Alcoholism and AIDS: Magnetic Resonance Imaging Approaches for Detecting Interactive Neuropathology

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.

Heavy Alcohol Use and Age Effects on HIV-Associated Neurocognitive Function

BACKGROUND

There is growing concern about the health impact of heavy alcohol use in people infected with human immunodeficiency virus (HIV+). Mixed findings of past studies regarding the cognitive impact of alcohol use in HIV+ adults have been mixed, with inconsistent evidence that alcohol consumption exacerbates HIV-associated brain dysfunction. This study examined contributions of current heavy drinking, lifetime alcohol use disorder (AUD), and age to cognitive deficits in HIV+ adults, and relative to other HIV-associated clinical factors.

METHODS

Cognitive performance of HIV+ adults (n = 104) was assessed, and comparisons were made between heavy current to nonheavy drinkers (NIAAA criteria), lifetime AUD versus no-AUD, and older (>50 years) versus younger participants. Hierarchical regression analyses were conducted to examine the association between cognitive performance and current heavy drinking, lifetime AUD, and older age, while also correcting for HIV clinical factors and history of other substance use.

RESULTS

Individuals reporting current heavy drinking and meeting criteria for lifetime AUD demonstrated the greatest degree of deficits across multiple cognitive domains. Deficits were greatest among HIV+ adults with lifetime AUD, and older age was also associated with weaker cognitive performance. Lifetime AUD and older age independently exhibited stronger associations with cognitive performance than HIV clinical factors (e.g., viral load, current CD4, and nadir CD4) or past opiate and cocaine use.

CONCLUSIONS

Current heavy drinking and lifetime AUD adversely affect cognitive function in HIV+ adults. Greatest deficits existed when there was a history of AUD and continued current heavy drinking, indicating that past AUD continues to have an adverse impact and should not be ignored. That alcohol use was more strongly associated with cognitive performance than HIV clinical factors underscore clinical importance of targeting reduction in heavy alcohol consumption in HIV+ adults.

The Aging Brain With HIV Infection: Effects of Alcoholism or Hepatitis C Comorbidity

As successfully treated individuals with Human Immunodeficiency Virus (HIV)-infected age, cognitive and health challenges of normal aging ensue, burdened by HIV, treatment side effects, and high prevalence comorbidities, notably, Alcohol Use Disorders (AUD) and Hepatitis C virus (HCV) infection. In 2013, people over 55 years old accounted for 26% of the estimated number of people living with HIV (~1.2 million). The aging brain is increasingly vulnerable to endogenous and exogenous insult which, coupled with HIV infection and comorbid risk factors, can lead to additive or synergistic effects on cognitive and motor function. This paper reviews the literature on neuropsychological and in vivo Magnetic Resonance Imaging (MRI) evaluation of the aging HIV brain, while also considering the effects of comorbidity for AUD and HCV.

Structural and microstructral imaging of the brain in alcohol use disorders

Magnetic resonance imaging (MRI), by enabling rigorous in vivo study of the longitudinal, dynamic course of alcoholism through periods of drinking, sobriety, and relapse, has enabled characterization of the effects of chronic alcoholism on the brain in the human condition. Importantly, MRI has distinguished alcohol-related brain effects that are permanent versus those that are reversible with abstinence. In support of postmortem neuropathologic studies showing degeneration of white matter, MRI has shown a specific vulnerability of brain white matter to chronic alcohol exposure by demonstrating white-matter volume deficits, yet not leaving selective gray-matter structures unscathed. Diffusion tensor imaging (DTI), by permitting microstructural characterization of white matter, has extended MRI findings in alcoholics. This review focuses on MRI and DTI findings in common concomitants of alcoholism, including Wernicke's encephalopathy, Korsakoff's syndrome, hepatic encephalopathy, central pontine myelinolysis, alcoholic cerebellar degeneration, alcoholic dementia, and Marchiafava-Bignami disease as a framework for findings in so-called "uncomplicated alcoholism," and also covers findings in abstinence and relapse.

