Reaction time slowing in HIV-1-infected individuals: role of the preparatory interval

Apathy correlates with cognitive performance, functional disability, and HIV RNA plasma levels in HIV-positive individuals

We examined the relationship of apathy with neurocognitive performance, age, disease markers, and functional disability in 116 HIV-infected individuals. Apathy was assessed with the Apathy Evaluation Scale and was significantly associated with highest HIV plasma level, functional disability, and neurocognitive performance. Individuals with higher apathy levels demonstrated a stronger association between age and processing speed performance. Our findings suggest that apathy is related to poor neuropsychological functioning, HIV plasma levels, and increased functional disability in individuals with HIV. Additionally, to our knowledge, this is the first study to demonstrate an interactive effect of age and apathy on neuropsychological performance in HIV.

Cognitive reserve protects against apathy in individuals with human immunodeficiency virus

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

A perspective on the proposal for neurocognitive disorder criteria in DSM-5 as applied to HIV-associated neurocognitive disorders

HIV-associated neurocognitive disorders remain common in the current era of effective antiretroviral therapy. However, the severity at presentation of these disorders has been reduced, and the typical manifestations have changed. A revision of the American Academy of Neurology (AAN) criteria has been made on this basis, and a revision of the analogous criteria by the American Psychiatric Association will be forthcoming in the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5. This article compares the relevant sets of diagnostic criteria that will be employed. It is concluded that a greater degree of integration of the revised, HIV-specific AAN criteria for HIV-associated neurocognitive disorders with the criteria proposed for the DSM-5 would prove advantageous for research, clinical, educational and administrative purposes.

Perceptual span deficits in adults with HIV

Studies have found that infection with the Human Immunodeficiency Virus (HIV) leads to cognitive dysfunction. In fact, attention problems have been reported to be the most frequent cognitive symptom in HIV-infected adults. One question is how early in the course of information processing can attention impairment be detected? To address this issue, performance on a perceptual span task was examined in 54 HIV-infected adults and 19 seronegative controls. In this task a target had to be identified in a briefly presented (50 ms) array of 1, 4, or 12 letter-characters. Response accuracy was differentially worse in the HIV+ group relative to seronegative controls in the most difficult condition, the 12-item array, but not in the easier conditions. There was no evidence of a group difference in response strategy due to disinhibition or in psychomotor speed. These data suggest that HIV infection leads to a reduction in early visual processing capacity (or span of apprehension). The present results illustrate a new type of attentional deficit in HIV and show the impact of HIV on cognition at an earlier point in information processing than has been previously reported.

Reaction time slowing in adults with HIV: results of a meta-analysis using brinley plots

A meta-analysis in the form of Brinley plots was conducted on the mean reaction times of HIV+ and HIV- groups. HIV+ reaction times were regressed on HIV- reaction times across 122 task conditions from 29 studies, producing a highly linear function (r(2) = .94), with a slope b = 1.039, which was not significantly different than b = 1.00. Asymptomatic and symptomatic HIV+ reaction times were also separately regressed on HIV- reaction times across 67 task conditions from 13 studies. Both functions were highly linear (r(2) = .97 and.90 respectively), with slopes of 1.034 and 1.117 respectively. Only the slope for symptomatic HIV+ groups was significantly larger than b = 1.00, suggesting a modest generalized slowing of cognition in these adults.

Effects of LP-BM5 murine leukemia virus infection on errors and response time in a two-choice serial reaction time task in C57BL/6 mice

Human immunodeficiency virus type 1 (HIV-1) infection is often accompanied by cognitive, motor, and behavioral dysfunction. Cognitive function diminishes in indices of attention, psychomotor speed, and learning and memory. These are collectively termed acquired immunodeficiency syndrome dementia complex (ADC or neuroAIDS). Inoculation with the LP-BM5 murine leukemia virus (MuLV) causes profound immunosuppression (murine acquired immunodeficiency syndrome, or MAIDS) in C57BL/6 mice. Previous studies show that the LP-BM5 MuLV impairs learning and memory without gross motor impairment. Since learning and memory performance deficits can be related to attention deficits, we assessed the effect of LP-BM5 MuLV infection on sustained attention performance using a two-choice serial reaction time task. This task required the animals to detect a visual stimulus presented randomly on the right or the left unit and respond by a nose-poke in the illuminated hole within a 5 s period for water reward. The LP-BM5 MuLV infected group, like the control group, improved sustained attention performance until 7 weeks of virus infection in all measures including choice accuracy, response omission, and correct response time. However, during the late stage of infection, LP-BM5 MuLV infected mice showed selective sustained attention performance deficits. From 8 weeks after LP-BM5 MuLV infection, the virus infected mice started to lose their improved sustained attention performance in response omission and began to make correct responses more slowly than the control mice when the duration of stimulus light was 5 s. Moreover, at 13 and 14 weeks after LP-BM5 MuLV infection, the virus infected group made correct choices significantly less accurately than the control group when duration of stimulus light was shortest (1 s). These data show that LP-BM5 MuLV infection causes not only the previously reported learning and memory deficits but also produces sustained attention performance deficits in mice.

