Acute alcohol effects on neuronal and attentional processing: striatal reward system and inhibitory sensory interactions under acute ethanol challenge

Animal model for high consumption and preference of ethanol and its interplay with high sugar and butter diet, behavior, and neuroimmune system

Introduction

Mechanisms that dictate the preference for ethanol and its addiction are not only restricted to the central nervous system (CNS). An increasing body of evidence has suggested that abusive ethanol consumption directly affects the immune system, which in turn interacts with the CNS, triggering neuronal responses and changes, resulting in dependence on the drug. It is known that neuroinflammation and greater immune system reactivity are observed in behavioral disorders and that these can regulate gene transcription. However, there is little information about these findings of the transcriptional profile of reward system genes in high consumption and alcohol preference. In this regard, there is a belief that, in the striatum, an integrating region of the brain reward system, the interaction of the immune response and the transcriptional profile of the Lrrk2 gene that is associated with loss of control and addiction to ethanol may influence the alcohol consumption and preference. Given this information, this study aimed to assess whether problematic alcohol consumption affects the transcriptional profile of the Lrrk2 gene, neuroinflammation, and behavior and whether these changes are interconnected.

Methods

An animal model developed by our research group has been used in which male C57BL/6 mice and knockouts for the Il6 and Nfat genes were subjected to a protocol of high fat and sugar diet intake and free choice of ethanol in the following stages: Stage 1 (T1)-Dietary treatment, for 8 weeks, in which the animals receive high-calorie diet, High Sugar and Butter (HSB group), or standard diet, American Institute of Nutrition 93-Growth (AIN93G group); and Stage 2 (T2)-Ethanol consumption, in which the animals are submitted, for 4 weeks, to alcohol within the free choice paradigm, being each of them divided into 10 groups, four groups continued with the same diet and in the other six the HSB diet is substituted by the AIN93G diet. Five groups had access to only water, while the five others had a free choice between water and a 10% ethanol solution. The weight of the animals was evaluated weekly and the consumption of water and ethanol daily. At the end of the 12-week experiment, anxiety-like behavior was evaluated by the light/dark box test; compulsive-like behavior by Marble burying, transcriptional regulation of genes Lrrk2, Tlr4, Nfat, Drd1, Drd2, Il6, Il1β, Il10, and iNOS by RT-qPCR; and inflammatory markers by flow cytometry. Animals that the diet was replaced had an ethanol high preference and consumption.

Results and discussion

We observed that high consumption and preference for ethanol resulted in (1) elevation of inflammatory cells in the brain, (2) upregulation of genes associated with cytokines (Il6 and Il1β) and pro-inflammatory signals (iNOS and Nfat), downregulation of anti-inflammatory cytokine (Il10), dopamine receptor (Drd2), and the Lrrk2 gene in the striatum, and (3) behavioral changes such as decreased anxiety-like behavior, and increased compulsive-like behavior. Our findings suggest that interactions between the immune system, behavior, and transcriptional profile of the Lrrk2 gene influence the ethanol preferential and abusive consumption.

Acute alcohol intoxication modulates the temporal dynamics of resting electroencephalography networks

This study aimed to provide a currently missing link between general intoxication-induced changes in overall brain activity and the multiple cognitive control deficits typically observed during acute alcohol intoxication. For that purpose, we analyzed the effects of acute alcohol intoxication (1.1‰) on the four archetypal electroencephalography (EEG) resting networks (i.e., microstates A-D) and their temporal dynamics (e.g., coverage and transitions from one microstate to another), as well as on self-reported resting-state cognition in n = 22 healthy young males using a counterbalanced within-subject design. Our microstate analyses indicated that alcohol increased the coverage of the visual processing-related microstate B at the expense of the autonomic processing-related microstate C. Add-on exploratory analyses revealed that alcohol increased transitions from microstate C to microstate B and decreased bidirectional transitions between microstate C and the attention-related microstate D. In line with the observed alcohol-induced decrease of the autonomic processing-related microstate C, participants reported decreases of their somatic awareness during intoxication, which were positively associated with more transitions from microstate C to microstate B. In sum, the observed effects provide mechanistic insights into how alcohol might hamper cognitive processing by generally prioritizing the bottom-up processing of visual stimuli over top-down internal information processing. The fact that this was found during the resting state further proves that alcohol-induced changes in brain activity are continuously present and do not only emerge during demanding situations or tasks.

Reduced attentional capture by reward following an acute dose of alcohol

RATIONALE

Previous research has shown that physically salient and reward-related distractors can automatically capture attention and eye gaze in a visual search task, even though participants are motivated to ignore these stimuli.

OBJECTIVES

To examine whether an acute, low dose of alcohol would influence involuntary attentional capture by stimuli signalling reward.

METHODS

Participants were assigned to the alcohol or placebo group before completing a visual search task. Successful identification of the target earned either a low or high monetary reward but this reward was omitted if any eye gaze was registered on the reward-signalling distractor.

RESULTS

Participants who had consumed alcohol were significantly less likely than those in the placebo condition to have their attention captured by a distractor stimulus that signalled the availability of high reward. Analysis of saccade latencies suggested that this difference reflected a reduction in the likelihood of impulsive eye movements following alcohol.

CONCLUSIONS

Our findings suggest that alcohol intoxication reduces the capacity to attend to information in the environment that is not directly relevant to the task at hand. In the current task, this led to a performance benefit under alcohol, but in situations that require rapid responding to salient events, the effect on behaviour would be deleterious.

BDNF and nicotine dependence: associations and potential mechanisms

Smoking is the leading preventable cause of death worldwide and tobacco addiction has become a serious public health problem. Nicotine is the main addictive component of tobacco, and the majority of people that smoke regularly develop nicotine dependence. Nicotine addiction is deemed to be a chronic mental disorder. Although it is well known that nicotine binds to the nicotinic acetylcholine receptors (nAChRs) and activates the mesolimbic dopaminergic system (MDS) to generate the pleasant and rewarding effects, the molecular mechanisms of nicotine addiction are not fully understood. Brain-derived neurotrophic factor (BDNF) is the most prevalent growth factor in the brain, which regulates neuron survival, differentiation, and synaptic plasticity, mainly through binding to the high affinity receptor tyrosine kinase receptor B (TrkB). BDNF gene polymorphisms are associated with nicotine dependence and blood BDNF levels are altered in smokers. In this review, we discussed the effects of nicotine on BDNF expression in the brain and summarized the underlying signaling pathways, which further indicated BDNF as a key regulator in nicotine dependence. Further studies that aim to understand the neurobiological mechanism of BDNF in nicotine addcition would provide a valuable reference for quitting smoking and developing the treatment of other addictive substances.