Monkey alcohol tissue research resource: banking tissues for alcohol research

BACKGROUND

An estimated 18 million adults in the United States meet the clinical criteria for diagnosis of alcohol abuse or alcoholism, a disorder ranked as the third leading cause of preventable death. In addition to brain pathology, heavy alcohol consumption is comorbid with damage to major organs including heart, lungs, liver, pancreas, and kidneys. Much of what is known about risk for and consequences of heavy consumption derive from rodent or retrospective human studies. The neurobiological effects of chronic intake in rodent studies may not easily translate to humans due to key differences in brain structure and organization between species, including a lack of higher-order cognitive functions, and differences in underlying prefrontal cortical neural structures that characterize the primate brain. Further, rodents do not voluntarily consume large quantities of ethanol (EtOH) and they metabolize it more rapidly than primates.

METHODS

The basis of the Monkey Alcohol Tissue Research Resource (MATRR) is that nonhuman primates, specifically monkeys, show a range of drinking excessive amounts of alcohol (>3.0 g/kg or a 12 drink equivalent per day) over long periods of time (12 to 30 months) with concomitant pathological changes in endocrine, hepatic, and central nervous system (CNS) processes. The patterns and range of alcohol intake that monkeys voluntarily consume parallel what is observed in humans with alcohol use disorders and the longitudinal experimental design spans stages of drinking from the EtOH-naïve state to early exposure through chronic abuse. Age- and sex-matched control animals self-administer an isocaloric solution under identical operant procedures.

RESULTS

The MATRR is a unique postmortem tissue bank that provides CNS and peripheral tissues, and associated bioinformatics from monkeys that self-administer EtOH using a standardized experimental paradigm to the broader alcohol research community.

CONCLUSIONS

This resource provides a translational platform from which we can better understand the disease processes associated with alcoholism.

Untreated HIV infection is associated with higher blood alcohol levels

BACKGROUND

Alcohol abuse has been associated with HIV/AIDS progression, but the effects of HIV infection and treatment on alcohol exposure have not been explored to date. This pilot study examines the relationship of untreated HIV infection to blood alcohol concentrations (BAC) relative to BAC after initiation of antiretroviral therapy (ART).

METHODS

Fifteen volunteers with untreated HIV/AIDS participated in 2 sets of alcohol or alcohol placebo administration studies before and after initiation of ART. Oral alcohol (1 g/kg) or alcohol placebo was administered, participants were followed for pharmacokinetics, subjective responses, and cognitive effects over 8 hours. After initial alcohol studies, the ART regimen selected by participant clinicians was instituted. Observed ART dosing took place for at least 2 weeks. Participants then returned for a second set of alcohol/placebo administration studies while on ART.

RESULTS

Participants had significantly higher BAC (P < 0.001) before ART than after ART administration. Alcohol area under the curve was significantly higher in untreated HIV disease (P = 0.011) with significantly higher C(max) (P = 0.015) and C(min) (P = 0.05). The elimination rate was not different between pre-ART and post-ART conditions. Despite declines in BAC after ART initiation, no differences in subjective responses were observed with alcohol administration.

CONCLUSIONS

Untreated HIV infection is associated with risk for higher BAC than that observed after ART. These findings indicate that patients with untreated HIV disease who ingest alcohol are at greater risk for alcohol associated adverse events and toxicities and underscores the need for simultaneous treatment of alcohol use disorders and HIV in patients with co-occurring conditions.