Working memory performance predicts subjective cognitive complaints in HIV infection

The authors examined the contribution of working memory performance to subjective cognitive complaints in HIV infection beyond the influence of depressive symptoms. Thirty-six adults with HIV infection were administered neuropsychological (NP) tests of working memory, complex psychomotor efficiency, verbal learning, delayed recall, and questionnaires measuring depressive symptoms and cognitive complaints. Working memory performance, depression scores, and complex psychomotor efficiency were most strongly associated with self-reported cognitive complaints, whereas verbal learning scores and simple psychomotor efficiency showed more modest associations. Regression analyses revealed working memory performance to be the strongest NP predictor of self-reported cognitive complaints, comparable with depression scores in the amount of variance explained. These results suggest that working memory performance may be well suited to reflect how patients function in their everyday environment.

The importance of cognitive self-report in early HIV-1 infection: validation of a cognitive functional status subscale

BACKGROUND

The Medical Outcomes Study HIV (MOS-HIV) Health Survey is a widely used instrument to assess quality of life in HIV-1-infected individuals. Its cognitive functional status subscale measures functional status owing to neuropsychological (NP) impairment.

OBJECTIVES

To determine the concurrent validity of the Dutch four-item MOS-HIV cognitive functional status subscale and its clinical significance in predicting NP test performance.

DESIGN

Cross-sectional analysis of baseline data collected between October, 1994, and March, 1997, in the Netherlands and in Flanders, Belgium.

SUBJECTS

A total of 85 HIV-1-infected homosexual men who participated in an ongoing longitudinal research project designed to study the effects of a support group.

RESULTS

The MOS-HIV cognitive functional status subscale showed significant associations with NP test performance overall and, specifically, with the domains of abstraction, language and visuospatial abilities, controlling for CD4 cell count and Centers for Disease Control and Prevention (CDC) clinical disease stage. A trend toward significance was also found in the memory domain.

CONCLUSIONS

To our knowledge, this is the first report of a cognitive functional status subscale used with HIV-1-infected subjects in a language other than English. The MOS-HIV cognitive functional status subscale seems particularly sensitive to changes in NP test performance in early HIV-1 infection. These results suggest the potential for clinical utility of a brief functional status self-report measure related to cognitive abilities in early HIV-1 infection for the screening and diagnosis of HIV-1 associated cognitive-motor disorders.

Preclinical psychopharmacology of AIDS-associated dementia: lessons to be learned from the cognitive psychopharmacology of other dementias

Following a brief discussion of the epidemiology, underlying neuropathological mechanisms, neuropsychological symptoms and present treatment strategies of AIDS-associated dementia (AAD), parallels are drawn between the longer standing research on drugs for the treatment of other cognitive disorders, particularly senile dementia, and ongoing efforts to develop psychopharmacological approaches for the treatment of the cognitive impairments in AAD. Important aspects of hypotheses designed to guide such a research are indicated with the help of a speculative, paradigmatic hypothesis concerning the role of cortical cholinergic inputs in AAD. Furthermore, aspects of validity of animal models, and cognition as a crucial intervening variable in the effects of potential treatments, are evaluated.

Cognitive Effects of HIV-1 Infection

The major neurological complication of human immunodeficiency virus type 1 (HIV-1) infection is cognitive impairment, which can range in severity from a mild subclinical cognitive inefficiency to a severe dementing illness. Mild to moderate cognitive impairment is identified primarily by neuropsychological tests. The prevalence and severity of cognitive impairment associated with HIV-1 infection increases as the disease progresses. Deficits in attention, information processing speed, memory, and motor abilities can occur early in the course of HIV-1 infection, with deficits in abstraction and executive functions observed in later stages of infection. The nature of the cognitive impairment observed is thought to reflect the effects of HIV-1 infection on the integrity of subcortical or frontostriatal brain systems. Issues related to the detection of subclinical to severe cognitive impairment are discussed, along with the clinical significance of mild cognitive impairment as a significant risk factor for mortality in HIV-1 infection. The need to control for possible confounding factors that can influence test performance is also reviewed.

Simple and choice reaction time performance in SIV-infected rhesus macaques

It is well established that HIV infection can lead to motor/cognitive disorders in humans. A number of studies have shown that simian immunodeficiency virus (SIV) infection in rhesus macaques parallels many aspects of HIV disease in humans. The purpose of this study was to define further the SIV-infected rhesus macaque as a model of neuro-AIDS. Our objective was to detect movement-related impairments in behaviorally trained, SIV-infected macaques using both simple and choice reaction time tasks. Reaction times (RTs), movement times (MTs), and error types were examined. Nine monkeys were infected with neurovirulent strains of SIVmac, four of which served initially as controls before their inoculation. Seven of the nine monkeys developed simian AIDS within 4 months of inoculation (rapid progressors), while two monkeys survived for more than 1 year postinoculation (slow progressors). Of the rapid progressors, four exhibited slowed reaction times and six showed movement time slowing. One rapid progressor showed evidence of a strategy shift to overcome impaired motor abilities. Monkeys with rapidly progressing SIV-related disease consistently show behavioral abnormalities reflecting underlying neuronal injury. Although the slow progressors also showed RT and/or MT slowing, a role for nonspecific factors related to late-stage simian AIDS could not be ruled out in these cases. The results demonstrate that motor impairments associated with SIV infection in rhesus macaques can be detected using RT and MT measures, further establishing the SIVmac-infected macaque monkey as a viable model of neuro-AIDS.