Acute effects of an alcoholic drink on food intake: Aperitif versus co-ingestion

Exploring the short-term impact of swapping consumption from standard protein snacks to higher protein snacks on energy intake in social drinkers: Is protein worth a nudge?

Drinking alcoholic beverages stimulates food intake and contributes to the passive overconsumption of dietary energy. As protein is the most satiating of all the macronutrients, increased levels in snacks taken with alcohol have the potential to minimize excess energy consumption. We hypothesized that swapping consumption from retail-available standard protein (SP) snacks to higher protein (HP) snack foods would increase satiety and reduce acute food energy intake in social drinkers. A randomized single-blind crossover trial with 19 healthy participants aged 19-31 years was conducted. Participants attended two separate testing sessions, where they ingested white wine (30 g alcohol) and were offered ad libitum access to either HP snacks with a protein-fortified dip or SP snacks with a dip. There were no significant differences in mean food mass, food energy intake, or subjective appetite ratings between the high and SP snacks (all p > .05). Mean protein intake was significantly increased with HP snacks compared with standard snacks (p < .001). Plasma glucose median incremental area under the curve and mean peak were significantly higher with the SP snacks (all p < .05) but remained within the reference range. This study demonstrated that consumption of a higher amount of protein after a moderate alcohol dose does not result in a change in food mass and energy intake or promote satiety in healthy young adults. The potential for a simple swap to different snack types is unlikely to bring substantial benefits to social drinkers and reduce passive energy consumption.

The association between alcohol intake and obesity in a sample of the Irish adult population, a cross-sectional study

BACKGROUND

Obesity epidemic is one of the most serious public health challenges of the twenty-first century. Alcohol has been studied as a possible risk factor for obesity, but the evidence is discordant. This study examined the association between alcohol consumption and obesity in a sample of the Irish adult population.

METHOD

An analytical cross-sectional study was conducted using secondary data from the 2017 Healthy Ireland Survey. The primary survey recruited patients using a two-stage probability-based technique and a face-to-face-administered questionnaire to collect data. Descriptive and comparative data were analysed to identify associations between alcohol-related variables with waist circumference (WC) and body mass index (BMI). Regression analysis was performed to examine the associations between harmful alcohol consumption (AUDIT-C score ≥ 5) (exposure variable) and obesity indicators (WC and BMI), the primary outcomes of interest. Adjustments were made for sociodemographic, health-related, and other alcohol-related variables.

RESULTS

Total of 6864 participants, aged 25 and older, took part in this survey (response rate = 60.4%). Most of the participants (81.9%) were alcohol drinkers, with the majority drinking less than three times per week (76.3%); 47.7% were considered harmful drinkers (AUDIT-C score ≥ 5). After controlling for possible confounders, positive associations of harmful alcohol consumption with WC (β = 1.72, 95% CI: 0.25, 3.19) and BMI (OR = 1.47, 95% CI: 1.10, 1.96) were observed. Binge drinking was positively associated with WC (β = 1.71, 95% CI: 0.50, 2.91), while alcohol consumption frequency was significantly and inversely associated with BMI (OR = 0.59, 95% CI: 0.44, 0.78).

CONCLUSION

Harmful alcohol consumption was associated with obesity (high BMI, large WC) after controlling for possible confounders. Frequent binge drinkers were more likely to have a large WC, while frequent alcohol consumers were less likely to have obesity. Further longitudinal studies to examine the exact association between alcohol consumption and obesity are warranted.

Microbiota and nutrition as risk and resiliency factors following prenatal alcohol exposure

Alcohol exposure in adulthood can result in inflammation, malnutrition, and altered gastroenteric microbiota, which may disrupt efficient nutrient extraction. Clinical and preclinical studies have documented convincingly that prenatal alcohol exposure (PAE) also results in persistent inflammation and nutrition deficiencies, though research on the impact of PAE on the enteric microbiota is in its infancy. Importantly, other neurodevelopmental disorders, including autism spectrum and attention deficit/hyperactivity disorders, have been linked to gut microbiota dysbiosis. The combined evidence from alcohol exposure in adulthood and from other neurodevelopmental disorders supports the hypothesis that gut microbiota dysbiosis is likely an etiological feature that contributes to negative developmental, including neurodevelopmental, consequences of PAE and results in fetal alcohol spectrum disorders. Here, we highlight published data that support a role for gut microbiota in healthy development and explore the implication of these studies for the role of altered microbiota in the lifelong health consequences of PAE.

