Chronic Tobacco-Smoking on Psychopathological Symptoms, Impulsivity and Cognitive Deficits in HIV-Infected Individuals

The Impact of Cannabis Use on Cognition in People with HIV: Evidence of Function-Dependent Effects and Mechanisms from Clinical and Preclinical Studies

PURPOSE OF REVIEW

Cannabis may have beneficial anti-inflammatory effects in people with HIV (PWH); however, given this population's high burden of persisting neurocognitive impairment (NCI), clinicians are concerned they may be particularly vulnerable to the deleterious effects of cannabis on cognition. Here, we present a systematic scoping review of clinical and preclinical studies evaluating the effects of cannabinoid exposure on cognition in HIV.

RECENT FINDINGS

Results revealed little evidence to support a harmful impact of cannabis use on cognition in HIV, with few eligible preclinical data existing. Furthermore, the beneficial/harmful effects of cannabis use observed on cognition were function-dependent and confounded by several factors (e.g., age, frequency of use). Results are discussed alongside potential mechanisms of cannabis effects on cognition in HIV (e.g., anti-inflammatory), and considerations are outlined for screening PWH that may benefit from cannabis interventions. We further highlight the value of accelerating research discoveries in this area by utilizing translatable cross-species tasks to facilitate comparisons across human and animal work.

Estimates of prevalence, time-trend, and association of smoking in adults living with HIV, HBV, and HCV (NHANES 1999-2018)

Although the smoking rate of human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) infected people was much higher than that of the general population, smoking cessation interventions have long been ineffective. We aimed to examine the estimates of prevalence, time-trend, and association of smoking among people living with HIV, HBV, or HCV. This cohort was composed of 32,115 individuals from the NHANES database (1999-2018) and they were collected in the US. The time trend analysis of smoking and quitting rates was conducted using different years of survey follow-up and different infected groups. Multivariable logistic regression analysis was used to identify the risk factors related to smoking behavior of these infected people. Compared to non-infected smokers, infected smokers were more likely to be older (aged 30-39, OR = 9.92, CI 6.07-16.21; aged 40-49,OR = 3.51, CI 2.49-4.94), males (1.99, 1.54-2.55), lower education and economic level (1.78, 1.39-2.29; 2.05, 1.59-2.65), unemployed (1.63, 1.21-2.20), suffering depression (1.35, 1.05-1.72), and drug users (7.65, 5.04-11.59). Taken together, our study showed that these complex psychosocial characteristics and unhealthy behavioral factors might be major independent risk factors for increasing smoking rate and decreasing smoking cessation rate among these infected people.

Contributions of chronic tobacco smoking to HIV-associated brain atrophy and cognitive deficits

OBJECTIVES

Tobacco smoking is linked to cognitive deficits and greater white matter (WM) abnormalities in people with HIV disease (PWH). Whether tobacco smoking additionally contributes to brain atrophy in PWH is unknown and was evaluated in this study.

DESIGN

We used a 2 × 2 design that included 83 PWH (43 nonsmokers, 40 smokers) and 171 HIV-seronegative (SN, 106 nonsmokers, 65 smokers) participants and assessed their brain structure and cognitive function.

METHODS

Selected subcortical volumes, voxel-wise cortical volumes and thickness, and total WM volume were analyzed using FreeSurfer. Independent and interactive effects of HIV and smoking were evaluated with two-way analysis of covariance on cognitive domain Z-scores and morphometric measures on T1-weighted MRI.

RESULTS

Regardless of smoking status, relative to SN, PWH had smaller brain volumes [basal ganglia, thalami, hippocampi, subcortical gray matter (GM) and cerebral WM volumes (P = 0.002-0.042)], steeper age-related declines in the right superior-parietal (interaction: P < 0.001) volumes, and poorer attention/working memory and learning (P = 0.016-0.027). Regardless of HIV serostatus, smokers tended to have smaller hippocampi than nonsmokers (-0.6%, P = 0.055). PWH smokers had the smallest total and regional subcortical GM and cortical WM volume and poorest cognitive performance.

CONCLUSIONS

Tobacco smoking additionally contributed to brain atrophy and cognitive deficits in PWH. The greater brain atrophy in PWH smokers may be due to greater neuronal damage or myelin loss in various brain regions, leading to their poor cognitive performance. Therefore, tobacco smoking may exacerbate or increase the risk for HIV-associated neurocognitive disorders.

