Sweet liking, novelty seeking, and gender predict alcoholic status

Sweet liking predicts liking and familiarity of some alcoholic beverages, but not alcohol intake: A population study using a split-sample approach

Sweetness has been proposed to be an important quality in the decision to consume alcohol, and strong preferences for sweet tastes have been associated with alcohol abuse. However, alcohol is characterized by a number of other sensory properties, including astringency and bitterness that may drive preference and consumption. Spinelli et al. (2021) classified individuals into three sweet-sensory liking clusters (High Sweet-Liking, Moderate Sweet-Liking, and Inverted-U) that differed in their sweetness optima and sensory-liking patterns (relationship between liking and sweetness, bitterness and astringency perception in a food model). The current paper replicates the sweet sensory-liking clusters in a new set of participants (n = 1976), and extends the predicted value of these clusters examining their relationship to wine and other types of alcoholic beverages by gender using a split-sample approach on a total of over 3000 adults. The sweet sensory-liking clusters had a predictive relationship for the familiarity and liking of some alcoholic beverages characterized by stronger tastes, but not weekly alcohol intake levels. Thus, although sweet sensory-liking clusters may be associated with the type of beverages and frequency with which a person will drink and enjoy a type of alcoholic beverage, they are poor predictors of the quantity of alcohol that a person ingests over the course of a week.

Daily associations between alcohol and sweets craving and consumption in early AUD recovery: Results from an ecological momentary assessment study

INTRODUCTION

Alcohol cravings can predict relapse in persons with alcohol use disorder (AUD). Consuming sweets is a commonly recommend strategy to quell alcohol cravings in early recovery from AUD, yet research is equivocal on whether consuming sweets mitigates alcohol cravings or relapse risk. The current study used ecological momentary assessment (EMA) data to examine real-time alcohol cravings, sweet cravings, and consumption of sweets among adults in early recovery from AUD.

METHODS

We used EMA methods to follow 25 adults (n = 14 women, 56%; M. age 40, S.D. 10.68) recently discharged from a partial hospitalization program for AUD for 21 days. Prompts were sent to the participants for completion four times per day via a mobile app. EMA data were disaggregated prior to analysis to examine between- and within-person effects. A series of three mixed linear models tested: 1) the contemporaneous effect of sweet and alcohol cravings, 2) alcohol cravings predicting sweet consumption later in the day, and 3) sweet consumption predicting alcohol craving later in the day.

RESULTS

The results of the first model revealed alcohol cravings were associated with sweet cravings early in recovery. In the second model, no effect occurred between alcohol cravings earlier in the day predicting sweet consumption later in the day. The third model suggested consuming sweets earlier in the day predicted higher alcohol cravings later in the day.

DISCUSSION

Sweet craving and consumption are associated with alcohol cravings among adults in early recovery from AUD. These findings suggest consuming sweets may increase alcohol cravings. If future studies can replicate this result, consuming sweets in early recovery may emerge as a potential risk for relapse in this population.

Gustatory Dysfunction among a Sample of Depressed Egyptian Adults under Antidepressants Therapy: A Retrospective Cohort Study

It is quite clear that the ability to perceive taste sensations significantly affects food choice, which consequently affects health status in the long term. Gustatory dysfunction is a neglected symptom among the depressed patients and those under antidepressants therapy, although these patients are suspectable to oral problems, due to general self-negligence related to mental disease, fear of dental treatment, and side effects of varied medications utilized in psychiatry. This study is aimed at assessing gustatory thresholds (detection and recognition thresholds) among a sample of 30 depressed Egyptian adults under antidepressants therapy for at least 3 months or psychotherapy with age ranging from 20 to 50 years old, seeking the Psychiatric Clinic at the Faculty of Medicine, Cairo University, Egypt. These patients were distributed into three equal groups (tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRIs), and psychotherapy) and were assessed for gustatory detection and recognition thresholds using the filter paper disc method through a scoring system. The participants were also divided into normal taste group in which both the detection and recognition scores were 1, while the scores from 2 till 5 were considered as hypogeusia group and the score of 6 was considered as dysgeusia group. The TCA group was statistically significant from the other 2 groups in sweet detection thresholds (p = 0.043) and sweet recognition thresholds (p = 0.007). Hypogeusia for sweet was statistically significant (p = 0.041), where it was more common among TCA (70%) than both SSRIs and the psychotherapy group (20%). Gustatory dysfunction was found to be mostly associated with TCA followed by SSRIs particularly for sweet taste thresholds. More attention has to be given to taste changes among these patients as oral health affects general health by causing considerable pain and by changing what people eat, their speech, and their quality of life and wellbeing. Proper awareness and evaluation of this problem will improve the quality of life for the depressed patients and avoid unnecessary treatment. This trial is registered with ClinicalTrials.gov ID: NCT03599011.