Ethanol metabolism: The good, the bad, and the ugly

Throughout the world, ethanol is both an important commercial commodity and a source of major medical and social problems. Ethanol readily passes through biological membranes and distributes throughout the body. It is oxidized, first to acetaldehyde and then to acetate, and finally by the citric acid cycle in virtually all tissues. The oxidation of ethanol is irreversible and unregulated, making the rate dependent only on local concentration and enzyme activity. This unregulated input of reducing equivalents increases reduction of both cytoplasmic and intramitochondrial NAD and, through the latter, cellular energy state {[ATP]/([ADP][Pi])}. In brain, this increase in energy state stimulates dopaminergic neural activity signalling reward and a sense of well being, while suppressing glutamatergic neural activity signalling anxiety and unease. These positive responses to ethanol ingestion are important to social alcohol consumption. Importantly, decreased free [AMP] decreases AMP-dependent protein kinase (AMPK) activity, an important regulator of cellular energy metabolism. Oxidation of substrates used for energy metabolism in the absence of ethanol is down regulated to accommodate the input from ethanol. In liver, chronic ethanol metabolism results in fatty liver and general metabolic dysfunction. In brain, transport of other oxidizable metabolites through the blood-brain barrier and the enzymes for their oxidation are both down regulated. For exposures of short duration, ethanol induced regulatory changes are rapid and reversible, recovering completely when the concentrations of ethanol and acetate fall again. Longer periods of ethanol exposure and associated chronic suppression of AMPK activity activates regulatory mechanisms, including gene expression, that operate over longer time scales, both in onset and reversal. If chronic alcohol consumption is abruptly ended, metabolism is no longer able to respond rapidly enough to compensate. Glutamatergic neural activity adapts to chronic dysregulation of glutamate metabolism and suppression of glutamatergic neural activity by increasing excitatory and decreasing inhibitory amino acid receptors. A point is reached (ethanol dependence) where withdrawal of ethanol results in significant metabolic energy depletion in neurons and other brain cells as well as hyperexcitation of the glutamatergic system. The extent and regional specificity of energy depletion in the brain, combined with hyperactivity of the glutamatergic neuronal system, largely determines the severity of withdrawal symptoms.

Intranasal Insulin: a Treatment Strategy for Addiction

Addiction to substances such as alcohol, cocaine, opioids, and methamphetamine poses a continuing clinical and public challenge globally. Despite progress in understanding substance use disorders, challenges remain in their treatment. Some of these challenges include limited ability of therapeutics to reach the brain (blood-brain barrier), adverse systemic side effects of current medications, and importantly key aspects of addiction not addressed by currently available treatments (such as cognitive impairment). Inability to sustain abstinence or seek treatment due to cognitive deficits such as poor decision-making and impulsivity is known to cause poor treatment outcomes. In this review, we provide an evidenced-based rationale for intranasal drug delivery as a viable and safe treatment modality to bypass the blood-brain barrier and target insulin to the brain to improve the treatment of addiction. Intranasal insulin with improvement of brain cell energy and glucose metabolism, stress hormone reduction, and improved monoamine transmission may be an ideal approach for treating multiple domains of addiction including memory and impulsivity. This may provide additional benefits to enhance current treatment approaches.

Extracellular cold inducible RNA-binding protein mediates binge alcohol-induced brain hypoactivity and impaired cognition in mice

BACKGROUND

Alcohol abuse affects the brain regions responsible for memory, coordination and emotional processing. Binge alcohol drinking has shown reductions in brain activity, but the molecular targets have not been completely elucidated. We hypothesized that brain cells respond to excessive alcohol by releasing a novel inflammatory mediator, called cold inducible RNA-binding protein (CIRP), which is critical for the decreased brain metabolic activity and impaired cognition.

METHODS

Male wild type (WT) mice and mice deficient in CIRP (CIRP-/-) were studied before and after exposure to binge alcohol level by assessment of relative brain glucose metabolism with fluorodeoxyglucose (18FDG) and positron emission tomography (PET). Mice were also examined for object-place memory (OPM) and open field (OF) tasks.

RESULTS

Statistical Parametric Analysis (SPM) of 18FDG-PET uptake revealed marked decreases in relative glucose metabolism in distinct brain regions of WT mice after binge alcohol. Regional analysis (post hoc) revealed that while activity in the temporal (secondary visual) and limbic (entorhinal/perirhinal) cortices was decreased in WT mice, relative glucose metabolic activity was less suppressed in the CIRP-/- mice. Group and condition interaction analysis revealed differing responses in relative glucose metabolism (decrease in WT mice but increase in CIRP-/- mice) after alcohol in brain regions including the hippocampus and the cortical amygdala where the percent changes in metabolic activity correlated with changes in object discrimination performance. Behaviorally, alcohol-treated WT mice were impaired in exploring a repositioned object in the OPM task, and were more anxious in the OF task, whereas CIRP-/- mice were not impaired in these tasks.

CONCLUSION

CIRP released from brain cells could be responsible for regional brain metabolic hypoactivity leading to cognitive impairment under binge alcohol conditions.

The neural correlates of alcohol-related aggression

Alcohol intoxication is implicated in approximately half of all violent crimes. Over the past several decades, numerous theories have been proposed to account for the influence of alcohol on aggression. Nearly all of these theories imply that altered functioning in the prefrontal cortex is a proximal cause. In the present functional magnetic resonance imaging (fMRI) experiment, 50 healthy young men consumed either a low dose of alcohol or a placebo and completed an aggression paradigm against provocative and nonprovocative opponents. Provocation did not affect neural responses. However, relative to sober participants, during acts of aggression, intoxicated participants showed decreased activity in the prefrontal cortex, caudate, and ventral striatum, but heightened activation in the hippocampus. Among intoxicated participants, but not among sober participants, aggressive behavior was positively correlated with activation in the medial and dorsolateral prefrontal cortex. These results support theories that posit a role for prefrontal cortical dysfunction as an important factor in intoxicated aggression.

