Biomarkers of Recent Cannabis Use in Blood, Oral Fluid and Breath.

Proving driving under the influence of cannabis (DUIC) is difficult. Establishing a biomarker of recent use to supplement behavioral observations may be a useful alternative strategy. We determined whether cannabinoid concentrations in blood, oral fluid (OF) or breath could identify use within the past 3 h-likely the period of the greatest impairment. In a randomized trial, 191 frequent (≥4/week) and occasional (<4/week) cannabis users smoked one cannabis (placebo [0.02%], or 5.9% or 13.4% Δ9-tetrahydrocannabinol [THC]) cigarette ad libitum. Blood, OF and breath samples were collected prior to and up to 6 h after smoking. Samples were analyzed for 10 cannabinoids in OF, 8 in blood and THC in breath. Frequent users had more residual THC in blood and were more likely to be categorized as 'recently used' prior to smoking; this did not occur in OF. Per se limits ranging from undetectable to 5 ng/mL THC in blood offered limited usefulness as biomarkers of recent use. Cannabinol (CBN, cutoff = 1 ng/mL) in blood offered 100% specificity but only 31.4% sensitivity, resulting in 100% positive predictive value (PPV) and 94.0% negative predictive value (NPV) at 4.3% prevalence; however, CBN may vary by cannabis chemovar. A 10 ng/mL THC cutoff in OF exhibited the overall highest performance to detect its use within 3 h (99.7% specificity, 82.4% sensitivity, 92.5% PPV and 99.2% NPV) but was still detectable in 23.2% of participants ∼4.4 h post-smoking, limiting specificity at later time points. OF THC may be a helpful indicator of recent cannabis intake, but this does not equate to impairment. Behavioral assessment of impairment is still required to determine DUIC. This study only involved cannabis inhalation, and additional research evaluating alternative routes of ingestion (i.e., oral) is needed.

The Impact of HIV-Associated Neurocognitive Impairment on Driving Performance in Commercial Truck Drivers.

Driving ability can be diminished amongst people with HIV with associated neurocognitive impairment (NCI). We explore the relationship between HIV status, NCI and driving ability in professional truck drivers. Forty male professional drivers (20 HIV-positive; mean age = 39.20 ± 7.05) completed a neuropsychological test battery, two driving simulator tasks that assessed driving ability, and a driving history and habits questionnaire. A higher proportion of HIV-positive drivers exhibited impaired overall cognitive performance (p ≤ 0.001). Overall, drivers with NCI (defined as z ≤ 1.00) were more likely than those without NCI to crash (p = 0.002). There were no significant between-group (HIV-positive versus HIV-negative) differences with regard to self-reported on-road driving events. Professional drivers with NCI, as measured on a driving simulator, are at increased risk of making driving errors under high-risk conditions compared to their neurocognitively normal counterparts. These data should inform driver health management with regard to annual medical screening and surveillance.

RESUMEN: La capacidad de conducción puede verse disminuida entre las personas con VIH con deterioro neurocognitivo asociado (neurocognitive impairment, NCI). Exploramos la relación entre la situación frente al VIH, el NCI y la capacidad de conducción en conductores profesionales de camiones. Cuarenta conductores profesionales masculinos (20 seropositivos, edad media = 39.20 ± 7.05) completaron una batería de pruebas neuropsicológicas, dos tareas de simulador de conducción que evaluaron la capacidad de conducción y un cuestionario de hábitos y antecedentes de conducción. Una mayor proporción de conductores VIH positivos exhibió un desempeño cognitivo general deficiente (p ≤ 0.001). En general, los conductores con NCI (definido como z ≤ 1.00) tenían más probabilidades de chocar que aquellos sin NCI (p = 0.002). No hubo diferencias significativas entre los grupos (VIH positivo frente a VIH negativo) con respecto a los eventos autoinformados de conducción en carretera. Los conductores profesionales con NCI, según lo medido en un simulador de conducción, tienen un mayor riesgo de cometer errores de conducción en condiciones de alto riesgo en comparación con sus homólogos neurocognitivamente normales. Estos datos deberían informar a la gestión de la salud del conductor en lo que respecta a la vigilancia y los exámenes médicos anuales.

Plasma CXCL10 correlates with HAND in HIV-infected women.

