Neuropsychological performance in asymptomatic HIV infection

Neurocognitive Complications of HIV Disease

Neurocognitive complications are the most common sequelae of HIV infection if the full spectrum of HIV disease—from initial seroconversion to death from advanced AIDS—is considered. Though resembling subcortical neurological disorders from a neuropsychological standpoint, the presentation is variable, and almost any pattern can be seen. Although neuropsychological impairment is often subtle, it can affect day-to-day life and is associated with earlier mortality. It is not clear if milder forms of neurocognitive disturbance necessarily presage advanced dementia, and current data suggest a two-factor model: a subacute relapsing-remitting condition that can occur at any stage of HIV disease and a progressive, more fulminant dementia. The pathological substrates of these conditions are not well characterized, although recent data support the notion that synaptodendritic damage underlies the neuropsychological impairment, and may precede the neuronal loss and other pathological features more characteristic of HIV encephalitis. Some reversibility of neurocognitive disturbance has been reported with zidovudine therapy, though the data are not consistent. New regimens involving protease inhibitors need to be evaluated in terms of benefit to the central nervous system because many drugs of this class do not penetrate the blood-brain barrier efficiently. Finally, studies utilizing experimental treatments that may affect the putative mechanisms of neural injury are in progress.

Neuropsychological Dysfunction in HIV Infection:A Review

FIfty-six studies which used neuropsychological tests to investigate areas of function affected by central nervous system dysfunction in HIV were reviewed. Only studies which compared the performance of HIV + subjects to HIV - controls using analysis of variance techniques were included. The results are examined in terms of broad neuropsychological function domains, and are examined separately for asymptomatic and symptomatic subjects. Studies which did and did not find significant differences between HIV + and HIV - subjects were compared in terms of various confounding factors such as risk groups, number of tests, sample size and subject characteristics. There was evidence for some dysfunction among subjects who are otherwise asymptomatic in the areas of verbal memory (27% of studies), executive function (43%), motor performance (20%) and information processing (44%). Studies of subjects with more advanced HIV infection showed consistent evidence of abnormal functioning in the areas of verbal (48% of studies) and visual memory (43%), executive functioning (71%), complex attention (62%), motor performance (37%) and information processing (69%). These deficits occurred prior to the onset of clinically apparent dementia. There were no consistent significant differences between studies which did and did not find significant differences between HIV + and HIV - subjects in terms of most of the confounding variables investigated, although studies of ASX subjects were more likely to find differences between HIV + subjects and controls with larger neuropsychological test battereies. However, much of the variation in results due to the neuropsychological tests used. In many cases, tests which relied on functions with a frontal lobe component were more likely to find significant results.

Neurocognitive status is associated with all-cause mortality among psychiatric, high-risk liver transplant candidates and recipients

OBJECTIVE

Judicious selection of potential liver transplant candidates and close monitoring of progress are essential to successful outcomes. Pretransplant psychosocial evaluations are the norm, but the relationship between psychosocial (and neurocognitive status) and longer term medical outcomes is understudied. This exploratory study sought to examine the relationship between objective measures of pretransplant psychosocial and neurocognitive status and service utilization, transplant status, and all-cause mortality.

METHODS

This retrospective chart review examined outcomes among 108 psychiatric, high-risk liver transplant candidates up to four years following initial evaluation. Predictor variables of outcomes included demographic, medical, neurocognitive, psychological, and mental health treatment variables.

RESULTS

Transplant status and neurocognitive functioning were independently associated with all-cause mortality. None of the other variables were associated with outcomes.

CONCLUSIONS

Better neurocognitive functioning in high-risk liver transplant candidates may allow for greater involvement in medical care and/or compliance with treatment recommendations. More aggressive assessment and management of neurocognitive dysfunction may improve outcomes. Objective measures identified significant psychopathology typical of liver transplant candidates but were not associated with outcomes; engagement in specialized mental health care may have attenuated this relationship. Further study is needed to better understand the relationship between psychosocial functioning and outcomes.