Recommendations of the treatment-resistant depression expert center network for promoting tobacco smoking cessation based on the results from the real-world FACE-TRD national cohort

BACKGROUND

Tobacco smoking has been associated with suicide, impulsivity and depression in non-clinical populations with differences across sexes.

OBJECTIVE

To determine the role of tobacco smoking in Treatment-Resistant Depression (TRD) according to sex in a precision-medicine approach.

METHOD

The FACE-TRD cohort is a national cohort of TRD patients recruited in 13 resistant depression expert centers between 2014 and 2021 and followed-up at 6 months. A standardized one-day long comprehensive battery was carried out, including trained-clinician and patient-reported outcomes, and patients were reevaluated at 6 months on their smoking and psychiatric hospitalization outcomes.

RESULTS

355 TRD participants were included (222 women). The smoking rate was much higher in TRD women compared to the French general population (34% vs 24%) while it was comparable for men (approximately 29%). In multivariate analyses, compared to non-smoking women, female smokers had significantly increased number of lifetime psychiatric hospitalizations (standardized beta B = 0.232, p = 0.014) and electro-convulsive therapy (adjusted odds ratio (aOR) = 2.748, p = 0.005), increased suicidal ideations (aOR = 4.047, p = 0.031), history of suicide attempt (aOR = 1.994, p = 0.033), and increased impulsivity (B = 0.210, p = 0.006) and were more frequently treated by benzodiazepines (aOR = 1.848, p = 0.035) and third- or fourth-line TRD treatments (antipsychotics aOR = 2.270, p = 0.006, mood stabilizers aOR = 2.067 p = 0.044). Tobacco smoking at baseline was predictive of psychiatric hospitalization within 6 months in persistent smoking women (aOR = 2.636, p = 0.031). These results were not replicated in men, for whom tobacco smoking was only associated with increased clinician-rated and self-reported depressive symptoms (respectively B = 0.207, p = 0.022 and B = 0.184, p = 0.048). The smoking cessation rate at 6 months was higher in women than in men (12% vs. 7%). No patient was administered nicotine substitute or varenicline at the two timepoints.

INTERPRETATION

Combining these results and those of the literature, we recommend that active tobacco cessation should be promoted in TRD to improve depression, suicide and impulsivity especially in women. Female smokers appear as a specific population with heavier mental health outcomes that should be specifically addressed.

Unbiased Metabolomics Links Fatty Acid Pathways to Psychiatric Symptoms in People Living with HIV

Psychiatric symptoms are prevalent in people living with HIV (PLWH), especially depression, anxiety, impulsivity, and substance use. Various biological mechanisms might play a role in the occurrence of psychiatric symptoms in this population. A hypothesis free, data-driven metabolomics approach can further our understanding of these mechanisms. In this study, we identified metabolic pathways associated with impulsivity, depression and substance use in 157 PLWH. First, Spearman’s rank correlations between metabolite feature intensities and psychiatric symptom levels were calculated, while controlling for age, gender and body mass index. Subsequently, a mummichog pathway analysis was performed. Finally, we analyzed which individual metabolites drove the observed effects. In our cohort of PLWH, fatty acid-related pathways were associated with both depressive as well as impulsive symptomatology. Substance use showed most extensive metabolic associations, and was positively associated with short chain fatty acids (SCFA’s), and negatively associated with glutamate levels. These findings suggest that PUFA metabolism might be associated with both internalising and externalising symptomatology in PLWH. Furthermore, glutamate and SCFA’s—microbiome derivatives with known neuroactive properties—might be involved in substance use in these patients. Future studies should explore potential causal mechanisms involved and whether these findings are HIV-specific.

No differences in delay discounting between smokers with and without HIV

RATIONALE

People with HIV (PWH) smoke cigarettes at much higher rates than the general population and evidence-based cessation methods are less effective, putting PWH at greater risk for negative health outcomes. It is critical to identify the factors that underlie this health disparity. Delay discounting-the decline in the value of a reward when it is delayed-may explain this disparity.

OBJECTIVES

This study aimed to (1) compare delay discounting between adult smokers with HIV and without HIV and (2) evaluate whether acute smoking abstinence disproportionately increases delay discounting among smokers with HIV.

