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

'Joining the Dots': Individual, Sociocultural and Environmental Links between Alcohol Consumption, Dietary Intake and Body Weight-A Narrative Review

Alcohol is energy-dense, elicits weak satiety responses relative to solid food, inhibits dietary fat oxidation, and may stimulate food intake. It has, therefore, been proposed as a contributor to weight gain and obesity. The aim of this narrative review was to consolidate and critically appraise the evidence on the relationship of alcohol consumption with dietary intake and body weight, within mainstream (non-treatment) populations. Publications were identified from a PubMed keyword search using the terms 'alcohol', 'food', 'eating', 'weight', 'body mass index', 'obesity', 'food reward', 'inhibition', 'attentional bias', 'appetite', 'culture', 'social'. A snowball method and citation searches were used to identify additional relevant publications. Reference lists of relevant publications were also consulted. While limited by statistical heterogeneity, pooled results of experimental studies showed a relatively robust association between acute alcohol intake and greater food and total energy intake. This appears to occur via metabolic and psychological mechanisms that have not yet been fully elucidated. Evidence on the relationship between alcohol intake and weight is equivocal. Most evidence was derived from cross-sectional survey data which does not allow for a cause-effect relationship to be established. Observational research evidence was limited by heterogeneity and methodological issues, reducing the certainty of the evidence. We found very little qualitative work regarding the social, cultural, and environmental links between concurrent alcohol intake and eating behaviours. That the evidence of alcohol intake and body weight remains uncertain despite no shortage of research over the years, indicates that more innovative research methodologies and nuanced analyses are needed to capture what is clearly a complex and dynamic relationship. Also, given synergies between 'Big Food' and 'Big Alcohol' industries, effective policy solutions are likely to overlap and a unified approach to policy change may be more effective than isolated efforts. However, joint action may not occur until stronger evidence on the relationship between alcohol intake, food intake and weight is established.

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.

Experimental and observational studies on alcohol use and dietary intake: a systematic review

The scientific literature on links among alcohol use, total energy intake, cardiometabolic disease and obesity is conflicting. To clarify the link between alcohol use and cardiometabolic health, this systematic review (PROSPERO CRD42016039308A) uses PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to synthesize how alcohol use affects dietary intake (carbohydrate, fat and protein intake) in humans. A search of Google Scholar, PsycINFO and PubMed from June 2016-March 2019 yielded 30 qualified studies. Experimental and observational studies allowed for inferences about effects of a single drinking occasion and of frequent drinking, respectively. Alcohol quantities were standardized according to the 2015-2020 Dietary Guidelines for Americans. On average, methodological quality of the studies was medium strength. Results indicated that a single occasion of light and moderate drinking as well as frequent light and moderate drinking were linked to greater fat and protein intake, albeit the majority of studies did not detect differences in dietary intake due to these drinking behaviours. Frequent heavy drinking, on the other hand, was linked to less carbohydrate intake in the majority of studies. Overall, alcohol use does not appear to uniformly affect diet but instead appears to affect intake of specific macronutrients in a dose-dependent manner, most consistently decreasing carbohydrate intake with heavier use.

Does the Neuroimmune Modulator Ibudilast Alter Food Craving? Results in a Sample With Alcohol Use Disorder

OBJECTIVE

Ibudilast (IBUD) is a neuroimmune modulator that inhibits phosphodiesterase-4 and -10 and macrophage migration inhibitory factor. A randomized, placebo-control, crossover human laboratory trial advanced IBUD development for alcohol use disorder and found that IBUD reduced tonic levels of alcohol craving. Given the importance of considering medication effects on other appetitive behavior, the present study tested the effect of IBUD (50 mg bid) on food craving.

METHOD

The present study was a secondary data analysis of the trial of IBUD in non-treatment seekers with alcohol use disorder (N = 19). High-fat/high-sugar food craving was measured daily. Moreover, because substantial literatures show that small alcohol doses and psychological stress increase eating of high-fat/high-sugar food, craving for high-fat/high-sugar food was measured after alcohol infusion and stress reactivity.