Regional areas and widths of the midsagittal corpus callosum among HIV-infected patients on stable antiretroviral therapies

Recent reports suggest that a growing number of human immunodeficiency virus (HIV)-infected persons show signs of persistent cognitive impairment even in the context of combination antiretroviral therapies (cART). The basis for this finding remains poorly understood as there are only a limited number of studies examining the relationship between CNS injury, measures of disease severity, and cognitive function in the setting of stable disease. This study examined the effects of HIV infection on cerebral white matter using quantitative morphometry of the midsagittal corpus callosum (CC) in 216 chronically infected participants from the multisite HIV Neuroimaging Consortium study currently receiving cART and 139 controls. All participants underwent MRI assessment, and HIV-infected subjects also underwent measures of cognitive function and disease severity. The midsagittal slice of the CC was quantified using two semi-automated procedures. Group comparisons were accomplished using ANOVA, and the relationship between CC morphometry and clinical covariates (current CD4, nadir CD4, plasma and CSF HIV RNA, duration of HIV infection, age, and ADC stage) was assessed using linear regression models. HIV-infected patients showed significant reductions in both the area and linear widths for several regions of the CC. Significant relationships were found with ADC stage and nadir CD4 cell count, but no other clinical variables. Despite effective treatment, significant and possibly irreversible structural loss of the white matter persists in the setting of chronic HIV disease. A history of advanced immune suppression is a strong predictor of this complication and suggests that antiretroviral intervention at earlier stages of infection may be warranted.

The role of medical imaging in defining CNS abnormalities associated with HIV-infection and opportunistic infections

In this review of the current literature, we examine the role of medical imaging in providing new and relevant information on central nervous system (CNS) injury associated with human immunodeficiency virus (HIV) infection and various clinical manifestations of this injury. Common imaging modalities used to examine CNS injury in HIV infection include structural magnetic resonance imaging, magnetic resonance spectroscopy, diffusion tensor imaging, functional MRI, and positron emissions tomography. Clinical implications for the findings are discussed for each of these modalities individually and collectively. In addition, the direction for future studies is suggested in an attempt to provide possible methods that might answer the many questions that remain to be answered on the evolution and progression of CNS injury in the context of HIV infection.

MR diffusion tensor imaging: a window into white matter integrity of the working brain

As Norman Geschwind asserted in 1965, syndromes resulting from white matter lesions could produce deficits in higher-order functions and "disconnexion" or the interruption of connection between gray matter regions could be as disruptive as trauma to those regions per se. The advent of in vivo diffusion tensor imaging, which allows quantitative characterization of white matter fiber integrity in health and disease, has served to strengthen Geschwind's proposal. Here we present an overview of the principles of diffusion tensor imaging (DTI) and its contribution to progress in our current understanding of normal and pathological brain function.

Drug abuse and hepatitis C infection as comorbid features of HIV associated neurocognitive disorder: neurocognitive and neuroimaging features

Substance abuse and co-infection with hepatitis C (HCV) are two highly relevant determinants of neurocognitive and neuroimaging abnormalities associated with HIV. Substance abuse and HCV are common in the HIV population and there is increasing evidence that the CNS is directly compromised by these comorbid conditions via additive or synergistic processes. In this article we review the current literature regarding mechanisms of neuronal injury as well as the neuropsychological and neuroimaging signatures associated with substance abuse and HCV status among HIV patients. We discuss specific methodological challenges and threats to validity associated with studies of HIV and comorbid substance use disorders or HCV and review potential strategies for minimizing their confounding effects. Efforts to understand the interactions between HIV, substance abuse and HCV co-infection will lead to more complete models of neuropathogenesis of HIV and a greater understanding of the variability in neuropsychological expression of HIV Associated Neurocognitive Disorder.

Metabolic markers of neuronal injury correlate with SIV CNS disease severity and inoculum in the macaque model of neuroAIDS