Effects of the experimental administration of oral estrogen on prefrontal functions in healthy young women

17-Beta-estradiol (E2) stimulates neural plasticity and dopaminergic transmission in the prefrontal cortex, which is critically involved in attentional control, working memory, and other executive functions. Studies investigating E2's actions on prefrontally mediated behavior in the course of the menstrual cycle or during hormone replacement therapy are inconclusive, with numerous null findings as well as beneficial and detrimental effects. The current study focused on the effect of E2 on attentional performance, as animal studies indicate that supraphysiological doses (i.e., above estrous cycle levels) of E2 have beneficial effects on measures of attention in female rodents. To translate these findings to humans, we administered 12 mg E2-valerate or placebo orally to 34 naturally cycling women in the low-hormone early follicular phase using a randomized, double-blinded, pre-post design. Behavioral performance was tested twice during baseline and E2 peak, where E2 levels reached mildly supraphysiological levels in the E2 group. Aside from mainly prefrontally mediated tasks of attention, working memory, and other executive functions, we employed tasks of affectively modulated attention, emotion recognition, and verbal memory. E2 administration had a significant, but subtle negative impact on general processing speed and working memory performance. These effects could be related to an overstimulation of dopaminergic transmission. The negative effect of supraphysiological E2 on working memory connects well to animal literature. There were no effects on attentional performance or any other measure. This could be explained by different E2 levels being optimal for changing behavioral performance in specific tasks, which likely depends on the brain regions involved.

Acute alcohol effects on set-shifting and its moderation by baseline individual differences: a latent variable analysis

AIMS

To compare the acute effects of alcohol on set-shifting task performance (relative to sober baseline performance) during ascending and descending limb breath alcohol concentration (BrAC), as well as possible moderation of these effects by baseline individual differences.

DESIGN

Shifting performance was tested during an initial baseline and a subsequent drinking session, during which participants were assigned randomly to one of three beverage conditions (alcohol, placebo or control) and one of two BrAC limb conditions [ascending and descending (A/D) or descending-only (D-only)].

SETTING

A human experimental laboratory on the University of Missouri campus in Columbia, MO, USA.

PARTICIPANTS

A total of 222 moderate-drinking adults (ages 21-30 years) recruited from Columbia, MO and tested between 2010 and 2013.

MEASUREMENTS

The outcome measure was performance on set-shifting tasks under the different beverage and limb conditions. Shifting performance assessed at baseline was a key moderator.

FINDINGS

Although performance improved across sessions, this improvement was reduced in the alcohol compared with no-alcohol groups (post-drink latent mean comparison across groups, all Ps ≤ 0.05), and this effect was more pronounced in individuals with lower pre-drink performance (comparison of pre- to post-drink path coefficients across groups, all Ps ≤ 0.05). In the alcohol group, performance was better on descending compared with ascending limb (P ≤ 0.001), but descending limb performance did not differ across the A/D and D-only groups.

CONCLUSIONS

Practising tasks before drinking moderates the acute effects of alcohol on the ability to switch between tasks. Greater impairment in shifting ability on descending compared with ascending breath alcohol concentration is not related to task practice.

Functional Benefits of (Modest) Alcohol Consumption

Alcohol use has a long and ubiquitous history. Despite considerable research on the misuse of alcohol, no one has ever asked why it might have become universally adopted, although the conventional view assumes that its only benefit is hedonic. In contrast, we suggest that alcohol consumption was adopted because it has social benefits that relate both to health and social bonding. We combine data from a national survey with data from more detailed behavioural and observational studies to show that social drinkers have more friends on whom they can depend for emotional and other support, and feel more engaged with, and trusting of, their local community. Alcohol is known to trigger the endorphin system, and the social consumption of alcohol may thus have the same effect as the many other social activities such as laughter, singing and dancing that we use as a means of servicing and reinforcing social bonds.

Intravenous Single-Dose Toxicity of Redaporfin-Based Photodynamic Therapy in Rodents

We assessed the tolerability and safety in rodents of a single intravenous (i.v.) dose of redaporfin, a novel photosensitizer for Photodynamic Therapy (PDT) of cancer. Two approaches were used to evaluate acute toxicity: (i) a dose escalation study in BALB/c mice to evaluate the maximum tolerated dose of redaporfin; and (ii) a safety toxicology study in Wistar rats, of a single dose of redaporfin, with or without illumination, to evaluate possible signs of systemic toxicity. Redaporfin formulation was well tolerated by mice, with no signs of adverse reactions up to 75 mg/kg. In rats, there were no relevant changes, except for a significant, but transient, increase in the blood serum markers for hepatic function and muscle integrity, and also on neutrophil counts, observed after the application of light. The overall results showed that redaporfin-PDT is very well tolerated. No abnormalities were observed, including reactions at the injection site or skin phototoxicity, although the animals were maintained in normal indoor lighting. Redaporfin also showed a high efficacy in the treatment of male BALB/c mice with subcutaneously implanted colon (CT26) tumours. Vascular-PDT with 1.5 mg/kg redaporfin and a light dose of 74 J/cm² led to the complete tumour regression in 83% of the mice.

Brain activation induced by voluntary alcohol and saccharin drinking in rats assessed with manganese-enhanced magnetic resonance imaging

The neuroanatomical and neurochemical basis of alcohol reward has been studied extensively, but global alterations of neural activity in reward circuits during chronic alcohol use remain poorly described. Here, we measured brain activity changes produced by long-term voluntary alcohol drinking in the alcohol-preferring AA (Alko alcohol) rats using manganese-enhanced magnetic resonance imaging (MEMRI). MEMRI is based on the ability of paramagnetic manganese ions to accumulate in excitable neurons and thereby enhance the T1-weighted signal in activated brain areas. Following 6 weeks of voluntary alcohol drinking, AA rats were allowed to drink alcohol for an additional week, during which they were administered manganese chloride (MnCl2 ) with subcutaneous osmotic minipumps before MEMRI. A second group with an identical alcohol drinking history received MnCl2 during the abstinence week following alcohol drinking. For comparing alcohol with a natural reinforcer, MEMRI was also performed in saccharin-drinking rats. A water-drinking group receiving MnCl2 served as a control. We found that alcohol drinking increased brain activity extensively in cortical and subcortical areas, including the mesocorticolimbic and nigrostriatal dopamine pathways and their afferents. Remarkably similar activation maps were seen after saccharin ingestion. Particularly in the prelimbic cortex, ventral hippocampus and subthalamic nucleus, activation persisted into early abstinence. These data show that voluntary alcohol recruits an extensive network that includes the ascending dopamine systems and their afferent connections, and that this network is largely shared with saccharin reward. The regions displaying persistent alterations after alcohol drinking could participate in brain networks underlying alcohol seeking and relapse.