Combined alcoholic and non-alcoholic steatohepatitis

While metabolic syndrome and alcohol consumption are the two main causes of chronic liver disease, one of the two conditions is often predominant, with the other acting as a cofactor of morbimortality. It has been shown that obesity and alcohol act synergistically to increase the risk of fibrosis progression, hepatic carcinogenesis and mortality, while genetic polymorphisms can strongly influence disease progression. Based on common pathogenic pathways, there are several potential targets that could be used to treat both diseases; based on the prevalence and incidence of these diseases, new therapies and clinical trials are needed urgently.

The relationship of personality traits to substance abuse in patients with bipolar disorder

Purpose

The aim of this study is to determine if personality traits contribute to the likelihood of substance abuse in Bipolar Disorder (BD).

Subjects/materials and methods

Fifty-nine patients meeting DSM-IV criteria for BD: 20 without any history of Substance Related Disorder (SRD), 21 with a lifetime history of SRD but without current SRD, and 18 with current SRD. Patients filled out the TCI, the differences were analyzed by ANOVA and the likelihood was obtained by Multinomial Logistic Regression.

Results

Only Novelty Seeking (NS) is statistically different between the groups. Patients with BD with current SRD have higher rates in NS than those with past SRD, and those without a history of SRD. NS was confirmed as a predicting variable, both to current SRD (OR [CI 95%] = 1.039/1.351; p = 0.011) and past SRD (OR [CI 95%] = 1.004/1.277; p = 0.042) on patients with BD.

Discussion

The results shown would appear to confirm the relationship of NS with the SRD, so long as there is no clear evidence that indicates the association of NS with BD.

Conclusions

There appears a greater predisposition to develop SRD in those patients with a higher degree of NS. The use of the Cloninger's TCI could be used in BD to determine the risk of developing an SRD. Early detection might help improve prognosis.

Using behavioral economic variables to predict future alcohol use in a crowdsourced sample

BACKGROUND

Theoretical perspectives at the intersection of behavioral economics and operant theory have resulted in numerous advances for addiction science. Three mechanisms (i.e. behavioral economic demand [consumption-price relationships], delay discounting [reinforcer devaluation with delay], and proportionate alcohol-related reinforcement [relative reinforcement attributable to alcohol]) are proposed to contribute to problematic alcohol use. Limited research has evaluated the unique contribution of these mechanisms for predicting future alcohol consumption.

AIM

The purpose of this study was to evaluate the predictive relationship between these mechanisms and self-reported alcohol use frequency, quantity, and severity.

METHODS

Participants (n=223) sampled from the crowdsourcing website Amazon Mechanical Turk completed a survey containing behavioral economic measures. Weekly reports of daily alcohol use were then collected for 18 weeks. Unadjusted and adjusted models determined the association between behavioral economic variables and alcohol use.

RESULTS/OUTCOMES

Behavioral economic measures were associated with alcohol and soda use at baseline in a stimulus-selective manner (e.g. alcohol demand associated with alcohol, but not soda, variables). Predictive models adjusted for Alcohol Use Disorder Identification Test scores indicated that increased proportionate alcohol-related reinforcement and behavioral economic demand were uniquely and incrementally associated with frequency (e.g. adjusted odds ratio (AOR)=5.54 for proportionate alcohol-related reinforcement, p<0.05) and quantity-severity measures (e.g. AOR=7.58 for alcohol demand intensity, p<0.001), respectively. Test-retest reliability was generally acceptable (r_xx=0.42-0.76) with the exception of proportionate alcohol-related reinforcement (r_xx=0.29).