In vivo MR spectroscopy (MRS) studies have shown reductions in NAA/Cr levels in patients with severe neurocognitive deficits due to AIDS dementia complex (ADC), also known as neuroAIDS. The relationship between the cellular changes within the brain during neuroAIDS and the role of NAA/Cr as a metabolic marker remains unclear. In order to clarify the relationship between NAA/Cr and disease severity we utilized the simian immunodeficiency virus (SIV)/macaque model of encephalitis. High-field proton MRS was performed on extracted metabolites from frontal cortex tissue samples of 29 rhesus macaques (6 healthy, 23 moribund with AIDS). Neuropathologic determination of encephalitis severity for each animal was completed and was found to correlate with NAA/Cr levels. Decreases in Glu/Cr and GABA/Cr may indicate that both excitatory and inhibitory neurons are affected. Highly significant correlations between NAA/Cr, Glu/Cr, and GABA/Cr were observed. These neuronal metabolites were also decreased in the absence of classical SIV encephalitis (SIVE). At any disease classification, animals inoculated with SIVmac251 were found to have lower levels of NAA/Cr than animals inoculated with SIVmac239. In considering therapy for neuroAIDS the findings here support prevention of the encephalitic process, but suggest that suppressing the formation of multinucleated giant cells alone would be insufficient to prevent neuronal injury.

Co-factors in HIV neurobehavioural disturbances: substance abuse, hepatitis C and aging

Neurocognitive disturbances associated with HIV infection may be modulated or confounded by coexisting and comorbid conditions that reflect the changing populations affected by the disease. HIV infection is often accompanied by substance dependence and/or hepatitis C co-infection. Both of these cofactors that may lead to brain dysfunction on their own, and therefore can affect the nature and course neurocognitive functioning in HIV. Improvements in antiretroviral therapies translate into greater longevity for people infected with HIV, many of whom are now entering their 6th and 7th decade of life and beyond. The increasing proportion of older persons with HIV is also the result of new infections in this age group. As aging confers additional metabolic, neurologic, and neuropsychiatric vulnerability, it is important to understand how this constellation of changes affects neurocognitive functioning in the context of HIV.

Callosal Compromise Differentially Affects Conflict Processing and Attentional Allocation in Alcoholism, HIV, and Their Comorbidity

Diffusion tensor imaging was used to study the combined effects of HIV-infection and alcoholism (ALC) on corpus callosum (CC) integrity in relation to processes of attentional allocation and conflict resolution assessed by a novel Stroop Match-to-Sample task. We tested 16 ALC, 19 HIV, 20 subjects with combined disorder and 17 controls. In ALC, low fractional anisotropy and high mean diffusivity throughout the CC correlated with poor Stroop-match performance, i.e., when the cue-color matched the color of the Stroop stimulus. By contrast, in the two HIV groups DTI relations were restricted to the genu and poor Stroop-nonmatch performance, i.e., when the cue-color was in conflict with the Stroop stimulus color. These results suggest that disruption of callosal integrity in HIV-infection and alcoholism differentially affects regionally-selective interhemispheric-dependent attentional processing. We speculate that callosal degradation in these diseases curtails the opportunity for collaboration between the two hemispheres that contributes to normal performance in HIV or alcoholic patients with higher callosal integrity.

Chronic cigarette smoking and heavy drinking in human immunodeficiency virus: consequences for neurocognition and brain morphology

Alcohol use disorders (AUD) and chronic cigarette smoking are common among individuals with human immunodeficiency virus infection (HIV). Concurrent AUD in HIV is related to greater abnormalities in brain morphology and neurocognition than either condition alone. However, the potential influence of chronic smoking on brain morphology and neurocognition in those concurrently afflicted with AUD and HIV has not been examined. The goal of this retrospective analysis was to determine if chronic smoking affected neurocognition and brain morphology in a subsample of HIV-positive non-treatment-seeking heavy drinking participants (HD+) from our earlier work. Regional volumetric and neurocognitive comparisons were made among age-equivalent smoking HD+(n=17), nonsmoking HD+ (n=27), and nonsmoking HIV-negative light drinking controls (n=27) obtained from our original larger sample. Comprehensive neuropsychological assessment evaluated multiple neurocognitive domains of functioning and for potential psychiatric comorbidities. Quantitative volumetric measures of neocortical gray matter (GM), white matter (WM), subcortical structures, and sulcal and ventricular cerebral spinal fluid (CSF) were derived from high-resolution magnetic resonance images. The main findings were (1) smoking HD+ performed significantly worse than nonsmoking HD+ on measures of auditory-verbal (AV) learning, AV memory, and cognitive efficiency; (2) relative to controls, smoking HD+ demonstrated significantly lower neocortical GM volumes in all lobes except the occipital lobe, while nonsmoking HD+ showed only lower frontal GM volume compared with controls; (3) in the HD+ group, regional brain volumes and neurocognition were not influenced by viremia, highly active antiretroviral treatment, or Center for Disease Control symptom status, and no interactions were apparent with these variables or smoking status. Overall, the findings suggested that the direct and/or indirect effects of chronic cigarette smoking created an additional burden on the integrity of brain neurobiology and neurocognition in this cohort of HIV-positive heavy drinkers.