METHODS

This sub-study was part of a larger study (NCT03169101) examining predictors of smoking cessation outcomes among smokers with HIV (n = 34) and smokers without HIV (n = 46) at two counterbalanced laboratory sessions (once smoking-as-usual and once following 24-h biochemically confirmed abstinence) then again, after 8 weeks of smoking cessation treatment.

RESULTS

There were no significant differences in delay discounting rates between HIV status groups (p = 0.49) or within-subject abstinence effects (p = 0.70). However, smokers without HIV exhibited a significant increase in delay discounting following smoking cessation treatment compared to baseline (p = 0.02), whereas the change among smokers with HIV did not reach statistical significance (p = 0.09).

CONCLUSIONS

These findings do not support differences in delay discounting as a reason for the lower success rates of HIV+ smokers at quitting. Although delay discounting may not explain the disparity in smoking rates between people with and without HIV, future work should focus on additional correlates of higher smoking rates and lower quit rates among people with HIV.

Neuroimaging and Cognitive Evidence for Combined HIV-Alcohol Effects on the Central Nervous System: A Review

Alcohol use disorder (AUD) among people living with HIV (PLWH) is a significant public health concern. Despite the advent of effective antiretroviral therapy, up to 50% of PLWH still experience worsened neurocognition, which comorbid AUD exacerbates. We report converging lines of neuroimaging and neuropsychological evidence linking comorbid HIV/AUD to dysfunction in brain regions linked to executive function, learning and memory, processing speed, and motor control, and consequently to impairment in daily life. The brain shrinkage, functional network alterations, and brain metabolite disruption seen in individuals with HIV/AUD have been attributed to several interacting pathways: viral proteins and EtOH are directly neurotoxic and exacerbate each other's neurotoxic effects; EtOH reduces antiretroviral adherence and increases viral replication; AUD and HIV both increase gut microbial translocation, promoting systemic inflammation and HIV transport into the brain by immune cells; and HIV may compound alcohol's damaging effects on the liver, further increasing inflammation. We additionally review the neurocognitive effects of aging, Hepatitis C coinfection, obesity, and cardiovascular disease, tobacco use, and nutritional deficiencies, all of which have been shown to compound cognitive changes in HIV, AUD, and in their comorbidity. Finally, we examine emerging questions in HIV/AUD research, including genetic and cognitive protective factors, the role of binge drinking in HIV/AUD-linked cognitive decline, and whether neurocognitive and brain functions normalize after drinking cessation.

Independent and Combined Effects of Nicotine or Chronic Tobacco Smoking and HIV on the Brain: A Review of Preclinical and Clinical Studies

Tobacco smoking is highly prevalent among HIV-infected individuals. Chronic smokers with HIV showed greater cognitive deficits and impulsivity, and had more psychopathological symptoms and greater neuroinflammation than HIV non-smokers or smokers without HIV infection. However, preclinical studies that evaluated the combined effects of HIV-infection and tobacco smoking are scare. The preclinical models typically used cell cultures or animal models that involved specific HIV viral proteins or the administration of nicotine to rodents. These preclinical models consistently demonstrated that nicotine had neuroprotective and anti-inflammatory effects, leading to cognitive enhancement. Although the major addictive ingredient in tobacco smoking is nicotine, chronic smoking does not lead to improved cognitive function in humans. Therefore, preclinical studies designed to unravel the interactive effects of chronic tobacco smoking and HIV infection are needed. In this review, we summarized the preclinical studies that demonstrated the neuroprotective effects of nicotine, the neurotoxic effects of the HIV viral proteins, and the scant literature on nicotine or tobacco smoke in HIV transgenic rat models. We also reviewed the clinical studies that evaluated the neurotoxic effects of tobacco smoking, HIV infection and their combined effects on the brain, including studies that evaluated the cognitive and behavioral assessments, as well as neuroimaging measures. Lastly, we compared the different approaches between preclinical and clinical studies, identified some gaps and proposed some future directions. Graphical abstract Independent and combined effects of HIV and tobacco/nicotine. Left top and bottom panels: Both clinical studies of HIV infected persons and preclinical studies using viral proteins in vitro or in vivo in animal models showed that HIV infection could lead to neurotoxicity and neuroinflammation. Right top and bottom panels: While clinical studies of tobacco smoking consistently showed deleterious effects of smoking, clinical and preclinical studies that used nicotine show mild cognitive enhancement, neuroprotective and possibly anti-inflammatory effects. In the developing brain, however, nicotine is neurotoxic. Middle overlapping panels: Clinical studies of persons with HIV who were smokers typically showed additive deleterious effects of HIV and tobacco smoking. However, in the preclinical studies, when nicotine was administered to the HIV-1 Tg rats, the neurotoxic effects of HIV were attenuated, but tobacco smoke worsened the inflammatory cascade.

