Alcohol effects on cerebral blood flow in subjects with low and high responses to alcohol

Neutral sphingomyelinase controls acute and chronic alcohol effects on brain activity

Alcohol consumption is a widespread phenomenon throughout the world. However, how recreational alcohol use evolves into alcohol use disorder (AUD) remains poorly understood. The Smpd3 gene and its coded protein neutral sphingomyelinase (NSM) are associated with alcohol consumption in humans and alcohol-related behaviors in mice, suggesting a potential role in this transition. Using multiparametric magnetic resonance imaging, we characterized the role of NSM in acute and chronic effects of alcohol on brain anatomy and function in female mice. Chronic voluntary alcohol consumption (16 vol% for at least 6 days) affected brain anatomy in WT mice, reducing regional structure volume predominantly in cortical regions. Attenuated NSM activity prevented these anatomical changes. Functional MRI linked these anatomical adaptations to functional changes: Chronic alcohol consumption in mice significantly modulated resting state functional connectivity (RS FC) in response to an acute ethanol challenge (i.p. bolus of 2 g kg-1) in heterozygous NSM knockout (Fro), but not in WT mice. Acute ethanol administration in alcohol-naïve WT mice significantly decreased RS FC in cortical and brainstem regions, a key finding that was amplified in Fro mice. Regarding direct pharmacological effects, acute ethanol administration increased the regional cerebral blood volume (rCBV) in many brain areas. Here, chronic alcohol consumption otherwise attenuated the acute rCBV response in WT mice but enhanced it in Fro mice. Altogether, these findings suggest a differential role for NSM in acute and chronic functional brain responses to alcohol. Therefore, targeting NSM may be useful in the prevention or treatment of AUD.

Transcranial Doppler Ultrasound and Concussion-Supplemental Symptoms with Physiology: A Systematic Review

Sport-related concussion (SRC) can impair the cerebrovasculature both acutely and chronically. Transcranial Doppler (TCD) ultrasound assessment has the potential to illuminate the mechanisms of impairment and provide an objective evaluation of SRC. The current systematic review investigated studies employing TCD ultrasound assessment of intracranial arteries across three broad categories of cerebrovascular regulation: neurovascular coupling (NVC), cerebrovascular reactivity (CVR), and dynamic cerebral autoregulation (dCA). The current review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42021275627). The search strategy was applied to PubMed, as this database indexes all biomedical journals. Original articles on TCD for athletes with medically diagnosed SRC were included. Title/abstract and full-text screening were completed by three authors. Two authors completed data extraction and risk of bias using the Methodological Index for Non-Randomized Studies and Scottish Intercollegiate Guideline Network checklists. Of the 141 articles identified, 14 met the eligibility criteria. One article used an NVC challenge, eight assessed CVR, and six investigated dCA. Methodologies varied widely among studies, and results were heterogeneous. There was evidence of cerebrovascular impairment in all three domains roughly 2 days post-SRC, but the magnitude and recovery of these impairments were not clear. There was evidence that clinical symptom resolution occurred before cerebrovascular function, indicating that physiological deficits may persist despite clinical recovery and return to play. Collectively, this emphasizes an opportunity for the use of TCD to illuminate the cerebrovascular deficits caused by SRC. It also highlights that there is need for consistent methodological rigor when employing TCD in a SRC population.

Alcohol degradation, learning, and memory-enhancing effect of Acetobacter pasteurianus BP2201 in Caenorhabditis elegans model

AIMS

This study aimed to investigate the probiotic effects of Acetobacter pasteurianus BP2201, isolated from brewing mass, for the treatment of alcohol-induced learning and memory ability impairments in a Caenorhabditis elegans model.

METHODS AND RESULTS

Acetobacter pasteurianus BP2201 was examined for probiotic properties, including acid and bile salt resistance, ethanol degradation, antioxidant efficacy, hemolytic activity, and susceptibility to antibiotics. The strain displayed robust acid and bile salt tolerance, efficient ethanol degradation, potent antioxidant activity, and susceptibility to specific antibiotics. Additionally, in the C. elegans model, administering A. pasteurianus BP2201 significantly improved alcohol-induced learning and memory impairments.

CONCLUSIONS

Acetobacter pasteurianus BP2201 proves to be a promising candidate strain for the treatment of learning and memory impairments induced by alcohol intake.

Blunted neural reward response to alcohol and greater alcohol motivation in binge drinkers in a randomized clinical experiment

BACKGROUND

Alcohol stimulates cerebral blood flow (CBF) in brain reward regions. However, neural processes that support sustained alcohol motivation after the first drink are not well understood.

METHODS

Using a novel placebo-controlled, randomized, crossover experiment, 27 individuals who binge drink (BD; 15 M, 12 F) and 25 social drinkers (SD; 15 M, 10 F) underwent a behavioral test of self-motivated alcohol consumption using an Alcohol Taste Test (ATT) involving alcoholic and nonalcoholic beer on separate days. The test was followed immediately by perfusion functional magnetic resonance imaging (fMRI). On both days, participants then engaged in a post-scan ATT with placebo beer to assess sustained alcohol self-motivation without active alcohol effects. Linear mixed effects models were used to examine the effects of drinking group on the placebo-controlled effect of initial alcohol motivation on brain perfusion (whole brain corrected p < 0.001, cluster corrected p < 0.025) and on the relationship between placebo-controlled brain perfusion and sustained alcohol motivation.

RESULTS

Initial alcohol self-motivation in the alcohol relative to placebo session led to markedly decreased activation in the medial orbitofrontal cortex (OFC) and the ventral striatum in BD relative to SD, indicative of neural reward tolerance. The BD group also showed an enhanced neural response in behavioral intention regions of the supplementary motor area (SMA) and inferior frontal gyrus (IFG) regions. Moreover, there was greater sustained alcohol motivation in BD than SD in the post-scan ATT in the alcohol relative to placebo session. Correspondingly, only in BD and only in the alcohol session, lower alcohol-induced OFC response correlated with concurrent sensitized SMA response, and each predicted the subsequent sustained higher alcohol motivation in the post-scan ATT.

CONCLUSIONS

Alcohol-related OFC tolerance may play an important role in sustained alcohol motivation. Furthermore, both specific alcohol-related neural reward tolerance and premotor sensitization responses may contribute to escalating alcohol motivation to drive excessive alcohol intake, even in individuals without alcohol use disorder.

Molecular Toxicology and Pathophysiology of Comorbid Alcohol Use Disorder and Post-Traumatic Stress Disorder Associated with Traumatic Brain Injury

The increasing comorbidity of alcohol use disorder (AUD) and post-traumatic stress disorder (PTSD) associated with traumatic brain injury (TBI) is a serious medical, economic, and social issue. However, the molecular toxicology and pathophysiological mechanisms of comorbid AUD and PTSD are not well understood and the identification of the comorbidity state markers is significantly challenging. This review summarizes the main characteristics of comorbidity between AUD and PTSD (AUD/PTSD) and highlights the significance of a comprehensive understanding of the molecular toxicology and pathophysiological mechanisms of AUD/PTSD, particularly following TBI, with a focus on the role of metabolomics, inflammation, neuroendocrine, signal transduction pathways, and genetic regulation. Instead of a separate disease state, a comprehensive examination of comorbid AUD and PTSD is emphasized by considering additive and synergistic interactions between the two diseases. Finally, we propose several hypotheses of molecular mechanisms for AUD/PTSD and discuss potential future research directions that may provide new insights and translational application opportunities.

Subjective response to alcohol in young adults with bipolar disorder and recent alcohol use: a within-subject randomized placebo-controlled alcohol administration study

Limited data exists on mechanisms contributing to elevated risk for alcohol use disorder (AUD) in bipolar disorder. Variation in subjective response to alcohol may relate to alcohol use and risk for AUD. This study used a randomized, placebo-controlled, cross-over, within-subjects design to investigate differences in subjective response to alcohol in 50 euthymic young adults (n = 24 with and n = 26 without bipolar disorder type I). Eighty-three percent of participants with bipolar disorder were medicated. Participants completed assessments of clinical history, alcohol expectancies, and recent alcohol use. Participants were dosed to a .08 g% breath alcohol concentration. The placebo condition occurred on a separate counter-balanced day. Subjective response to alcohol was investigated at similar time points during both conditions. Group, condition, and group-by-condition interactions were modeled, with condition and time of subjective response assessment as repeated within-subject variables, and subjective response to alcohol as the dependent variable. Greater stimulating effects and liking of alcohol were reported in people with bipolar disorder (group-by-condition interactions, p < .05) than healthy young adults. While young adults with bipolar disorder reported anticipating feeling less "mellow/relaxed" when drinking (p = .02), during both beverage conditions they reported feeling more "mellow/relaxed" (main effect of group, p = .006). Feeling more "mellow/relaxed" during the alcohol condition related to greater recent alcohol use in bipolar disorder (p = .001). Exploratory analyses suggested anticonvulsants and sedatives/antihistamines may relate to differences in subjective response to alcohol in bipolar disorder. Results suggest young adults with bipolar disorder may differ in alcohol expectancies and experience alcohol intoxication differently-with distinct relations between subjective response to alcohol and alcohol use-compared to healthy young adults.

