Longitudinal changes in neurocognitive performance related to drug use intensity in a sample of persons with and without HIV who use illicit stimulants

BACKGROUND

Illicit stimulant use remains a public health concern that has been associated with multiple adverse outcomes, including cognitive deficits. The effects of stimulant use on cognition may be particularly deleterious in persons with HIV. Stimulant use intensity may be an important factor in the magnitude of observed deficits over time.

METHODS

We completed neurocognitive testing in a sample of people who use stimulants with (n = 84) and without HIV (n = 123) at baseline and up to 4 follow-up time points over approximately 1 year. Participants reported on substance use at each visit, including frequency of use and stimulant dependence. Mixed effects models examined the relationship between stimulant-related factors and neurocognitive function over time.

RESULTS

Participants were mostly male (57%), African American (86%), and 47.41 years old on average. All participants actively used stimulants at enrollment and use remained prevalent throughout the follow-up period, with an average of ≥24 days of use in the past 90 days at all time points. Retention was excellent, with 86% completing all 4 follow-up assessments. Mixed effects models showed that stimulant dependence was associated with lower neurocognitive performance independent of HIV status (p = 0.002), whereas frequency of use had a greater negative impact on performance in participants with HIV compared to those without HIV (p = 0.045).

CONCLUSIONS

Our key finding is that stimulant-related factors are associated with neurocognitive performance over time, but in complex ways. These findings have important implications for harm reduction approaches, particularly those that target cognitive function.

Cocaine use is associated with cerebral white matter hyperintensities in HIV disease

BACKGROUND

White matter hyperintensities (WMH), a marker of cerebral small vessel disease and predictor of cognitive decline, are observed at higher rates in persons with HIV (PWH). The use of cocaine, a potent central nervous system stimulant, is disproportionately common in PWH and may contribute to WMH.

METHODS

The sample included of 110 PWH on antiretroviral therapy. Fluid-attenuated inversion recovery (FLAIR) and T1-weighted anatomical MRI scans were collected, along with neuropsychological testing. FLAIR images were processed using the Lesion Segmentation Toolbox. A hierarchical regression model was run to investigate predictors of WMH burden [block 1: demographics; block 2: cerebrovascular disease (CVD) risk; block 3: lesion burden].

RESULTS

The sample was 20% female and 79% African American with a mean age of 45.37. All participants had persistent HIV viral suppression, and the median CD4+ T-cell count was 750. Nearly a third (29%) currently used cocaine regularly, with an average of 23.75 (SD = 20.95) days in the past 90. In the hierarchical linear regression model, cocaine use was a significant predictor of WMH burden (β = .28). WMH burden was significantly correlated with poorer cognitive function (r = -0.27). Finally, higher WMH burden was significantly associated with increased serum concentrations of interferon-γ-inducible protein 10 (IP-10) but lower concentrations of myeloperoxidase (MPO); however, these markers did not differ by COC status.

CONCLUSIONS

WMH burden is associated with poorer cognitive performance in PWH. Cocaine use and CVD risk independently contribute to WMH, and addressing these conditions as part of HIV care may mitigate brain injury underlying neurocognitive impairment.

HIV viremia contributes to neurocognitive impairments in persons who use cocaine

Persons with HIV (PWH) who use illicit drugs are at elevated risk for neurocognitive impairment (NCI). This study investigated the effects of HIV disease and HIV viremia on NCI among adults who use cocaine. PWH who were not virologically suppressed showed greater global deficits compared to participants with HIV viral suppression and HIV-negative participants, but no differences emerged between the latter two groups. These findings highlight the adverse effects of poorly controlled HIV disease on NCI, beyond the independent effects of cocaine on cognition, and underscore the importance of strengthening the HIV care continuum for persons who use cocaine.

Cortico-striatal networking deficits associated with advanced HIV disease and cocaine use

Cocaine use is disproportionately prevalent in people with HIV (PWH) and is known to potentiate HIV neuropathogenesis. As both HIV and cocaine have well-documented cortico-striatal effects, PWH who use cocaine and have a history of immunosuppression may exhibit greater FC deficits compared to PWH without these conditions. However, research investigating the legacy effects of HIV immunosuppression (i.e., a history of AIDS) on cortico-striatal functional connectivity (FC) in adults with and without cocaine use is sparse. Resting-state functional magnetic resonance imaging (fMRI) and neuropsychological assessment data from 273 adults were analyzed to examine FC in relation to HIV disease: HIV-negative (n = 104), HIV-positive with nadir CD4 ≥ 200 (n = 96), HIV-positive with nadir CD4 < 200 (AIDS; n = 73), and cocaine use (83 COC and 190 NON). Using independent component analysis/dual regression, FC was assessed between the basal ganglia network (BGN) and five cortical networks: dorsal attention network (DAN), default mode network, left executive network, right executive network, and salience network. There were significant interaction effects such that AIDS-related BGN-DAN FC deficits emerged in COC but not in NON participants. Independent of HIV, cocaine effects emerged in FC between the BGN and executive networks. Disruption of BGN-DAN FC in AIDS/COC participants is consistent with cocaine potentiation of neuro-inflammation and may be indicative of legacy HIV immunosuppressive effects. The current study bolsters previous findings linking HIV and cocaine use with cortico-striatal networking deficits. Future research should consider the effects of the duration of HIV immunosuppression and early treatment initiation.