CONCLUSION/INTERPRETATION

These findings indicate the unique, predictive, and incremental validity of behavioral economic measures for evaluating future alcohol consumption, supporting their continued use in addiction science research.

Quantifying Sweet Taste Liker Phenotypes: Time for Some Consistency in the Classification Criteria

Taste hedonics is a well-documented driver of food consumption. The role of sweetness in directing ingestive behavior is largely rooted in biology. One can then intuit that individual differences in sweet-liking may constitute an indicator of variations in the susceptibility to diet-related health outcomes. Despite half a century of research on sweet-liking, the best method to identify the distinct responses to sweet taste is still debated. To help resolve this issue, liking and intensity ratings for eight sucrose solutions ranging from 0 to 1 M were collected from 148 young adults (29% men). Hierarchical cluster analysis (HCA) revealed three response patterns: a sweet-liker (SL) phenotype characterized by a rise in liking as concentration increased, an inverted U-shaped phenotype with maximum liking at 0.25 M, and a sweet-disliker (SD) phenotype characterized by a decline in liking as a function of concentration. Based on sensitivity and specificity analyses, present data suggest the clearest discrimination between phenotypes is seen with 1.0 M sucrose, where a liking rating between -15 and +15 on a -50/+50 scale reliably distinguished individuals with an inverted U-shaped response from the SLs and the SDs. If the efficacy of this approach is confirmed in other populations, the discrimination criteria identified here can serve as the basis for a standard method for classifying sweet taste liker phenotypes in adults.

Identifying and Characterizing Subpopulations of Heavy Alcohol Drinkers Via a Sucrose Preference Test: A Sweet Road to a Better Phenotypic Characterization?

Aims

Sweet preference in individuals with alcohol use disorder (AUD) has been associated with family history of AUD and personality traits. Therefore, testing sweet preference may help identify subpopulations of AUD individuals.

Short summary

Sweet preference has been associated with family history of AUD and personality traits. We compared heavy drinkers based on their sweet liker status and using two cutoffs. Our findings support the role of sweet preference in heavy drinkers and point to the importance of how sweet likers are defined.

Methods

This study aimed at describing and comparing heavy drinkers based on their sweet liker status, through demographic, neuroendocrine, inflammatory, behavioral and drinking characteristics. Participants rated the pleasantness and intensity of sucrose solutions (0.05, 0.10, 0.21, 0.42 and 0.83 M). Two cutoffs were used to identify likers versus dislikers: Grouping A likers preferred 0.83 M and Grouping B likers preferred 0.83 or 0.42 M; the rest were dislikers.

Results

Sweet likers were 36% (n = 20) using Grouping A and 58.2% (n = 32) using Grouping B. Grouping B, but not Grouping A, sweet likers had higher BMI (P = 0.01). In Grouping B, sweet likers had higher plasma leptin and insulin concentrations and higher insulin resistance (P's < 0.05). C-reactive protein concentrations were higher in sweet likers in Grouping A (P = 0.0015) and at a trend level in Grouping B (P = 0.07). Grouping A sweet likers had higher alcohol craving (P = 0.0004). Sweet likers preferred spirits compared to nonspirits (wine and beer) across both grouping (P's < 0.05).

Conclusions

These results provide further support for the role of sweet liking phenotype in identifying subpopulations of AUD individuals. These findings also point to the importance of how sweet likers are defined, therefore highlighting the need for further research.

Thalamic Cortical Error-Related Responses in Adult Social Drinkers: Sex Differences and Problem Alcohol Use

BACKGROUND

Error-related brain activities are altered in individuals with substance use disorders. Here we examined error-related activities in relation to problem drinking in nondependent alcohol drinkers. In particular, we investigated sex differences and whether altered error responses are related to post-error behavioral control.