Effects of Acute Alcohol Consumption on Food Intake and Pictorial Stroop Response to High-Calorie Food Cues

AIMS

We examined (a) the effect of an acute dose of alcohol on the consumption of energy-dense food and (b) on cognitive bias towards high-energy-dense food cues and (3) whether the effect of an acute dose of alcohol on the consumption of energy-dense food would be mediated by cognitive bias towards high-energy-dense food cues.

METHODS

Heavy social drinkers (n = 40) abstained from drinking for 12 hours before testing. On the test day, participants completed pre-challenge measures of alcohol and food craving, and cognitive bias towards alcohol in a placebo-controlled, double-blind design. Participants performed post-challenge measures of alcohol and food craving, ad lib energy-dense food consumption and cognitive bias.

RESULTS

We did not observe any of the hypothesized interactions between challenge condition, consumption of energy-dense food and cognitive bias towards high-energy-dense food cues.

CONCLUSIONS

Our data suggest that acute alcohol consumption does not influence the consumption of energy-dense food or cognitive bias towards high-energy-dense food cues. These findings may reflect that alcohol does not increase the appetitive value of food and food-related cues or that the measures used in this study were not sensitive to detect an effect. Further research is required to determine whether alcohol at higher doses and/or food cues that are frequently paired with alcohol intake stimulates changes in food intake and the reward value of food cues.

The effect of alcohol on food-related attentional bias, food reward and intake: Two experimental studies

Acute alcohol consumption has been shown to increase food intake, and long-term alcohol consumption may be a risk for weight gain. A potential, but under-studied, mechanism for this effect is alcohol's ability to enhance food reward. In two studies, participants consumed an alcoholic drink (Study 1: 0.3 grams of alcohol per kilogram of bodyweight (g/kg); Study 2: 0.6 g/kg) and a placebo-alcohol drink in a within-subjects design. In both studies, food-related appetitive and motivational states, and attentional bias (AB) towards food-related cues were measured. In Study 1 (N = 44), participants completed a visual probe task with concurrent recording of eye-movements which measured AB towards images of palatable foods, unpalatable foods, and non-food control items. Participants also completed measures of appetite and snack urge ratings, salivary response towards palatable foods and an ad libitum food taste test. In Study 2 (N = 84), participants completed a similar procedure, but completed a modified Stroop task which measured differences in food-related and alcohol-related AB across the two drink conditions. In Study 1, there was no difference in food-related AB between drink conditions, and no differences in snack urge, appetite ratings, salivary response, or food intake. In contrast, Study 2 showed an alcohol-induced increase in AB towards food, but not alcohol. Snack urge, alcohol urge ratings and ad libitum food intake were also higher after alcohol consumption, relative to the placebo. Collectively, these findings suggest that alcohol can increase food reward and food intake, but these effects may only occur at a higher dose.

Binge Eating and Binge Drinking: A Two-Way Road? An Integrative Review

Unhealthy diet and alcohol are serious health problems, especially in adolescents and young adults. "Binge" is defined as the excessive and uncontrolled consumption of food (binge eating) and alcohol (binge drinking). Both behaviors are frequent among young people and have a highly negative impact on health and quality of life. Several studies have explored the causes and risk factors of both behaviors, and the evidence concludes that there is a relationship between the two behaviors. In addition, some research postulates that binge eating is a precipitating factor in the onset and escalation of excessive alcohol consumption, while other studies suggest that alcohol consumption leads to excessive and uncontrollable food consumption. Given that no review has yet been published regarding the directionality between the two behaviors, we have set out to provide an upto- date overview of binge eating and binge drinking problems, analyzing their commonalities and differences, and their uni- and bidirectional associations. In addition, we explore the reasons why young people tend to engage in both behaviors and consider directions for future research and clinical implications.