Chronic HIV-1 Tat exposure alters anterior cingulate cortico-basal ganglia-thalamocortical synaptic circuitry, associated behavioral control, and immune regulation in male mice

HIV-1 selectively disrupts neuronal integrity within specific brain regions, reflecting differences in viral tropism and/or the regional differences in the vulnerability of distinct neuronal subpopulations within the CNS. Deficits in prefrontal cortex (PFC)-mediated executive function and the resultant loss of behavioral control are a particularly debilitating consequence of neuroHIV. To explore how HIV-1 disrupts executive function, we investigated the effects of 48 h, 2 and/or 8 weeks of HIV-1 Tat exposure on behavioral control, synaptic connectivity, and neuroimmune function in the anterior cingulate cortex (ACC) and associated cortico-basal ganglia (BG)-thalamocortical circuitry in adult, Tat transgenic male mice. HIV-1 Tat exposure increased novelty-exploration in response to novel food, flavor, and environmental stimuli, suggesting that Tat triggers increased novelty-exploration in situations of competing motivation (e.g., drive to feed or explore vs. fear of novel, brightly lit open areas). Furthermore, Tat induced adaptability in response to an environmental stressor and pre-attentive filtering deficits. The behavioral insufficiencies coincided with decreases in the inhibitory pre- and post-synaptic proteins, synaptotagmin 2 and gephyrin, respectively, in the ACC, and alterations in specific pro- and anti-inflammatory cytokines out of 23 assayed. The interaction of Tat exposure and the resultant time-dependent, selective alterations in CCL4, CXCL1, IL-12p40, and IL-17A levels in the PFC predicted significant decreases in adaptability. Tat decreased dendritic spine density and cortical VGLUT1 inputs, while increasing IL-1β, IL-6, CCL5, and CCL11 in the striatum. Alternatively, IL-1α, CCL5, and IL-13 were decreased in the mediodorsal thalamus despite the absence of synaptic changes. Thus, HIV-1 Tat appears to uniquely and systematically disrupt immune regulation and the inhibitory and excitatory synaptic balance throughout the ACC-BG-thalamocortical circuitry resulting in a loss of behavioral control.

Extracellular Vesicles in Smoking-Mediated HIV Pathogenesis and their Potential Role in Biomarker Discovery and Therapeutic Interventions

In the last two decades, the mortality rate in people living with HIV/AIDS (PLWHA) has decreased significantly, resulting in an almost normal longevity in this population. However, a large portion of this population still endures a poor quality of life, mostly due to an increased inclination for substance abuse, including tobacco smoking. The prevalence of smoking in PLWHA is consistently higher than in HIV negative persons. A predisposition to cigarette smoking in the setting of HIV potentially leads to exacerbated HIV replication and a higher risk for developing neurocognitive and other CNS disorders. Oxidative stress and inflammation have been identified as mechanistic pathways in smoking-mediated HIV pathogenesis and HIV-associated neuropathogenesis. Extracellular vesicles (EVs), packaged with oxidative stress and inflammatory agents, show promise in understanding the underlying mechanisms of smoking-induced HIV pathogenesis via cell-cell interactions. This review focuses on recent advances in the field of EVs with an emphasis on smoking-mediated HIV pathogenesis and HIV-associated neuropathogenesis. This review also provides an overview of the potential applications of EVs in developing novel therapeutic carriers for the treatment of HIV-infected individuals who smoke, and in the discovery of novel biomarkers that are associated with HIV-smoking interactions in the CNS.

The effect of varenicline on mood and cognition in smokers with HIV

RATIONALE

Barriers to smoking cessation, including negative affect and cognitive dysfunction, may contribute to high smoking rates among people living with HIV/AIDS (PLWH). Varenicline may help PLWH quit smoking by improving mood and cognition, yet this has not been explored.

OBJECTIVES

The goal of this study was to evaluate the effect of varenicline on mood and cognition among PLWH enrolled in a smoking cessation clinical trial.