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

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

Deficits in complex motor functions, despite no evidence of procedural learning deficits, among HIV+ individuals with history of substance dependence

Human immunodeficiency virus (HIV) and drugs of abuse affect common neural systems underlying procedural memory, including the striatum. The authors compared performance of 48 HIV seropositive (HIV+) and 48 HIV seronegative (HIV-) participants with history of cocaine and/or heroin dependence across multiple Trial Blocks of three procedural learning (PL) tasks: Rotary Pursuit (RP), Mirror Star Tracing (MST), and Weather Prediction (WP). Groups were well matched on demographic, psychiatric, and substance use parameters, and all participants were verified abstinent from drugs. Mixed model analyses of variance revealed that the individuals in the HIV+ group performed more poorly across all tasks, with a significant main effect of HIV serostatus observed on the Mirror Star Tracing and a trend toward significance obtained for the Rotary Pursuit task. No significant differences were observed on the Weather Prediction task. Both groups demonstrated significant improvements in performance across all three procedural learning tasks. It is important to note that no significant Serostatus x Trial Block interactions were observed on any task. Thus, the individuals in the HIV+ group tended to perform worse than those in the HIV- group across all trial blocks of procedural learning tasks with motor demands, but showed no differences in their rate of improvement across all tasks. These findings are consistent with HIV--associated deficits in complex motor skills, but not in procedural learning.

Cognitive executive functioning in relation to HIV medication adherence among gay, bisexual, and other men who have sex with men

A longitudinal study of 300 HIV-positive gay, bisexual or non-gay-identified men-who-have-sex-with-men was undertaken to consider patterns relating to HIV medication adherence. The purpose of our analyses was to consider the rate of adherence in relation to both age and executive functioning as assessed by the Trail Making Test A and B. Executive functioning was assessed at baseline and month 10. Our analytic sample consisted of 213 men who remained on the same protease inhibitor throughout the assessment timeframe. Adherence rates were relatively high with more than 50% of the sample maintaining a 95%+ adherence rate at both baseline and month 10. Analyses at baseline indicated executive functioning and age were related to rate of adherence. Analyses at month 10 indicated no significant relations. Findings support previous research and suggest that the status of executive functioning as well as age be given consideration when working with HIV-positive individuals.

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.

Utility of the HIV dementia scale in assessing risk for significant HIV-related cognitive-motor deficits in a high-risk urban adult sample

Considerable literature reflects the range of HIV-related neurocognitive complications, including relatively poor performance on tests of: movement and coordination; attention and concentration; reaction time; and mental flexibility. Efforts to develop appropriate screening techniques include the HIV Dementia Scale (HDS), a brief measure that has demonstrated promise but is lacking extensive independent evaluation. The present study examines the utility of the HDS in a sample of HIV-seropositive adults with a co-morbid history of psychiatric and substance use disorders. Forty subjects (65% male; mean age 41 years; mean education 12.2 years; 55% African American, 30% Caucasian) recruited for a study of the impact of brief psychotherapy on adherence to medications and medical appointments, relapse prevention, and/or enhancement of mental health functioning completed a battery of neuropsychological measures, including the HDS. Forty percent were identified as at high risk for significant cognitive-motor disorder (HDS total score < or =10). After controlling for age, education, illness (absolute CD4), and depressed mood, high-risk participants performed significantly worse on measures of simple and sustained divided attention, psychomotor speed, and working memory. However, only 25 of 40 (63%) were correctly classified based on their performance on traditional tests of neuropsychological functioning. Implications and limitations of the study are discussed.

Medication adherence among HIV+ adults: effects of cognitive dysfunction and regimen complexity

BACKGROUND

Although the use of highly active antiretroviral therapy in the treatment of HIV infection has led to considerable improvement in morbidity and mortality, unless patients are adherent to their drug regimen (i.e., at least 90 to 95% of doses taken), viral replication may ensue and drug-resistant strains of the virus may emerge.

METHODS

The authors studied the extent to which neuropsychological compromise and medication regimen complexity are predictive of poor adherence in a convenience sample of 137 HIV-infected adults. Medication adherence was tracked through the use of electronic monitoring technology (MEMS caps).

RESULTS

Two-way analysis of variance revealed that neurocognitive compromise as well as complex medication regimens were associated with significantly lower adherence rates. Cognitively compromised participants on more complex regimens had the greatest difficulty with adherence. Deficits in executive function, memory, and attention were associated with poor adherence. Logistic regression analysis demonstrated that neuropsychological compromise was associated with a 2.3 times greater risk of adherence failure. Older age (>50 years) was also found to be associated with significantly better adherence.

CONCLUSIONS

HIV-infected adults with significant neurocognitive compromise are at risk for poor medication adherence, particularly if they have been prescribed a complex dosing regimen. As such, simpler dosing schedules for more cognitively impaired patients might improve adherence.

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.