Additive cortical gray matter deficits in people living with HIV who use cocaine

Cocaine use, which is disproportionately common in people living with HIV (PWH), is known to have neurotoxic effects that may exacerbate HIV neuropathogenesis. While both cocaine use and HIV disease are independently associated with deficits in gray matter (GM) volume, the additive effect of cocaine use to HIV disease on GM volume has not been explored. Here, we investigated subcortical and cortical brain volume differences between four groups of individuals with and without HIV disease and/or cocaine use. Participants also completed a comprehensive neuropsychological testing battery, and HIV disease characteristics were recorded. Within subcortical regions, cocaine use was independently associated with higher volume in the dorsal striatum and pallidum, while HIV disease was associated with lower volume in the nucleus accumbens and thalamus. For cortical regions, there was an additive effect of cocaine use on HIV disease in parietal and occipital lobe volume with PWH who used cocaine displaying the lowest GM volume. Within regions that differed between groups, higher neurocognitive function was positively associated with thalamic, nucleus accumbens, dorsal striatum, and occipital lobe volume. For regions that showed a significant main effect of HIV disease, lower nadir CD4 + T cell count was associated with lower nucleus accumbens and occipital lobe volume. Lower current CD4 + T cell count was associated with lower occipital lobe volume. These results suggest that PWH who use cocaine are at greater risk for cortical atrophy than cocaine use or HIV disease alone.

Neuroimaging and immunological features of neurocognitive function related to substance use in people with HIV

This study sought to identify neuroimaging and immunological factors associated with substance use and that contribute to neurocognitive impairment (NCI) in people with HIV (PWH). We performed cross-sectional immunological phenotyping, neuroimaging, and neurocognitive testing on virally suppressed PWH in four substance groups: cocaine only users (COC), marijuana only users (MJ), dual users (Dual), and Non-users. Participants completed substance use assessments, multimodal MRI brain scan, neuropsychological testing, and blood and CSF sampling. We employed a two-stage analysis of 305 possible biomarkers of cognitive function associated with substance use. Feature reduction (Kruskal Wallis p-value < 0.05) identified 53 biomarkers associated with substance use (22 MRI and 31 immunological) for model inclusion along with clinical and demographic variables. We employed eXtreme Gradient Boosting (XGBoost) with these markers to predict cognitive function (global T-score). SHapley Additive exPlanations (SHAP) values were calculated to rank features for impact on model output and NCI. Participants were 110 PWH with sustained HIV viral suppression (33 MJ, 12 COC, 22 Dual, and 43 Non-users). The ten highest ranking biomarkers for predicting global T-score were 4 neuroimaging biomarkers including functional connectivity, gray matter volume, and white matter integrity; 5 soluble biomarkers (plasma glycine, alanine, lyso-phosphatidylcholine (lysoPC) aC17.0, hydroxy-sphingomyelin (SM.OH) C14.1, and phosphatidylcholinediacyl (PC aa) C28.1); and 1 clinical variable (nadir CD4 count). The results of our machine learning model suggest that substance use may indirectly contribute to NCI in PWH through both metabolomic and neuropathological mechanisms.

The Individualized Prediction of Neurocognitive Function in People Living with HIV Based on Clinical and Multimodal Connectome Data

Neurocognitive impairment continues to be common comorbidity for people living with HIV (PLWH). Given the chronic nature of HIV disease, identifying reliable biomarkers of these impairments is essential to advance our understanding of the underlying neural foundation and facilitate screening and diagnosis in clinical care. While neuroimaging provides immense potential for such biomarkers, to date, investigations in PLWH have been mostly limited to either univariate mass techniques or a single neuroimaging modality. In the present study, connectome-based predictive modeling (CPM) was proposed to predict individual differences of cognitive functioning in PLWH, using resting-state functional connectivity (FC), white matter structural connectivity (SC), and clinical relevant measures. We also adopted an efficient feature selection approach to identify the most predictive features, which achieved an optimal prediction accuracy of r = 0.61 in the discovery dataset (n = 102) and r = 0.45 in an independent validation HIV cohort (n = 88). Two brain templates and nine distinct prediction models were also tested for better modeling generalizability. Results show that combining multimodal FC and SC features enabled higher prediction accuracy of cognitive scores in PLWH, while adding clinical and demographic metrics may further improve the prediction by introducing complementary information, which may help better evaluate the individual-level cognitive performance in PLWH.

Strengthened and posterior-shifted structural rich-club organization in people who use cocaine

BACKGROUND

People with cocaine use disorder (CUD) often have abnormal cognitive function and brain structure. Cognition is supported by brain networks that typically have characteristics like rich-club organization, which is a group of regions that are highly connected across the brain and to each other, and small worldness, which is a balance between local and long-distance connections. However, it is unknown whether there are abnormalities in structural brain network connectivity of CUD.

METHODS

Using diffusion-weighted imaging, we measured structural connectivity in 37 people with CUD and 38 age-matched controls. We identified differences in rich-club organization and whether such differences related to small worldness and behavior. We also tested whether rich-club reorganization was associated with caudate and putamen structural connectivity due to the relevance of the dopamine system to cocaine use.

RESULTS

People with CUD had a higher normalized rich-club coefficient than controls, more edges connecting rich-club nodes to each other and to non-rich-club nodes, and fewer edges connecting non-rich-club nodes. Rich-club nodes were shifted posterior and lateral. Rich-club reorganization was related to lower clustered connectivity around individual nodes found in CUD, to increased impulsivity, and to a decrease in caudate connectivity.

CONCLUSIONS

These findings are consistent with previous work showing increased rich-club connectivity in conditions associated with a hypofunctional dopamine system. The posterior shift in rich-club nodes in CUD suggests that the structural connectivity of posterior regions may be more impacted than previously recognized in models based on brain function and morphology.

Principal component analysis denoising improves sensitivity of MR diffusion to detect white matter injury in neuroHIV

BACKGROUND AND PURPOSE

Diffusion-weighted imaging is able to capture important information about cerebral white matter (WM) structure. However, diffusion data can suffer from MRI and biological noise that degrades the quality of the images and makes finding important features difficult. We investigated how effectively local and nonlocal denoising increased the sensitivity to detect differences in cerebral WM in neuroHIV.