Alcohol decreases baseline brain glucose metabolism more in heavy drinkers than controls but has no effect on stimulation-induced metabolic increases

During alcohol intoxication, the human brain increases metabolism of acetate and decreases metabolism of glucose as energy substrate. Here we hypothesized that chronic heavy drinking facilitates this energy substrate shift both for baseline and stimulation conditions. To test this hypothesis, we compared the effects of alcohol intoxication (0.75 g/kg alcohol vs placebo) on brain glucose metabolism during video stimulation (VS) versus when given with no stimulation (NS), in 25 heavy drinkers (HDs) and 23 healthy controls, each of whom underwent four PET-(18)FDG scans. We showed that resting whole-brain glucose metabolism (placebo-NS) was lower in HD than controls (13%, p = 0.04); that alcohol (compared with placebo) decreased metabolism more in HD (20 ± 13%) than controls (9 ± 11%, p = 0.005) and in proportion to daily alcohol consumption (r = 0.36, p = 0.01) but found that alcohol did not reduce the metabolic increases in visual cortex from VS in either group. Instead, VS reduced alcohol-induced decreases in whole-brain glucose metabolism (10 ± 12%) compared with NS in both groups (15 ± 13%, p = 0.04), consistent with stimulation-related glucose metabolism enhancement. These findings corroborate our hypothesis that heavy alcohol consumption facilitates use of alternative energy substrates (i.e., acetate) for resting activity during intoxication, which might persist through early sobriety, but indicate that glucose is still favored as energy substrate during brain stimulation. Our findings are consistent with reduced reliance on glucose as the main energy substrate for resting brain metabolism during intoxication (presumably shifting to acetate or other ketones) and a priming of this shift in HDs, which might make them vulnerable to energy deficits during withdrawal.

Translational clinical neuroscience perspectives on the cognitive and neurobiological mechanisms underlying alcohol-related aggression

Alcohol-related violence, a longstanding, serious, and pervasive social problem, has provided researchers from diverse disciplines with a model to study individual differences in aggressive and violent behavior. Of course, not all alcohol consumers will become aggressive after drinking and similarly, not all individuals with alcohol use disorders will exhibit such untoward behavior. Rather, the relationship is best conceptualized as complex and indirect and is influenced by a constellation of social, cognitive, and biological factors that differ greatly from one person to the next. Animal experiments and human studies have elucidated how these mechanisms and processes explain (i.e., mediate) the relation between acute and chronic alcohol consumption and aggressive behavior. Further, the rich body of literature on alcohol-related aggression has allowed for identification of several potential high-yield targets for clinical intervention, e.g., cognitive training for executive dysfunction; psychopharmacology targeting affect and threat perception, which may also generalize to other psychiatric conditions characterized by aggressive behavior. Here we aim to integrate pertinent findings, derived from different methodological approaches and theoretical models, which explain heterogeneity in aggressive responses to alcohol. A translational platform is provided, highlighting common factors linking alcohol and aggression that warrant further, interdisciplinary study in order to reduce the devastating social impact of this phenomenon.

Disinhibition of olfaction: human olfactory performance improves following low levels of alcohol

We hypothesize that true human olfactory abilities are obscured by cortical inhibition. Alcohol reduces inhibition. We therefore tested the hypothesis that olfactory abilities will improve following alcohol consumption. We measured olfaction in 85 subjects, 45 in a between-subjects design, and 40 in a repeated-measures within-subjects design before and after consumption of alcoholic or non-alcoholic beverages. Subjects were also assessed using neurocognitive measures of inhibition. Following alcohol consumption, blood alcohol levels ranged from 0.005% to 0.11%. Across subjects, before any consumption of alcohol, we found that individuals who were less inhibited had lower (better) olfactory detection thresholds (r=0.68, p<0.005). Moreover, after alcohol consumption, subjects with low alcohol levels could make olfactory discriminations that subjects with 0% alcohol could not make (chance=33%, alcohol=51.3±22.7%, control=34.7±31.6%, t(43)=2.03, p<0.05). Within subjects, we found correlations between levels of alcohol and olfactory detection (r=0.63, p<0.005) and discrimination (r=-0.50, p<0.05), such that performance was improved at low levels of alcohol (significantly better than baseline for detection) and deteriorated at higher levels of alcohol. Finally, levels of alcohol-induced improved olfactory discrimination were correlated with levels of alcohol-induced cognitive disinhibition (r=0.48, p<0.05). Although we cannot rule out alternative non-inhibitory alcohol-induced routes of influence, we conclude that improved olfaction at low levels of alcohol supports the notion of an inhibitory mechanism obscuring true olfactory abilities.

Positive Emotion Regulation and Psychopathology: A Transdiagnostic Cultural Neuroscience Approach

There is burgeoning interest in the study of positive emotion regulation and psychopathology. Given the significant public health costs and the tremendous variance in national prevalence rates associated with many disorders of positive emotion, it is critical to reach an understanding of how cultural factors, along with biological factors, mutually influence positive emotion regulation. Progress in this domain has been relatively unexplored, however, underscoring the need for an integrative review and empirical roadmap for investigating the cultural neuroscientific contributions to positive emotion disturbance for both affective and clinical science domains. The present paper thus provides a multidisciplinary, cultural neuroscience approach to better understand positive emotion regulation and psychopathology. We conclude with a future roadmap for researchers aimed at harnessing positive emotion and alleviating the burden of mental illness cross-culturally.

Low-Dose Alcohol Effects on Attention in Adolescents

Objective: Relatively little is known about the effects of low-dose alcohol effects on attentional performance in adolescents. In the present study, we examined these effects compared to those in adults. Method: 44 healthy subjects (21 adolescents and 23 adults) received either an alcoholic cocktail (average blood alcohol concentration: 0.054 %) or a placebo drink (randomized placebo-controlled). Before and after consuming the drink, participants completed tests on Alertness, Working Memory, Flexibility and Divided Attention. Results: Significant effects were found for the subtest Flexibility, which showed less improvement in the adolescents with alcohol compared to the non-alcohol condition and adults. Furthermore, an age-independent alcohol-induced impairment of the subtest Working Memory was observed. Conclusions: These findings point to a particular vulnerability for alcohol effects in adolescents regarding cognitive flexibility.

Acute alcohol intoxication decreases glucose metabolism but increases acetate uptake in the human brain

Alcohol intoxication results in marked reductions in brain glucose metabolism, which we hypothesized reflect not just its GABAergic enhancing effects but also the metabolism of acetate as an alternative brain energy source. To test this hypothesis we separately assessed the effects of alcohol intoxication on brain glucose and acetate metabolism using Positron Emission Tomography (PET). We found that alcohol intoxication significantly decreased whole brain glucose metabolism (measured with FDG) with the largest decrements in cerebellum and occipital cortex and the smallest in the thalamus. In contrast, alcohol intoxication caused a significant increase in [1-(11)C]acetate brain uptake (measured as standard uptake value, SUV), with the largest increases occurring in the cerebellum and the smallest in the thalamus. In heavy alcohol drinkers [1-(11)C]acetate brain uptake during alcohol challenge tended to be higher than in occasional drinkers (p<0.06) and the increases in [1-(11)C]acetate uptake in cerebellum with alcohol were positively associated with the reported amount of alcohol consumed (r=0.66, p<0.01). Our findings corroborate a reduction of brain glucose metabolism during intoxication and document an increase in brain acetate uptake. The opposite changes observed between regional brain metabolic decrements and regional increases in [1-(11)C]acetate uptake support the hypothesis that during alcohol intoxication the brain may rely on acetate as an alternative brain energy source and provides preliminary evidence that heavy alcohol exposures may facilitate the use of acetate as an energy substrate. These findings raise the question of the potential therapeutic benefits that increasing plasma acetate concentration (i.e. ketogenic diets) may have in alcoholics undergoing alcohol detoxification.