METHODS

In this secondary analysis of a varenicline trial (NCT01710137), we assessed mood (depression, anxiety) and cognition (attention, working memory) at weeks 0 (baseline), 1, 3, and 12 (end-of-treatment, EOT). Primary outcomes were changes in mood and cognition from baseline to EOT. Secondarily, mood and cognition were evaluated as predictors of biochemically confirmed 7-day point-prevalence abstinence at EOT.

RESULTS

Overall, 173 subjects (87 varenicline, 86 placebo) were included. At EOT, varenicline reduced anxiety (P < 0.001), vs. placebo (P = 0.31; interaction P = 0.05). Across both treatment arms, reductions in anxiety from baseline to EOT were associated with a higher likelihood of abstinence (OR = 1.3, 95% CI 1.1 to 1.6, P = 0.01). There were no significant treatment by time interactions for cognition or depression.

CONCLUSIONS

These data suggest that varenicline operates, at least in part, by reducing anxiety. Anxiety should be an intervention target for smokers with HIV interested in quitting.

Bidirectional Associations among Nicotine and Tobacco Smoke, NeuroHIV, and Antiretroviral Therapy

People living with HIV (PLWH) in the antiretroviral therapy (ART) era may lose more life-years to tobacco use than to HIV. Yet, smoking rates are more than twice as high among PLWH than the general population, contributing not just to mortality but to other adverse health outcomes, including neurocognitive deficits (neuroHIV). There is growing evidence that synergy with chronic inflammation and immune dysregulation that persists despite ART may be one mechanism by which tobacco smoking contributes to neuroHIV. This review will summarize the differential effects of nicotine vs tobacco smoking on inflammation in addition to the effects of tobacco smoke components on HIV disease progression. We will also discuss biomarkers of inflammation via neuroimaging as well as biomarkers of nicotine dependence (e.g., nicotine metabolite ratio). Tobacco smoking and nicotine may impact ART drug metabolism and conversely, certain ARTs may impact nicotine metabolism. Thus, we will review these bidirectional relationships and how they may contribute to neuroHIV and other adverse outcomes. We will also discuss the effects of tobacco use on the interaction between peripheral organs (lungs, heart, kidney) and subsequent CNS function in the context of HIV. Lastly, given the dramatic rise in the use of electronic nicotine delivery systems, we will discuss the implications of vaping on these processes. Despite the growing recognition of the importance of addressing tobacco use among PLWH, more research is necessary at both the preclinical and clinical level to disentangle the potentially synergistic effects of tobacco use, nicotine, HIV, cognition and immune dysregulation, as well as identify optimal approaches to reduce tobacco use. Graphical Abstract Proposed model of the relationships among HIV, ART, smoking, inflammation, and neurocognition. Solid lines represent relationships supported by evidence. Dashed lines represent relationships for which there is not enough evidence to make a conclusion. (a) HIV infection produces elevated levels of inflammation even among virally suppressed individuals. (b) HIV is associated with deficits in cognition function. (c) Smoking rates are higher among PLWH, compared to the general population. (d) The nicotine metabolite ratio (NMR) is associated with smoking behavior. (e) HIV and tobacco use are both associated with higher rates of psychiatric comorbidities, such as depression, and elevated levels of chronic stress. These factors may represent other mechanisms linking HIV and tobacco use. (f) The relationship between nicotine, tobacco smoking, and inflammation is complex, but it is well-established that smoking induces inflammation; the evidence for nicotine as anti-inflammatory is supported in some studies, but not others. (g) The relationship between tobacco use and neurocognition may differ for the effects of nicotine (acute nicotine use may have beneficial effects) vs. tobacco smoking (chronic use may impair cognition). (h) Elevated levels of inflammation may be associated with deficits in cognition. (i) PLWH may metabolize nicotine faster than those without HIV; the mechanism is not yet known and the finding needs validation in larger samples. We also hypothesize that if HIV-infection increases nicotine metabolism, then we should observe an attenuation effect once ART is initiated. (j) It is possible that the increase in NMR is due to ART effects on CYP2A6. (k) We hypothesize that faster nicotine metabolism may result in higher levels of inflammation since nicotine has anti-inflammatory properties.