METHODS

We utilized principal component analysis (PCA) denoising to detect WM differences using fractional anisotropy. Local and nonlocal PCA denoising paradigms were implemented that varied in search area and number of components. We examined different-sized WM tracts that consistently show differences between people living with Human Immunodeficiency Virus (HIV) (PWH) and HIV-negative individuals (corpus callosum, forceps minor, and right uncinate fasciculus), and size-matched tracts not typically associated with HIV-related differences (spinothalamic, right medial lemniscus, and left occipitopontine). We first conducted a full sample comparison of WM differences between groups, and then randomly reduced the sample to the point where we still found differences in WM.

RESULTS

Nonlocal PCA denoising allowed us to detect differences after a sample reduction of 35% in the forceps minor, 17% in the right uncinate fasciculus, and 6% in the corpus callosum.

CONCLUSIONS

PCA denoising had a beneficial effect on detecting significant differences in PWH after sample size reduction. The smaller forceps minor tract and right uncinate fasciculus showed greater sensitivity to PCA denoising than the larger corpus callosum. These results show the importance of identifying the most effective PCA denoising strategy when investigating WM in PWH.

Effects of substance use on monetary delay discounting among people who use stimulants with and without HIV: An ecological momentary assessment study

Exploration of the real-time relationship between substance use and delay discounting may reveal potential mechanisms driving high-risk behaviors. We conducted an ecological momentary assessment (EMA) study to investigate the effects of substance use on delay discounting in a sample of people who use stimulants (HIV+: 30; HIV-: 34). Participants completed multiple EMAs throughout the day for 28 days. The EMAs collected data on delay discounting and substance use (time since last substance use and level of intoxication). Delay discounting was assessed using a brief Monetary Choice Questionnaire (MCQ). Analyses were conducted using linear mixed effects modeling. Most participants (99.1%) used cocaine as their primary stimulant. Among participants without HIV, MCQ score remained relatively stable during the first 2 hr after stimulant use, followed by an increase during 2-6 hr (p < .05), before decreasing again. For alcohol and marijuana, the MCQ score was stable during the first 4 hr after use, with a sharp increase at 4-6 hr (p < .05), before decreasing again. Among participants with HIV, there were no changes in MCQ score as a function of time since recent substance use. These findings provide evidence of a plausible connection between delay discounting and acute withdrawal that may have relevance for risky behaviors. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Human immunodeficiency virus-related decreases in corpus callosal integrity and corresponding increases in functional connectivity

People living with human immunodeficiency virus (PLWH) often have neurocognitive impairment. However, findings on HIV-related differences in brain network function underlying these impairments are inconsistent. One principle frequently absent from these reports is that brain function is largely emergent from brain structure. PLWH commonly have degraded white matter; we hypothesized that functional communities connected by degraded white matter tracts would show abnormal functional connectivity. We measured white matter integrity in 69 PLWH and 67 controls using fractional anisotropy (FA) in 24 intracerebral white matter tracts. Then, among tracts with degraded FA, we identified gray matter regions connected to these tracts and measured their functional connectivity during rest. Finally, we identified cognitive impairment related to these structural and functional connectivity systems. We found HIV-related decreased FA in the corpus callosum body (CCb), which coordinates activity between the left and right hemispheres, and corresponding increases in functional connectivity. Finally, we found that individuals with impaired cognitive functioning have lower CCb FA and higher CCb functional connectivity. This result clarifies the functional relevance of the corpus callosum in HIV and provides a framework in which abnormal brain function can be understood in the context of abnormal brain structure, which may both contribute to cognitive impairment.

Structural and Functional Brain Abnormalities in Human Immunodeficiency Virus Disease Revealed by Multimodal Magnetic Resonance Imaging Fusion: Association With Cognitive Function

BACKGROUND

Human immunodeficiency virus (HIV)-associated neurocognitive impairment remains a prevalent comorbidity that impacts daily functioning and increases morbidity. While HIV infection is known to cause widespread disruptions in the brain, different magnetic resonance imaging (MRI) modalities have not been effectively integrated. In this study, we applied 3-way supervised fusion to investigate how structural and functional coalterations affect cognitive function.

METHODS

Participants (59 people living with HIV and 58 without HIV) completed comprehensive neuropsychological testing and multimodal MRI scanning to acquire high-resolution anatomical, diffusion-weighted, and resting-state functional images. Preprocessed data were reduced using voxel-based morphometry, probabilistic tractography, and regional homogeneity, respectively. We applied multimodal canonical correlation analysis with reference plus joint independent component analysis using global cognitive functioning as the reference.

RESULTS

Compared with controls, participants living with HIV had lower global cognitive functioning. One joint component was both group discriminating and correlated with cognitive function. This component included the following covarying regions: fractional anisotropy in the corpus callosum, short and long association fiber tracts, and corticopontine fibers; gray matter volume in the thalamus, prefrontal cortex, precuneus, posterior parietal regions, and occipital lobe; and functional connectivity in frontoparietal and visual processing regions. Component loadings for fractional anisotropy also correlated with immunosuppression.

CONCLUSIONS

These results suggest that coalterations in brain structure and function can distinguish people with and without HIV and may drive cognitive impairment. As MRI becomes more commonplace in HIV care, multimodal fusion may provide neural biomarkers to support diagnosis and treatment of cognitive impairment.

Brain multimodal co-alterations related to delay discounting: a multimodal MRI fusion analysis in persons with and without cocaine use disorder

BACKGROUND

Delay discounting has been proposed as a behavioral marker of substance use disorders. Innovative analytic approaches that integrate information from multiple neuroimaging modalities can provide new insights into the complex effects of drug use on the brain. This study implemented a supervised multimodal fusion approach to reveal neural networks associated with delay discounting that distinguish persons with and without cocaine use disorder (CUD).