Frontal lobe neuronal injury correlates to altered function in FIV-infected cats

Six cats infected intravenously at 8 weeks of age with feline immunodeficiency virus Maryland isolate (FIV-MD), were evaluated at 8 and 14 months of age (6 months and 12 months postinfection, respectively) with high spatial resolution proton magnetic resonance spectroscopy (MRS) of the frontal cortex. Two separate control cat groups were evaluated at 8 months and 16 months of age. Single voxel two-dimensional high-resolution proton magnetic resonance imaging was performed using the PRESS sequence by selecting a 0.125 ml volume of interest in the medial frontal cortex. A significant reduction in both N-acetylaspartate (NAA) and NAA: choline ratio was found in the FIV 14-month-old group compared with FIV 8-month-old cats, and to the respective age-matched control 16-month-old cats. A negative correlation between NAA and CD4 lymphocyte count was seen in the FIV-14 group only. This group of FIV cats also exhibited a higher proportion of quantitative electroencephalographic relative slow wave activity (RSWA) that correlated to lower NAA content in the frontal cortical voxel. Although peripheral blood proviral load increased over time of infection, no correlation was found between proviral blood or lymph node load and NAA values, CD4 lymphocyte counts, or frontal cortical RSWA. Thus, this study demonstrated that neurologic functional disruption of the frontal cortex correlated strongly with neuronal injury and/or loss in FIV-MD-infected cats independent of peripheral proviral load. The ability to define in vivo neurodegeneration further in this animal model helps in understanding the neuropathogenesis of lentivirus infection, and possibly, a means to follow progression and reversibility during the initial stages of brain infection as therapeutic agents are identified.

Motor skill impairment in SIV-infected rhesus macaques with rapidly and slowly progressing disease

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 further characterize the rhesus macaque infected with neurovirulent SIV as a model of neuroAIDS. Using a motor skill task, our objective was to detect SIV-related movement impairments in behaviorally trained macaques. The motor skill task required retrieval of a food pellet from a cup in a rotating turntable across a range of speeds. Nine monkeys were infected with neurovirulent strains of SIVmac (R71/17E): four monkeys served initially as controls pre-inoculation. Seven monkeys developed simian AIDS within 4 months of inoculation (rapid progressors), and two survived more than 18 months post-inoculation (slow progressors). Of the rapid progressors, five exhibited significant deficits in this task, most showing a gradual decline in performance terminating in a sharp drop to severely impaired levels of performance. One slow progressor (AQ15) showed no performance declines. The other slow progressor (AQ94) showed a significant decrease in maximum speed that was concurrent with the onset of clinical signs. For AQ94, the role of sickness behavior related to late stage simian AIDS could not be ruled out. These results demonstrate that motor system impairment can be detected early in the course of SIV infection in rhesus macaques, further establishing the SIVmac-infected macaque monkey as a viable model of neuroAIDS.

Methodological issues in the study of HIV+ individuals

Because of advances in the treatment of the human immunodeficiency virus (HIV), increased numbers of individuals infected with HIV are remaining in the work force longer. Ergonomists will be called upon soon to modify the work environment or job to allow these individuals to remain productive. Few data, however, exist that can help an ergonomist make such changes for HIV+ individuals. The ergonomist, therefore, either must extrapolate from existing data or collect relevant data. This paper addresses some of the issues that an ergonomist will confront when interpreting existing data or conducting research using HIV+ individuals.

Neuropsychological deficits in HIV-1 seropositive and seronegative intravenous drug users (IVDUs): a follow-up study

Human immunodeficiency virus type 1 (HIV-1) seropositive AIDS free and HIV-1 seronegative intravenous drug users were tested twice with a comprehensive neuropsychological test battery. Only minor group differences were found. Memory difficulties were the most pronounced difference with lower scores in the HIV-1 seropositive group. The memory difficulties were to some degree associated with emotional difficulties, that is, anxiety. The HIV-1 seropositive subjects were tested a third time and there was no further decline in any test with memory content at this testing. The only test that showed a significant decline in the HIV-1 seropositive group was the Trail Making Test.

Longitudinal neuropsychological evaluation of HIV-infected intravenous drug users

The present study aimed to describe the cognitive status of a group of HIV-positive asymptomatic intravenous drug users (IVDU) and changes which occurred over a 12-month follow-up period. Forty-two HIV positive IVDU were selected and matched for age, sex, educational level and pattern of drug abuse with 39 seronegative IVDU controls. Baseline and follow-up evaluation included neuropsychological tests exploring attention, language, memory, logic and visuomotor abilities, biological markers and clinical parameters. About one-third of both seropositive and seronegative subjects showed at baseline slight cognitive deficits, which did not change during the follow-up period.