Patterns of functional connectivity alterations induced by alcohol reflect somatostatin interneuron expression in the human cerebral cortex

Acute alcohol administration affects functional connectivity, yet the underlying mechanism is unknown. Previous work suggested that a moderate dose of alcohol reduces the activity of gamma-aminobutyric acidergic (GABAergic) interneurons, thereby leading to a state of pyramidal disinhibition and hyperexcitability. The present study aims to relate alcohol-induced changes in functional connectivity to regional genetic markers of GABAergic interneurons. Healthy young adults (N = 15, 5 males) underwent resting state functional MRI scanning prior to alcohol administration, immediately and 90 min after alcohol administration. Functional connectivity density mapping was performed to quantify alcohol-induced changes in resting brain activity between conditions. Patterns of differences between conditions were related to regional genetic markers that express the primary GABAergic cortical interneuron subtypes (parvalbumin, somatostatin, and 5-hydroxytryptamine receptor 3A) obtained from the Allen Human Brain Atlas. Acute alcohol administration increased local functional connectivity density within the visual cortex, sensorimotor cortex, thalamus, striatum, and cerebellum. Patterns of alcohol-induced changes in local functional connectivity density inversely correlated with somatostatin cortical gene expression. These findings suggest that somatostatin-expressing interneurons modulate alcohol-induced changes in functional connectivity in healthy individuals.

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.

Impact of binge drinking during college on resting state functional connectivity

AIM

The current study examined the longitudinal effects of standard binge drinking (4+/5+ drinks for females/males in 2 hours) and extreme binge drinking (8+/10+ drinks for females/males in 2 hours) on resting-state functional connectivity.

METHOD

119 college students (61 males) were recruited in groups of distinct bingeing patterns at baseline: non-bingeing controls, standard and extreme bingers. Resting-state scans were first obtained when participants were freshmen/sophomores and again approximately two years later. Associations between longitudinal bingeing (reported during this two-year gap) and network connectivity were examined. Network connectivity was calculated by aggregating all edges affiliated with the same network (an edge is a functional connection between two brain regions). The relationship between longitudinal bingeing and connectivity edges was also studied using connectome-based predictive modeling (CPM).

RESULTS

Greater standard bingeing was negatively associated with change in connectivity between Default Mode Network and Ventral Attention Network (DMN-VAN; False Discovery Rate corrected), controlling for initial binge groups, longitudinal network changes, motions, scanner, SES, sex, and age. The correlations between change in DMN-VAN connectivity and change in cognitive performance (Stroop, Digit Span, Letter Fluency, and Trail Making) were also tested, but the results were not significant. Lastly, CPM failed to identify a generalizable predictive model of longitudinal bingeing from change in connectivity edges.

CONCLUSIONS

Binge drinking is associated with abnormality in networks implicated in attention and self-focused processes, which, in turn, have been implicated in rumination, craving, and relapse. More extensive alterations in functional connectivity might be observed with heavier or longer binge drinking pattern.

MRI Analysis Of the Water Content Change In the Brain During Acute Ethanol Consumption Via Quantitative Water Mapping

AIMS

Alcohol consumption influences the water balance in the brain. While the impact of chronic alcohol misuse on cerebral water content has been the subject of several studies, less is known about the effects of acute alcohol misuse, with contradictory results in the literature. Therefore, we investigated the effects of acute alcohol intoxication on cerebral water content using a precise quantitative magnetic resonance imaging (MRI) sequence.

METHODS

In a prospective study, we measured cerebral water content in 20 healthy volunteers before alcohol consumption and after reaching a breath alcohol concentration of 1 ‰. A quantitative MRI water mapping sequence was conducted on a clinical 3 T system. Non-alcoholic fluid input and output were documented and accounted for. Water content was assessed for whole brain, grey and white matter and more specifically for regions known to be affected by acute or chronic alcohol misuse (occipital and frontal lobes, thalamus and pons). Changes in the volume of grey and white matter as well as the whole brain were examined.

RESULTS

Quantitative cerebral water content before and after acute alcohol consumption did not differ significantly (P ≥ 0.07), with changes often being within the range of measurement accuracy. Whole brain, white and grey matter volume did not change significantly (P ≥ 0.12).

CONCLUSION

The results of our study show no significant water content or volume change in the brain after recent alcohol intake in healthy volunteers. This accounts for the whole brain, grey and white matter, occipital and frontal lobes, thalamus and pons.

Acute effects of alcohol on resting-state functional connectivity in healthy young men

Alcohol abuse and dependence remain significant public health issues, and yet the brain circuits that are involved in the rewarding effects of alcohol are poorly understood. One promising way to study the effects of alcohol on neural activity is to examine its effects on functional connectivity between brain areas involved in reward and other functions. Here, we compared the effects of two doses of alcohol (0.4 and 0.8 g/kg) to placebo on resting-state functional connectivity in brain circuits related to reward in 19 healthy young men without histories of alcohol problems. The higher, but not the lower, dose of alcohol, significantly increased connectivity from reward-related regions to sensory and motor cortex, and between seeds associated with cognitive control. Contrary to expectation, alcohol did not significantly change connectivity for the ventral striatum at either dose. These findings reveal unrecognized effects of alcohol on connectivity from reward-related regions to visual and sensory cortical areas.

Alcohol Induced Brain and Liver Damage: Advantages of a Porcine Alcohol Use Disorder Model

Alcohol is one of the most commonly abused intoxicants with 1 in 6 adults at risk for alcohol use disorder (AUD) in the United States. As such, animal models have been extensively investigated with rodent AUD models being the most widely studied. However, inherent anatomical and physiological differences between rodents and humans pose a number of limitations in studying the complex nature of human AUD. For example, rodents differ from humans in that rodents metabolize alcohol rapidly and do not innately demonstrate voluntary alcohol consumption. Comparatively, pigs exhibit similar patterns observed in human AUD including voluntary alcohol consumption and intoxication behaviors, which are instrumental in establishing a more representative AUD model that could in turn delineate the risk factors involved in the development of this disorder. Pigs and humans also share anatomical similarities in the two major target organs of alcohol- the brain and liver. Pigs possess gyrencephalic brains with comparable cerebral white matter volumes to humans, thus enabling more representative evaluations of susceptibility and neural tissue damage in response to AUD. Furthermore, similarities in the liver result in a comparable rate of alcohol elimination as humans, thus enabling a more accurate extrapolation of dosage and intoxication level to humans. A porcine model of AUD possesses great translational potential that can significantly advance our current understanding of the complex development and continuance of AUD in humans.

Poor inhibitory control is associated with greater stimulation and less sedation following alcohol

RATIONALE AND OBJECTIVE

Poor inhibitory control is a well-established risk factor for alcohol use disorder (AUD). Similarly, greater sensitivity to the stimulant effects and less sensitivity to the sedative effects of alcohol are also strongly linked to risk for AUD. Traditionally, these two risk factors have been considered to be orthogonal, and thus they have been studied independently. However, recent evidence from animal and human studies suggests that they may be related. The current study examined the relationship between inhibitory control and subjective responses to alcohol in a sample of healthy young adults.

METHODS

Moderate social drinkers (N = 69) first completed the stop signal task to assess inhibitory control. They then participated in four sessions in which they received an oral dose of ethanol (0.8 g/kg) or placebo in alternating order, providing self-report measures of stimulation and sedation on the Biphasic Alcohol Effects Scale (BAES) at regular intervals.

RESULTS

Linear mixed effects models showed that poor inhibitory control was associated with greater stimulation and less sedation following alcohol compared with placebo.