METHODS

A sample of 145 nondependent drinkers (77 women) performed the stop-signal task during functional magnetic resonance imaging. Imaging data were processed and modeled using statistical parametric mapping. Independent sample t test and linear regression were employed to examine sex differences in error response and relationship between error response and problem drinking.

RESULTS

Compared with men, women showed greater error-related (stop error > go success) activations in the bilateral thalamus, right middle/superior temporal cortex, and bilateral dorsal anterior cingulate cortex. In whole-brain linear regression of error responses against the Alcohol Use Disorders Identification Test score, a wide swath of cortical and subcortical regions, including the thalamus, showed decreased activation in association with problem drinking in women but not in men. However, men and women were not different in the extent of post-error slowing and decreased thalamic error response in association with problem drinking was not related to the extent of post-error slowing in women.

CONCLUSIONS

The results suggest sex differences in error-related activations with heavier drinking associated with reduced error activations in women but not in men. These differences in cerebral activations may reflect higher physiological arousal in response to errors and greater vulnerability of saliency-related arousal response to problem drinking in female as compared with male social drinkers.

Family history of alcoholism and the human brain response to oral sucrose

A heightened hedonic response to sweet tastes has been associated with increased alcohol preference and alcohol consumption in both humans and animals. The principal goal of this study was to examine blood oxygenation level dependent (BOLD) activation to high- and low-concentration sweet solutions in subjects who are either positive (FHP) or negative (FHN) for a family history of alcoholism. Seventy-four non-treatment seeking, community-recruited, healthy volunteers (22.8 ± 1.6 SD years; 43% men) rated a range of sucrose concentrations in a taste test and underwent functional magnetic resonance imaging (fMRI) during oral delivery of water, 0.83 M, and 0.10 M sucrose. Sucrose compared to water produced robust activation in primary gustatory cortex, ventral insula, amygdala, and ventral striatum. FHP subjects displayed greater bilateral amygdala activation than FHN subjects in the low sucrose concentration (0.10 M). In secondary analyses, the right amygdala response to the 0.10 M sucrose was greatest in FHP women. When accounting for group differences in drinks per week, the family history groups remained significantly different in their right amygdala response to 0.10 M sucrose. Our findings suggest that the brain response to oral sucrose differs with a family history of alcoholism, and that this response to a mildly reinforcing primary reward might be an endophenotypic marker of alcoholism risk.

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Studies in humans and animals have suggested sweet tastes as a trait correlate of alcohol risk.

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Oral sucrose resulted in robust BOLD activation of gustatory and limbic areas.

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Amygdala responses to 0.10 M sucrose were greatest in drinkers with family histories of alcoholism.

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This study is first to suggest endophenotypic brain responses to sucrose in familial alcoholism.

Sweet taste liking is associated with subjective response to amphetamine in women but not men

RATIONALE AND OBJECTIVE

Preference for sweet taste rewards has been linked to the propensity for drug use in both animals and humans. Here, we tested the association between sweet taste liking and sensitivity to amphetamine reward in healthy adults. We hypothesized that sweet likers would report greater euphoria and stimulation following D-amphetamine (20 mg) compared to sweet dislikers.

METHODS

Men (n = 36) and women (n = 34) completed a sweet taste test in which they rated their liking of various concentrations of sucrose and filtered water (0.05, 0.10, 0.21, 0.42, and 0.83 M). Participants who preferred the highest concentration were classified as "sweet likers." All others were classified as "sweet dislikers." They then completed four sessions in which they received D-amphetamine (20 mg) and placebo in alternating order, providing self-report measures of euphoria and stimulation on the Addiction Research Center Inventory (ARCI) at regular intervals. We conducted linear mixed effects models to examine relationships between sweet liking and drug-induced euphoria and stimulation.

RESULTS

Sweet likers reported significantly greater amphetamine-induced euphoria than did sweet dislikers among women. By contrast, sweet liking was not associated with amphetamine response in men. No associations with stimulation were observed.

CONCLUSION

The association between sweet preference and amphetamine response in women is consistent with animal studies linking sweet taste preference and drug reward and also fits with observations that individuals who use drugs show a preference for sweet tastes. Whether the sex difference is related to circulating hormones, or other variables, remains to be determined.