HIV-associated neurocognitive disorder (HAND) is characterized by chronic immune activation. We aimed to identify biomarkers associated with HAND and to investigate their association with cognitive function and sex, in a homogenous cohort of HIV-infected (HIV+) young adults, parenterally infected during early childhood. One hundred forty-four HIV+ Romanian participants (51% women) without major confounders underwent standardized neurocognitive and medical evaluation in a cross-sectional study. IFN-γ, IL-1ß, IL-6, CCL2, CXCL8, CXCL10, and TNF-α were measured in plasma in all participants and in cerebrospinal fluid (CSF) in a subgroup of 56 study participants. Biomarkers were compared with neurocognitive outcomes, and the influence of sex and HIV disease biomarkers was assessed. In this cohort of young adults (median age of 24 years), the rate of neurocognitive impairment (NCI) was 36.1%. Median current CD4+ count was 479 cells/mm3 and 36.8% had detectable plasma viral load. Women had better HIV-associated overall status. In plasma, controlling for sex, higher levels of IL-6 and TNF-α were associated with NCI (p < 0.05). Plasma CXCL10 showed a significant interaction with sex (p = 0.02); higher values were associated with NCI in women only (p = 0.02). Individuals with undetectable viral load had significantly lower plasma CXCL10 (p < 0.001) and CCL2 (p = 0.02) levels, and CSF CXCL10 (p = 0.01), IL-6 (p = 0.04), and TNF-α (p = 0.04) levels. NCI in young men and women living with HIV was associated with higher IL-6 and TNF-α in plasma, but not in the CSF. CXCL10 was identified as a biomarker of NCI specifically in women with chronic HIV infection.

Latent toxoplasmosis is associated with neurocognitive impairment in young adults with and without chronic HIV infection.

We evaluated the impact of latent toxoplasmosis (LT) on neurocognitive (NC) and neurobehavioural functioning in young adults with and without chronic HIV infection, using a standardised NC test battery, self-reported Beck Depression Inventory, Frontal System Behavior Scale, MINI-International Neuropsychiatric Interview and risk-assessment battery. 194 young adults (median age 24years, 48.2% males) with chronic HIV infection (HIV+) since childhood and 51 HIV seronegative (HIV-) participants were included. HIV+ individuals had good current immunological status (median CD4: 479 cells/µl) despite a low CD4 nadir (median: 93 cells/µl). LT (positive anti-Toxoplasma IgG antibodies) was present in one third of participants. The impairment rates in the HIV- with and without Toxo were not significantly different (p=0.17). However, we observed an increasing trend (p<0.001) in impairment rates with HIV and LT status: HIV-/LT- (6.1%); HIV-/LT+ (22%), HIV+/LT- (31%), HIV+/LT+ (49%). In a multivariable analysis using the entire study group there were main effects on cognition for HIV and also for LT. Within the HIV+ group LT was associated with worse performance globally (p=0.006), in memory (p=0.009), speed of information processing (p=0.01), verbal (p=0.02) and learning (p=0.02) domains. LT was not associated with depressive symptoms, frontal systems dysfunction or risk behaviors in any of the groups. HIV participants with lower Toxoplasma antibody concentration had worse NC performance, with higher GDS values (p=0.03) and worse learning (p=0.002), memory (p=0.006), speed of information processing (p=0.01) T scores. Latent Toxoplasmosis may contribute to NC impairment in young adults, including those with and without chronic HIV infection.

Visuospatial and Attentional Abilities Predict Driving Simulator Performance Among Older HIV-infected Adults.

OBJECTIVES: To examine the effects of aging and neuropsychological (NP) impairment on driving simulator performance within a human immunodeficiency virus (HIV)-infected cohort. METHODS: Participants included 79 HIV-infected adults (n = 58 > age 50, n = 21 ≤ 40) who completed a NP battery and a personnel computer-based driving simulator task. Outcome variables included total completion time (time) and number of city blocks to complete the task (blocks). RESULTS: Compared to the younger group, the older group was less efficient in their route finding (blocks over optimum: 25.9 [20.1] vs 14.4 [16.9]; P = .02) and took longer to complete the task (time: 1297.6 [577.6] vs 804.4 [458.5] seconds; P = .001). Regression models within the older adult group indicated that visuospatial abilities (blocks: b = -0.40, P <.001; time: b = -0.40, P = .001) and attention (blocks: b = -0.49, P = .001; time: b = -0.42, P = .006) independently predicted simulator performance. The NP-impaired group performed more poorly on both time and blocks, compared to the NP normal group. CONCLUSIONS: Older HIV-infected adults may be at risk of driving-related functional compromise secondary to HIV-associated neurocognitive decline.