RESULTS

Results indicated that IBUD did not alter tonic high-fat/high-sugar food craving. Alcohol infusion did not generally increase high-fat/high-sugar food craving but psychological stress did. Likewise, IBUD did not affect high-fat/high-sugar food craving after alcohol infusion but IBUD did increase high-fat/high-sugar food craving after psychological stress. Follow-up analyses revealed that, among individuals with lower depressive symptomatology, IBUD compared to placebo heightened the effect of psychological stress on high-fat/high-sugar food craving.

CONCLUSIONS

These results advance the development of IBUD for addiction indications by demonstrating that IBUD compared to placebo does not suppress other appetitive responses, namely craving for high-fat/high-sugar food among individuals with alcohol use disorder.

Hypothalamic Responses to Cocaine and Food Cues in Individuals with Cocaine Dependence

BACKGROUND

Individuals with cocaine addiction are characterized by under-responsiveness to natural reinforcers. As part of the dopaminergic pathways, the hypothalamus supports motivated behaviors. Rodent studies suggested inter-related roles of the hypothalamus in regulating drug and food intake. However, few studies have investigated hypothalamic responses to drugs and food or related cues in humans.

METHODS

We examined regional responses in 20 cocaine-dependent and 24 healthy control participants exposed to cocaine/food (cocaine dependent) and food (healthy control) vs neutral cues during functional magnetic resonance imaging. We examined the relationship between imaging findings and clinical variables and performed mediation analyses to examine the inter-relationships between cue-related activations, tonic cocaine craving, and recent cocaine use.

RESULTS

At a corrected threshold, cocaine-dependent participants demonstrated higher activation to cocaine than to food cues in the hypothalamus, inferior parietal cortex, and visual cortex. Cocaine-dependent participants as compared with healthy control participants also demonstrated higher hypothalamic activation to food cues. Further, the extent of these cue-induced hypothalamic activations was correlated with tonic craving, as assessed by the Cocaine Craving Questionnaire, and days of cocaine use in the prior month. In mediation analyses, hypothalamic activation to cocaine and food cues both completely mediated the relationship between the Cocaine Craving Questionnaire score and days of cocaine use in the past month.

CONCLUSIONS

The results were consistent with the proposition that the mechanisms of feeding and drug addiction are inter-linked in the hypothalamus and altered in cocaine addiction. The findings provide new evidence in support of hypothalamic dysfunction in cocaine addiction.

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.

Alcohol Intake and Weight Loss During Intensive Lifestyle Intervention for Adults with Overweight or Obesity and Diabetes

OBJECTIVE

This study aimed to assess whether alcohol consumption decreases during an intensive lifestyle intervention (ILI) and whether alcohol consumption is associated with weight loss among participants with overweight or obesity and type 2 diabetes.

METHODS

Participants (n = 4,901) were from the Action for Health in Diabetes (Look AHEAD) study, a randomized controlled trial that compared an ILI with a diabetes support and education (DSE) control. Mixed-effects models were used to estimate the effect of the ILI on alcohol consumption and the influence of alcohol consumption on weight loss at year 4.

RESULTS

ILI and DSE participants did not differ in changes in alcohol consumption. Alcohol intake was not associated with weight loss at year 1 of the ILI. ILI participants who abstained from alcohol lost 5.1% ± 0.3% of initial weight at year 4 compared with a significantly (P = 0.04) smaller 2.4% ± 1.3% for consistent heavy drinkers. ILI participants who abstained from alcohol consumption over the 4 years lost 1.6% ± 0.5% more weight relative to individuals who drank alcohol at any time during the intervention (P = 0.003). DSE participants did not differ in weight loss by alcohol consumption.

CONCLUSIONS

Heavy alcohol drinkers are at risk for suboptimal long-term weight loss. Decreasing alcohol consumption may improve weight management among individuals with diabetes.