Manipulations of Central Amygdala Neurotensin Neurons Alter the Consumption of Ethanol and Sweet Fluids in Mice

The central nucleus of the amygdala plays a significant role in alcohol use and other affective disorders; however, the genetically-defined neuronal subtypes and projections that govern these behaviors are not well known. Here we show that neurotensin neurons in the central nucleus of the amygdala of male mice are activated by in vivo ethanol consumption and that genetic ablation of these neurons decreases ethanol consumption and preference in non-ethanol-dependent animals. This ablation did not impact preference for sucrose, saccharin, or quinine. We found that the most robust projection of the central amygdala neurotensin neurons was to the parabrachial nucleus, a brain region known to be important in feeding behaviors, conditioned taste aversion, and alarm. Optogenetic stimulation of projections from these neurons to the parabrachial nucleus is reinforcing, and increases ethanol drinking as well as consumption of sucrose and saccharin solutions. These data suggest that this central amygdala to parabrachial nucleus projection influences the expression of reward-related phenotypes and is a novel circuit promoting consumption of ethanol and palatable fluids.SIGNIFICANCE STATEMENT Alcohol use disorder (AUD) is a major health burden worldwide. Although ethanol consumption is required for the development of AUD, much remains unknown regarding the underlying neural circuits that govern initial ethanol intake. Here we show that ablation of a population of neurotensin-expressing neurons in the central amygdala decreases intake of and preference for ethanol in non-dependent animals, whereas the projection of these neurons to the parabrachial nucleus promotes consumption of ethanol as well as other palatable fluids.

Preliminary support for the role of alcohol cues in food cravings and attentional biases

This study examined whether alcohol odors, in isolation or when combined with pictures, would influence food attentional biases and cravings. Participants' cravings and attentional biases to food and alcohol pictures were assessed after exposure to alcohol or water odors ( n = 77; mean age = 30.84 years, 51.9% female, 83.1% Caucasian). Food attentional biases were increased by alcohol odors, but food cravings were increased only by a combination of alcohol odors and food pictures. These effects were related with self-reported problematic food consumption. These findings support a research program for further examining the effect of alcohol cues on problematic food consumption.

Effect of alcohol consumption on food energy intake: a systematic review and meta-analysis

The relationship between alcohol consumption and body weight is complex and inconclusive being potentially mediated by alcohol type, habitual consumption levels and sex differences. Heavy and regular alcohol consumption has been positively correlated with increasing body weight, although it is unclear whether this is due to alcohol consumption per se or to additional energy intake from food. This review explores the effects of alcohol consumption on food energy intake in healthy adults. CINAHL Plus, EMBASE, Medline and PsycINFO were searched through February 2018 for crossover and randomised controlled trials where an alcohol dose was compared with a non-alcohol condition. Study quality was assessed using the Effective Public Health Practice Project tool. A total of twenty-two studies involving 701 participants were included from the 18 427 papers retrieved. Studies consistently demonstrated no compensation for alcoholic beverage energy intake, with dietary energy intake not decreasing due to alcoholic beverage ingestion. Meta-analyses using the random-effects model were conducted on twelve studies and demonstrated that alcoholic beverage consumption significantly increased food energy intake and total energy intake compared with a non-alcoholic comparator by weighted mean differences of 343 (95 % CI 161, 525) and 1072 (95 % CI 820, 1323) kJ, respectively. Generalisability is limited to younger adults (18–37 years), and meta-analyses for some outcomes had substantial statistical heterogeneity or evidence of small-study effects. This review suggests that adults do not compensate appropriately for alcohol energy by eating less, and a relatively modest alcohol dose may lead to an increase in food consumption.

Body mass index across adolescence and substance use problems in early adulthood

Excessive substance use and obesity are underpinned by a number of shared risk factors (e.g., reward dysfunction, impulsivity). Food and drugs of abuse engage similar reward-related neural circuitry and the food-drug competition hypothesis proposes that excess consumption of food may diminish desire for drugs of abuse by competing for neural receptors associated with reward and motivation. Adolescence is a high-risk period for both increased substance use and excessive weight gain. In the present study, the authors tested whether, consistent with the food-drug competition hypothesis, elevated body mass index (BMI) across adolescence predicted fewer substance use problems in young adulthood. In a multiwave prospective study of a community sample of families enriched for high levels of substance use disorders, the authors first identified BMI trajectories across adolescence in 565 participants using latent class growth analysis. They then used maximum likelihood methods to compare the equality of mean alcohol-, drug-, and nicotine-related problems during early adulthood across adolescent BMI trajectories. Participants in the obese relative to the normal weight trajectory in adolescence had fewer drinking and illicit drug problems in early adulthood. Relative to the overweight trajectory, nicotine dependence was significantly higher among both the normal weight and obese trajectories. The current findings provide partial support for the food-drug competition hypothesis, which suggests that highly palatable foods may be rewarding enough to compete with drugs of abuse and that transdiagnostic approaches to reducing problematic substance use and overeating in adolescence may be useful. However, the relationship between nicotine and food requires further study. (PsycINFO Database Record