Chronic binge ethanol consumption accelerates progression of simian immunodeficiency virus disease

BACKGROUND

While alcohol consumption is known to increase the incidence and severity of infections, the impact of alcohol consumption on human immunodeficiency virus (HIV) disease progression has been difficult to assess. Therefore, we examined the effect of ethanol on simian immunodeficiency virus (SIV) disease progression in a well-defined model utilizing rhesus macaques.

METHODS

Alcohol was administered for 5 hours via an indwelling intragastric catheter to achieve an alcohol concentration of 50 to 60 mM for 4 consecutive days per week for the duration of the study. Control animals received isocaloric sucrose. After 3 months, animals were inoculated intravenously with 10,000 times the ID(50) of SIV(DeltaB670) and followed to end-stage disease.

RESULTS

Plasma SIV ribonucleic acid (RNA) was higher in alcohol-consuming animals compared with sucrose-treated animals during the early asymptomatic stage of disease but not at later time points. This increase in viral set point was associated with more rapid progression to end-stage disease in macaques administered alcohol (median=374 days) compared with sucrose (median=900 days). The decline in blood CD4+ cells was similar in both groups of animals.

CONCLUSIONS

This study indicates that frequent episodes of alcohol intoxication in SIV+ macaques increase viral set point in association with more rapid development of end-stage disease.

Contribution of alcoholism to brain dysmorphology in HIV infection: Effects on the ventricles and corpus callosum

Nonrigid registration and atlas-based parcellation methods were used to compare the volume of the ventricular system and the cross-sectional area of the midsagittal corpus callosum on brain MRIs from 272 subjects in four groups: patients with HIV infection, with and without alcoholism comorbidity, alcoholics, and controls. Prior to testing group differences in regional brain metrics, each measure was corrected by regression analysis for significant correlations with supratentorial cranial volume and age, observed in 121 normal control men and women, whose age spanned six decades. Disregarding HIV disease severity, we observed a graded pattern of modest enlargement of the total ventricular system (0.28 SD for uncomplicated HIV, 0.65 SD for HIV comorbid with alcoholism, and 0.72 SD for the alcoholism group). The pattern of callosal thinning showed a similar but small ( approximately 0.5 SD) graded effect. A different pattern emerged, however, when HIV severity in the context of alcoholism comorbidity was factored into the analysis. Substantially greater volume abnormalities were present in individuals with a history of an AIDS-defining event or low CD4+ T cell counts (<or=200 mm(3)) irrespective of alcoholism comorbidity, and the effect of HIV severity was disproportionately exacerbated by alcoholism comorbidity, with 1 SD size deficit in the genu of corpus callosum and nearly 2 SD greater volume of the frontal and body regions of the ventricles for the AIDS + alcohol comorbid group. The differences in brain volumes between the AIDS groups with vs. without alcoholism could not be attributed to differences in HIV disease severity, defined by CD4+ count, viral load, or Karnofsky score. The substantial effect of the alcoholism-AIDS interaction on ventricular and callosal dysmorphology, in the context of the modest changes observed in non-AIDS, nonalcohol abusing HIV-infected individuals, highlight the need to consider alcohol use disorders as a major risk factor for neuropathology among HIV-infected persons.