CONCLUSION

These findings provide the first direct evidence that individuals with poor inhibitory control experience greater sensitivity to the rewarding, stimulant effects of alcohol, and less sensitivity to the negative, sedative effects. These findings suggest that inhibition and subjective response to alcohol are not independent risk factors, and that together they constitute a heightened profile of risk for AUD.

Getting to the Heart of Low Sensitivity to Alcohol: Context Moderates Low Cardiovascular Response to Alcohol in Persons With a Family History of Alcohol Use Disorder

Background

Low sensitivity to alcohol in persons with a family history of alcoholism (FH+), compared to those without (FH−), contributes to risk for alcohol use disorder (AUD). However, sensitivity of FH+ cardiovascular response to alcohol is not well understood. This gap is significant because cardiovascular processes contribute to emotional regulation and stress response problems theorized to be central to the development and persistence of AUD. This study compared changes in heart rate (HR) and HR variability (HRV) between FH groups after consuming alcohol and control beverages and examined how these changes were moderated by emotional and alcohol‐related contexts.

Methods

Young adults (N = 165) with FH+ (n = 110) or FH− (n = 55) each completed 2 sessions, separated by 1 week. They received one of 3 different beverages (alcohol, placebo, and told‐no‐alcohol) in each session. Electrocardiogram data were recorded during pre–beverage consumption and post–beverage consumption baselines, and then during 4 picture cue tasks (neutral, positive, negative, and alcohol‐related). Generalized estimating equations were used to examine differences in cardiovascular reactivity (changes in HR and HRV power at ~ 0.1 Hz) across FH groups, beverage conditions, and picture cue tasks.

Results

A significant beverage condition × cue task × FH interaction effect on HRV was observed. The FH+ group, compared to the FH− group, showed (a) significantly less HRV suppression in specific cue contexts following alcohol, (b) a mixed pattern of more and less HRV suppression across cue contexts following placebo, and (c) a similar HRV reactivity pattern in the told‐no‐alcohol condition across cue tasks. For HR, there were no significant effects involving FH.

Conclusions

Diminished cardiovascular sensitivity to oral alcohol in FH+ persons varied within a given drinking episode depending on emotional and alcohol‐related features of the context, suggesting that environmental characteristics play a role in the expression of low sensitivity to alcohol among FH+ individuals.

Association Between Alcoholic Cirrhosis and Hemorrhagic Stroke: A Nationwide Population-based Study

AIMS

This study investigated whether patients with alcoholic cirrhosis have a high risk of hemorrhagic stroke.

METHODS

In this study, 17,094 patients diagnosed with cirrhosis between 2000 and 2010 were identified using the Taiwan National Health Insurance claims data. Identified patients were randomly selected and propensity score matched with individuals without cirrhosis according to age, sex, comorbidities and index year.

RESULTS

The overall incidence rate of stroke was 4.41 and 12.1 per 1000 person-years in the chronic liver disease and cirrhosis (CLDC) with hepatitis B virus (HBV) or hepatitis C virus (HCV) cohort and the alcoholic CLDC cohort, respectively. The alcoholic CLDC cohort exhibited a 4.53-fold higher risk of hemorrhagic stroke (adjusted subhazard ratio [aSHR] = 4.53, 95% confidence interval [CI] = 3.05-6.71) than did the non-CLDC cohort, and the CLDC with HBV or HCV cohort exhibited a 1.40-fold higher risk of hemorrhagic stroke (aSHR = 1.40, 95% CI = 1.10-1.78) than did the non-CLDC cohort. The alcoholic CLDC cohort and the CLDC with HBV or HCV cohort showed an aSHR of 1.80 (95% CI = 1.36-2.40) and 0.95 (95% CI = 0.83-1.07) for ischemic stroke, respectively, compared with the non-CLDC cohort.

CONCLUSION

Alcoholic patients with CLDC had a higher risk of hemorrhagic stroke compared with non-alcoholic patients with CLDC and patients without CLDC.

Effects of Alcohol and Acetate on Cerebral Blood Flow: A Pilot Study

BACKGROUND

Acute alcohol produces effects on cerebral metabolism and blood flow. Alcohol is converted to acetate, which serves as a source of energy for the brain and is an agonist at G protein-coupled receptors distributed in different cell types in the body including neurons. Acetate has been hypothesized to play a role in the cerebral blood flow (CBF) response after alcohol ingestion. We tested whether administration of acetate would alter CBF in a pattern similar to or different from that of alcohol ingestion in healthy individuals.

METHODS

Twenty-four healthy participants were assigned by convenience to receive either 0.6 g/kg alcohol orally (n = 12) or acetate intravenously (n = 12). For each participant, CBF maps were acquired using an arterial spin labeling sequence on a 3T magnetic resonance scanner after placebo and after drug administration. Whole-brain CBF maps were compared between placebo and drug using a paired t-test, and set at a threshold of p < 0.05 corrected for multiple comparisons (k ≥ 142 voxels, ≥3.78 cm3 ), voxel-level p < 0.005. Intoxication was measured after placebo and drug administration with a Subjective High Assessment Scale (SHAS-7).

RESULTS

Compared to placebo, alcohol and acetate were associated with increased CBF in the medial thalamus. Alcohol, but not acetate, was associated with increased CBF in the right orbitofrontal, medial prefrontal and cingulate cortex, and hippocampus. Plasma acetate levels increased following administration of alcohol and acetate and did not differ between the 2 arms. Alcohol, but not acetate, was associated with an increase in SHAS-7 scores (p < 0.001).

CONCLUSIONS

Increased thalamic CBF associated with either alcohol or acetate administration suggests that the thalamic CBF response after alcohol could be mediated by acetate. Compared to other brain regions, thalamus may differ in its ability to metabolize acetate or expression of receptors responsive to acetate. Increased prefrontal and limbic CBF associated with alcohol may be linked to alcohol's behavioral effects.

Applications of Pueraria lobata in treating diabetics and reducing alcohol drinking

Pueraria lobata is one of the most important medicinal herbs used traditionally in China. According to Shanghan Lun (Treatise on Exogenous Febrile Disease), it has been used traditionally to relieve body heat, eye soring, dry mouth, headache associated with high blood pressure, and stiff neck problems. Modern studies in the 1970s revealed that isoflavonoids extracted from P. lobata were the bioactive components of an herbal remedy namely Yufeng Ningxin Tablets for the treatment of patients after stroke. This article reviews recent application of P. lobota in the treatment of diabetics and in reducing alcohol drinking. In view of its low toxicity profile, P. lobota stands an excellent chance to be developed as a phytomedicine for treating human diseases.

The Relationship Between Regional Cerebral Blood Flow Estimates and Alcohol Problems at 5-Year Follow-Up: The Role of Level of Response

BACKGROUND

Acute alcohol consumption is associated with temporarily increased regional cerebral blood flow (CBF). The extent of this increase appears to be moderated by individual differences in the level of response (LR) to alcohol's subjective effects. The low LR phenotype is a known risk factor for the development of alcohol problems. This study investigates how the low LR phenotype relates to the relationship between alcohol-related changes in CBF and alcohol problems 5 years later.

METHODS

Young adults (ages 18 to 25) were selected based on their LR to alcohol and underwent a neuroimaging protocol including arterial spin labeling and functional scans. These participants were recontacted ~5 years later and assessed on alcohol outcomes. A final sample of 107 subjects (54 low and 53 high LR subjects) was included in the analyses. Whole-brain analysis revealed 5 clusters of significant alcohol-induced, versus placebo-induced, CBF changes that were consistent with a previous report. Peak alcohol-placebo CBF response was extracted from these regions and, along with the LR group, submitted to a hierarchical linear regression predicting alcohol problems. Analyses controlled for age, sex, and baseline alcohol problems.

RESULTS

In the regression analysis, greater alcohol-placebo CBF difference in the right middle/superior/inferior frontal gyri and bilateral anterior cingulate gyri clusters predicted greater future alcohol problems for the low LR group, whereas this relationship was not found to be significant in the high LR group.

CONCLUSIONS

This study demonstrates a clinically important relationship between CBF and future alcohol problems, particularly in individuals with a low LR phenotype. These initial results help to elucidate the neurobiological pathways involved in the development of alcohol use disorders for individuals with low LR.