The relationship of alcohol use to weight loss in the context of behavioral weight loss treatment

Despite common wisdom that reducing alcohol intake will facilitate weight loss, little research has examined whether participants in behavioral weight loss treatments actually decrease their alcohol intake, or whether reduced alcohol intake relates to weight loss outcomes in this context. This study examined the relationship of alcohol use to energy intake excluding alcohol and to weight in 283 overweight and obese adults participating in a 26-session behavioral weight loss treatment. The majority of participants consumed low to moderate levels of alcohol at baseline. Participants who consumed alcohol at baseline meaningfully reduced their alcohol intake by end-of-treatment. Alcohol use did not relate to weight at baseline or end-of-treatment when controlling for relevant demographic variables, and change in alcohol use was unrelated to weight change in the overall sample during treatment. However, end-of-treatment alcohol intake did relate to end-of-treatment energy intake excluding alcohol. In addition, behavioral impulsivity and change in alcohol intake interacted to predict weight loss, such that decreases in alcohol intake were associated with greater percent weight loss at end-of-treatment for participants with higher levels of impulsivity. Alcohol consumption may lead to overeating episodes, and highly impulsive individuals may be at risk for increased energy intake during or after episodes of drinking. Therefore, the recommendation to reduce alcohol intake in the context of behavioral weight loss treatment seems warranted, particularly for individuals with high levels of impulsivity.

The apéritif effect: Alcohol's effects on the brain's response to food aromas in women

OBJECTIVE

Consuming alcohol prior to a meal (an apéritif) increases food consumption. This greater food consumption may result from increased activity in brain regions that mediate reward and regulate feeding behavior. Using functional magnetic resonance imaging, we evaluated the blood oxygenation level dependent (BOLD) response to the food aromas of either roast beef or Italian meat sauce following pharmacokinetically controlled intravenous infusion of alcohol.

METHODS

BOLD activation to food aromas in non-obese women (n = 35) was evaluated once during intravenous infusion of 6% v/v EtOH, clamped at a steady-state breath alcohol concentration of 50 mg%, and once during infusion of saline using matching pump rates. Ad libitum intake of roast beef with noodles or Italian meat sauce with pasta following imaging was recorded.

RESULTS

BOLD activation to food relative to non-food odors in the hypothalamic area was increased during alcohol pre-load when compared to saline. Food consumption was significantly greater, and levels of ghrelin were reduced, following alcohol.

CONCLUSIONS

An alcohol pre-load increased food consumption and potentiated differences between food and non-food BOLD responses in the region of the hypothalamus. The hypothalamus may mediate the interplay of alcohol and responses to food cues, thus playing a role in the apéritif phenomenon.

Alcohol, Appetite and Loss of Restraint

Alcoholic beverages have long been associated with feasts, celebration and marking special events. Today, it is commonplace to consume alcoholic beverages before, with and/or after a meal. Alcohol provides additional pleasure to the meal and enhances appetite. However, consuming an alcoholic beverage with or before a meal is associated with poor short-term energy compensation; energy from alcohol is additive to total energy intake with the added property of stimulating further eating. Limiting alcohol intake is an obvious means to reduce total energy intake for those who wish to lose weight. However, dieters and restrained eaters drink more and report greater binge drinking than unrestrained eaters despite employing cognitive strategies to reduce their intake. Increased intake may be attributable to greater attentional bias to alcohol related cues as well as to food cues, since these are more salient to those limiting intake. Alcohol increases energy intake in dieters, in part due to abandonment of restraint (disinhibition) and consumption of forbidden items including alcohol exacerbates attempts to resist temptation. Paradoxically, links between binge drinking or increased drinking frequency to overweight and obesity may be mediated by dietary restraint. Efforts to limit food and alcohol intake for weight control appear to be unsuccessful and have the net effect of promoting overconsumption. The potential role of restrained eating in the association between alcohol, appetite and obesity has been overlooked by much of the current research and further investigation of this is therefore warranted.