Expanding research on the role of alcohol consumption and related risks in the prevention and treatment of HIV/AIDS

This article is a review of some of the major epidemiological, behavioral, biological, and integrative prevention research issues and priorities in the area of HIV/AIDS and alcohol consumption. Drinking alcohol increases both the risk for infection with HIV and related illnesses and the morbidity and mortality of patients who progress to AIDS. New and improved measurement procedures have helped in assessment of the complex patterns of alcohol use, identification of intervening explanatory mechanisms for risk behaviors and contexts, and determination of intervention outcomes. Both the direct and indirect effects of alcohol misuse appear to be major contributors to both the risk for infection with HIV and the transmission of HIV/AIDS at the individual and population levels. There is increasing evidence that perhaps no level of alcohol consumption is "safe" for those who are HIV infected and receiving antiretroviral treatment. Interdisciplinary basic behavioral and biomedical research is needed to develop comprehensive culturally appropriate strategies for programs that can be effectively delivered in community contexts in the United States and abroad and that focus on the integration of our understanding of individual behaviors, high-risk group membership, biological mechanisms, and the social and physical environments that place individuals at risk for HIV infection. High-priority topics include improving adherence to antiretroviral medications, prevention of infection in young minority women in the United States, and treatment of HIV+ pregnant women who are alcohol abusers to prevent adverse fetal outcomes, which is an international focus in under-resourced settings in Africa.

Cortical NAA deficits in HIV infection without dementia: influence of alcoholism comorbidity

Alcoholism comorbidity is highly prevalent in individuals infected with human immunodeficiency virus (HIV). Each condition is known to affect brain structure, function, and metabolism, but the combined effects on the brain have only recently been considered. Single-voxel, proton MR spectroscopy (MRS) has yielded sensitive measures of early brain deterioration in the progression of HIV, but has limited coverage of neocortex, whereas MRS imaging (MRSI) can simultaneously interrogate large regions of cortex. Included were 15 men with HIV+alcoholism, nine men with HIV alone, eight men with alcoholism alone (abstinent for 3-17 months), and 23 controls. The two HIV groups were matched in T-cell count and were not demented; the two alcoholism groups were relatively matched in lifetime alcohol consumption. We used MRSI with a variable-density spiral sequence to quantify major proton metabolites--N-acetylaspartate (NAA), creatine (Cr), and choline (Cho)-in the superior parietal-occipital cortex. Metabolites were expressed in absolute units and as the NAA/Cr ratio. Significant group effects were present for NAA and Cr. Only the HIV+alcoholism group was significantly affected, exhibiting a 0.8 SD deficit in NAA and a 1.0 SD deficit in Cr. The deficits were not related to highly active antiretroviral therapy (HAART) status. Neither HIV infection nor alcoholism independently resulted in parietal-occipital cortical metabolite abnormalities, yet each disease carried a liability that put affected individuals at a heightened risk of neuronal compromise when the diseases were compounded. Further, the use of absolute measures revealed deficits in NAA and Cr that would have gone undetected if these metabolites were expressed as a ratio.

Corpus callosal microstructural integrity influences interhemispheric processing: a diffusion tensor imaging study

Normal aging and chronic alcoholism result in disruption of brain white matter microstructure that does not typically cause complete lesions but may underlie degradation of functions requiring interhemispheric information transfer. We examined whether the microstructural integrity of the corpus callosum assessed with diffusion tensor imaging (DTI) would relate to interhemispheric processing speed. DTI yields estimates of fractional anisotropy (FA), a measure of orientation and intravoxel coherence of water diffusion usually in white matter fibers, and diffusivity (<D>), a measure of the amount of intracellular and extracellular fluid diffusion. We tested the hypothesis that FA and <D> would be correlated with (i) the crossed-uncrossed difference (CUD), testing visuomotor interhemispheric transfer; and (ii) the redundant targets effect (RTE), testing parallel processing of visual information presented to each cerebral hemisphere. FA was lower and <D> higher in alcoholics than in controls. In controls but not alcoholics, large CUDs correlated with low FA and high <D> in total corpus callosum and regionally in the genu and splenium. In alcoholics but not controls, small RTEs, elicited with equiluminant stimuli, correlated with low FA in genu and splenium and high <D> in the callosal body. The results provide in vivo evidence for disruption of corpus callosum microstructure in normal aging and alcoholism that has functional ramifications for efficiency in interhemispheric processing.