METHODS

Adults with (n = 35) and without (n = 37) CUD completed a magnetic resonance imaging (MRI) scan to acquire high-resolution anatomical, resting-state functional, and diffusion-weighted images. Pre-computed features from each data modality included whole-brain voxel-wise maps for gray matter volume, fractional anisotropy, and regional homogeneity, respectively. With delay discounting as the reference, multimodal canonical component analysis plus joint independent component analysis was used to identify co-alterations in brain structure and function.

RESULTS

The sample was 58% male and 78% African-American. As expected, participants with CUD had higher delay discounting compared to those without CUD. One joint component was identified that correlated with delay discounting across all modalities, involving regions in the thalamus, dorsal striatum, frontopolar cortex, occipital lobe, and corpus callosum. The components were negatively correlated with delay discounting, such that weaker loadings were associated with higher discounting. The component loadings were lower in persons with CUD, meaning the component was expressed less strongly.

CONCLUSIONS

Our findings reveal structural and functional co-alterations linked to delay discounting, particularly in brain regions involved in reward salience, executive control, and visual attention and connecting white matter tracts. Importantly, these multimodal networks were weaker in persons with CUD, indicating less cognitive control that may contribute to impulsive behaviors.

Using mobile health technologies to test the association of cocaine use with sexual desire and risky sexual behaviors among people with and without HIV who use illicit stimulants

BACKGROUND

Cocaine use is broadly associated with risky sexual behavior potentially through elevated sexual desire. Understanding the within-person effects of cocaine on sexual desire and risky sexual behavior and the modification of HIV infection may inform primary and secondary HIV interventions.

METHODS

We conducted a mobile health (mHealth) study in a community sample of males and females with (n = 28) and without (n = 32) HIV who use illicit stimulant drugs. Participants completed ecological momentary assessments (EMAs) and daily diaries over 28 days. Mixed effects models were employed to examine the within-person association of cocaine use with sexual desire and risky sexual behavior.

RESULTS

Participants completed 3505 EMA responses, with 36 % involving recent cocaine use, including powder and/or crack cocaine. They completed 1427 daily diary responses, with cocaine use reported on 49 % of these days and sexual behavior on 21 % of these days. Sexual desire was highest in the first hour since cocaine use and gradually decreased with time. Sexual desire was lowest when participants had not used any cocaine in the past 6 h, and it correlated positively with the amount of use. Participants were more likely to have risky sexual behavior on days they used cocaine. These associations were similar for participants with and without HIV.

CONCLUSION

This study demonstrates the dynamic and proximal effects of cocaine use on sexual desire and risky sexual behavior. Our findings support the development of HIV prevention interventions that utilize mHealth technology to reduce sexual risk behavior among persons who use stimulant drugs.

Hypoactivation in the precuneus and posterior cingulate cortex during ambiguous decision making in individuals with HIV

People with human immunodeficiency virus (HIV) often have neurocognitive impairment. People with HIV make riskier decisions when the outcome probabilities are known, and have abnormal neural architecture underlying risky decision making. However, ambiguous decision making, when the outcome probabilities are unknown, is more common in daily life, but the neural architecture underlying ambiguous decision making in people with HIV is unknown. Eighteen people with HIV and 20 controls completed a decision making task while undergoing functional magnetic resonance imaging scanning. Participants chose between a certain reward and uncertain reward with a known (risky) or unknown (ambiguous) probability of winning. There were three levels of risk: high, medium, and low. Ambiguous > risky brain activity was compared between groups. Ambiguous > risky brain activity was correlated with emotional/psychiatric functioning in people with HIV. Both groups were similarly ambiguity-averse. People with HIV were more risk-averse than controls and chose the high-risk uncertain option less often. People with HIV had hypoactivity in the precuneus, posterior cingulate cortex (PCC), and fusiform gyrus during ambiguous > medium risk decision making. Ambiguous > medium risk brain activity was negatively correlated with emotional/psychiatric functioning in individuals with HIV. To make ambiguous decisions, people with HIV underrecruit key regions of the default mode network, which are thought to integrate internally and externally derived information to come to a decision. These regions and related cognitive processes may be candidates for interventions to improve decision-making outcomes in people with HIV.

Perceived Healthcare Access among Persons with and without HIV Who Use Illicit Stimulants: The Role of Cumulative Risk

Background: Persons who use stimulant drugs have greater morbidity and mortality relative to non-users. HIV infection has the potential to contribute to even great disparity in health outcomes among persons who use stimulants. These health disparities likely result in part due to poorer access to healthcare. Our study used a cumulative risk model to examine the impact of multiple risk factors on healthcare access in a sample of persons with and without HIV who use stimulants. Method: Our sample included 453 persons who reported recent use of illicit stimulants (102 HIV+, 351 HIV-). Participants completed clinical interviews, questionnaires, and a rapid oral HIV test. We constructed an 8-item cumulative risk index that included factors related to socioeconomic status, homelessness, legal history, and substance use. Results: Participants with HIV (PHW) were older than participants without HIV and more likely to have health insurance. Participants with and without HIV reported similar prior treatment utilization, but PWH reported better healthcare access and lower cumulative risk scores. Regression analyses showed cumulative risk was a significant predictor of healthcare access (β = -0.20, p < 0.001) even after controlling for age, HIV status, and health insurance status. We did not observe an interaction of HIV status by cumulative risk. Conclusions: Access to care among persons who use stimulants, both with and without HIV, is negatively impacted by the accumulation of risk factors from a number of different domains. Understanding the cumulative effects of these factors is critical for developing interventions to facilitate access to care, thus reducing health disparities and improving health outcomes.