Effects of Acute Alcohol Consumption on the Human Brain: Diffusional Kurtosis Imaging and Arterial Spin-Labeling Study

BACKGROUND AND PURPOSE

Brain function and microstructure are affected by alcohol consumption. Until recently, the effect of alcohol on neural mechanisms has not been fully elucidated. Our aim was to explore the acute effects of alcohol on healthy human brains by diffusional kurtosis imaging and 3D arterial spin-labeling and elucidate structural and functional changes in the brain on acute alcohol intake.

MATERIALS AND METHODS

Conventional MR imaging, diffusional kurtosis imaging, and 3D arterial spin-labeling were performed on 24 healthy volunteers before and 0.5 and 1 hour after drinking alcohol. Participants were divided into 2 groups according to the response to alcohol: blushing (n = 12) and unblushing (n = 12) groups. Twenty brain regions were analyzed.

RESULTS

Diffusional kurtosis imaging revealed an increase in mean kurtosis and fractional anisotropy at 0.5 hour post-alcohol intake in most brain regions, whereas mean diffusion was decreased in several brain regions at 1 hour after drinking. 3D arterial spin-labeling showed increased cerebral blood flow in most brain regions, particularly in the frontal regions. However, perfusion in the anterior commissure decreased. Regional changes in the brain correlated with various behavioral performances with respect to blush response and sex. In general, blushing individuals and men are more sensitive to alcohol with acute effects.

CONCLUSIONS

Physiologic and microstructural alterations in the brain on alcohol consumption were examined. Brain areas with blood flow alteration detected by 3D arterial spin-labeling were highly consistent with susceptible areas detected by diffusional kurtosis imaging. The current study provides new insight into the effects of alcohol on the brain and behavioral performance in different blush response and sex populations.

Acute alcohol administration dampens central extended amygdala reactivity

Alcohol use is common, imposes a staggering burden on public health, and often resists treatment. The central extended amygdala (EAc)—including the bed nucleus of the stria terminalis (BST) and the central nucleus of the amygdala (Ce)—plays a key role in prominent neuroscientific models of alcohol drinking, but the relevance of these regions to acute alcohol consumption in humans remains poorly understood. Using a single-blind, randomized-groups design, multiband fMRI data were acquired from 49 social drinkers while they performed a well-established emotional faces paradigm after consuming either alcohol or placebo. Relative to placebo, alcohol significantly dampened reactivity to emotional faces in the BST. To rigorously assess potential regional differences in activation, data were extracted from unbiased, anatomically predefined regions of interest. Analyses revealed similar levels of dampening in the BST and Ce. In short, alcohol transiently reduces reactivity to emotional faces and it does so similarly across the two major divisions of the human EAc. These observations reinforce the translational relevance of addiction models derived from preclinical work in rodents and provide new insights into the neural systems most relevant to the consumption of alcohol and to the initial development of alcohol abuse in humans.

Neural correlates of correct and failed response inhibition in heavy versus light social drinkers: an fMRI study during a go/no-go task by healthy participants

The ability to suppress responses that are inappropriate, as well as the mechanisms monitoring the accuracy of actions in order to compensate for errors, is central to human behavior. Neural alterations that prevent stopping an inaccurate response, combined with a decreased ability of error monitoring, are considered to be prominent features of alcohol abuse. Moreover, (i) alterations of these processes have been reported in heavy social drinkers (i.e. young healthy individuals who do not yet exhibit a state of alcohol dependence); and (ii) through longitudinal studies, these alterations have been shown to underlie subsequent disinhibition that may lead to future alcohol use disorders. In the present functional magnetic resonance imaging study, using a contextual Go/No-Go task, we investigated whether different neural networks subtended correct inhibitions and monitoring mechanisms of failed inhibitory trials in light versus heavy social drinkers. We show that, although successful inhibition did not lead to significant changes, neural networks involved in error monitoring are different in light versus heavy drinkers. Thus, while light drinkers exhibited activations in their right inferior frontal, right middle cingulate and left superior temporal areas; heavy drinkers exhibited activations in their right cerebellum, left caudate nucleus, left superior occipital region, and left amygdala. These data are functionally interpreted as reflecting a "visually-driven emotional strategy" vs. an "executive-based" neural response to errors in heavy and light drinkers, respectively. Such a difference is interpreted as a key-factor that may subtend the transition from a controlled social heavy consumption to a state of clinical alcohol dependence.

Cerebral Blood Flow Measurements in Adults: A Review on the Effects of Dietary Factors and Exercise

Improving cerebrovascular function may be a key mechanism whereby a healthy lifestyle, of which a healthy diet combined with increased physical activity levels is a cornerstone, protects against cognitive impairments. In this respect, effects on cerebral blood flow (CBF)—a sensitive physiological marker of cerebrovascular function—are of major interest. This review summarizes the impact of specific dietary determinants and physical exercise on CBF in adults and discusses the relation between these effects with potential changes in cognitive function. A limited number of randomized controlled trials have already demonstrated the beneficial effects of an acute intake of nitrate and polyphenols on CBF, but evidence for a relationship between these effects as well as improvements in cognitive functioning is limited. Moreover, long-term trans-resveratrol supplementation has been shown to increase CBF in populations at increased risk of accelerated cognitive decline. Long-term supplementation of n-3 long-chain polyunsaturated fatty acids may also increase CBF, but related effects on cognitive performance have not yet been found. Significant decreases in cerebral perfusion were observed by commonly consumed amounts of caffeine, while alcohol intake was shown to increase CBF in a dose-dependent way. However, the long-term effects are not clear. Finally, long-term exercise training may be a promising approach to improve CBF, as increases in perfusion may contribute to the beneficial effects on cognitive functioning observed following increased physical activity levels.

Adolescent alcohol exposure decreases frontostriatal resting-state functional connectivity in adulthood

Connectivity of the prefrontal cortex (PFC) matures through adolescence, coinciding with emergence of adult executive function and top-down inhibitory control over behavior. Alcohol exposure during this critical period of brain maturation may affect development of PFC and frontolimbic connectivity. Adult rats exposed to adolescent intermittent ethanol (AIE; 5 g/kg ethanol, 25 percent v/v in water, intragastrically, 2-day-on, 2-day-off, postnatal day 25-54) or water control underwent resting-state functional MRI to test the hypothesis that AIE induces persistent changes in frontolimbic functional connectivity under baseline and acute alcohol conditions (2 g/kg ethanol or saline, intraperitoneally administered during scanning). Data were acquired on a Bruker 9.4-T MR scanner with rats under dexmedetomidine sedation in combination with isoflurane. Frontolimbic network regions-of-interest for data analysis included PFC [prelimbic (PrL), infralimbic (IL), and orbitofrontal cortex (OFC) portions], nucleus accumbens (NAc), caudate putamen (CPu), dorsal hippocampus, ventral tegmental area, amygdala, and somatosensory forelimb used as a control region. AIE decreased baseline resting-state connectivity between PFC subregions (PrL-IL and IL-OFC) and between PFC-striatal regions (PrL-NAc, IL-CPu, IL-NAc, OFC-CPu, and OFC-NAc). Acute ethanol induced negative blood-oxygen-level-dependent changes within all regions of interest examined, along with significant increases in functional connectivity in control, but not AIE animals. Together, these data support the hypothesis that binge-like adolescent alcohol exposure causes persistent decreases in baseline frontolimbic (particularly frontostriatal) connectivity and alters sensitivity to acute ethanol-induced increases in functional connectivity in adulthood.

Alcohol affects brain functional connectivity and its coupling with behavior: greater effects in male heavy drinkers

Acute and chronic alcohol exposure significantly affect behavior but the underlying neurobiological mechanisms are still poorly understood. Here, we used functional connectivity density (FCD) mapping to study alcohol-related changes in resting brain activity and their association with behavior. Heavy drinkers (HD, N=16, 16 males) and normal controls (NM, N=24, 14 males) were tested after placebo and after acute alcohol administration. Group comparisons showed that NM had higher FCD in visual and prefrontal cortices, default mode network regions and thalamus, while HD had higher FCD in cerebellum. Acute alcohol significantly increased FCD within the thalamus, impaired cognitive and motor functions, and affected self-reports of mood/drug effects in both groups. Partial least squares regression showed that alcohol-induced changes in mood/drug effects were associated with changes in thalamic FCD in both groups. Disruptions in motor function were associated with increases in cerebellar FCD in NM and thalamus FCD in HD. Alcohol-induced declines in cognitive performance were associated with connectivity increases in visual cortex and thalamus in NM, but in HD, increases in precuneus FCD were associated with improved cognitive performance. Acute alcohol reduced 'neurocognitive coupling', the association between behavioral performance and FCD (indexing brain activity), an effect that was accentuated in HD compared with NM. Findings suggest that reduced cortical connectivity in HD contribute to decline in cognitive abilities associated with heavy alcohol consumption, whereas increased cerebellar connectivity in HD may have compensatory effects on behavioral performance. The results reveal how drinking history alters the association between brain FCD and individual differences in behavioral performance.