Differential effect of HIV infection and alcoholism on conflict processing, attentional allocation, and perceptual load: evidence from a Stroop Match-to-Sample task

BACKGROUND

Alcoholism and human immunodeficiency virus (HIV) infection each can impair components of selective attention, probably through disruption of the integrity of the frontoparietal neural systems that underlie conflict processing, attentional allocation, and perceptual load.

METHODS

We studied 18 patients with alcoholism (ALC) alone, 19 with HIV infection alone (HIV), 20 with both disorders (H+A), and 19 healthy control subjects (CTL). We used a novel paradigm (Stroop Match-to-Sample tasks), in which subjects saw either a valid or invalid color cue before a target word, printed in a color that was either congruent or incongruent with the word's meaning.

RESULTS

All groups showed a significant Stroop effect, cue-target color Match effect, and interaction between Match and Stroop, with an exaggerated Stroop effect for the Match condition. The HIV patients were comparable to CTL, whereas ALC showed mild delays, with further delays associated with comorbidity with HIV. Although H+A profited from a valid match to Stroop stimuli, they were compromised in disengaging attention from the invalidly cued color.

CONCLUSIONS

Impairment in conflict processing and attentional allocation in alcoholism suggests disruption of frontal-parietal attentional systems. Although HIV alone did not demonstrate detectable impairment in performance, HIV conferred liability on attentional processes when combined with alcohol abuse.

Heavy alcohol consumption in individuals with HIV infection: effects on neuropsychological performance

Higher rates of alcohol use have been reported in HIV+ individuals compared to the general population. Both heavy alcohol use and HIV infection are associated with increased risk of neuropsychological (NP) impairment. We examined effects of heavy active alcohol use and HIV on NP functioning in a large sample of community-residing HIV+ individuals and HIV- controls. The four main study groups included 72 HIV- light/non-drinkers, 70 HIV- heavy drinkers (>100 drinks per month), 70 HIV+ light/non-drinkers, and 56 HIV+ heavy drinkers. The heavy drinking group was further subdivided to assess effects of the heaviest levels of active alcohol use (>6 drinks per day) on NP functioning. A comprehensive NP battery was administered. Multivariate analysis of covariance was employed to examine the effect of HIV and alcohol on NP functioning after adjusting for group differences in age and estimated premorbid verbal intellectual functioning. The analyses identified main effects of heavy drinking and HIV on NP function, with greatest effects involving the contrast of HIV+ heavy drinkers and the HIV- light drinkers. Synergistic effects of heaviest current drinking and HIV infection were identified in analyses of motor and visuomotor speed. Supplementary analyses also revealed better NP function in the HIV+ group with antiretroviral treatment (ART) and lower level of viral burden, a finding that was consistent across levels of alcohol consumption. Finally, heavy alcohol use and executive functioning difficulties were associated with lower levels of self-reported medication adherence in the HIV+ group. The findings suggest that active heavy alcohol use and HIV infection have additive adverse effects on NP function, that they may show synergistic effects in circumstances of very heavy active alcohol use, and that heavy drinking and executive functioning may mediate health-related behaviors in HIV disease.