Web-Based Cognitive Training to Improve Working Memory in Persons with Co-Occurring HIV Infection and Cocaine Use Disorder: Outcomes from a Randomized Controlled Trial

Neurocognitive impairment (NCI) remains a persistent complication of HIV disease that nearly half of persons with HIV experience, and rates are even higher in persons who use substances such as cocaine. Cognitive training is a promising intervention for HIV-associated NCI. In this randomized controlled trial, we examined the feasibility and effectiveness of a web-based cognitive training program to improve working memory in a sample of 58 persons with HIV and cocaine use disorder. Participants were randomly assigned to either the experimental working memory training arm or the attention control training arm and completed up to 48 daily sessions over 10 weeks. Overall, treatment completion (74%) and retention rates (97%) were high, and participant feedback indicated the intervention was acceptable. Our results show that the intervention successfully reduced working memory deficits in the experimental arm relative to the control arm. Our findings support both the feasibility and effectiveness of cognitive training in this population.

Examining the Potential of Pre-exposure Prophylaxis (PrEP) for HIV Prevention in a Community Sample of Persons Who Use Stimulants Living in the Southern United States

Pre-exposure prophylaxis (PrEP), a highly effective HIV prevention strategy, is currently underutilized by several at-risk groups, including both persons who inject drugs and those who use drugs via other routes. Stimulant use is associated with increased HIV risk due to both sexual and injection risk behaviors. In this study, we examined PrEP awareness and acceptability in persons with biologically confirmed HIV-negative status who use stimulant drugs. We also examined HIV risk behaviors to identify how many participants met behavioral eligibility for PrEP. The sample of 352 participants was 46% female, 87% African American, and 45.69 years old on average. Over half the sample (n = 213) met criteria for PrEP candidacy, but less than 20% had heard of PrEP. Ratings for willingness to take PrEP were high. PrEP candidates reported more frequent and problematic stimulant use relative to non-candidates. Our results show that persons who use stimulants are a high-risk population that could benefit significantly from PrEP. Efforts to increase PrEP awareness among high-risk populations are critical for facilitating PrEP implementation and ensuring effective HIV prevention within these communities.

Machine learning prediction of neurocognitive impairment among people with HIV using clinical and multimodal magnetic resonance imaging data

Diagnosis of HIV-associated neurocognitive impairment (NCI) continues to be a clinical challenge. The purpose of this study was to develop a prediction model for NCI among people with HIV using clinical- and magnetic resonance imaging (MRI)-derived features. The sample included 101 adults with chronic HIV disease. NCI was determined using a standardized neuropsychological testing battery comprised of seven domains. MRI features included gray matter volume from high-resolution anatomical scans and white matter integrity from diffusion-weighted imaging. Clinical features included demographics, substance use, and routine laboratory tests. Least Absolute Shrinkage and Selection Operator Logistic regression was used to perform variable selection on MRI features. These features were subsequently used to train a support vector machine (SVM) to predict NCI. Three different classification tasks were performed: one used only clinical features; a second used only selected MRI features; a third used both clinical and selected MRI features. Model performance was evaluated by area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity with a tenfold cross-validation. The SVM classifier that combined selected MRI with clinical features outperformed the model using clinical features or MRI features alone (AUC: 0.83 vs. 0.62 vs. 0.79; accuracy: 0.80 vs. 0.65 vs. 0.72; sensitivity: 0.86 vs. 0.85 vs. 0.86; specificity: 0.71 vs. 0.37 vs. 0.52). Our results provide preliminary evidence that combining clinical and MRI features can increase accuracy in predicting NCI and could be developed as a potential tool for NCI diagnosis in HIV clinical practice.

Synergistic effects of HIV and marijuana use on functional brain network organization

HIV is associated with disruptions in cognition and brain function. Marijuana use is highly prevalent in HIV but its effects on resting brain function in HIV are unknown. Brain function can be characterized by brain activity that is correlated between regions over time, called functional connectivity. Neuropsychiatric disorders are increasingly being characterized by disruptions in such connectivity. We examined the synergistic effects of HIV and marijuana use on functional whole-brain network organization during resting state. Our sample included 78 adults who differed on HIV and marijuana status (19 with co-occurring HIV and marijuana use, 20 HIV-only, 17 marijuana-only, and 22 controls). We examined differences in local and long-range brain network organization using eight graph theoretical metrics: transitivity, local efficiency, within-module degree, modularity, global efficiency, strength, betweenness, and participation coefficient. Local and long-range connectivity were similar between the co-occurring HIV and marijuana use and control groups. In contrast, the HIV-only and marijuana-only groups were both associated with disruptions in brain network organization. These results suggest that marijuana use in HIV may normalize disruptions in brain network organization observed in persons with HIV. However, future work is needed to determine whether this normalization is suggestive of a beneficial or detrimental effect of marijuana on cognitive functioning in HIV.

Reciprocal Influences of HIV and Cannabinoids on the Brain and Cognitive Function

Globally, cannabis is the most commonly used illicit drug, with disproportionately high use among persons with HIV. Despite advances in HIV care, nearly half of persons living with HIV continue to experience neurocognitive deficits or impairments that may have negative impacts on their daily function. Chronic cannabis use may play a role in the development or exacerbation of these impairments. Here we present a review summarizing existing research detailing the effect of cannabis use associated with the neuropathogenesis of HIV. We examine evidence for possible additive or synergistic effects of HIV infection and cannabis use on neuroHIV in both the preclinical and adult human literatures, including in vitro studies, animal models, clinical neuroimaging research, and studies examining the cognitive effects of cannabis. We discuss the limitations of existing research, including methodological challenges involved with clinical research with human subjects. We identify gaps in the field and propose critical research questions to advance our understanding of how cannabis use affects neuroHIV. Graphical Abstract.

