary-adrenal (HPA) axis plays an important immunomodulatory role during viral infection. Activation of the HPA axis ultimately leads to elevated plasma levels of glucocorticoid (GC) hormones with the ability to mediate adaptive behavioral, metabolic, cardiovascular and immune system effects. In this review, we focus on the modulation of anti-viral immunity and viral pathogenesis by the HPA axis.

Influence of depressed mood on neuropsychologic performance in HIV-seropositive drug users

Some studies point out that depression affects the performance of HIV patients in neuropsychological tasks, but at present this effect is not clear. The purpose of the present paper was to study whether the presence of symptoms of depression affects the neuropsychologic performance of seropositive drug users in tasks of attention/concentration, learning and memory, language, construction and visuospatial function, speed of motor performance, cognitive flexibility, manual skill and concept formation and reasoning. In order to carry out this research a sample consisting of 127 male volunteer subjects was used. These subjects were distributed in four groups: one group consisted of HIV-seropositive drug users with symptoms of depression (n = 33); the second group consisted of HIV-seropositive drug users without symptoms of depression (n = 47); the third group was formed by HIV-seronegative drug users with symptoms of depression (n = 15) and the fourth group was formed by HIV-seronegative drug users without symptoms of depression (n = 32). The results reveal the effect of symptoms of depression (evaluated by the Beck Depression Inventory) on the neuropsychologic performance of seropositive drug users. This effect, however, was not observed in the seronegative group. These findings lead us to suggest that symptoms of depression constitute a risk factor for presenting neuropsychologic disturbances in seropositive subjects, which could well be acting as a factor that foments the neuropsychological effects of HIV.

HIV- and FIV-derived gp120 alter spatial memory, LTP, and sleep in rats

Human immunodeficiency virus (HIV)-associated dementia (HAD) has been detected in 20-30% of patients suffering AIDS. The envelope glycoprotein 120 (gp120) derived from HIV seems to play a critical role in the pathophysiology of this dementia. Likewise, the feline immunodeficiency virus (FIV)-derived gp120 causes neurological and electrophysiological abnormalitites in cats. We have studied the effects of gp120 derived from HIV or FIV on learning and memory processing, hippocampal long-term potentiation (LTP), hippocampal neuronal cAMP production, the sleep-waking cycle, and locomotor activity and equilibrium in rats. Results showed that while both HIV- and FIV-gp120 impaired the rat's performance in the Barnes maze task, only HIVgp120 impaired the induction and maintenance of LTP. However, both glycoproteins induced a significant decrease in the posttetanic potentiation. HIVgp120 also caused a significant reduction in cAMP production in the hippocampus. Regarding the sleep-waking cycle, HIV- and FIV-gp120 increased the waking state and slow-wave sleep 1 (SWS1), while decreasing both SWS2 and REM sleep. Locomotor activity and equilibrium were significantly altered by these glycoproteins. These results suggest that HIVgp120 causes neurophysiological abnormalities and therefore may facilitate HAD development in AIDS patients.

Dementia and the Neurovirulence of HIV-1

Infection with human immunodeficiency virus type 1 (HIV-1) leads rapidly to infection of the brain and subsequent neuropsychological impairment, including subclinical impairment, minor cognitive-motor disorder, and HIV-1-associated dementia (HAD). This article reviews HAD and the factors involved in its pathogenesis; the effectiveness of antiretroviral therapy; the prevalence of HIV-1 and subtypes; and the role of chemokines and cytokines as the capstones associated with neuropathology due to inflammation.

Evidence of CNS impairment in HIV infection: clinical, neuropsychological, EEG, and MRI/MRS study

OBJECTIVES

To identify by clinical examination, EEG, MRI, and proton spectroscopy, and neuropsychological assessment the prevalence of signs of CNS involvement in patients infected with HIV, and to relate such findings to the evidence of immunosuppression.

METHODS

The design was a cross sectional analysis of a cohort of male patients with infected HIV with an AIDS defining diagnosis or low CD4 count (<350), and seropositive asymptomatic subjects, both groups being followed up in a longitudinal study. Control groups consisted of seronegative subjects from the same genitourinary medicine clinics.