Association between shunt-responsive idiopathic normal pressure hydrocephalus and alcohol

OBJECTIVE Idiopathic normal pressure hydrocephalus (iNPH) is characterized by ventriculomegaly, gait difficulty, incontinence, and dementia. The symptoms can be ameliorated by CSF drainage. The object of this study was to identify factors associated with shunt-responsive iNPH. METHODS The authors reviewed the medical records of 529 patients who underwent shunt placement for iNPH at their institution between July 2001 and March 2015. Variables associated with shunt-responsive iNPH were identified using bivariate and multivariate analyses. Detailed alcohol consumption information was obtained for 328 patients and was used to examine the relationship between alcohol and shunt-responsive iNPH. A computerized patient registry from 2 academic medical centers was queried to determine the prevalence of alcohol abuse among 1665 iNPH patients. RESULTS Bivariate analysis identified associations between shunt-responsive iNPH and gait difficulty (OR 4.59, 95% CI 2.32-9.09; p < 0.0001), dementia (OR 1.79, 95% CI 1.14-2.80; p = 0.01), incontinence (OR 1.77, 95% CI 1.13-2.76; p = 0.01), and alcohol use (OR 1.98, 95% CI 1.23-3.16; p = 0.03). Borderline significance was observed for hyperlipidemia (OR 1.56, 95% CI 0.99-2.45; p = 0.054), a family history of hyperlipidemia (OR 3.09, 95% CI 0.93-10.26, p = 0.054), and diabetes (OR 1.83, 95% CI 0.96-3.51; p = 0.064). Multivariate analysis identified associations with gait difficulty (OR 3.98, 95% CI 1.81-8.77; p = 0.0006) and alcohol (OR 1.94, 95% CI 1.10-3.39; p = 0.04). Increased alcohol intake correlated with greater improvement after CSF drainage. Alcohol abuse was 2.5 times more prevalent among iNPH patients than matched controls. CONCLUSIONS Alcohol consumption is associated with the development of shunt-responsive iNPH.

Differences between healthy adults and patients with type 2 diabetes mellitus in reactivity of toe microcirculation by ultrasound combined with a warm bath test

The aim of this study was to explore the feasibility and clinical value of ultrasound combined with a warm bath test in assessing the differences in reactivity of toe microcirculation between healthy adults and patients with type 2 diabetes mellitus (T2DM).A total of 56 T2DM patients were recruited as case group, whereas 50 healthy volunteers were enrolled as control group.Fasting blood glucose, glycated hemoglobin, total cholesterol, triglyceride, low-density lipoprotein cholesterol in T2DM group were significantly higher than in control group. Under stationary condition, peak systolic velocity (PSV), end-diastolic velocity (EDV), and mean velocity (MV) were lower, but pulsatility index (PI) and resistance index (RI) were higher in patients with T2DM than in controls both in dorsalis pedis artery (DPA) and plantar digital artery (PDA). On response to the warm test, PSV, EDV, and MV increased and PI and RI decreased both in DPA and PDA in these 2 groups. Moreover, the change rate in PSV, EDV, MV, PI, and RI of PDA was significantly lower in T2DM group than in control group.Color Doppler combined with a warm bath test may be used as a new method in evaluating the differences in reactivity of distal limb microvascular between healthy adults and patients with T2DM.

Changes in cerebral [18F]-FDG uptake induced by acute alcohol administration in a rat model of alcoholism

Several [¹⁸F]-FDG positron emission tomography (PET) studies in alcoholics have consistently reported decreases in overall brain glucose metabolism at rest and following acute alcohol administration. However, changes in cerebral glucose utilization associated with the transition to addiction are not well understood and require longitudinal translational imaging studies in animal models of alcoholism. Here, we studied brain glucose uptake in alcohol drinking rats in order to provide convergent evidence to what has previously been reported in human studies. Brain glucose metabolism was measured by [¹⁸F]-FDG microPET imaging in different male Wistar rat groups: short-term drinking (three months), long-term drinking (twelve months) and alcohol-naïve. Global and regional cerebral glucose uptake was measured at rest and following acute alcohol administration. We showed that alcohol significantly reduced the whole-brain glucose metabolism. This effect was most pronounced in the parietal cortex and cerebellum. Alcohol-induced decreases in brain [¹⁸F]-FDG uptake was most apparent in alcohol-naïve rats, less intense in short-term drinkers and absent in long-term drinkers. The latter finding indicates the occurrence of tolerance to the intoxicating effects of alcohol in long-term drinking individuals. In contrast, some regions, like the ventral striatum and entorhinal cortex, showed enhanced metabolic activity, an effect that did not undergo tolerance during long-term alcohol consumption. Our findings are comparable to those described in human studies using the same methodology. We conclude that [¹⁸F]-FDG PET studies in rat models of alcoholism provide good translation and can be used for future longitudinal studies investigating alterations in brain function during different stages of the addiction cycle.

Nalmefene Reduces Reward Anticipation in Alcohol Dependence: An Experimental Functional Magnetic Resonance Imaging Study

BACKGROUND

Nalmefene is a µ and δ opioid receptor antagonist, κ opioid receptor partial agonist that has recently been approved in Europe for treating alcohol dependence. It offers a treatment approach for alcohol-dependent individuals with "high-risk drinking levels" to reduce their alcohol consumption. However, the neurobiological mechanism underpinning its effects on alcohol consumption remains to be determined. Using a randomized, double-blind, placebo-controlled, within-subject crossover design we aimed to determine the effect of a single dose of nalmefene on striatal blood oxygen level-dependent (BOLD) signal change during anticipation of monetary reward using the monetary incentive delay task following alcohol challenge.

METHODS

Twenty-two currently heavy-drinking, non-treatment-seeking alcohol-dependent males were recruited. The effect of single dose nalmefene (18 mg) on changes in a priori defined striatal region of interest BOLD signal change during reward anticipation compared with placebo was investigated using functional magnetic resonance imaging. Both conditions were performed under intravenous alcohol administration (6% vol/vol infusion to achieve a target level of 80 mg/dL).

RESULTS

Datasets from 18 participants were available and showed that in the presence of the alcohol infusion, nalmefene significantly reduced the BOLD response in the striatal region of interest compared with placebo. Nalmefene did not alter brain perfusion.

CONCLUSIONS

Nalmefene blunts BOLD response in the mesolimbic system during anticipation of monetary reward and an alcohol infusion. This is consistent with nalmefene's actions on opioid receptors, which modulate the mesolimbic dopaminergic system, and provides a neurobiological basis for its efficacy.

Biomarkers, designs, and interpretations of resting-state fMRI in translational pharmacological research: A review of state-of-the-Art, challenges, and opportunities for studying brain chemistry

A decade of research and development in resting-state functional MRI (RSfMRI) has opened new translational and clinical research frontiers. This review aims to bridge between technical and clinical researchers who seek reliable neuroimaging biomarkers for studying drug interactions with the brain. About 85 pharma-RSfMRI studies using BOLD signal (75% of all) or arterial spin labeling (ASL) were surveyed to investigate the acute effects of psychoactive drugs. Experimental designs and objectives include drug fingerprinting dose-response evaluation, biomarker validation and calibration, and translational studies. Common biomarkers in these studies include functional connectivity, graph metrics, cerebral blood flow and the amplitude and spectrum of BOLD fluctuations. Overall, RSfMRI-derived biomarkers seem to be sensitive to spatiotemporal dynamics of drug interactions with the brain. However, drugs cause both central and peripheral effects, thus exacerbate difficulties related to biological confounds, structured noise from motion and physiological confounds, as well as modeling and inference testing. Currently, these issues are not well explored, and heterogeneities in experimental design, data acquisition and preprocessing make comparative or meta-analysis of existing reports impossible. A unifying collaborative framework for data-sharing and data-mining is thus necessary for investigating the commonalities and differences in biomarker sensitivity and specificity, and establishing guidelines. Multimodal datasets including sham-placebo or active control sessions and repeated measurements of various psychometric, physiological, metabolic and neuroimaging phenotypes are essential for pharmacokinetic/pharmacodynamic modeling and interpretation of the findings. We provide a list of basic minimum and advanced options that can be considered in design and analyses of future pharma-RSfMRI studies. Hum Brain Mapp 38:2276-2325, 2017. © 2017 Wiley Periodicals, Inc.