Neural sensitivity to risk in adults with co-occurring HIV infection and cocaine use disorder

Persons with co-occurring HIV infection and cocaine use disorder tend to engage in riskier decision-making. However, the neural correlates of sensitivity to risk are not well-characterized in this population. The purpose of this study was to examine the neural interaction effects of HIV infection and cocaine use disorder to sensitivity to risk. The sample included 79 adults who differed on HIV status and cocaine use disorder. During functional magnetic resonance imaging (fMRI), participants completed a Wheel of Fortune (WoF) task that assessed neural activation in response to variations of monetary risk (i.e., lower probability of winning a larger reward). Across groups, neural activation to increasing risk was in cortical and subcortical regions similar to previous investigations using the WoF in nondrug-using populations. Our analyses showed that there was a synergistic effect between HIV infection and cocaine use in the left precuneus/posterior cingulate cortex and hippocampus, and right postcentral gyrus, lateral occipital cortex, cerebellum, and posterior parietal cortex. HIV+ individuals with cocaine use disorder displayed neural hyperactivation to increasing risk that was not observed in the other groups. These results support a synergistic effect of co-occurring HIV infection and cocaine dependence in neural processing of risk probability that may reflect compensation. Future studies can further investigate and validate how neural activation to increasing risk is associated with risk-taking behavior.

HIV Prevalence and Associated Risks in a Respondent-Driven Sample of Illicit Stimulant Users in a Southern United States City

Stimulant abuse is a major contributor to HIV transmission in the United States, yet HIV prevalence among persons who use illicit stimulants remains unknown. We implemented respondent driven sampling (RDS) to estimate the prevalence of HIV infection in this high-risk population. We also examined RDS-adjusted rates of risk behaviors among HIV-positive and HIV-negative participants. Recruited from seven seeds, our sample of 387 participants was 46% female, 89% African American, and 45.94 years old on average. Participants were predominantly non-injection cocaine users, had large networks of stimulant users, and reported an established relationship with their recruiter. The adjusted population proportion of HIV infection was 0.07 (0.04, 0.11). The majority of sexually active participants reported engagement in risk behaviors (73%), but rates generally did not differ by HIV status. Our results highlight that stimulant use is a risk factor for HIV infection. This study also demonstrates that RDS is a very effective strategy for reaching stimulant users in the community.

Cocaine-related alterations in fronto-parietal gray matter volume correlate with trait and behavioral impulsivity

BACKGROUND

Chronic cocaine use is associated with structural brain abnormalities within prefrontal regions implicated in impulsivity. Despite high levels of impulsivity among persons who use cocaine, it is not known how reductions in gray matter volume (GMV) may relate to trait and behavioral measures of impulsivity.

METHODS

The sample included 39 active cocaine users (COC+) and 40 controls with no history of cocaine use (COC-). Participants had a brain scan on a 3 T MRI machine and completed out-of-scanner measures of trait impulsivity and delayed reward discounting. Whole-brain voxel-based morphometry was used to compare GMV between COC+ and COC-. Within regions that differed between groups, voxelwise correlations were conducted to examine the relationship between GMV and impulsivity.

RESULTS

In a whole-brain analysis, COC+ had broad reductions in GMV compared to COC- in bilateral frontal, parietal, occipital, and cerebellar regions. Lower GMV correlated with trait impulsivity in lateral prefrontal regions and with delayed reward discounting in medial prefrontal regions, while lower GMV correlated with both measures in the posterior parietal cortex. COC+ demonstrated significantly higher impulsivity than COC- on all measures, but the nature of the correlation with GMV was similar in both groups.

CONCLUSIONS

Reflecting the multi-faceted nature of impulsivity, these results show that trait and behavioral measures of impulsivity map differentially onto altered brain morphology. While the brain-behavior patterns were similar in COC+ and COC-, suggesting that impulsivity varies on a continuous spectrum, cocaine-related abnormalities in frontal-parietal brain systems may contribute to heightened impulsivity.

Synergistic effects of marijuana abuse and HIV infection on neural activation during a cognitive interference task

Marijuana use, which is disproportionately prevalent among human immunodeficiency virus (HIV)-infected persons, can alter activity in fronto-parietal regions during cognitively demanding tasks. While HIV is also associated with altered neural activation, it is not known how marijuana may further affect brain function in this population. Our study examined the independent and additive effects of HIV infection and regular marijuana use on neural activation during a cognitive interference task. The sample included 93 adults who differed on marijuana (MJ) and HIV statuses (20 MJ+/HIV+, 19 MJ+/HIV-, 29 MJ-/HIV+, 25 MJ-/HIV-). Participants completed a counting Stroop task during a functional magnetic resonance imaging scan. Main and interactive effects on neural activation during interference versus neutral blocks were examined using a mixed-effects analysis. The sample showed the expected Stroop effect for both speed and accuracy. There were main effects of MJ in the right and left inferior parietal lobules, with the left cluster extending into the posterior middle temporal gyrus and a main effect of HIV in the dorsal anterior cingulate cortex. There was an interaction in the left fronto-insular cortex, such that the MJ+/HIV+ group had the largest increase in activation compared with other groups. Among MJ+, signal change in this cluster correlated positively with cumulative years of regular marijuana use. These results suggest that comorbid HIV and marijuana use is associated with complex neural alterations in multiple brain regions during cognitive interference. Follow-up research is needed to determine how marijuana-related characteristics may moderate HIV neurologic disease and impact real-world functioning.

A Comparison of Motivations for Marijuana Use in HIV-Positive and HIV-Negative Adults

While medicinal marijuana use is common among persons with HIV, it is not known whether persons with HIV are more motivated to use marijuana medically compared to HIV-negative counterparts. This study examined motivations for marijuana use in a sample of 94 HIV+ and HIV- adults. Participants used marijuana 21.27 days in the last 30 days on average. HIV+ participants reported using marijuana for medical reasons more often than HIV- participants, but HIV+ and HIV- participants did not differ in other domains. Problematic marijuana use was associated with motives, regardless of HIV status. Motives were associated with mental and physical health functioning, but there were no interactions between motivations and HIV status. Overall this study found that motivations were similar for HIV+ and HIV- participants. Future research including qualitative work to further understand motivations would benefit the field, as would research examining the effectiveness of marijuana in treating physical symptoms.