Tobacco use and HIV symptom severity in Chinese people living with HIV

Exposure to nicotine among people living with HIV (PLWH) may impact physical health as indicated by experienced symptoms. Yet, the empirical evidence documenting the relations between tobacco use and symptom experiences among PLWH remains limited. This study aims to assess the relationships between tobacco use and HIV symptoms through a cross-sectional survey conducted in Beijing and Shanghai. The WHO ASSIST screening test was used for frequency of tobacco use. Sixty-four items from the revised signs and symptoms checklist for persons with HIV disease (SSC-HIVrev) were used. "Total number of symptoms" was created by summing all the binary coded and "Maximal symptom severity" was created by taking the maximal severity level across all symptoms for each participant. After controlling for confounding variables, tobacco use was not associated with the total number of symptom, yet was associated with the maximal symptom severity. This study documents the link between tobacco use and experienced symptoms among PLWH by demonstrating that higher frequency of tobacco use is associated with greater odds of reporting more severe symptoms. Smoking cessation strategies should be integrated into symptom management interventions for PLWH to optimize their effectiveness.

A qualitative study of the feasibility and acceptability of a smoking cessation program for people living with HIV and emotional dysregulation

Despite high rates of co-occurring tobacco use and anxiety among persons living with HIV, evidence-based interventions for these individuals are limited. An existing cognitive-behavioral treatment protocol for smoking cessation and anxiety (Norton, P. J., & Barrera, T. L. (2012). Transdiagnostic versus diagnosis-specific CBT for anxiety disorders: A preliminary randomized controlled noninferiority trial. Depression and Anxiety, 29(10), 874-882. https://doi.org/10.1002/da.21974) was modified to address transdiagnostic constructs, such as anxiety sensitivity, distress tolerance, and depressive symptomatology (Labbe, A. K., Wilner, J. G., Kosiba, J. D., Gonzalez, A., Smits, J. A., Zvolensky, M. J., … O'Cleirigh, C. (2017). Demonstration of an Integrated Treatment for Smoking Cessation and Anxiety Symptoms in People with HIV: A Clinical Case Study. Cognitive and Behavioral Practice, 24(2), 200-214. https://doi.org/10.1016/j.cbpra.2016.03.009). This study examines the feasibility and acceptability of the intervention as determined from qualitative data from structured exit interviews from 10 participants who completed treatment. Results demonstrated that participants were very motivated to quit smoking and enrolled in the program for health-related reasons and to be able to quit. Participants found nearly all the treatment components to be useful for reaching their smoking cessation goal and in managing emotional dysregulation. Last, all participants stated that they would strongly recommend the treatment program. This qualitative study provides initial evidence for the feasibility and acceptability of a modified smoking cessation treatment protocol for HIV+ individuals with anxiety and emotional dysregulation. Future research will focus on evaluating the efficacy of the protocol in a full-scale randomized controlled trial, as well as working to collect qualitative data from participants who discontinue treatment to better understand reasons for treatment attrition.

Independent and Combined Effects of Chronic HIV-Infection and Tobacco Smoking on Brain Microstructure

HIV-infected individuals (HIV+) have 2-3 times higher prevalence of tobacco smoking than the general U.S. population. This study aims to evaluate the independent and combined effects of tobacco-smoking and HIV-infection on brain microstructure and cognition using a 2 × 2 design. 21 HIV + Smokers, 25 HIV + Nonsmokers, 25 Seronegative (SN)-Smokers and 23 SN-Nonsmokers were evaluated using diffusion tensor imaging. Fractional anisotropy (FA), mean (MD), radial (RD) and axial (AD) diffusivity were assessed in 8 major cerebral fiber tracts and 5 subcortical regions. Cognitive performance in 7 neurocognitive domains was also assessed. Compared to SN, HIV+ had higher AD in genu of corpus callosum (GCC, p = 0.002). Smokers also had higher diffusivities in GCC, splenium of corpus callosum (SCC), anterior corona radiata (ACR), sagittal stratum (SS) and superior fronto-occipital fasciculus (SFO), than Nonsmokers (p-values<0.001-0.003). Tobacco-Smoking and HIV-infection showed synergistic effects on AD_SS (p = 0.002) and RD_SFO (p = 0.02), but opposite effects in FA_putamen (p = 0.024). Additive effects from HIV+ and Tobacco-Smoking were observed in 9 other white matter tracts, with highest diffusivities and lowest FA in HIV + Smokers. Higher diffusivities in the GCC, SCC, ACR and SS predicted poorer cognitive performance across all participants (p ≤ 0.001). Higher AD_GCC also predicted slower Speed of information processing and poorer Fluency and Attention only in HIV + Smokers (p = 0.001-0.003). Chronic tobacco smoking and HIV-infection appear to have additive and synergistic adverse effects on brain diffusivities, suggesting greater neuroinflammation, which may contribute to poorer cognition. Therefore, chronic tobacco-smoking may be a risk factor for HIV-associated neurocognitive disorders. Graphical Abstract ᅟ.