The effect of alcohol on the nature of lexical representations in different taste domains

Moderate alcohol consumption may be involved in cognitive feedback mechanisms (Hofmann & Friese, 2008), participants execute verbal fluency test (VFT) better (Cerhan et al., 1998) and there is positive association between sweet taste and excessive alcohol intake (Lange, Kampov-Polevoy, & Garbutt, 2010). We investigate the immediate pharmacological consequences of moderate to light alcohol consumption in verbal fluency and categorical sorting within the different taste domains (i.e. sweet, salty, sour and bitter). Our hypothesis is that subjects under the influence of light to moderate alcohol will produce more items in the sweet domain. 53 healthy adults had moderate alcohol consumption and were compared in two semantic tasks to 53 adults, who did not drink alcohol. Mann-Whitney U tests showed that the total number of clusters, switches, and repetitions were equal between the two groups in all taste domains (p-values: .211, .401, and .684 respectively). The number of responses in the alcohol group generated more disinhibiting intrusive words during the VFTs as compared to the control group (p-value: <.001). VFTs and the order of taste preference in the card-sorting task showed positive correlation and agreement. Light to moderate alcohol did not affect verbal fluency. However, participants under the influence of alcohol generated significantly more errors in the VFTs that were emotionally laden. This corroborates with research that certain emotions are innervated with taste domains. This leaves open question about the effects of alcohol on decision making in eating and executive functions as they relate to lexical representations.

Ethanol Increases Mechanical Pain Sensitivity in Rats via Activation of GABAA Receptors in Medial Prefrontal Cortex

Ethanol is widely known for its ability to cause dramatic changes in emotion, social cognition, and behavior following systemic administration in humans. Human neuroimaging studies suggest that alcohol dependence and chronic pain may share common mechanisms through amygdala-medial prefrontal cortex (mPFC) interactions. However, whether acute administration of ethanol in the mPFC can modulate pain perception is unknown. Here we showed that bilateral microinjections of ethanol into the prelimbic and infralimbic areas of the mPFC lowered the bilateral mechanical pain threshold for 48 h without influencing thermal pain sensitivity in adult rats. However, bilateral microinjections of artificial cerebrospinal fluid into the mPFC or bilateral microinjections of ethanol into the dorsolateral PFC (also termed as motor cortex area 1 in Paxinos and Watson's atlas of The Rat Brain. Elsevier Academic Press, Amsterdam, 2005) failed to do so, suggesting regional selectivity of the effects of ethanol. Moreover, bilateral microinjections of ethanol did not change the expression of either pro-apoptotic (caspase-3 and Bax) or anti-apoptotic (Bcl-2) proteins, suggesting that the dose was safe and validating the method used in the current study. To determine whether γ-aminobutyric acid A (GABAA) receptors are involved in mediating the ethanol effects, muscimol, a selective GABAA receptor agonist, or bicuculline, a selective GABAA receptor antagonist, was administered alone or co-administered with ethanol through the same route into the bilateral mPFC. The results showed that muscimol mimicked the effects of ethanol while bicuculline completely reversed the effects of ethanol and muscimol. In conclusion, ethanol increases mechanical pain sensitivity through activation of GABAA receptors in the mPFC of rats.

Sex differences in alcohol-related neurobehavioral consequences

In this chapter, we review existing research regarding sex differences in alcohol's effects on neurobehavioral functions/processes. Drawn largely from laboratory studies, literature regarding acute alcohol administration and chronic alcohol misuse is explored focusing on commonly employed neuropsychologic domains (e.g., executive function, visuospatial skills, learning and memory, gait and balance), neurophysiologic measures (e.g., electroencephalography and event-related potentials), and structural and functional neuroimaging (e.g., magnetic resonance imaging (MRI), functional MRI, diffusion tensor imaging, positron emission tomography, and magnetic resonance spectroscopy). To provide a historical perspective on the development of these questions, we have included reference to early and more recent research. Additionally, specific biases, knowledge gaps, and continuing controversies are noted.

The acute effects of alcohol on cerebral hemodynamic changes induced by the head-up tilt test in healthy subjects

BACKGROUND

Alcohol is a known triggering factor for orthostatic dysfunction, increasing the risk of neurally-mediated syncope. Since orthostatic tolerance may be affected by both systemic and cerebral hemodynamic changes, our aim was to investigate the acute effects of alcohol on cerebral vasoreactivity measured during the head-up tilt (HUT) test in 20 healthy subjects.

METHODS

Mean arterial blood pressure (mBP), heart rate, and flow parameters in both middle cerebral arteries (MCAs) were continuously recorded in the supine and during a 10-minute HUT positions before and after alcohol intake.

RESULTS

The HUT test resulted in a more prominent decline of adjusted mBP at the level of MCAs (mBPMCA) and a significantly larger decrease of MCA mean flow velocities (MFVMCA) in the post-alcohol period than before alcohol intake. During the HUT phase, the relative decrease in MFVMCA was significantly smaller than the reduction in mBPMCA before drinking alcohol, while these changes were similar after alcohol ingestion. The cerebrovascular resistance index (CVRi) decreased during the HUT phase in the control period, however, it increased after alcohol intake.

CONCLUSION

The similar decrease in mBPMCA and MFVMCA during orthostatic stress after alcohol ingestion together with the increased CVRi indicated the impairment of the compensatory vasodilation of cerebral resistance vessels, i.e. impaired cerebral autoregulation. These findings suggest that alcohol may contribute to impaired orthostatic tolerance not only by a hypotensive response but also by the alteration of cerebral blood flow regulation.

Phenomenologically distinct psychotomimetic effects of ketamine are associated with cerebral blood flow changes in functionally relevant cerebral foci: a continuous arterial spin labelling study

RATIONALE

The N-methyl-D-aspartate (NMDA) receptor antagonist ketamine provides a pragmatic approach to address the link between glutamate-mediated changes in brain function and psychosis-like experiences. Most studies using PET or BOLD fMRI have assessed these symptoms broadly, which may limit inference about specific mechanisms.

OBJECTIVES

The objective of this study is to identify the cerebral blood flow (CBF) correlates of ketamine-induced psychopathology, focusing on individual psychotomimetic symptom dimensions, which may have separable neurobiological substrates.

METHODS

We measured validated psychotomimetic symptom factors following intravenous ketamine administration in 23 healthy male volunteers (10 given a lower dose and 13 a higher dose) and correlated ketamine-induced changes in symptoms with regional changes in CBF, measured non-invasively using arterial spin labelling (ASL).

RESULTS

The main effect of ketamine paralleled previous studies, with increases in CBF in anterior and subgenual cingulate cortex and decreases in superior and medial temporal cortex. Subjective effects were greater in the high-dose group. For this group, ketamine-induced anhedonia inversely related to orbitofrontal cortex CBF changes and cognitive disorganisation was positively correlated with CBF changes in posterior thalamus and the left inferior and middle temporal gyrus. Perceptual distortion was correlated with different regional CBF changes in the low- and high-dose groups.

CONCLUSIONS

Here, we provide evidence for the sensitivity of ASL to the effects of ketamine and the strength of subjective experience, suggesting plausible neural mechanisms for ketamine-induced anhedonia and cognitive disorganisation.

Neural Firing in the Prefrontal Cortex During Alcohol Intake in Alcohol-Preferring "P" Versus Wistar Rats

BACKGROUND

Neural activity within the prefrontal cortex (PFC) is altered by alcohol and alcohol-associated stimuli and is mediated by genetic susceptibility to alcoholism. However, very little is known about how genetic risk of excessive drinking might mediate neural firing in the PFC during alcohol consumption.

METHODS

To determine how genetic risk influences alcohol seeking, intake, and neural activity, a Pavlovian alcohol consumption task was used-the 2-Way Cued Access Protocol (2CAP). Alcohol-preferring "P" rats and relatives of their (heterogeneous) founding Wistar population were used for these studies. After acquisition of 2CAP, extinction of responding for alcohol was evaluated by substituting water for alcohol. Following these experiments, in vivo electrophysiological recordings were obtained during 2CAP from the PFC in a separate cohort of Wistar and P rats implanted with moveable tetrode microdrives.