University of Southern California Repeatable Episodic Memory Test

The University of Southern California Repeatable Episodic Memory Test (USC-REMT) was developed to provide a brief assay of memory in clinical drug trials where the same subject is tested multiple times over days or weeks. Therefore, it had to be minimally affected by repeated testing. The test also provides a measure of subjective organization, a cognitive strategy that might be sensitive to frontal lobe dysfunction and HIV-related memory deficits. The USC-REMT has seven different lists, each composed of 15 semantically unrelated, high-frequency nouns. The words are presented in a different order on three study-test trials. After each study trial the subject recalls the words in any order. The test takes about 10 min to administer and score. The recall protocol can be scored for (a) global mnemonic efficiency, (b) primary and secondary memory, (c) subjective organization, (d) recall consistency and (e) recall as a function of serial position. We report initial data showing that the test is sensitive to memory decrements. Thirty-six HIV-1 seropositive men, at various stages of illness, recalled significantly fewer words and exhibited less subjective organization than 14 matched controls. The test had no significant practice effects over the first three administrations when separated by several days. The seven alternate lists are essentially equivalent. The USC-REMT appears to complement currently published verbal memory tasks.

Relationship between psychiatric disease and neuropsychological impairment in HIV seropositive individuals

Neuropsychological impairment and DSM-III-R Axis I psychiatric diagnoses were evaluated in a heterogenous group of HIV seropositive individuals and seronegative individuals with similar risk factors for HIV infection. Neuropsychological and psychiatric disorders were common in the HIV seropositive group, but there were no relationships between these two aspects of neuropsychiatric dysfunction in seropositive patients. Results indicate that psychiatric disorders in HIV seropositive individuals tend to predate infection and decrease over time following knowledge of seroconversion, suggesting that they are primarily a function of psychosocial factors. Neuropsychological disorders are specific to HIV seropositive patients and tend to increase over time following seroconversion, suggesting that they are due to neurological effects of HIV-infection.

Neuropsychological deficits in tests of executive function in asymptomatic and symptomatic HIV-1 seropositive men

There has been much debate about the exact nature and time of onset of the cognitive impairments associated with infection by the human immunodeficiency virus type 1 (HIV-1). Studies to date have not reached consistent conclusions. The present study comprised 22 asymptomatic and 18 symptomatic HIV-1 seropositive men, whose only risk factor for contraction of the virus was sexual intercourse, and 18 seronegative controls matched for age and IQ. Subjects were given computerized neuropsychological tests from the CANTAB battery, which assessed visuospatial memory, attention and executive function. Both the asymptomatic and the symptomatic HIV-1 seropositive subjects showed a selective pattern of deficits relative to the controls. In addition, the seropositive subjects were subtly but significantly impaired on tests of executive function but unimpaired on certain tests of visual memory. This finding supports an hypothesis that frontostriatal dysfunction occurs in HIV-1 infected individuals prior even to the expression of clinical symptoms.

Diagnostic value of stereotactic biopsy of cerebral lesions in patients with AIDS

A neurological complication occurs in 40-60% of HIV infected patients during the course of the disease. In 10-20% the neurological complication is the first manifestation of the HIV infection. A reliable neuropathological diagnosis is a prerequisite for a specifically selected treatment. While modern computer-assisted imaging techniques, such as computed tomography or magnetic resonance imaging, do possess a high sensitivity, they do not as a rule permit an unambiguous diagnosis. Between October 1989 and July 1994 we biopsied 38 HIV infected patients stereotactically. The indication for the biopsy was determined by having radiologically detectable lesions with no regression tendency in patients under antitoxoplasmosis therapy. In 89% an unambiguous diagnosis was made based on the biopsy; 11% of the biopsies were not diagnostic. For the most part, toxoplasmosis (31%) and progressive multifocal leucoencephalopathy (29%) were involved. 18% of the patients suffered from a non-Hodgkin lymphoma. The foci were primarily frontal (47%), parietal (21%) or localised in the basal ganglia area (11%). The result of the biopsy led to a change in treatment for 52% of the patients. Morbidity and mortality of the operation were 0%. The results or our research series are similar to other groups. It was shown that stereotactic brain biopsy is a safe and effective method for establishing a sound basis for treating the frequently life-threatening cerebral complications of AIDS.