Operationalization of the updated diagnostic algorithm for classifying HIV-related cognitive impairment and dementia.

BACKGROUND: This study applies the updated HIV-Associated Neurocognitive Disorders (HAND) diagnostic algorithm. METHODS: Participants were 210 HIV-infected-adults, classified using proposed HAND criteria: HIV-Associated Dementia (HAD), Mild Neurocognitive Disorder (MND), Asymptomatic Neurocognitive Impairment (ANI). RESULTS: The algorithm yielded: normal = 32.8%, ANI = 21.4%, MND = 34.3%, and HAD = 11.4%. Normal participants performed superior to HAND-defined participants on cognition, and HAD participants performed more poorly on global cognition and executive functioning. Two distinct subgroups of interest emerged: (1) functional decline without cognitive impairment; (2) severe cognitive impairment and minimal functional compromise. CONCLUSIONS: The algorithm discriminates between HIV-infected cognitively impaired individuals. Diagnosis yields two unique profiles requiring further investigation. Findings largely support the algorithm's utility for diagnosing HIV-cognitive-impairment, but suggest distinct subsets of individuals with discrepant cognitive/functional performances that may not be readily apparent by conventional application of HAND diagnosis.

HIV-associated neurocognitive disorders persist in the era of potent antiretroviral therapy: CHARTER Study.

OBJECTIVES: This is a cross-sectional, observational study to determine the frequency and associated features of HIV-associated neurocognitive disorders (HAND) in a large, diverse sample of infected individuals in the era of combination antiretroviral therapy (CART). METHODS: A total of 1,555 HIV-infected adults were recruited from 6 university clinics across the United States, with minimal exclusions. We used standardized neuromedical, psychiatric, and neuropsychological (NP) examinations, and recently published criteria for diagnosing HAND and classifying 3 levels of comorbidity (minimal to severe non-HIV risks for NP impairment). RESULTS: Fifty-two percent of the total sample had NP impairment, with higher rates in groups with greater comorbidity burden (40%, 59%, and 83%). Prevalence estimates for specific HAND diagnoses (excluding severely confounded cases) were 33% for asymptomatic neurocognitive impairment, 12% for mild neurocognitive disorder, and only 2% for HIV-associated dementia (HAD). Among participants with minimal comorbidities (n = 843), history of low nadir CD4 was a strong predictor of impairment, and the lowest impairment rate on CART occurred in the subset with suppressed plasma viral loads and nadir CD4 ≥200 cells/mm(3) (30% vs 47% in remaining subgroups). CONCLUSIONS: The most severe HAND diagnosis (HAD) was rare, but milder forms of impairment remained common, even among those receiving CART who had minimal comorbidities. Future studies should clarify whether early disease events (e.g., profound CD4 decline) may trigger chronic CNS changes, and whether early CART prevents or reverses these changes.

Demographic influences and suggested cut-scores for the Beck Depression Inventory in a non-clinical Spanish speaking population from the US-Mexico border region.

The Beck Depression Inventory-I (BDI-I) is a self-report measure of depressive symptomatology that is widely used in both research and clinical settings. While the Spanish language version of the BDI-I is frequently used in the USA, there are currently no available guidelines to determine depressive symptomatology base rates in Spanish speaking populations using this instrument. In the present study, base rates of depressive symptoms and demographic influences on the BDI-I were measured in a non-clinical Spanish speaking population from the US-Mexico border region. A sample of 198 neurologically normal Spanish speaking individuals, mostly of Mexican decent, completed the BDI-I as part of a larger neuropsychological norming study. The results indicated that while there were no effects of age or education on overall BDI-I scores, those with lower education tended to report higher severity of individual symptoms. Consistent with findings in other populations, women endorsed a greater number of depressive symptoms. Therefore separate cut-scores were derived for men and women to represent these differences. Future research should assess the impact of acculturation and socioeconomic stressors on the BDI scores in this mostly immigrant population.

Variable patterns of neuropsychological performance in HIV-1 infection.