RESULTS

P and Wistar rats increased daily alcohol seeking and intake with P rats consuming roughly twice as much alcohol as Wistar. Both rat populations decreased seeking behavior during extinction. However, P rats displayed persistent increases in seeking after controlling for intake versus Wistar. Higher firing rates (FRs) were observed in P rats prior to 2CAP and throughout alcohol and water consumption compared with Wistars that were matched for alcohol-drinking history. Differences in FR were driven, in part, by a larger percentage of neurons in P rats versus Wistars that increased FR compared with those that decreased, or did not change.

CONCLUSIONS

These data provide additional evidence of increased alcohol consumption and persistent alcohol seeking in P versus Wistar rats. Differences in PFC neural firing observed in P rats prior to drinking could be heritable and/or related to an enhanced response to alcohol-associated contextual cues. FR differences observed during alcohol drinking might be related to an augmented sensitivity of PFC neurons to orally consumed alcohol.

Resting-state regional cerebral blood flow during adolescence: associations with initiation of substance use and prediction of future use disorders

BACKGROUND

Adolescence is a period of developmental flux when brain systems are vulnerable to influences of early substance use, which in turn relays increased risk for substance use disorders. Our study intent was to assess adolescent regional cerebral blood flow (rCBF) as it relates to current and future alcohol use. The aim was to identify brain-based predictors for initiation of alcohol use and onset of future substance use disorders.

METHODS

Quantitative rCBF was assessed in 100 adolescents (age 12-15). Prospective behavioral assessments were conducted annually over a three-year follow-up period to characterize onset of alcohol initiation, future drinking patterns and use disorders. Comparisons amongst use groups (i.e., current-, future-, and non-alcohol using adolescents) identified rCBF associated with initiation of alcohol use. Regression by future drinking patterns identified rCBF predictive of heavier drinking. Survival analysis determined whether or not baseline rCBF predicted later development of use disorders.

RESULTS

Baseline rCBF was decreased to the parietal cortex and increased to mesolimbic regions in adolescents currently using alcohol as well as those who would use alcohol in the future. Higher baseline rCBF to the left fusiform gyrus and lower rCBF to the right inferior parietal cortex and left cerebellum was associated with future drinking patterns as well as predicted the onset of alcohol and substance use disorders in this cohort.

CONCLUSIONS

Variations in resting rCBF to regions within reward and default mode or control networks appear to represent trait markers of alcohol use initiation and are predictive of future development of use disorders.

Dose-dependent effects of intravenous alcohol administration on cerebral blood flow in young adults

RATIONALE

Functional magnetic resonance imaging (fMRI) studies involving alcohol challenge are important for identifying neural correlates of alcohol's psychopharmacological effects. However, evaluating acute alcohol effects on blood oxygen level-dependent (BOLD) signal change is complicated by alcohol-related increases in cerebral blood flow (CBF).

OBJECTIVES

The present study aimed to further characterize acute alcohol effects on CBF using intravenous alcohol administration to maximize control over brain alcohol exposure.

METHODS

Twenty heavy-drinking young adults (M = 19.95 years old, SD = 0.76) completed alcohol and placebo imaging sessions in a within-subject, counter-balanced, placebo-controlled design. Arterial spin labeling (ASL) provided estimates of perfusion change at two target blood alcohol concentrations (40 and 80 mg%) relative to baseline and relative to a saline control infusion.

RESULTS

Voxel-wise analyses showed widespread and dose-dependent effects of alcohol on CBF increase. Region-of-interest analyses confirmed these findings, also indicating regional variation in the magnitude of perfusion change. Additional findings indicated that lower self-reported sensitivity to alcohol corresponded with reduced perfusion change during alcohol administration.

CONCLUSIONS

This study provides further evidence for widespread effects of acute alcohol on cerebral perfusion, also demonstrating regional, dose-dependent, and inter-individual variation. Further research is needed to evaluate implications of these effects for the design and interpretation of pharmacological fMRI studies involving alcohol challenge.

Disruption of sensory gating by moderate alcohol doses

RATIONALE

Evidence from a growing body of literature suggests that alcohol, even at moderate-dose levels, disrupts the ability to ignore distractors. However, little work has been done to elucidate the neural processes underlying this deficit.

OBJECTIVE

The present study was conducted to determine if low-to-moderate alcohol doses affect sensory gating, an electrophysiological phenomenon believed to reflect the pre-attentive filtering of irrelevant sensory information.

METHODS

Sixty social drinkers were administered one of three doses intended to produce breath alcohol concentrations of 0.0% (placebo), 0.04% (i.e., low dose), and 0.065% (i.e., moderate dose). A paired-click paradigm consisting of 100 pairs of identical tones (S1 and S2) was used to assess sensory gating. Amplitudes of P50, N100, and P200 auditory evoked potentials (AEPs) were used to calculate gating difference (S1-S2) and ratio (S2/S1) scores.

RESULTS

The moderate alcohol dose significantly decreased P50 and N100 gating relative to placebo. Comparisons between the difference and ratio scores helped characterize the gating mechanisms affected at these stages of information processing. Alcohol did not alter P200 sensory gating.

CONCLUSIONS

These data suggest that alcohol disrupts pre-attentional sensory-filtering processes at breath alcohol concentrations (BrACs) below the current 0.08% legal limit. Future studies should perform a combined assessment of sensory gating and selective attention to better understand the relationship between these two alcohol-induced deficits.

The effects of acute alcohol administration on the human brain: insights from neuroimaging

Over the last quarter century, researchers have peered into the living human brain to develop and refine mechanistic accounts of alcohol-induced behavior, as well as neurobiological mechanisms for development and maintenance of addiction. These in vivo neuroimaging studies generally show that acute alcohol administration affects brain structures implicated in motivation and behavior control, and that chronic intoxication is correlated with structural and functional abnormalities in these same structures, where some elements of these decrements normalize with extended sobriety. In this review, we will summarize recent findings about acute human brain responses to alcohol using neuroimaging techniques, and how they might explain behavioral effects of alcohol intoxication. We then briefly address how chronic alcohol intoxication (as inferred from cross-sectional differences between various drinking populations and controls) may yield individual brain differences between drinking subjects that may confound interpretation of acute alcohol administration effects. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.

Advice on lifestyle changes (diet, red wine and physical activity) does not affect internal carotid and middle cerebral artery blood flow velocity in patients with carotid arteriosclerosis in a randomized controlled trial

BACKGROUND

A Mediterranean diet, with and without small daily amounts of red wine, and physical activity reduce the risk of cerebrovascular disease and improve cognition. An increase in cerebral blood flow may be the underlying mechanism. Under normal conditions, cerebral blood flow velocity changes in the internal carotid arteries and in large basal cerebral arteries correlate closely with cerebral blood flow changes, as the diameter of these vessels hardly changes and only the smaller vessels downstream change their diameter.

METHODS

A prospective randomized controlled trial was performed in 108 patients with carotid atherosclerosis (mean age 64 years, 67% men, 66% on statin therapy). Half of them were advised to follow a polyphenol-rich modified Mediterranean diet including 1-2 tomatoes, 3-5 walnuts and a bar of dark chocolate (25 g) a day and to perform moderate physical exercise for 30 min/day (lifestyle changes). Within these two groups, half of the patients were randomized either to avoid any alcohol or to drink 100 ml of red wine (women) or 200 ml of red wine (men) daily. Bilateral middle cerebral and internal carotid blood flow velocity (peak systolic, peak end-diastolic and mean) was measured at baseline and after 4 and 20 weeks using colour-coded duplex ultrasound. Insonation depth and insonation angle were used to identically place the sample volume during follow-up investigations. A general linear model with Tukey-Kramer adjustment for multiple comparisons was used to assess the primary end points. For the analysis we used the mean values of the right and left artery.

RESULTS

Neither lifestyle changes nor red wine had an effect on peak systolic, peak end-diastolic or mean cerebral blood flow velocity.