Factors that determine energy compensation: a systematic review of preload studies

Insufficient energy compensation after a preload (meal, snack, or beverage) has been associated with excess energy intake, but experimental studies have used heterogeneous methodologies, making energy compensation difficult to predict. The aim of this systematic review was to analyze the relative contributions of two key variables, preload physical form and intermeal interval (IMI), to differences in energy compensation. Forty-eight publications were included, from which percent energy compensation (%EC) data were extracted for 253 interventions (121 liquid, 69 semisolid, 20 solid, and 43 composite preloads). Energy compensation ranged from −370% (overconsumption, mostly of liquids) to 450% (overcompensation). A meta-regression analysis of studies reporting positive energy compensation showed that IMI (as the predominant factor) together with preload physical form and energy contributed significantly to %EC differences, accounting for 50% of the variance, independently from gender and BMI. Energy compensation was maximized when the preload was in semisolid/solid form and the IMI was 30–120 min. These results may assist in the interpretation of studies assessing the relative efficacy of interventions to enhance satiety, including functional foods and weight management products.

Diets of drinkers on drinking and nondrinking days: NHANES 2003-2008

BACKGROUND

Alcohol may affect dietary intake. However, little is known about diets on drinking days in the US population.

OBJECTIVE

We determined whether the diets of drinkers differ on drinking compared with nondrinking days.

DESIGN

Data were from the 2003-2008 NHANES Mobile Examination Center interview. We identified 1864 current drinkers (1126 men and 738 women) who completed two 24-h dietary recalls, one of which was on a drinking day and the other of which was on a nondrinking day. Sex-specific repeated-measures analyses that were adjusted for dietary recall order and recall day of the week were used to compare within-individual differences in energy, nutrient, and food-group intakes. Analyses were weighted to produce representative estimates.

RESULTS

On their drinking (compared with nondrinking) days, men consumed an excess 168 nonalcohol kcal (P < 0.01), which was reflected in higher intakes of nutrients including total protein (P < 0.001), total fat (P < 0.01), saturated fat (P < 0.01), monounsaturated fat (P < 0.01), potassium (P < 0.001), and sodium (P < 0.05). Men also had higher intakes of food groups including meat (P < 0.001), white potatoes (P < 0.05), and discretionary oil and solid fat (P < 0.05) and lower intakes of total fruit (P < 0.05) and milk (P < 0.05). Women did not consume excess nonalcohol kilocalories but had higher intakes of total fat (P < 0.05), monounsaturated fat (P < 0.05), polyunsaturated fat (P < 0.05), potassium (P < 0.01), and discretionary oil and solid fat (P < 0.05) and lower intakes of milk (P < 0.01) and milk products (P < 0.01).

CONCLUSIONS

These mostly moderate drinkers had poorer diets on drinking days. Same-day associations between alcohol and diet could be useful targets for public health efforts to improve dietary intake.

Lifestyle determinants of the drive to eat: a meta-analysis

BACKGROUND

Obesity is emerging as the most significant health concern of the 21st century. Although this is attributable in part to changes in our environment-including the increased prevalence of energy-dense food-it also appears that several lifestyle factors may increase our vulnerability to this calorie-rich landscape. Epidemiologic studies have begun to show links between adiposity and behaviors such as television watching, alcohol intake, and sleep deprivation. However, these studies leave unclear the direction of this association. In addition, studies that investigated the acute impact of these factors on food intake have reported a wide variety of effect sizes, from highly positive to slightly negative.

OBJECTIVE

The purpose of this article was to provide a meta-analysis of the relation between lifestyle choices and increases in acute food intake.

DESIGN

An initial search was performed on PubMed to collect articles relating television watching, sleep deprivation, and alcohol consumption to food intake. Only articles published before February 2012 were considered. Studies that took place in a controlled, laboratory setting with healthy individuals were included. Studies were analyzed by using 3 meta-analyses with random-effects models. In addition, a 1-factor ANOVA was run to discover any main effect of lifestyle.

