Neurological characteristics of HIV-infected men and women seeking primary medical care

Neuropathogenesis of human immunodeficiency virus infection

Human immunodeficiency virus (HIV)-associated neurocognitive disorders (HAND) remain a common end-organ manifestation of viral infection. Subclinical and mild symptoms lead to neurocognitive and behavioral abnormalities. These are associated, in part, with viral penetrance and persistence in the central nervous system. Infections of peripheral blood monocytes, macrophages, and microglia are the primary drivers of neuroinflammation and neuronal impairments. While current antiretroviral therapy (ART) has reduced the incidence of HIV-associated dementia, milder forms of HAND continue. Depression, comorbid conditions such as infectious liver disease, drugs of abuse, antiretroviral drugs themselves, age-related neurodegenerative diseases, gastrointestinal maladies, and concurrent social and economic issues can make accurate diagnosis of HAND challenging. Increased life expectancy as a result of ART clearly creates this variety of comorbid conditions that often blur the link between the virus and disease. With the discovery of novel biomarkers, neuropsychologic testing, and imaging techniques to better diagnose HAND, the emergence of brain-penetrant ART, adjunctive therapies, longer life expectancy, and better understanding of disease pathogenesis, disease elimination is perhaps a realistic possibility. This review focuses on HIV-associated disease pathobiology with an eye towards changing trends in the face of widespread availability of ART.

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.

Associations between Cognition, Gender and Monocyte Activation among HIV Infected Individuals in Nigeria

The potential role of gender in the occurrence of HIV-related neurocognitive impairment (NCI) and associations with markers of HIV-related immune activity has not been previously examined. In this study 149 antiretroviral-naïve seropositive subjects in Nigeria (SP, 92 women and 57 men) and 58 seronegative (SN, 38 women and 20 men) were administered neuropsychological testing that assessed 7 ability domains. From the neuropsychological test scores was calculated a global deficit score (GDS), a measure of overall NCI. Percentages of circulating monocytes and plasma HIV RNA, soluble CD163 and soluble CD14 levels were also assessed. HIV SP women were found to be younger, more educated and had higher CD4+ T cell counts and borderline higher viral load measures than SP men. On the neuropsychological testing, SP women were more impaired in speed of information processing and verbal fluency and had a higher mean GDS than SN women. Compared to SP men, SP women were also more impaired in speed of information processing and verbal fluency as well as on tests of learning and memory. Numbers of circulating monocytes and plasma sCD14 and sCD163 levels were significantly higher for all SP versus all SN individuals and were also higher for SP women and for SP men versus their SN counterparts. Among SP women, soluble CD14 levels were slightly higher than for SP men, and SP women had higher viral load measurements and were more likely to have detectable virus than SP men. Higher sCD14 levels among SP women correlated with more severe global impairment, and higher viral load measurements correlated with higher monocyte numbers and sCD14 and sCD14 levels, associations that were not observed for SP men. These studies suggest that the risk of developing NCI differ for HIV infected women and men in Nigeria and, for women, may be linked to effects from higher plasma levels of HIV driving activation of circulating monocytes.

Select neurocognitive impairment in HIV-infected women: associations with HIV viral load, hepatitis C virus, and depression, but not leukocyte telomere length

BACKGROUND

Through implementation of combination antiretroviral therapy (cART) remarkable gains have been achieved in the management of HIV infection; nonetheless, the neurocognitive consequences of infection remain a pivotal concern in the cART era. Research has often employed norm-referenced neuropsychological scores, derived from healthy populations (excluding many seronegative individuals at high risk for HIV infection), to characterize impairments in predominately male HIV-infected populations.

METHODS

Using matched-group methodology, we assessed 81 HIV-seropositive (HIV+) women with established neuropsychological measures validated for detection of HIV-related impairments, as well as additional detailed tests of executive function and decision-making from the Cambridge Neuropsychological Test Automated Battery (CANTAB).

RESULTS

On validated tests, the HIV+ women exhibited impairments that were limited to significantly slower information processing speed when compared with 45 HIV-seronegative (HIV-) women with very similar demographic backgrounds and illness comorbidities. Additionally, select executive impairments in shifting attention (i.e., reversal learning) and in decision-making quality were revealed in HIV+ participants. Modifiers of neurocognition in HIV-infected women included detectable HIV plasma viral load, active hepatitis C virus co-infection, and self-reported depression symptoms. In contrast, leukocyte telomere length (LTL), a marker of cellular aging, did not significantly differ between HIV+ and HIV- women, nor was LTL associated with overall neurocognition in the HIV+ group.

CONCLUSIONS

The findings suggest that well-managed HIV infection may entail a more circumscribed neurocognitive deficit pattern than that reported in many norm-referenced studies, and that common comorbidities make a secondary contribution to HIV-related neurocognitive impairments.

Cognitive Performance in Men and Women Infected with HIV-1

Introduction. Very few studies have examined the neuropsychological performance of HIV-positive women, and even fewer have attempted a comparison of cognitive functioning by gender. The aim of this study was to describe the nature of the neuropsychological performance of HIV seropositive patients by gender. Methods. A clinical sample made up of 151 subjects was recruited to participate in this study. All of the subjects underwent the same assessment process, consisting of a neuropsychological evaluation and an interview to gather sociodemographic, toxicological, and clinical data. Results and Discussion. Despite the fact that men obtained higher scores in visual memory, attention/psychomotor speed, and abstract reasoning/verbal intelligence, these differences were not statistically significant. In contrast, significant differences were found depending on subjects' serological status. Seropositive participants' neuropsychological performance was significantly lower than that of the seronegative participants in all of the areas assessed as follows: (1) visual memory; (2) attention/psychomotor speed; (3) abstract reasoning/verbal intelligence; (4) verbal memory for texts; (5) verbal memory for digits and words. Conclusions. The results from this study reveal no significant gender differences in the cognitive performance of patients infected with HIV-1.