Cigarette smoking duration mediates the association between future thinking and norepinephrine level

Fixating on the present moment rather than considering future consequences of behavior is considered to be a hallmark of drug addiction. As an example, cigarette smokers devalue delayed consequences to a greater extent than nonsmokers, and former smokers devalue delayed consequences more than nonsmokers, but less than current smokers. Further, cigarette smokers have higher norepinephrine levels than nonsmokers, which is indicative of poor future health outcomes. It is unclear how duration of cigarette smoking may impact these associations. The current secondary analysis of publicly available data investigated whether extent of future thinking is associated with smoking duration, as well as norepinephrine level, in a large national US sample (N = 985) of current, former, and never smokers. Individuals scoring lower on future thinking tended to smoke for longer durations and had higher norepinephrine levels relative to individuals scoring higher on future thinking. In addition, duration of cigarette abstinence interacted significantly with future thinking and smoking duration for former smokers. Specifically, the mediation relationship between future thinking, smoking duration, and norepinephrine level for former smokers was strongest at shorter durations of cigarette abstinence and decreased as a function of increasing duration of cigarette abstinence. Overall, results from this study suggest the potential importance of implementing smoking cessation treatments as early as possible for smokers and support future thinking as a potential therapeutic target for smoking cessation treatment.

Association Between Health-Related Quality of Life and Physical Functioning in Antiretroviral-Naive HIV-Infected Patients

Background:

Poor functional status can significantly affect Health-Related Quality of Life (HRQoL) of HIV patients. However, there is scarce information on the functional profile of such patients before starting antiretroviral therapy (ART).

Objective:

To estimate the association between health-related quality of life and physical functioning in Antiretroviral-Naive HIV-infected patients.

Methods:

We conducted a cross-sectional study with HIV-infected patients older than 18 years, and naïve to antiretroviral therapy. The patients were evaluated for functional profile by pulmonary function (forced vital capacity, forced expiratory volume at one second, and Tiffeneau index), handgrip strength, and six-minute walk test in a cross-sectional study. HRQoL was evaluated by the 36-Item Short-Form Health Survey and its Physical (PCS) and Mental (MCS) Component Summaries. Multiple linear regression analyses were used to evaluate the association of predictor variables with PCS and MCS scores.

Results:

We found lower HRQoL among females patients, with far below average impairment of mental health component. Both male and female patients presented lower 6MWD function test values. Patients with dynapenia were older than patients without it, presented lower PCS mean score, lower family income, poor 6 MWD function test, lower FVC, and lower FEV1 t. Multivariable logistic regression analyses showed that Grip Strength, age and family income were predictor variables for Physical component of HRQoL. Female gender and smoking habit were predictive for the mental component of HRQoL.

Conclusion:

HRQoL in HIV, drug-naïve patients is predicted by level of dynapenia, smoking, income and gender. Therefore, lifestyle changes and active exercising can help to improve HRQoL in such patients.

Modulatory Effects of Nicotine on neuroHIV/neuroAIDS

Nicotine, one of the key active ingredients in tobacco smoke, exerts its effects via binding to nicotinic acetylcholine receptors (nAChRs). Although both negative and positive pharmacological effects of nicotine have been shown in numerous animals and human studies, its interaction with human immunodeficiency virus-1 (HIV-1) have not been fully elucidated. Even though combined anti-retroviral therapy (cART) limits the progression of HIV-1 to acquired immune deficiency syndrome (AIDS), HIV-associated neurocognitive disorders (HAND) remain prevalent. There is thus a compelling need to enhance our understanding of HAND-related neurologic dysfunction. Some biochemical pathways and physiological dysfunctions have been found to be shared by HAND and Alzheimer's (AD) or Parkinson's (PD) diseases, and nicotine may exert the same neuroprotection in HAND that has been observed in both AD and PD. In the past dozen years, various potential therapeutic effects of nicotine such as neuroprotection have been revealed in both in vivo and in vitro studies, including using HIV-1 transgenic (HIV-1Tg) rat model, which mimics HIV-infected patients receiving cART. In the current review, we describe recent progress in the prevalence of HIV/AIDS with and without cigarette smoking, some animal models for studying neural dysfunction associated with HIV-1 infection, elucidating the modulatory effects of cigarette smoking/nicotine on HIV/AIDS, the anti-inflammatory effects of nicotine, and the neuroprotective effects observed in HIV-1Tg rat model. Taken together, these findings suggest the following: although tobacco smoking does cause deleterious effects in both health and disease conditions such as HIV infection, nicotine, the significant component of tobacco smoke, has been shown to possess some neuroprotective effects in HIV patients, possible via its anti-inflammatory activities. It is therefore necessary to study nicotine's dual effects on neuroHIV/neuroAIDS in hope of better defining the potential medical uses of nicotine or its analogues, and to make them available in a purer and less dangerous form.