The Impact of Marijuana Use on Memory in HIV-Infected Patients: A Comprehensive Review of the HIV and Marijuana Literatures

BACKGROUND

The most robust neurocognitive effect of marijuana use is memory impairment. Memory deficits are also high among persons living with HIV/AIDS, and marijuana is the most commonly used drug in this population. Yet research examining neurocognitive outcomes resulting from co-occurring marijuana and HIV is limited.

OBJECTIVE

The primary objectives of this comprehensive review are to: (1) examine the literature on memory functioning in HIV-infected individuals; (2) examine the literature on memory functioning in marijuana users; (3) synthesize findings and propose a theoretical framework to guide future research.

METHOD

PubMed was searched for English publications 2000-2013. Twenty-two studies met inclusion criteria in the HIV literature, and 23 studies in the marijuana literature.

RESULTS

Among HIV-infected individuals, memory deficits with medium to large effect sizes were observed. Marijuana users also demonstrated memory problems, but results were less consistent due to the diversity of samples.

CONCLUSION

A compensatory hypothesis, based on the cognitive aging literature, is proposed to provide a framework to explore the interaction between marijuana and HIV. There is some evidence that individuals infected with HIV recruit additional brain regions during memory tasks to compensate for HIV-related declines in neurocognitive functioning. Marijuana is associated with disturbance in similar brain systems, and thus it is hypothesized that the added neural strain of marijuana can exhaust neural resources, resulting in pronounced memory impairment. It will be important to test this hypothesis empirically, and future research priorities are discussed.

Frequency of Cannabis Use and Medical Cannabis Use Among Persons Living With HIV in the United States: Findings From a Nationally Representative Sample

Little is known about cannabis use frequency, medical cannabis use, or correlates of use among persons living with HIV (PLWH) in United States nationally representative samples. Data came from 626 PLWH from the 2005-2015 National Survey on Drug Use and Health. Logistic regression identified characteristics associated with frequency of cannabis use. Chi-squares identified characteristics associated with medial cannabis use. Non-daily and daily cannabis use was reported by 26.9% and 8.0%. Greater perceived risk of cannabis use was negatively associated with daily and non-daily use. Younger age, substance use, and binge drinking were positively associated with non-daily cannabis use. Smoking and depression were associated with non-daily and daily use. One-quarter reported medical cannabis use. Medical users were more likely to be White, married, and nondrinkers. Cannabis use was common among PLWH. Findings help to differentiate between cannabis users based on frequency of use and medical versus recreational use.

Cocaine and HIV are independently associated with neural activation in response to gain and loss valuation during economic risky choice

Stimulant abuse is disproportionately common in HIV-positive persons. Both HIV and stimulants are independently associated with deficits in reward-based decision making, but their interactive and/or additive effects are poorly understood despite their prevalent co-morbidity. Here, we examined the effects of cocaine dependence and HIV infection in 69 adults who underwent functional magnetic resonance imaging while completing an economic loss aversion task. We identified two neural networks that correlated with the evaluation of the favorable characteristics of the gamble (i.e. higher gains/lower losses: ventromedial prefrontal cortex, anterior cingulate, anterior and posterior precuneus and visual cortex) versus unfavorable characteristics of the gamble (i.e. lower gains/higher losses: dorsal prefrontal, lateral orbitofrontal, posterior parietal cortex, anterior insula and dorsal caudate). Behaviorally, cocaine and HIV had additive effects on loss aversion scores, with HIV-positive cocaine users being the least loss averse. Cocaine users had greater activation in brain regions that tracked the favorability of gamble characteristics (i.e. increased activation to gains, but decreased activation to losses). In contrast, HIV infection was independently associated with lesser activation in regions that tracked the unfavorability of gamble characteristics. These results suggest that cocaine is associated with an overactive reward-seeking system, while HIV is associated with an underactive cognitive control system. Together, these alterations may leave HIV-positive cocaine users particularly vulnerable to making unfavorable decisions when outcomes are uncertain.

The Acceptability and Potential Utility of Cognitive Training to Improve Working Memory in Persons Living With HIV: A Preliminary Randomized Trial

HIV-associated neurocognitive impairments that impact daily function persist in the era of effective antiretroviral therapy. Cognitive training, a promising low-cost intervention, has been shown to improve neurocognitive functioning in some clinical populations. We tested the feasibility, acceptability, and preliminary effects of computerized cognitive training to improve working memory in persons living with HIV infection (PLWH) and working memory impairment. In this randomized clinical trial, we assigned 21 adult PLWH to either an experimental cognitive training intervention or an attention-matched control training intervention. Participants completed 12 training sessions across 10 weeks with assessments at baseline and post-training. Session attendance was excellent and participants rated the program positively. Participants in the experimental arm demonstrated improved working memory function over time; participants in the control arm showed no change. Our results suggest that cognitive training may be a promising intervention for working memory impairment in PLWH and should be evaluated further.

Food Insecurity Is Associated with Cognitive Deficits Among HIV-Positive, But Not HIV-Negative, Individuals in a United States Sample

People living with HIV/AIDS (PLWHA) in the United States (US) have disproportionately high rates of food insecurity (FI). In the general population, FI has been associated with cognitive impairment among older adults and may exacerbate HIV-associated neurocognitive disorders. The current study assessed the effects of FI and HIV infection on the neuropsychological performance of 61 HIV-positive and 36 HIV-negative adults in the US. While the main effects were minimal, the interactive effects revealed that FI was related to deficits in speed of information processing, learning, memory, motor function, and overall cognitive impairment for the HIV-positive group, but not the HIV-negative group. The interactive effects remained after controlling for relevant sociodemographic characteristics. Although bidirectional associations cannot be ruled out in a cross-sectional study, the results suggest that FI may contribute to cognitive impairment among HIV-positive adults in the US. Given the high rates of socioeconomic disadvantage among PLWHA in the US, addressing FI as part of routine clinical care may be warranted.