Alcohol consumption induces endogenous opioid release in the human orbitofrontal cortex and nucleus accumbens

Excessive consumption of alcohol is among the leading causes of preventable death worldwide. Although ethanol modulates a variety of molecular targets, including several neurotransmitter receptors, the neural mechanisms that underlie its rewarding actions and lead to excessive consumption are unknown. Studies in animals suggest that release of endogenous opioids by ethanol promotes further consumption. To examine this issue in humans and to determine where in the brain endogenous opioids act to promote alcohol consumption, we measured displacement of a radiolabeled μ opioid receptor agonist, [¹¹C]carfentanil, before and immediately after alcohol consumption in both heavy drinkers and control subjects. Drinking alcohol induced opioid release in the nucleus accumbens and orbitofrontal cortex, areas of the brain implicated in reward valuation. Opioid release in the orbitofrontal cortex and nucleus accumbens was significantly positively correlated. Furthermore, changes in orbitofrontal cortex binding correlated significantly with problem alcohol use and subjective high in heavy drinkers, suggesting that differences in endogenous opioid function in these regions contribute to excessive alcohol consumption. These results also suggest a possible mechanism by which opioid antagonists such as naltrexone act to treat alcohol abuse.

Cognitive and neurobiological mechanisms of alcohol-related aggression

Alcohol-related violence is a serious and common social problem. Moreover, violent behaviour is much more common in alcohol-dependent individuals. Animal experiments and human studies have provided insights into the acute effect of alcohol on aggressive behaviour and into common factors underlying acute and chronic alcohol intake and aggression. These studies have shown that environmental factors, such as early-life stress, interact with genetic variations in serotonin-related genes that affect serotonergic and GABAergic neurotransmission. This leads to increased amygdala activity and impaired prefrontal function that, together, predispose to both increased alcohol intake and impulsive aggression. In addition, acute and chronic alcohol intake can further impair executive control and thereby facilitate aggressive behaviour.

Effects of morphine and alcohol on functional brain connectivity during "resting state": a placebo-controlled crossover study in healthy young men

A major challenge in central nervous system (CNS) drug research is to develop a generally applicable methodology for repeated measurements of drug effects on the entire CNS, without task-related interactions and a priori models. For this reason, data-driven resting-state fMRI methods are promising for pharmacological research. This study aimed to investigate whether different psychoactive substances cause drug-specific effects in functional brain connectivity during resting-state. In this double blind placebo-controlled (double dummy) crossover study, seven resting-state fMRI scans were obtained in 12 healthy young men in three different drug sessions (placebo, morphine and alcohol; randomized). Drugs were administered intravenously based on validated pharmacokinetic protocols to minimize the inter- and intra-subject variance in plasma drug concentrations. Dual-regression was used to estimate whole-brain resting-state connectivity in relation to eight well-characterized resting-state networks, for each data set. A mixed effects analysis of drug by time interactions revealed dissociable changes in both pharmacodynamics and functional connectivity resulting from alcohol and morphine. Post hoc analysis of regions of interest revealed adaptive network interactions in relation to pharmacokinetic and pharmacodynamic curves. Our results illustrate the applicability of resting-state functional brain connectivity in CNS drug research.

The effect of aripiprazole on cue-induced brain activation and drinking parameters in alcoholics

Because the effects of alcohol and its environmental cues on brain dopamine have been implicated in the maintenance of heavy drinking, drugs that modify dopamine might be useful in reducing drinking or promoting abstinence. The goal of the current study was to use an established brain imaging paradigm to explore the effect of aripiprazole (final dose 15 mg over a 14-day period), a dopamine stabilizer medication, on alcohol cue-induced brain activation and drinking in alcoholics. Non-treatment-seeking alcoholics were randomly assigned aripiprazole (n = 14) or identical placebo (n = 16) and reported their alcohol use while taking study medication for 14 days before an alcohol cue-induced brain functional magnetic resonance imaging study. In a Philips 3.0-T magnetic resonance imaging scanner, subjects were given a sip of alcohol before viewing a randomized presentation alcoholic- and nonalcoholic-beverage photographs while subjects rated their urge to drink. During photograph presentation, changes in regional brain activity were measured, and differences between viewing alcoholic beverage and nonalcoholic beverages were compared within and between groups. Brain activity analysis revealed increased activation for placebo-treated subjects in the right ventral striatum (P < 0.005; threshold 15 voxels), while there was a blunting of activation in this area in the aripiprazole-treated subjects. Aripiprazole-treated subjects, compared with placebo-treated subjects, also had significantly less heavy drinking during the 14-day medication period. The study provides both novel and valuable information regarding the effect of aripiprazole on cue-induced brain activation and voluntary drinking during treatment.

Acute alcohol impairs conditioning of a behavioural reward-seeking response and inhibitory control processes--implications for addictive disorders

AIMS

To investigate whether acute alcohol would affect performance of a conditioned behavioural response to obtain a reward outcome and impair performance in a task measuring inhibitory control to provide new knowledge of how the acute effects of alcohol might contribute to the transition from alcohol use to dependence.

DESIGN

A randomized controlled between-subjects design was employed.

SETTINGS

The laboratory of experimental psychology at the University of Sussex.

PARTICIPANTS

Thirty-two light to moderate social drinkers recruited from the undergraduate and postgraduate population.

MEASUREMENTS

After the administration of alcohol (0.8 g/kg) or placebo participants underwent an instrumental reward-seeking procedure, with abstract stimuli serving as S+ (always predicting a win of 10 pence) and S- (always predicting a loss of 10 pence). In addition, a Stop Signal task was administered before and after the administration of alcohol.

FINDINGS

Participants of the alcohol group performed the behavioural response to obtain the reward outcome more often than placebo subjects in trials associated with loss of money. This finding was observed, although alcohol was not affecting explicit knowledge of stimulus-response outcome contingencies and acquisition of conditioned attentional and emotional responses. In addition, alcohol increased Stop Signal reaction time indicating disinhibiting effects of alcohol, and this was associated positively with response probability to the S-.