RESULTS

The 3 most prominent lifestyle factors-television watching, alcohol intake, and sleep deprivation-had significant short-term effects on food intake, with alcohol being more significant (Cohen's d = 1.03) than sleep deprivation (Cohen's d = 0.49) and television watching (Cohen's d = 0.2).

CONCLUSIONS

Our results suggest that television watching, alcohol intake, and sleep deprivation are not merely correlated with obesity but likely contribute to it by encouraging excessive eating. Because these behaviors are all known to affect cognitive functions involved in reward saliency and inhibitory control, it may be that they represent common mechanisms through which this eating is facilitated.

Sociodemographic, health and lifestyle predictors of poor diets

OBJECTIVE

Poor-quality diet, regarded as an important contributor to health inequalities, is linked to adverse health outcomes. We investigated sociodemographic and lifestyle predictors of poor-quality diet in a population sample.

DESIGN

A cross-sectional analysis of the Survey of Lifestyle, Attitudes and Nutrition (SLÁN). Diet was assessed using an FFQ (n 9223, response rate = 89%), from which a dietary score (the DASH (Dietary Approaches to Stop Hypertension) score) was constructed.

SETTING

General population of the Republic of Ireland.

SUBJECTS

The SLÁN survey is a two-stage clustered sample of 10,364 individuals aged 18 years.

RESULTS

Adjusting for age and gender, a number of sociodemographic, lifestyle and health-related variables were associated with poor-quality diet: social class, education, marital status, social support, food poverty (FP), smoking status, alcohol consumption, underweight and self-perceived general health. These associations persisted when adjusted for age, gender and social class. They were not significantly altered in the multivariate analysis, although the association with social support was attenuated and that with FP was borderline significant (OR = 1·2, 95% CI 1·03, 1·45). A classical U-shaped relationship between alcohol consumption and dietary quality was observed. Dietary quality was associated with social class, educational attainment, FP and related core determinants of health.

CONCLUSIONS

The extent to which social inequalities in health can be explained by socially determined differences in dietary intake is probably underestimated. The use of composite dietary quality scores such as the DASH score to address the issue of confounding by diet in the relationship between alcohol consumption and health merits further study.

Effect on gastric function and symptoms of drinking wine, black tea, or schnapps with a Swiss cheese fondue: randomised controlled crossover trial

OBJECTIVE

To compare the effects of drinking white wine or black tea with Swiss cheese fondue followed by a shot of cherry schnapps on gastric emptying, appetite, and abdominal symptoms.

DESIGN

Randomised controlled crossover study.

PARTICIPANTS

20 healthy adults (14 men) aged 23-58.

INTERVENTIONS

Cheese fondue (3260 kJ, 32% fat) labelled with 150 mg sodium (13)Carbon-octanoate was consumed with 300 ml of white wine (13%, 40 g alcohol) or black tea in randomised order, followed by 20 ml schnapps (40%, 8 g alcohol) or water in randomised order.

MAIN OUTCOME MEASURES

Cumulative percentage dose of (13)C substrate recovered over four hours (higher values indicate faster gastric emptying) and appetite and dyspeptic symptoms (visual analogue scales).

RESULTS

Gastric emptying was significantly faster when fondue was consumed with tea or water than with wine or schnapps (cumulative percentage dose of (13)C recovered 18.1%, 95% confidence interval 15.2% to 20.9% v 7.4%, 4.6% to 10.3%; P<0.001). An inverse dose-response relation between alcohol intake and gastric emptying was evident. Appetite was similar with consumption of wine or tea (difference 0.11, -0.12 to 0.34; P=0.35), but reduced if both wine and schnapps were consumed (difference -0.40, -0.01 to -0.79; P<0.046). No difference in dyspeptic symptoms was present.

CONCLUSIONS

Gastric emptying after a Swiss cheese fondue is noticeably slower and appetite suppressed if consumed with higher doses of alcohol. This effect was not associated with dyspeptic symptoms.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00943696.

A polymorphism in GABRA2 is associated with the medial frontal response to alcohol cues in an fMRI study

BACKGROUND

Significant evidence has accumulated to suggest an association between single-nucleotide polymorphisms (SNPs) in the GABRA2 gene and alcoholism. However, research has yet to show an association between these polymorphisms and the human brain's reward system function. In this study, we stratified subjects who had participated in an fMRI study of alcohol cue responses according to their genotype at a SNP in GABRA2 (rs279871) shown to be associated with alcohol dependence (Edenberg et al., 2004).