Utility of a brief computerized battery to assess HIV-associated neurocognitive impairment in a resource-limited setting

Despite the persistently high prevalence of neurocognitive impairment in HIV-positive patients, routine HIV care in many resource-limited settings does not include neuropsychological assessment. The objective of this study was to examine the utility of a brief computerized battery for identifying neurocognitive impairment in a busy HIV clinic in Uganda. Specifically, we compared performance on a gold standard neuropsychological exam to that on the CogState Brief Battery. In this cross-sectional study, 181 HIV-positive patients completed both assessment batteries in a randomized order. The primary outcome measures were neurocognitive impairment on the standard exam defined by the global deficit score and cumulative performance on the CogState Brief Battery. Sixty-nine participants (38 %) were classified as impaired on the standard neuropsychological exam, and participants who were classified as impaired performed significantly worse on CogState compared to those who were unimpaired (p < 0.001). CogState had adequate specificity but low sensitivity, suggesting that it may not be a clinically useful screening tool to identify patients who likely have neurocognitive impairment in Uganda. This study supports the feasibility of using a computerized battery for assessing neurocognitive impairment in HIV-positive patients in resource-limited settings, but additional research is needed to identify screening tools with higher sensitivity for use in HIV clinics.

Adaptation of the Monetary Choice Questionnaire to accommodate extreme monetary discounting in cocaine users

Delay discounting, which refers to the phenomenon that rewards decrease in subjective value as the delay associated with their receipt increases, is a paradigm that has been used extensively in substance abuse research to understand impulsive decision making. One common measure to assess delay discounting is the Monetary Choice Questionnaire (MCQ) developed by Kirby, Petry, and Bickel (1999). While the MCQ has great utility because of its simplicity and brief administration time, it is possible that the MCQ produces a ceiling effect in estimating delay discounting parameters in highly impulsive individuals. In the present study, we adapted the MCQ to attempt to address this ceiling effect by extending the original scale with 9 items, and we then compared scores on the original MCQ with the extended MCQ in a sample of active cocaine users. The ceiling effect, while observed in the original MCQ scores for over a quarter of the sample, was largely eliminated with the extended scale. Highly impulsive participants, whose scores on the extended scale exceeded the highest possible score on the original scale, had higher levels of sensation seeking compared to other participants, but not trait impulsivity. The extended MCQ may be useful in populations with high rates of impulsivity, where the original measure may underestimate discounting rates due to a ceiling effect.

Primary and Secondary HIV Prevention Among Persons with Severe Mental Illness: Recent Findings

Persons with severe mental illness (SMI) have been disproportionately affected by the HIV epidemic, with higher rates of HIV prevalence and morbidity than the general population. Recent research has advanced our understanding of the complex factors that influence primary and secondary HIV prevention for those with SMI. Sex risk in this population is associated with socioeconomic factors (e.g., low income, history of verbal violence) and other health risk behaviors (e.g., substance use, no prior HIV testing). Several interventions are effective at reducing risk behavior, and reviews highlight the need for more well-controlled studies that assess long-term outcomes. Recent research has elucidated barriers that interfere with HIV treatment for SMI populations, including individual (e.g., apathy, substance use), social (e.g., stigma), and system factors (e.g., transportation, clinic wait times). Interventions that coordinate HIV care for individuals with SMI show promise as cost-effective methods for improving medication adherence and quality of life.

Addiction and treatment experiences among active methamphetamine users recruited from a township community in Cape Town, South Africa: A mixed-methods study

BACKGROUND

Since 2000, there has been a dramatic increase in methamphetamine use in South Africa, but little is known about the experiences of out-of-treatment users. This mixed-methods study describes the substance use histories, addiction symptoms, and treatment experiences of a community-recruited sample of methamphetamine users in Cape Town.

METHODS

Using respondent driven sampling, 360 methamphetamine users (44% female) completed structured clinical interviews to assess substance abuse and treatment history and computerized surveys to assess drug-related risks. A sub-sample of 30 participants completed in-depth interviews to qualitatively explore experiences with methamphetamine use and drug treatment.

RESULTS

Participants had used methamphetamine for an average of 7.06 years (SD=3.64). They reported using methamphetamine on an average of 23.49 of the past 30 days (SD=8.90); 60% used daily. The majority (90%) met ICD-10 criteria for dependence, and many reported severe social, financial, and legal consequences. While only 10% had ever received drug treatment, 90% reported that they wanted treatment. In the qualitative interviews, participants reported multiple barriers to treatment, including beliefs that treatment is ineffective and relapse is inevitable in their social context. They also identified important motivators, including desires to be drug free and improve family functioning.

CONCLUSION

This study yields valuable information to more effectively respond to emerging methamphetamine epidemics in South Africa and other low- and middle-income countries. Interventions to increase uptake of evidence-based services must actively seek out drug users and build motivation for treatment, and offer continuing care services to prevent relapse. Community education campaigns are also needed.

Motives for cannabis use in high-risk adolescent users

The present investigation examined the relationships between motives for cannabis use and negative consequences associated with cannabis use following a brief intervention. The sample consisted of 205 adolescent cannabis users (66.3% male), who were recruited in high schools and randomly assigned to a brief two-session motivational enhancement therapy (MET) or an educational feedback control (EFC). Results supported the hypothesis that using cannabis to cope with negative affect would predict the number of problems and dependence symptoms related to cannabis use, after controlling for age, gender, years and frequency of cannabis use, and internalizing and externalizing behavior problems. Significant interactions between internalizing behavior problems and the coping motive showed that using to cope was associated with a higher number of cannabis dependence symptoms among adolescents reporting lower levels internalizing behavior problems. Findings support the potential utility of conducting further research to explore the coping motive as an important indicator of problematic cannabis use.