CONCLUSIONS

Advice on lifestyle changes, including a modified polyphenol-rich Mediterranean diet, a glass of red wine daily and physical exercise, did not affect middle cerebral and internal carotid blood flow velocity in our patient group with carotid atherosclerosis. An increase in cerebral blood flow is thus unlikely to be the cause of the reduced risk of cerebrovascular disease and improved cognitive functioning described in the literature. One possible explanation for the fact that blood flow velocity was not affected by red wine, diet and physical activity advice is that two thirds of our patients were already on statin therapy. Statins increase cerebral blood flow and vasomotor reactivity via nitric oxide.

Acute effects of alcohol on brain perfusion monitored with arterial spin labeling magnetic resonance imaging in young adults

While a number of studies have established that moderate doses of alcohol increase brain perfusion, the time course of such an increase as a function of breath alcohol concentration (BrAC) has not yet been investigated, and studies differ about regional effects. Using arterial spin labeling (ASL) magnetic resonance imaging, we investigated (1) the time course of the perfusion increase during a 15-minute linear increase of BrAC up to 0.6 g/kg followed by a steady exposure of 100 minutes, (2) the regional distribution, (3) a potential gender effect, and (4) the temporal stability of perfusion effects. In 48 young adults who participated in the Dresden longitudinal study on alcohol effects in young adults, we observed (1) a 7% increase of global perfusion as compared with placebo and that perfusion and BrAC are tightly coupled in time, (2) that the increase reaches significance in most regions of the brain, (3) that the effect is stronger in women than in men, and (4) that an acute tolerance effect is not observable on the time scale of 2 hours. Larger studies are needed to investigate the origin and the consequences of the effect, as well as the correlates of inter-subject variations.

Interactions between age and moderate alcohol effects on simulated driving performance

RATIONALE

There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption.

OBJECTIVES

The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance of older and younger adults.

METHODS

Healthy older (55-70) and younger (25-35) adults were tested during a baseline session and again following consumption of one of three beverages [0.0 % (placebo), 0.04 % or 0.065 % target breath alcohol concentration]. Measures of driving precision and average speed were recorded.

RESULTS

Older adults performed more poorly on precision driving measures and drove more slowly than younger adults at baseline. After controlling for baseline performance, interactions between alcohol and age were observed following beverage consumption on two measures of driving precision with older adults exhibiting greater impairment as a result of alcohol consumption.

CONCLUSIONS

These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance. An investigation of mechanisms accounting for alcohol's effects on driving in older and younger adults is required. Further evaluation using more complex driving environments is needed to assess the real-world implication of this interaction.

Inattention, impulsive action, and subjective response to D-amphetamine

BACKGROUND

Both impulsivity and sensitivity to the rewarding effects of drugs have long been considered risk factors for drug abuse. There is some preclinical evidence to suggest that the two are related; however, there is little information about how specific behavioral components of impulsivity are related to the acute euphorigenic effects of drugs in humans. The aim of the current study was to examine the degree to which both inattention and impulsive action predicted subjective response to amphetamine.

METHODS

Healthy adults (n=165) performed the behavioral tasks and rated their subjective response to amphetamine (0, 5, 10, and 20 mg). Inattention was assessed as attention lapses on a simple reaction time task, and impulsive action was measured by stop RT on the stop task. Subjective response to amphetamine was assessed with the Drug Effects Questionnaire (DEQ) and the Profile of Mood States (POMS).

RESULTS

Hierarchical linear regression analyses showed significant negative associations between attention lapses and subjective response to amphetamine on DEQ measures. By contrast, stop RT was positively associated with responses on both DEQ and POMS measures. Additionally, a dose-response relationship was observed, such that the strength of these associations increased with higher doses of amphetamine.

CONCLUSIONS

These findings suggest that inattention is associated with less subjective response to amphetamine. By contrast, the heightened sensitivity to stimulant drug reward observed in individuals high in impulsive action suggests that this might be one mechanism contributing to increased risk for stimulant drug abuse in these individuals.

Compensatory effort parallels midbrain deactivation during mental fatigue: an fMRI study

Fatigue reflects the functioning of our physiological negative feedback system, which prevents us from overworking. When fatigued, however, we often try to suppress this system in an effort to compensate for the resulting deterioration in performance. Previous studies have suggested that the effect of fatigue on neurovascular demand may be influenced by this compensatory effort. The primary goal of the present study was to isolate the effect of compensatory effort on neurovascular demand. Healthy male volunteers participated in a series of visual and auditory divided attention tasks that steadily increased fatigue levels for 2 hours. Functional magnetic resonance imaging scans were performed during the first and last quarter of the study (Pre and Post sessions, respectively). Tasks with low and high attentional load (Low and High conditions, respectively) were administrated in alternating blocks. We assumed that compensatory effort would be greater under the High-attentional-load condition compared with the Low-load condition. The difference was assessed during the two sessions. The effect of compensatory effort on neurovascular demand was evaluated by examining the interaction between load (High vs. Low) and time (Pre vs. Post). Significant fatigue-induced deactivation (i.e., Pre>Post) was observed in the frontal, temporal, occipital, and parietal cortices, in the cerebellum, and in the midbrain in both the High and Low conditions. The interaction was significantly greater in the High than in the Low condition in the midbrain. Neither significant fatigue-induced activation (i.e., Pre<Post), nor its interaction with factor Load, was identified. The observed midbrain deactivation ([PreH - PostH]>[PreE- PostE]) may reflect suppression of the negative feedback system that normally triggers recuperative rest to maintain homeostasis.

High versus low level of response to alcohol: evidence of differential reactivity to emotional stimuli

BACKGROUND

The low level of response (LR) or sensitivity to alcohol is genetically influenced and predicts heavy drinking and alcohol problems. Functional magnetic resonance imaging (fMRI) studies using cognitive tasks suggest that subjects with a low-LR process cognitive information differently after placebo and alcohol than those with a high LR, but no studies have evaluated whether similar LR group differences are seen during an emotional processing task.

METHODS

The fMRI data were gathered from 116 nonalcoholic subjects (60 women) after oral placebo or approximately .7 mL/kg of ethanol while performing a modified emotional faces processing task. These included 58 low- and high-LR pairs matched on demography and aspects of substance use.

RESULTS

Blood alcohol levels and task performance were similar across LR groups, but low-LR subjects consumed approximately .8 drinks more/occasion. Thirteen brain regions (mostly the middle and inferior frontal gyri, cingulate, and insula) showed significant LR group or LR × placebo/alcohol condition interactions for emotional (mostly happy) faces relative to non-face trials. Low-LR subjects generally showed decreasing blood-oxygen level-dependent response contrasts across placebo to alcohol, whereas high LR showed increasing contrasts from placebo to alcohol, even after controlling for drinking quantities and alcohol-related changes in cerebral blood flow.

CONCLUSIONS

Thus, LR group fMRI differences are as prominent during an emotional face task as during cognitive paradigms. Low-LR individuals processed both types of information in a manner that might contribute to an impaired ability to recognize modest levels of alcohol intoxication in a range of life situations.

Reduced subjective response to acute ethanol administration among young men with a broad bipolar phenotype

Elevated lifetime prevalence rates of alcohol use disorders (AUDs) are a feature of bipolar disorder (BD). Individuals at-risk for AUDs exhibit blunted subjective responses to alcohol (low levels of response), which may represent a biomarker for AUDs. Thus, individuals at-risk for BD may exhibit low responses to alcohol. Participants were 20 unmedicated adult males who reported high rates of hypomanic experiences (bipolar phenotype participants; BPPs), aged 18 to 21 years, and 20 healthy controls matched on age, gender, IQ, BMI, and weekly alcohol intake. Subjective and pharmacokinetic responses to acute alcohol (0.8 g/kg) vs placebo administration were collected in a randomized, double-blind, cross-over, placebo-controlled, within-subjects design. BPP participants reported significantly lower subjective intoxication effects ('feel high': F=14.2, p=0.001; 'feel effects': F=8.1, p=0.008) across time, but did not differ in their pharmacokinetic, stimulant, or sedative responses. Paradoxically, however, the BPP participants reported significantly higher expectations of the positive effects of alcohol than controls. Our results suggest that unmedicated young males with previous hypomanic experiences exhibit diminished subjective responses to alcohol. These blunted alcohol responses are not attributable to differences in weekly alcohol intake, pharmacokinetic effects (eg, absorption rates), or familial risk of AUDs. These observations suggest that the dampened intoxication may contribute to the increased rates of alcohol misuse in young people at-risk for BD, and suggest possible shared etiological factors in the development of AUDs and BD.