An assessment of rates of psychiatric morbidity and functioning in HIV disease

This study examined demography, rates of psychopathology, and functional impairment in HIV-seropositive women and men in a large, urban, public outpatient infectious disease clinic. Fifty-three percent of the women and 70% of the men met Structural Clinical Interview for DSM-III-R criteria for psychiatric disorders. Current mood disorders were the most frequent diagnoses, followed by psychoactive substance abuse/dependence disorders and psychotic disorders. Seventy-six percent of the women and 90% of the men had previous psychiatric histories, including 59% of the women and 55% of the men who had psychiatric histories prior to their knowledge of HIV seroconversion. Depressed subjects reported significant impairment in physical, social, and role functioning. Similarly, impairment in physical functioning was highly correlated with self-reported anxiety symptoms. These data suggest considerable past and current psychiatric comorbidity in HIV-infected individuals seeking medical care, and draw attention to the need for recognition and aggressive psychiatric treatment, particularly for those depressed and anxious patients with impaired functioning.

The HNRC 500--neuropsychology of HIV infection at different disease stages. HIV Neurobehavioral Research Center

The present study examined neuropsychological (NP) functioning and associated medical, neurological, brain magnetic resonance imaging (MRI), and psychiatric findings in 389 nondemented males infected with Human Immunodeficiency Virus-Type 1 (HIV-1), and in 111 uninfected controls. Using a comprehensive NP test battery, we found increased rates of impairment at each successive stage of HIV infection. HIV-related NP impairment was generally mild, especially in the medically asymptomatic stage of infection, and most often affected attention, speed of information processing, and learning efficiency; this pattern is consistent with earliest involvement of subcortical or frontostriatal brain systems. NP impairment could not be explained on the bases of mood disturbance, recreational drug or alcohol use, or constitutional symptoms; by contrast, impairment in HIV-infected subjects was related to central brain atrophy on MRI, as well as to evidence of cellular immune activation and neurological abnormalities linked to the central nervous system.

Neuropsychological studies of asymptomatic human immunodeficiency virus-type-1 infected individuals. The HNRC Group. HIV Neurobehavioral Research Center

The current review was conducted to address the ongoing debate regarding the presence or absence of neuropsychological impairment in asymptomatic HIV-Type 1 (HIV-1) seropositive individuals. Results were summarized from 57 studies that compared the performances of seropositive asymptomatic and seronegative individuals. Overall, the differences observed between median rates of impairment for asymptomatic (35%) and seronegative (12%) groups provided the clearest indication of deficits in asymptomatics. In addition, five variables were examined as possible contributors to inconsistencies found in the literature: mode of infection, test battery type, test battery size, sample size, and method of data analysis. Of these variables, only mode of infection and test battery size appeared to substantially influence the outcome of the studies reviewed with regard to identifying neuropsychological impairment in asymptomatics.

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

Psychomotor speed and directed attention were evaluated in 83 human immunodeficiency virus-1-infected individuals (HIV+) and 50 HIV-1 seronegative (HIV-) control participants using simple and choice reaction time (RT) tasks. The simple RT task included 1- and 3-s, irregularly varied preparatory intervals (PI) between the warning and target lights. Relative to the HIV- group, simple and choice RT were significantly slowed in the HIV+ group. Further, again relative to the HIV- controls, the HIV+ group did not show expected faster RT with increased response preparation time in the simple RT task. This also occurred in some HIV+ subjects who did not have psychomotor slowing. These findings suggest that RT performance in HIV-1-infected individuals may reflect separate processes associated with psychomotor slowing and impaired ability to direct attention. Possible neural mechanisms associated with control of these processes are discussed.

Neuropsychological performance and CD4 levels in HIV-1 asymptomatic infection

The performance of 68 HIV-1 seropositive asymptomatic (HIV+) subjects stratified on CD4 levels were compared with 82 HIV-1 seronegative (HIV-) subjects on a battery of neuropsychological, mood state, and perceived health status measures. The neuropsychological test battery included measures of attention, reaction time, memory, intellectual ability, psychomotor speed, frontal lobe or "executive" function, and decision time. None of the HIV+ subjects were taking antiviral agents. The groups did not differ for age, mood state, or WAIS-R Verbal and Performance IQ scores. Due to group differences for education and weekly ethanol consumption, both variables were used as covariates in multivariate analyses of variance. Relatively few differences were observed between subgroups of HIV+ patients or between these subgroups and control subjects. These data suggest that factors other than absolute levels of immunosuppression as expressed by CD4 levels alone, appear to be responsible for the deficits observed in HIV+ asymptomatic patients.