Cigarette smoke and nicotine effects on brain proinflammatory responses and behavioral and motor function in HIV-1 transgenic rats

Cognitive impairment in HIV-1 infection is associated with the induction of chronic proinflammatory responses in the brains of infected individuals. The risk of HIV-related cognitive impairment is increased by cigarette smoking, which induces brain inflammation in rodent models. To better understand the role of smoking and the associated immune response on behavioral and motor function in HIV infection, wild-type F344 and HIV-1 transgenic (HIV1Tg) rats were exposed to either smoke from nicotine-containing (regular) cigarettes, smoke from nicotine-free cigarettes, or to nicotine alone. The animals were then tested using the rotarod test (RRT), the novel object recognition test (NORT), and the open field test (OFT). Subsequently, brain frontal cortex from the rats was analyzed for levels of TNF-α, IL-1, and IL-6. On the RRT, impairment was noted for F344 rats exposed to either nicotine-free cigarette smoke or nicotine alone and for F344 and HIV1Tg rats exposed to regular cigarette smoke. Effects from the exposures on the OFT were seen only for HIV1Tg rats, for which function was worse following exposure to regular cigarette smoke as compared to exposure to nicotine alone. Expression levels for all three cytokines were overall higher for HIV1Tg than for F344 rats. For HIV1Tg rats, TNF-α, IL-1, and IL-6 gene expression levels for all exposure groups were higher than for control rats. All F344 rat exposure groups also showed significantly increased TNF-α expression levels. However, for F344 rats, IL-1 expression levels were higher only for rats exposed to nicotine-free and nicotine-containing CS, and no increase in IL-6 gene expression was noted with any of the exposures as compared to controls. These studies, therefore, demonstrate that F344 and HIV1Tg rats show differential behavioral and immune effects from these exposures. These effects may potentially reflect differences in the responsiveness of the various brain regions in the two animal species as well as the result of direct toxicity mediated by the proinflammatory cytokines that are produced by HIV proteins and by other factors that are present in regular cigarette smoke.

Imaging studies of the HIV-infected brain

Human immunodeficiency virus (HIV) enters the brain early after infecting humans and may remain in the central nervous system despite successful antiretroviral treatment. Many neuroimaging techniques were used to study HIV+ patients with or without opportunistic infections. These techniques assessed abnormalities in brain structures (using computed tomography, structural magnetic resonance imaging (MRI), diffusion MRI) and function (using functional MRI at rest or during a task, and perfusion MRI with or without a contrast agent). In addition, single-photon emission computed tomography with various tracers (e.g., thallium-201, Tc99-HMPAO) and positron emission tomography with various agents (e.g., [18F]-dexoyglucose, [11C]-PiB, and [11C]-TSPO tracers), were applied to study opportunistic infections or HIV-associated neurocognitive disorders. Neuroimaging provides diagnoses and biomarkers to quantitate the severity of brain injury or to monitor treatment effects, and may yield insights into the pathophysiology of HIV infection. As the majority of antiretroviral-stable HIV+ patients are living longer, age-related comorbid disorders (e.g., additional neuroinflammation, cerebrovascular disorders, or other dementias) will need to be considered. Other highly prevalent conditions, such as substance use disorders, psychiatric illnesses, and the long-term effects of combined antiretroviral therapy, all may lead to additional brain injury. Neuroimaging studies could provide knowledge regarding how these comorbid conditions impact the HIV-infected brain. Lastly, specific molecular imaging agents may be needed to assess the central nervous system viral reservoir.