Based upon prior findings with group means, a "prototypical pattern" of neuropsychological results with HIV infection has emerged: impaired executive functioning, motor skills, speed of information processing, and learning, with intact memory retention, most language skills, and visuospatial functioning. We examined neuropsychological results from 553 HIV+ adults to determine the number of patterns seen among individuals with HIV infection. Factor analysis of a relatively comprehensive neuropsychological battery identified 6 component factors: verbal memory (VeM), visual memory (ViM), processing speed (PS), attention/working memory (A/WM), executive function (EF), and motor (M). These factor scores were submitted to hierarchical cluster analysis, to determine the appropriate number of clusters or patterns in the cohort. Final cluster membership was then determined by K-means analysis, based on the Lange, Iverson, Senior, and Chelune (2002) method. A 6-cluster solution was found to be most appropriate. The definitions of the clusters were based upon ipsative scoring of factor scores to indicate relative strengths and weaknesses (independent of overall level of performance): Cluster 1: strong EF; Cluster 2: strong M, weak VeM and EF; Cluster 3: strong PS, weak ViM and EF; Cluster 4: strong VeM, weak M; Cluster 5: strong A/WM; Cluster 6: strong VeM, weak EF. Neuropsychological-impairment rates differed across clusters, but all 6 clusters contained substantial numbers of impaired and unimpaired individuals. Cluster membership was not explained by demographic variables or psychiatric or neuromedical confounds. Thus, there does not appear to be a single, prototypical pattern of neuropsychological impairment associated with HIV infection for this battery of representative neuropsychological tests.

A multimodal assessment of driving performance in HIV infection.

OBJECTIVE: To examine if HIV-seropositive (HIV+) individuals are at risk for impaired driving. METHODS: Sixty licensed drivers (40 HIV+, 20 HIV-) completed a neuropsychological (NP) test battery and driving assessments. Eleven HIV+ subjects were NP-impaired. Driving-related skills were assessed using 1) two driving simulations (examining accident avoidance and navigational abilities), 2) the Useful Field of View (UFOV) test, and 3) an on-road evaluation. RESULTS: HIV+ NP-impaired subjects had greater difficulty than cognitively intact subjects on all driving measures, whereas the HIV- and HIV+ NP-normal groups performed similarly. On the UFOV, the HIV+ NP-impaired group had worse performance on Visual Processing and Divided Attention tasks but not in overall risk classification. They also had a higher number of simulator accidents (1.3 vs 2.0; p = 0.03), were less efficient at completing the navigation task (3.2 vs 9.2 blocks; p = 0.001), and were more likely to fail the on-road evaluation (6 vs 36%; p = 0.02). Impairment in Executive Functioning was the strongest NP predictor of failing the on-road drive test. NP performance and both simulations independently contributed to a model predicting 48% of the variance in on-road performance. CONCLUSION: HIV+ NP-impaired individuals are at increased risk for on-road driving impairments, whereas HIV+ individuals with normal cognition are not at a significantly higher risk than HIV- subjects. Executive Functioning is most strongly associated with impaired on-road performance. Cognitive and simulator testing may each provide data in identifying driving-impaired individuals.

Neurocognitive dysfunction predicts postmortem findings of HIV encephalitis.

OBJECTIVE: To investigate the value of antemortem cognitive functioning in predicting postmortem evidence of HIV encephalitis (HIVE). METHODS: Thirty-nine subjects were assessed during life with a comprehensive neuropsychological battery and went on to autopsy within 18 months of testing. Cognitive impairment was determined by blind clinical ratings, based on demographically corrected test scores. Presence of HIVE was based on postmortem immunocytochemical detection of the viral protein gp41 or by measurement of HIV RNA by PCR in multiple brain areas as well as by histopathologic evidence such as microgliosis, presence of multinucleated giant cells, and myelin pallor in several brain regions. RESULTS: The sensitivity and specificity of neurocognitive impairment in detecting the occurrence of HIVE were 67 and 92%. Eighteen of 19 subjects with antemortem neurocognitive impairment had evidence of HIV-related brain disease (positive predictive value = 95%). CONCLUSION: Neuropsychological assessment can help select HIV-positive patients for treatment of CNS disease.

Long-term effects of high-dose zidovudine treatment on neuropsychological performance in mildly symptomatic HIV-positive patients: results of a randomized, double-blind, placebo-controlled investigation.