CONCLUSIONS

These results demonstrate that alcohol is affecting inhibitory control of behavioural responses to external signals even when associated with punishment, contributing in this way to the transition from alcohol use to dependence.

The hippocampus and cingulate cortex differentially mediate the effects of nicotine on learning versus on ethanol-induced learning deficits through different effects at nicotinic receptors

The current study examined the effects of nicotine infusion into the dorsal hippocampus or anterior cingulate on fear conditioning and on ethanol-induced deficits in fear conditioning, and whether these effects involved receptor activation or inactivation. Conditioning consisted of two white noise (30 s, 85 dB)-foot-shock (2 s, 0.57 mA) pairings. Saline or ethanol was administered to C57BL/6 mice 15 min before training and saline or nicotine was administered 5 min before training or before training and testing. The ability of the high-affinity nicotinic acetylcholinergic receptor (nAChR) antagonist dihydro-beta-erythroidine (DHbetaE) to modulate the effects of ethanol and nicotine was also tested; saline or DHbetaE was administered 25 (injection) or 15 (infusion) minutes before training or before training and testing. Infusion of nicotine into the hippocampus enhanced contextual fear conditioning but had no effect on ethanol-induced learning deficits. Infusion of nicotine into the anterior cingulate ameliorated ethanol-induced deficits in contextual and cued fear conditioning but had no effect on learning in ethanol-naive mice. DHbetaE blocked the effects of nicotine on ethanol-induced deficits; interestingly, DHbetaE alone and co-administration of subthreshold doses of DHbetaE and nicotine also ameliorated ethanol-induced deficits but failed to enhance learning. Finally, DHbetaE failed to ameliorate ethanol-induced deficits in beta2 nAChR subunit knockout mice. These results suggest that nicotine acts in the hippocampus to enhance contextual learning, but acts in the cingulate to ameliorate ethanol-induced learning deficits through inactivation of high-affinity beta2 subunit-containing nAChRs.

A new behavioral test for assessment of drug effects on attentional performance and its validity in cynomolgus monkeys

The assessment of drug effects on attention is important in non-clinical pharmacology, for both evaluation of safety and therapeutic efficacy of medicinal products. In the present study, we have developed a two-lever choice behavioral test to assess drug effects on attentional performance in monkeys. In each trial of this experiment, one of two lamps in front of a monkey was randomly illuminated for a brief period of time and the monkey was required to press a lever beneath the lamp 30 times to obtain a food reward. The percentage of correct responses, response latency of correct choice responses and response speed were measured. Using this test, we examined the effects of three sedative drugs, diazepam (0.25, 1 and 4 mg/kg, i.g.), ethanol (0.5, 1 and 2 g/kg, i.g.), and pentobarbital (0.25, 1 and 4 mg/kg, i.v.). Diazepam and pentobarbital lengthened response latency without significantly affecting the percentage of correct responses, response and response speed, suggesting selective disruptive effects on attentional performance. In contrast, ethanol at the high dose tested caused deterioration in all three measurements, which is thought to reflect a general sedative effect including motor impairment as reflected by lengthening response speed. It is suggested that the present behavioral test method could detect drug effects on attentional performance in monkeys and could be a useful tool for safety assessment in drug development.

Effects of alcohol on performance on a distraction task during simulated driving

BACKGROUND

Prior studies report that accidents involving intoxicated drivers are more likely to occur during performance of secondary tasks. We studied this phenomenon, using a dual-task paradigm, involving performance of a visual oddball (VO) task while driving in an alcohol challenge paradigm. Previous functional MRI (fMRI) studies of the VO task have shown activation in the anterior cingulate, hippocampus, and prefrontal cortex. Thus, we predicted dose-dependent decreases in activation of these areas during VO performance.

METHODS

Forty healthy social drinkers were administered 3 different doses of alcohol, individually tailored to their gender and weight. Participants performed a VO task while operating a virtual reality driving simulator in a 3T fMRI scanner.

RESULTS

Analysis showed a dose-dependent linear decrease in Blood Oxygen Level Dependent activation during task performance, primarily in hippocampus, anterior cingulate, and dorsolateral prefrontal areas, with the least activation occurring during the high dose. Behavioral analysis showed a dose-dependent linear increase in reaction time, with no effects associated with either correct hits or false alarms. In all dose conditions, driving speed decreased significantly after a VO stimulus. However, at the high dose this decrease was significantly less. Passenger-side line crossings significantly increased at the high dose.

CONCLUSIONS

These results suggest that driving impairment during secondary task performance may be associated with alcohol-related effects on the above brain regions, which are involved with attentional processing/decision-making. Drivers with high blood alcohol concentrations may be less able to orient or detect novel or sudden stimuli during driving.

Pharmacological treatment of schizophrenia and co-occurring substance use disorders

Substance abuse among individuals with schizophrenia is common and is often associated with poor clinical outcomes. Comprehensive, integrated pharmacological and psychosocial treatments have been shown to improve these outcomes. While a growing number of studies suggest that second-generation antipsychotic medications may have beneficial effects on the treatment of co-occurring substance use disorders, this review suggests that the literature is still in its infancy. Few existing well controlled trials support greater efficacy of second-generation antipsychotics compared with first-generation antipsychotics or any particular second-generation antipsychotic. This article focuses on and reviews studies involving US FDA-approved medications for co-occurring substance abuse problems among individuals with schizophrenia.Comprehensive treatment for individuals with schizophrenia and co-occurring substance use disorders must include specialized, integrated psychosocial intervention. Most approaches use some combination of cognitive-behavioural therapy, motivational enhancement therapy and assertive case management. The research on antipsychotic and other pharmacological treatments is also reviewed, as well as psychosocial treatments for individuals with schizophrenia and co-occurring substance use disorders, and clinical recommendations to optimize care for this population are offered.

Effects of acute alcohol consumption on ratings of attractiveness of facial stimuli: evidence of long-term encoding

AIM

A strongly held popular belief is that alcohol increases the perceived attractiveness of members of the opposite sex. Despite this, there are no experimental data that investigate this possibility. We therefore explored the relationship between acute alcohol consumption and ratings of attractiveness of facial stimuli.

METHODS

We investigated male and female participants (n=84), using male and female facial stimuli, in order to investigate possible sex differences, and whether any effects of alcohol are selective for opposite-sex facial stimuli. We tested participants immediately following consumption of alcohol or placebo and one day later, in order to investigate whether any effects of alcohol persist beyond acute effects.

RESULTS

Attractiveness ratings were higher in the alcohol compared to the placebo group (F[1, 80]=4.35, P=0.040), but there was no evidence that this differed between males and females or was selective for opposite-sex faces. We did not observe marked effects of alcohol on self-reported measures of mood, suggesting that the effects on ratings of attractiveness were not due simply to global hedonic effects or reporting biases.