Resting State Functional Connectivity of the Lateral and Medial Hypothalamus in Cocaine Dependence: An Exploratory Study

The role of dopamine in cocaine misuse has been extensively documented for the mesocorticolimbic circuit. Preclinical work from earlier lesion studies to recent multidisciplinary investigations has suggested that the hypothalamus is critically involved in motivated behavior, with the lateral and medial hypothalamus each involved in waking/feeding and resting/satiety. However, little is known of hypothalamus function and dysfunction in cocaine misuse. Here, we examined resting state functional connectivity of the lateral and medial hypothalamus in 70 individuals with cocaine dependence (CD) and 70 age as well as gender matched healthy controls (HC). Image pre-processing and analyses followed published work. Compared to HC, CD showed increased lateral hypothalamic connectivity with dorsolateral prefrontal cortex and decreased functional connectivity with the ventral precuneus. CD showed increased medial hypothalamic connectivity with the inferior parietal lobule and decreased connectivity with the ventromedial prefrontal cortex, temporal gyrus, fusiform gyrus, and ventral striatum. Further, at trend level significance, the connectivity strength between lateral hypothalamus and dorsolateral prefrontal cortex was positively correlated with total amount of cocaine use in the past month (p = 0.004, r = 0.35) and the connectivity strength between medial hypothalamus and ventral striatum was negatively correlated with cocaine craving as assessed by the Tiffany Cocaine Craving Questionnaire (p = 0.008, r = -0.33). Together, the findings demonstrated altered resting state functional connectivity of the hypothalamus and may provide new insight on circuit level deficits in cocaine dependence.

Cancer anorexia: hypothalamic activity and its association with inflammation and appetite-regulating peptides in lung cancer

BACKGROUND

Energy homeostasis is mediated by the hypothalamus, whose inflammation-induced functional derangements contribute to the onset of anorexia in cancer. By using functional magnetic resonance imaging (fMRI), we determined the patterns of hypothalamic activation after oral intake in anorexic (A), non-anorexic (NA) cancer patients, and in controls (C).

METHODS

Lung cancer patients were considered. Hypothalamic activation was recorded in A and NA patients and in C by fMRI, before (T0), immediately after (T1) the administration of an oral nutritional supplement, and after 15 min (T2). The grey of the hypothalamus and Blood Oxygen Level Dependent (BOLD) intensity were calculated and normalized for basal conditions. Interleukin (IL)-1, IL-6, tumour necrosis factor (TNF)-α, ghrelin, and leptin plasma levels were measured. A statistical parametric mapping was used.

RESULTS

Thirteen lung cancer patients (7 M, 6 F; 9A, 4NA) and 2 C (1 M, 1 F) were enrolled. Controls had the lowest BOLD intensity. At all-time points, anorexic patients showed lower hypothalamic activity compared with NA (P < 0.001) (T0: 585.57 ± 55.69 vs. 667.92 ± 33.18, respectively; T1: 536.50 ± 61.70 vs. 624.49 ± 55.51, respectively; T2: 556.44 ± 58.51 vs. 615.43 ± 71.50, respectively). Anorexic patients showed greater BOLD signal reduction during T0-T1 than NA (-8.5% vs. -6.80%, P < 0.001). Independently from the presence of anorexia, BOLD signals modification before and after oral challenge correlated with basal values of IL-1 and ghrelin (P < 0.001).

CONCLUSIONS

Hypothalamic activity in A cancer patients is reduced respect to NA and responds differently to oral challenges. This suggests a central control of appetite dysregulation during cancer anorexia, before, and after oral intake.

Agrp neuron activity is required for alcohol-induced overeating

Alcohol intake associates with overeating in humans. This overeating is a clinical concern, but its causes are puzzling, because alcohol (ethanol) is a calorie-dense nutrient, and calorie intake usually suppresses brain appetite signals. The biological factors necessary for ethanol-induced overeating remain unclear, and societal causes have been proposed. Here we show that core elements of the brain's feeding circuits-the hypothalamic Agrp neurons that are normally activated by starvation and evoke intense hunger-display electrical and biochemical hyperactivity on exposure to dietary doses of ethanol in brain slices. Furthermore, by circuit-specific chemogenetic interference in vivo, we find that the Agrp cell activity is essential for ethanol-induced overeating in the absence of societal factors, in single-housed mice. These data reveal how a widely consumed nutrient can paradoxically sustain brain starvation signals, and identify a biological factor required for appetite evoked by alcohol.