This study examined the treatment outcome of high-dose (1500 mg/day) zidovudine (AZT) on neuropsychological (NP) functioning (Trailmaking Test A & B, WAIS-R Digit Symbol, and Rey Auditory Verbal Learning Test) across a 12-month period in mildly symptomatic HIV-1 seropositive men (n = 46 at entry) enrolled in a randomized, double-blind, placebo-controlled trial (VA Cooperative Studies Program #298). Neither short-term (0-6 months) nor long-term (0-12 months) AZT administration revealed enhancement in NP performance. The results suggest that, although AZT may afford patients prophylactic benefits, protracted high-dose AZT treatment does not improve NP functioning in mildly symptomatic HIV-positive individuals.

Stability and course of neuropsychological deficits in schizophrenia.

BACKGROUND: Neuropsychological deficits in schizophrenia appear to predate clinical symptoms of the disease and become more pronounced at illness onset, but controversy exists about whether and when further neuropsychological progression may occur. OBJECTIVE: To identify and characterize any subset of patients who evidenced progressive neuropsychological impairment, we compared the longitudinal stability of neuropsychological functioning in schizophrenic outpatients and normal comparison subjects. METHODS: One hundred forty-two schizophrenic outpatients and 206 normal comparison subjects were given annually scheduled comprehensive neuropsychological evaluations during an average of 3 years (range, 6 months to 10 years). Clinically and demographically defined subgroups were compared, and test-retest norms were used to identify individual patients who showed unusual worsening over time. RESULTS: The schizophrenic group was neuropsychologically more impaired than the normal comparison subjects but showed comparable test-retest reliability and comparable neuropsychological stability over both short (mean, 1.6 years) and long (mean, 5 years) follow-up periods. No significant differences in neuropsychological change were found between schizophrenic subgroups defined by current age, age at onset of illness, baseline level of neuropsychological impairment, improvement or worsening of clinical symptoms, and occurrence of incident tardive dyskinesia. Norms for change also failed to show neuropsychological progression in individuals with schizophrenia. CONCLUSIONS: Neuropsychological impairment in ambulatory persons with schizophrenia appears to remain stable, regardless of baseline characteristics and changes in clinical state. Our results may not be generalizable to the minority of institutionalized poor-outcome patients.

Detecting change: A comparison of three neuropsychological methods, using normal and clinical samples.

Detecting change in individual patients is an important goal of neuropsychological testing. However, limited information is available about test-retest changes, and well-validated prediction methods are lacking. Using a large nonclinical subject group (N = 384), we recently investigated test-retest reliabilities and practice effects on the Wechsler Adult Intelligence Scale and Halstead-Reitan Battery. Data from this group also were used to develop models for predicting follow-up test scores and establish confidence intervals around them. In this article we review those findings, examine their generalizability to new nonclinical and clinical groups, and explore the sensitivity of the prediction models to real change. Despite similarities across samples in reliability coefficients and practice effects, limits to the generalizability of prediction methods were found. Also, when multiple test measures were considered together, one or more "significant" changes were common in all (including stable) subject groups. By employing normative cut-offs that correct for this, sensitivity of the models to neurological recovery and deterioration was modest to good. More complex regression models were not more accurate than the simpler Reliable Change Index with correction for practice effects when confidence intervals for all methods were adjusted for variations in level of baseline test performance.

Extending the p-plot: heuristics for multiple testing. HNRC group.

In the problem of large-scale multiple testing the p-plot is a graphically based competitor to the notoriously weak Bonferroni method. The p-plot is less stringent and more revealing in that it gives a gauge of how many hypotheses are decidedly false. The method is elucidated and extended here: the bootstrap reveals bias and sampling error in the usual point estimates, a bootstrap-based confidence interval for the gauge is given, as well as two acceptably powerful blanket tests of significance. Guidelines for use are given, and interpretational pitfalls pointed out, in the discussion of a case study linking premortem neuropsychological and postmortem neuropathologic data in an HIV cohort study.

Screening for dementia: comparison of three commonly used instruments.

The sensitivity and specificity of three cognitive screening measures - the Mini-Mental State Exam (MMSE), Mattis Dementia Rating Scale (MDRS), and Neurobehavioral Cognitive Status Examination (NCSE) - were compared in a cohort of subjects with dementia as well as normal elderly individuals. Twenty-two patients met criteria for probable Alzheimer' s disease (AD), 19 for vascular dementia (VaD), and 12 were normal control subjects. The use of standard cutpoints resulted in poor to good classification accuracy for the three measures, but measurable improvement in sensitivity was obtained by adjusting the cutpoints for each measure. Discriminatory power was maximized with an MMSE cutpoint of < or = 26, an MDRS cutpoint of < or = 134, and requiring one or more NCSE subtests to be in the impaired range. Use of age and education adjusted norms resulted in good to excellent classification accuracy for the MMSE and MDRS. The NCSE subtest score pattern failed to differentiate between AD and VaD.