CONCLUSIONS

Alcohol consumption increases ratings of attractiveness of facial stimuli, and this effect is not selective for opposite-sex faces. In addition, the effects of alcohol consumption on ratings of attractiveness persist for up to 24 h after consumption, but only in male participants when rating female (i.e. opposite-sex) faces.

Why we like to drink: a functional magnetic resonance imaging study of the rewarding and anxiolytic effects of alcohol

People typically drink alcohol to induce euphoria or reduce anxiety, and they frequently drink in social settings, yet the effect of alcohol on human brain circuits involved in reward and emotion has been explored only sparingly. We administered alcohol intravenously to social drinkers while brain response to visual threatening and nonthreatening facial stimuli was measured using functional magnetic resonance imaging (fMRI). Alcohol robustly activated striatal reward circuits while attenuating response to fearful stimuli in visual and limbic regions. Self-ratings of intoxication correlated with striatal activation, suggesting that activation in this area may contribute to subjective experience of pleasure and reward during intoxication. These results show that the acute pharmacological rewarding and anxiolytic effects of alcohol can be measured with fMRI.

Short-term exposure to alcohol in rats affects brain levels of anandamide, other N-acylethanolamines and 2-arachidonoyl-glycerol

Chronic alcohol exposure leads to significant changes in the levels of endocannabinoids and their receptors in the brains of humans and laboratory animals, as well as in cultured neuronal cells. However, little is known about the effects of short-term periods of alcohol exposure. In the present study, we examined the changes in endocannabinoid levels (anandamide and 2-arachidonoylglycerol), as well as four additional N-acylethanolamines, in four brain regions of rats exposed to alcohol through the liquid diet for a period of 24h. The levels of N-acylethanolamines were diminished 24h after the onset of alcohol exposure. This was particularly evident for anandamide in the hypothalamus, amygdala and caudate-putamen, for N-palmitoylethanolamine in the caudate-putamen, for N-oleoylethanolamine in the hypothalamus, caudate-putamen and prefrontal cortex, and for N-stearoylethanolamine in the amygdala. The only exception was N-linoleoylethanolamine for which the levels increased in the amygdala after the exposure to alcohol. The levels of the other major endocannabinoid, 2-arachidonoylglycerol, were also reduced with marked effects in the prefrontal cortex. These results support the notion that short-term alcohol exposure reduces endocannabinoid levels in the brain accompanied by a reduction in several related N-acylethanolamines.

Tiagabine does not attenuate alcohol-induced activation of the human reward system

RATIONALE

The rewarding effects of ethanol and other drugs of abuse are mediated by activation of the mesolimbic dopamine system. Recent neuroimaging studies in primates and humans suggest that cocaine-induced dopamine stimulation might be diminished by drugs augmenting gamma-aminobutyric acid A (GABA-A) receptor function such as the GABA transaminase inhibitor vigabatrin.

OBJECTIVES

The objective of this study was to test the property of the selective GABA transporter 1 (GAT1) inhibitor tiagabine to block ethanol-induced activation of the mesolimbic reward system in an i.v. ethanol challenge.

MATERIALS AND METHODS

Twenty nonaddicted healthy volunteers underwent an i.v. ethanol challenge after 1 week of tiagabine (15 mg/day) administration. Neuronal activation was measured using [(18)F]-fluoro-deoxyglucose positron emission tomography (PET).

RESULTS

Tiagabine did not prevent ethanol-induced stimulation of the mesolimbic reward system but augmented ethanol-induced hypometabolism within areas of the visual system and the cerebellum. Tiagabine alone also decreased neuronal metabolism within parts of the right temporal cortex that are highly enriched with GABA-ergic neurons.

CONCLUSIONS

Our ethanol challenge imaging study does not provide supporting evidence that the GAT1 inhibitor tiagabine diminishes the rewarding effects of ethanol. Further PET imaging studies using established anticraving compounds, such as the mu-opioid receptor antagonist naltrexone and antiepileptic drugs affecting the GABA-ergic system more broadly, will provide additional important insights on the interaction between the GABA-ergic and the brain reward system in vivo and the suitability of GABA-ergic drugs as anticraving compounds.

Acute effects of alcohol on neural correlates of episodic memory encoding

Although it is well established that alcohol impairs episodic memory encoding, it is unknown how this occurs on a cerebral level. We scanned intoxicated and sober individuals with functional magnetic resonance imaging (fMRI) while they encoded various materials that were recalled the following day. Alcohol impaired memory for object pairs and face-name pairs, but not for words and phrase-word pairs. Impaired performance was associated with reduced bilateral prefrontal activation and non-specific activation of the parahippocampal gyrus. These results suggest that alcohol impairs episodic memory by interfering with activity of regions involved in encoding, and further indicate which regions are critical for human memory.

Neuropsychological profile of acute alcohol intoxication during ascending and descending blood alcohol concentrations

Numerous studies have investigated the effects of alcohol on motor processes during rising and declining blood alcohol concentrations (BAC), however, relatively little research has examined the alcohol-induced impairment of cognitive performance on the two limbs of the BAC curve. This experiment administered a neuropsychological test battery to assess the degree to which rising and declining BACs during an acute dose of alcohol impair nine cognitive processes within an individual. In all, 20 healthy male social drinkers (university students) were assigned to one of two groups (n = 10) who received a beverage containing either 0.0 g/kg (placebo) or 0.65 g/kg alcohol and performed the test battery when BAC was increasing and was decreasing. Comparisons of alcohol and placebo groups revealed impairment (slower response and/or increased errors) in seven of the cognitive processes: long-term verbal memory; information processing; declarative memory; inhibitory control; short-term visual memory; long-term visual memory, and visual-spatial working memory. However, some processes were impaired only during rising BACs whereas the impairment of others during declining BACs was evident only by an increase in errors. These results show cognitive tasks performed by an individual are not similarly affected by rising and declining BACs, and call attention to the importance of assessing both speed and accuracy on both limbs of the BAC curve. The particular cognitive processes differentially affected by rising vs declining BACs raised the possibility that acute alcohol intoxication may impair one cerebral hemisphere to a greater degree than the other, and this could be explored by neuroimaging techniques.