METHODS

Genotyping showed 13 subjects to be homozygous for the high-risk allele (AA), and 23 subjects to be heterozygous (AG). In fMRI, subjects were exposed to the aromas of their preferred alcoholic drink odors (AO), as well as to appetitive control odors (ApCO) under both alcohol intoxication and placebo control conditions.

RESULTS

Homozygous AA subjects had a larger [AO > ApCO] response than did AG subjects in medial frontal cortical areas thought to code reward value. However, AG subjects had a larger [AO > ApCO] effect in the ventral tegmental area. Alcohol intoxication did not alter these group differences.

CONCLUSIONS

These are the first data to suggest that GABRA2 genotype could affect the brain's responses to cues associated with alcohol.

Alcohol, appetite and energy balance: is alcohol intake a risk factor for obesity?

The increased recognition that the worldwide increase in incidence of obesity is due to a positive energy balance has lead to a focus on lifestyle choices that may contribute to excess energy intake, including the widespread belief that alcohol intake is a significant risk factor for development of obesity. This brief review examines this issue by contrasting short-term laboratory-based studies of the effects of alcohol on appetite and energy balance and longer-term epidemiological data exploring the relationship between alcohol intake and body weight. Current research clearly shows that energy consumed as alcohol is additive to that from other dietary sources, leading to short-term passive over-consumption of energy when alcohol is consumed. Indeed, alcohol consumed before or with meals tends to increase food intake, probably through enhancing the short-term rewarding effects of food. However, while these data might suggest that alcohol is a risk factor for obesity, epidemiological data suggests that moderate alcohol intake may protect against obesity, particularly in women. In contrast, higher intakes of alcohol in the absence of alcohol dependence may increase the risk of obesity, as may binge-drinking, however these effects may be secondary to personality and habitual beverage preferences.

Family history of alcoholism mediates the frontal response to alcoholic drink odors and alcohol in at-risk drinkers

Although a family history of alcoholism is the strongest risk factor for developing alcohol dependence, there are few studies of the association between familial alcoholism and the human brain's reward system activity. We used functional magnetic resonance imaging (fMRI) to determine how family history affects the brain's response to subjects' preferred alcoholic drink odors (AO) as compared to appetitive control odors (ApCO). Fourteen non-dependent heavy drinkers (HD) who were family history positive (FHP) participated, as did 12 HD who were family history negative (FHN). Subjects were imaged under both alcohol intoxication and placebo, using intravenous infusion and pharmacokinetic modeling to target a blood alcohol level of 50 mg%. Under placebo, HD-FHP had a larger medial frontal [AO>ApCO] effect than did HD-FHN. Alcohol intoxication dampened this response in the HD-FHP but potentiated it in the HD-FHN. This suggests that a family history of alcoholism and brain exposure to alcohol interact in heavy drinkers to differentially affect how the brain responds to alcohol cues.

Acute tolerance to rate-decreasing effects of single doses of ethanol

Acute tolerance occurs when behavioral impairment is greater at a given blood ethanol concentration (BAC) on the ascending versus descending limb of the BAC-time curve following administration of a single dose of ethanol, however studies utilizing learned behaviors have not been widely reported. We assessed acute tolerance to single doses of ethanol in five Lewis rats responding under a fixed-ratio (FR8) schedule of food presentation. Response rates for food during 1-min components (ending 2, 4, 11, 18, 33, and 57 min after ethanol administration) were determined, and BAC was measured immediately after each component using a rat breathalyzer. Ethanol (0.4, 0.6, 0.8, and 1.2 g/kg, i.p.) produced dose-related decreases in responding for food that tended to recover over time for all but the highest dose tested. Similarly, dose-related increases in BAC were also observed. Using either an analysis that expressed impairment per unit BAC on the ascending limb versus the descending limb (by assessing the area under the curve (AUC) for behavior and BAC on each limb), the slope of the function that relates the behavioral effect to BAC (each expressed as percent maximum effect), or a variant of the Mellanby method (hysteresis), acute tolerance was observed following a dose of 0.4 g/kg ethanol. Though behavior appeared to recover on the descending limb following higher doses (especially 0.6 and 0.8 g/kg), acute tolerance to these doses was not present.