Cortical synaptic density is reduced in mild to moderate human immunodeficiency virus neurocognitive disorder. HNRC Group. HIV Neurobehavioral Research Center.

Dendritic and synaptic damage (without frank neuronal loss) may be seen in milder human immunodeficiency virus (HIV)-related cognitive disorders. Synapse volume estimates, performed by stereological methods, could enhance the ability to detect subtle neuronal changes that may accompany cognitive impairment in HIV infection. For the present study, synaptic density and neuronal number were assessed by combined stereology/confocal microscopy and these measures were then correlated with ante-mortem levels of cognitive performance in AIDS patients. Three-dimensional stereological measures showed a significant correlation between reduced synaptic density and poor neuropsychological performance. To evaluate the specificity of any observed associations, additional variables including viral burden, astrogliosis and number of calbindin-immunoreactive neurons were measured. Factor analysis of a set of neuropathological variables revealed two factors; one defined by synaptic density and volume fraction, calbindin pyramidal neuronal densities and viral burden; the second by astrocytosis and calbindin interneuron density. Only the first factor correlated significantly with neuropsychological functioning during life. It is concluded that a combination of factors including synaptic damage, specific neuronal loss and increasing viral load underlies HIV-associated cognitive impairment. As synaptic damage is potentially reversible, early diagnosis and treatment of mild cogntive disorders may improve functioning and prevent the progression of brain disease.

Neuropsychological impairment-associated visual field deficits in HIV infection. HNRC Group. HIV Neurobehavioral Research Center.

PURPOSE: To examine the relationship between loss in peripheral visual sensitivity and neuropsychological functioning in seropositive patients with human immunodeficiency virus (HIV) without infectious retinopathy. METHODS: Subjects carefully screened for retinal disease and well-matched across demographic and medical variables were grouped according to normal (perimetry-nl) versus abnormal (perimetry-abnl) performance on achromatic automated perimetry and short-wavelength automated perimetry, standard clinical ophthalmologic measures of visual function. All subjects completed a detailed neuropsychological test battery and were classified as impaired or unimpaired, globally and across eight neurocognitive domains. Subjects were also classified according to whether they met diagnostic criteria for minor cognitive/motor disorder (MCMD) or HIV-associated dementia (HAD). RESULTS: Visual field loss was associated with lower performance in the abstraction, perceptual-motor, learning, and motor domains. Significant group differences were also found on numerous individual neuropsychological tests. Based on clinical ratings, we found deficits in learning and motor functioning. No perimetry-nl subjects met criteria for MCMD or HAD, whereas 32% of perimetry-abnl subjects met diagnostic criteria for syndromic cognitive disorders (five MCMD and one HAD). In a subset of subjects who underwent a lumbar puncture, there was a trend for the perimetry-abnl group to have a higher concentration of beta2 microglobulin, a marker for central nervous system immune activation. CONCLUSIONS: These results suggest that in some HIV-infected people reduced visual function may be caused by nonretinal disease, and perimetry may present a sensitive measure of HIV-related brain dysfunction.

The impact of HIV-related neuropsychological dysfunction on driving behavior. The HNRC Group.

HIV infection often results in neuropsychological (NP) impairment. In order to assess the impact that HIV-related NP deficits may have on automobile driving, we evaluated 68 HIV-seropositive drivers using an NP battery and two PC-based driving simulations. Thirty-two participants were classified as NP impaired; most (72%) evidenced only mild impairment, and none met criteria for HIV-associated dementia. After controlling for degree of immunosuppression and disease stage, NP-impaired participants failed a previously validated driving simulation at a much higher rate than cognitively intact participants [OR = 5.3, 95% CI (1.7, 17.0), p = .006]. Similarly, on a simulation of city driving, NP impaired participants were more likely to fail based upon the number of accidents [OR = 6.1, 95% CI (1.5, 24.6), p = .01]. Simulator performance was predicted by functioning in a number of NP domains, with NP tests accounting for 13-30% of the variance on the simulations. Although it would be premature to extrapolate these findings to impairment in on-the-road driving, they do argue for greater attention to the impact that even mild HIV-related NP deficits may have on driving skills.