Imaging alcohol cue exposure in alcohol dependence using a PET 15O-H2O paradigm: results from a pilot study

Craving is a commonly used term to describe an intense desire for a substance or behaviour; however, its underlying neurobiology is not fully characterized. We have successfully used a cue exposure paradigm with functional neuro-imaging (H2 15O PET; PET, positron emission tomography) in abstinent opiate addicts. This study showed that salient cue exposure results in activation in the left anterior cingulate/mediofrontal cortex and elicited craving correlated with activity in the left orbitofrontal cortex. We therefore aimed to replicate this study in alcohol dependence to see if a similar pattern of neural activation occurred. We recruited six abstinent alcohol-dependent and six non-dependent subjects who each underwent a 12-run PET scan using H2 15O to measure changes in regional blood flow during exposure to an alcoholic drink or its visually matched non-alcoholic drink. Physiological data and subjective ratings were also recorded. Statistical parametric mapping (SPM99) was used to analyse the PET images. Compared with control subjects, abstinent alcohol-dependent subjects rated their alcohol craving higher at baseline and throughout the study, but there was no significant change in the scores in response to the cues in either group. SPM analysis across all subjects showed significant activation in the occipital cortex in response to the alcohol cue as compared with the neutral one. Analysis of the same regions that were activated in the opiate study, revealed significant increases in signal activation in the left medial prefrontal area, but only in abstinent alcohol-dependent subjects. In conclusion, in abstinent alcohol dependence we suggest that a simple cue exposure paradigm is not sufficiently powerful in functional imaging studies to determine the underlying neurobiology of subjective craving. Comparisons with the finding in opiate dependence suggest a shared region, the anterior cingulate/left medial prefrontal cortex is involved in the cue response in dependent subjects but not controls.

Low doses of alcohol substantially decrease glucose metabolism in the human brain

Moderate doses of alcohol decrease glucose metabolism in the human brain, which has been interpreted to reflect alcohol-induced decreases in brain activity. Here, we measure the effects of two relatively low doses of alcohol (0.25 g/kg and 0.5 g/kg, or 5 to 10 mM in total body H2O) on glucose metabolism in the human brain. Twenty healthy control subjects were tested using positron emission tomography (PET) and FDG after placebo and after acute oral administration of either 0.25 g/kg, or 0.5 g/kg of alcohol, administered over 40 min. Both doses of alcohol significantly decreased whole-brain glucose metabolism (10% and 23% respectively). The responses differed between doses; whereas the 0.25 g/kg dose predominantly reduced metabolism in cortical regions, the 0.5 g/kg dose reduced metabolism in cortical as well as subcortical regions (i.e. cerebellum, mesencephalon, basal ganglia and thalamus). These doses of alcohol did not significantly change the scores in cognitive performance, which contrasts with our previous results showing that a 13% reduction in brain metabolism by lorazepam was associated with significant impairment in performance on the same battery of cognitive tests. This seemingly paradoxical finding raises the possibility that the large brain metabolic decrements during alcohol intoxication could reflect a shift in the substrate for energy utilization, particularly in light of new evidence that blood-borne acetate, which is markedly increased during intoxication, is a substrate for energy production by the brain.

Alcohol consumption impairs stimulus- and error-related processing during a Go/No-Go Task

Alcohol consumption has been shown to increase the number of errors in tasks that require a high degree of cognitive control, such as a go/no-go task. The alcohol-related decline in performance may be related to difficulties in maintaining attention on the task at hand and/or deficits in inhibiting a prepotent response. To test these two accounts, we investigated the effects of alcohol on stimulus- and response-locked evoked potentials recorded during a go/no-go task that involved the withholding of key presses to rare targets. All participants performed the task prior to drinking and were then assigned randomly to either a control, low-dose, or moderate-dose treatment. Both doses of alcohol increased the number of errors relative to alcohol-free performance. Success in withholding a prepotent response was associated with an early-enhanced stimulus-locked negativity at inferior parietal sites, which was delayed when participants failed to inhibit the motor command. Moreover, low and moderate doses of alcohol reduced N170 and P3 amplitudes during go, no-go, and error trials. In comparison with the correct responses, errors generated large response-locked negative (Ne) and positive (Pe) waves at central sites. Both doses of alcohol reduced the Ne amplitude whereas the Pe amplitude decreased only after moderate doses of alcohol. These results are consistent with the interpretation that behavioral disinhibition following alcohol consumption involved alcohol-induced deficits in maintaining and allocating attention thereby affecting the processing of incoming stimuli and the recognition that an errant response has been made.

Memory encoding and retrieval on the ascending and descending limbs of the blood alcohol concentration curve

RATIONALE

Little is known about acute effects of alcohol on memory encoding and retrieval on different limbs (ascending and descending) of the blood alcohol concentration (BAC) curve.

OBJECTIVES

This extensive experiment was designed to examine alcohol's effects on memory encoding and retrieval throughout a protracted drinking episode.

METHODS

In a 9-h session, male participants consumed either alcohol (1 ml/kg) or placebo (n = 32/32) over a period of 90 min and learned various materials in different memory tasks before, during, and after consuming the drinks, while their BAC levels were monitored. A week later, in a similar session, they were tested on learned materials before, during, and after drinking. Mood was assessed throughout both sessions.

RESULTS

Alcohol impaired recall of words more than recognition, and cued recall most severely. Perceptual priming and picture recognition were not affected by alcohol. Alcohol impaired encoding in cued recall, recognition of completed word fragments, and free recall regardless of limb, but impaired retrieval in word recognition only during the ascending BAC. Alcohol increased negative mood on the descending limb during the first session, and on the ascending limb during the second session.

CONCLUSIONS

Under naturalistic drinking conditions, alcohol's effects on memory depend on task, memory process, and limb of the BAC curve. The differential effects of alcohol on retrieval during the ascending and descending limbs demonstrate the importance of examining the differential effects on the two limbs.

Treatment of substance use disorders in schizophrenia: a unifying neurobiological mechanism?

Substance use disorders (SUDs) are highly prevalent and are associated with poor outcomes among individuals with schizophrenia. Integrating treatments for both disorders improves outcomes. Numerous individual pharmacologic and psychosocial treatments have shown effectiveness at reducing substance use in individuals with a primary diagnosis of schizophrenia and co-occurring substance use disorders. Of these treatments, medications such as certain atypical antipsychotics and naltrexone, and psychosocial treatments such as contingency management, seem to be particularly promising. The development and evaluation of psychopharmacologic and psychosocial treatments for SUDs in schizophrenia would benefit from a better understanding of the neurobiological mechanisms underlying the effectiveness of such treatments. Several theories have been put forth to explain the heightened risk for SUDs in schizophrenia. Of these, brain reward circuitry dysfunction, hypothesized to be etiologically important in SUDs, may be an especially salient target for treatments aimed at the reduction of substance use in patients with schizophrenia. We review current pharmacologic and psychosocial treatments for SUDs in schizophrenia, and theoretical mechanisms underlying the increased risk for SUDs in this population. We propose that effective treatments may in part work through the modulation of brain reward circuitry dysfunction.