RESULTS

This report sets out the cross sectional findings at the seventh visit in the longitudinal study. Patients with AIDS had more signs of neurological dysfunction, poorer performance on a neuropsychological test battery, were more likely to have an abnormal EEG, and to have abnormalities on MRI. They more often had cerebral atrophy, abnormal appearing white matter, and abnormal relaxometry and spectroscopy. There was little evidence of abnormality in seropositive people who had a CD4 count >350 compared with seronegative people from a similar background.

CONCLUSIONS

Detailed testing failed to disclose significant CNS impairment without immunosuppression in men infected with HIV. Findings from MRI and magnetic resonance spectroscopy (MRS) correlated with those of the neurological examination and neuropsychological assessment. A combination of such assessments offers a simple surrogate for studies of CNS involvement in HIV disease.

Neuronal Loss in FIV-MD Infected Cats

Previously, this laboratory has shown that the Maryland strain of feline immunodeficiency virus (FIV-MD) causes neurological disease in cats similar to human immunodeficiency virus type 1 (HIV-1) in people. Using morphometrical methods on neocortical histologic sections we now show a significant loss of neurons in FIV-MD infected cats compared to age-matched uninfected controls. The neuronal populations affected resembles those lost in HIV-1 infection of the brain in published reports, providing further evidence for the utility of FIV-MD infection as a model for HIV-1 infections of the brain.

Impact of antiretroviral treatment on AIDS dementia: a longitudinal prospective event-related potential study

We investigated the impact of antiretroviral treatment on event-related potentials (ERP) as a possible marker of AIDS dementia. A total of 154 HIV-infected patients without central nervous system (CNS) neoplasm or opportunistic infection were examined and randomized to receive either zidovudine 500 mg/day or no antiretroviral treatment. The participants were prospectively examined by visually evoked ERP in a longitudinal design. Latencies and amplitudes of ERP were evaluated at the beginning of the study, after 1 year, and after 2 years. After 1 year, 98 patients could be analyzed, 47 of whom were taking zidovudine. In the treatment group, P3 latency was 419 +/- 55 msec at baseline and 424 +/- 52 msec at follow-up (not significant). In the patients without treatment, P3 latency was 437 +/- 42 msec at baseline and 462 +/- 53 msec at follow-up (p < .0001, Wilcoxon test). A significant inverse correlation existed between P3 latency and CD4 cell count in both groups. The increase of P3 latency in untreated patients and a stable P3 latency in treated patients could be confirmed in a subgroup analysis of 21 patients with a follow-up of three examinations in a 2-year period. Our data suggest that zidovudine has a positive impact on AIDS dementia as measured by ERP. This finding was observed in patients in different stages of HIV infection, thus suggesting that zidovudine is indicated in all stages of HIV infection to treat encephalopathy.

Cerebral proton magnetic resonance spectroscopy in asymptomatic HIV infection

OBJECTIVE

To determine whether proton magnetic resonance spectroscopy (MRS) demonstrates central nervous system abnormalities in asymptomatic HIV-1-infected individuals.

DESIGN

Both prospective and retrospective cross-sectional analyses of MRS in asymptomatic HIV-infected individuals.

SETTING

Two specialists HIV/AIDS outpatient facilities in London.

PARTICIPANTS

Eighty-four HIV-1 seropositive asymptomatic men; 29 HIV-1 antibody-negative homosexual men at high-risk for HIV infection and 48 HIV-1 antibody-negative men at low-risk for HIV infection as controls.

MAIN OUTCOME MEASURES

Single voxel, gradient-localized proton MRS performed at 1.5 T with 135 msec echo-time and 1,600 msec repeat-time in an 8 ml volume of interest positioned in the parieto-occipital white matter. Spectroscopic results were expressed as ratios between the areas under the N-acetyl (NA), creatine (Cr) and choline (Cho) resonance peaks.

RESULTS

There were no differences between those controls at high and those at low-risk for HIV infection. Comparing the combined control groups with the asymptomatic seropositive patients there were statistically significant differences in NA/Cho, NA/Cr (both P < 0.05) and NA/(NA + Cho + Cr) (P < 0.01).

CONCLUSION

Abnormalities in cerebral biochemistry may be demonstrated by proton MRS during asymptomatic HIV-1 infection.