Magnetic resonance detects brainstem changes in chronic, active heavy drinkers

Neuropathological and neuroimaging studies show cortical and subcortical volume loss in alcohol-dependent individuals. Using quantitative magnetic resonance imaging (MRI) and proton magnetic resonance spectroscopic imaging ((1)H MRSI), we studied the size and potential cellular injury of the brainstem in untreated heavy alcohol drinkers. The brainstem is considered critical in the development and maintenance of drug and alcohol dependence. Two methods of brainstem size determination were compared: standard volumetry vs. midsagittal MR image area measurement. Heavy drinkers (n=12) and light drinkers (n=10) were compared with MRI; (1)H MRSI brainstem data were obtained from a subset of this cohort. Chronic heavy drinking was associated with significantly smaller midsagittal areas of the brainstem, midbrain, and pons, and with significantly smaller overall brainstem volume. Heavy drinking was also associated with significantly lower ratios of N-acetyl-aspartate and choline-containing metabolites compared with creatine-containing compounds in the brainstem, independent of brainstem atrophy. Additionally, brainstem volume and midsagittal brainstem area were correlated (r=0.78). These structural and metabolite findings are consistent with neuronal injury in the brainstem of untreated chronic heavy drinkers. The results also indicate that the midsagittal MRI brainstem area is an easily determined and reliable indicator of brainstem volume.

Neurocognitive ability in adults coping with alcohol and drug relapse temptations

Coping is important for preventing relapse, but may be utilized differently depending on the individual's level of cognitive functioning. Impaired reasoning, attention, and memory are commonly observed in alcohol-dependent individuals. This study describes the prospective relationship between neuropsychological functioning and utilization of coping strategies in predicting outcome one year after discharge from an inpatient alcohol treatment program. Male veterans (n = 43) hospitalized in an alcohol treatment facility were given structured interviews, coping questionnaires, and neuropsychological testing, and were followed three and 12 months after discharge. Neuropsychological ability moderated the relationship between coping and drinking outcomes one year after treatment. This was particularly true for patients with better neurocognitive functioning. Specifically, patients with higher neurocognitive performances and more maladaptive coping responses, such as self-blame, had a greater percentage of drinking days at follow-up. Alcohol-dependent adults with good neuropsychological functioning may be able to benefit more from coping skills training. For those with neuropsychological deficits, coping skills training may need to take cognitive limitations into consideration.

Proton MR spectroscopic studies of chronic alcohol exposure on the rat brain

PURPOSE

To better understand the long-term pathophysiologic mechanisms of alcoholism-related organic brain damage by serially assessing brain metabolites in chronically exposed rats using both in vivo magnetic resonance spectroscopy (MRS) and high-resolution nuclear magnetic resonance (NMR) from brain extracts.

MATERIALS AND METHODS

The alcoholic regimen was continued up to 60 weeks. In vivo proton MRS studies were performed at 200 MHz using a small animal imaging/spectrometer. In vitro rat brain extracts were also examined using a 500 MHz vertical bore magnet. Comparison measurements were also obtained in an age-matched control group.

RESULTS

In vivo results showed that there is a significant increase in the Cho/NAA ratio in the chronic alcohol-exposed group that reached a maximum around 16 weeks. After 44 weeks of alcohol exposure, Cho/NAA in the alcohol group decreased significantly from its maximum value to a value that was significantly lower than those from the control groups. Brain extract studies demonstrated that PC and GPC were the main components responsible for the observed in vivo spectral changes after 16 and 60 weeks of alcohol consumption, respectively.

CONCLUSION

The fluctuation of choline-containing metabolites during alcohol intoxication could explain sometimes seemingly conflicting and confusing results from MRS studies in human and animal studies in which the duration of alcohol consumption and amount are varied widely.

Diffusion tensor imaging in normal aging and neuropsychiatric disorders

The application of diffusion imaging to the quantitative study of the effects of normal aging and neuropsychiatric diseases on brain tissue microstructure has witnessed its greatest development just over the last few years. Measures derived from diffusion imaging have already been shown to have great utility in identifying age- and disease-related degradation of regional microstructure, particularly of white matter. Investigations comparing diagnoses hold promise for contribution to differential diagnosis. Correlations with cognitive and motor performance provide evidence for functional ramifications of these diffusion measures.