Hormone replacement therapy and risk for neurodegenerative diseases

Over the past two decades, there has been a significant amount of research investigating the risks and benefits of hormone replacement therapy (HRT) with regards to neurodegenerative disease. Here, we review basic science studies, randomized clinical trials, and epidemiological studies, and discuss the putative neuroprotective effects of HRT in the context of Alzheimer's disease, Parkinson's disease, frontotemporal dementia, and HIV-associated neurocognitive disorder. Findings to date suggest a reduced risk of Alzheimer's disease and improved cognitive functioning of postmenopausal women who use 17β-estradiol. With regards to Parkinson's disease, there is consistent evidence from basic science studies for a neuroprotective effect of 17β-estradiol; however, results of clinical and epidemiological studies are inconclusive at this time, and there is a paucity of research examining the association between HRT and Parkinson's-related neurocognitive impairment. Even less understood are the effects of HRT on risk for frontotemporal dementia and HIV-associated neurocognitive disorder. Limits to the existing research are discussed, along with proposed future directions for the investigation of HRT and neurodegenerative diseases.

The relationship between race and HIV-distal sensory polyneuropathy in a large cohort of US women

INTRODUCTION

HIV-distal sensory polyneuropathy (HIV-DSPN) is a common complication of HIV infection, yet race as a potential risk factor is not known.

METHODS

Between April and October 2009, as part of the NIH Women's Interagency HIV Study (WIHS), 1414 women, 973 of whom were HIV-infected, were clinically evaluated for peripheral neuropathy. Utilizing available clinical, laboratory, and sociodemographic variables, we conducted a cross-sectional analysis of factors associated with HIV-DSPN. Multivariable logistic regression was used to examine factors independently associated with HIV-DSPN.

RESULTS

36% of HIV-infected women met our definition of HIV-DSPN. 41.3% of African Americans, 34.8% of Whites and 24.7% of Hispanics had DSPN. Age, Hepatitis C-co-infection, and diabetes were each significantly associated with HIV-DSPN. After controlling for age, diabetes, Hepatitis C co-infection, alcohol use, current dideoxy-nucleoside reverse transcriptase inhibitor use, current CD4 count, and plasma HIV viral load, HIV-DSPN was significantly associated with ethnicity; the odds ratio was 1.67 (p=0.001) in African-Americans compared to other racial groups.

CONCLUSION

The prevalence of HIV-DSPN in women was lower than reported in prior studies. The likelihood of HIV-DSPN was higher in African-Americans compared to other racial groups. HIV-DSPN was more common in those co-infected with Hepatitis C, older individuals, and diabetics. Further prospective studies are needed to explore the relationship between gender, race, and HIV-DSPN, and the mechanistic basis for racial differences.

HIV, cognition and women

Although the incidence of HIV in the United States is higher among men compared to women, the global proportion of women versus men who are infected has been approximately 50% since the late 1990s. Women have been under-represented in neuropsychological studies of HIV. A small number of studies have reported a significantly higher prevalence of neurocognitive impairment among HIV+ women compared to HIV- controls regardless of symptom status and with or without an AIDS diagnosis. Impairment was most evident on psychomotor tasks. The risk of neuropsychological impairment was increased among HIV+ women not on antiretroviral therapy. Age and depressive symptoms also increase neurocognitive risk. New neurocognitive studies of ovarian steroid hormones, PTSD and other psychiatric conditions are critical for addressing potential female-specific aspects of HIV-Associated Neurocognitive Disorder. Such studies will also address questions regarding involvement of the hippocampus and verbal memory, which may be of particular significance among HIV+ women.

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.

3D pattern of brain atrophy in HIV/AIDS visualized using tensor-based morphometry

35% of HIV-infected patients have cognitive impairment, but the profile of HIV-induced brain damage is still not well understood. Here we used tensor-based morphometry (TBM) to visualize brain deficits and clinical/anatomical correlations in HIV/AIDS. To perform TBM, we developed a new MRI-based analysis technique that uses fluid image warping, and a new alpha-entropy-based information-theoretic measure of image correspondence, called the Jensen-Rényi divergence (JRD).

METHODS

3D T1-weighted brain MRIs of 26 AIDS patients (CDC stage C and/or 3 without HIV-associated dementia; 47.2+/-9.8 years; 25M/1F; CD4+ T-cell count: 299.5+/-175.7/microl; log10 plasma viral load: 2.57+/- 1.28 RNA copies/ml) and 14 HIV-seronegative controls (37.6+/-12.2 years; 8M/6F) were fluidly registered by applying forces throughout each deforming image to maximize the JRD between it and a target image (from a control subject). The 3D fluid registration was regularized using the linearized Cauchy-Navier operator. Fine-scale volumetric differences between diagnostic groups were mapped. Regions were identified where brain atrophy correlated with clinical measures.

RESULTS

Severe atrophy ( approximately 15-20% deficit) was detected bilaterally in the primary and association sensorimotor areas. Atrophy of these regions, particularly in the white matter, correlated with cognitive impairment (P = 0.033) and CD4+ T-lymphocyte depletion (P = 0.005).

CONCLUSION

TBM facilitates 3D visualization of AIDS neuropathology in living patients scanned with MRI. Severe atrophy in frontoparietal and striatal areas may underlie early cognitive dysfunction in AIDS patients, and may signal the imminent onset of AIDS dementia complex.