The prevalence of food addiction in a large sample of adolescents and its association with addictive substances

The prevalence of overweight and obesity is increasing, due to, among other factors, increased availability of highly palatable food (food high in fat, salt and/or sugar). It has been proposed that certain foods and/or eating behaviours may be addictive, to a degree comparable to substances of abuse. The Yale Food Addiction Scale (YFAS) measures 'food addiction' by translating the diagnostic criteria for substance use disorder to eating behaviour. So far, only a few studies have examined the prevalence of food addiction in children with the YFAS for children (YFAS-C). Large-scale studies, especially among adolescents, are lacking. Adolescence is of particular interest because it is a period wherein unhealthy eating behaviours or addictive tendencies are likely to develop. The current study examines the prevalence of food addiction using the YFAS-C in a large group of Dutch adolescents (N = 2653) aged 14-21 years. With Generalized Estimation Equation (GEE) analysis we tested the relationship between food addiction symptoms and smoking, cannabis use, alcohol use, and sugar intake through drinks, while controlling for gender, age, educational level and weight class. In the total sample 2.6% met the criteria for a food addiction 'diagnosis', and the average symptom count was 1.0 (SD = 1.3, range 0-7). Symptoms of food addiction were positively associated with smoking, alcohol use, cannabis use and sugar intake. We propose that future studies focus on possible genetic/(neuro)biological mechanisms involved in both food addiction and substance use and that longitudinal designs are needed to examine possible causal pathways.

Sex differences in the interacting roles of impulsivity and positive alcohol expectancy in problem drinking: A structural brain imaging study

Alcohol expectancy and impulsivity are implicated in alcohol misuse. However, how these two risk factors interact to determine problem drinking and whether men and women differ in these risk processes remain unclear. In 158 social drinkers (86 women) assessed for Alcohol Use Disorder Identification Test (AUDIT), positive alcohol expectancy, and Barratt impulsivity, we examined sex differences in these risk processes. Further, with structural brain imaging, we examined the neural bases underlying the relationship between these risk factors and problem drinking. The results of general linear modeling showed that alcohol expectancy best predicted problem drinking in women, whereas in men as well as in the combined group alcohol expectancy and impulsivity interacted to best predict problem drinking. Alcohol expectancy was associated with decreased gray matter volume (GMV) of the right posterior insula in women and the interaction of alcohol expectancy and impulsivity was associated with decreased GMV of the left thalamus in women and men combined and in men alone, albeit less significantly. These risk factors mediated the correlation between GMV and problem drinking. Conversely, models where GMV resulted from problem drinking were not supported. These new findings reveal distinct psychological factors that dispose men and women to problem drinking. Although mediation analyses did not determine a causal link, GMV reduction in the insula and thalamus may represent neural phenotype of these risk processes rather than the consequence of alcohol consumption in non-dependent social drinkers. The results add to the alcohol imaging literature which has largely focused on dependent individuals and help elucidate alterations in brain structures that may contribute to the transition from social to habitual drinking.

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Alcohol expectancy (AE) and impulsivity are risk factors for problem drinking.

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AE mediates the correlation between right insula GMV and problem drinking in women.

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AE and impulsivity interacts to mediate left thalamus GMV and problem drinking in all.

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Models where changes in GMV as a result of problem drinking are not supported.

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.

Heritability of high sugar consumption through drinks and the genetic correlation with substance use

BACKGROUND

High sugar consumption contributes to the rising prevalence of obesity. Sugar can have rewarding effects that are similar to, but less strong than, the effects of addictive substances. People who consume large amounts of sugar also tend to use more addictive substances, but it is unclear whether this is due to shared genetic or environmental risk factors.

OBJECTIVE

We examined whether there are genetic influences on the consumption of sugar-containing drinks and whether genetic factors can explain the association with substance use.

DESIGN

The frequency of consumption of sugar-containing drinks (e.g., cola, soft drinks, and energy drinks) and addictive substances (nicotine, caffeine, alcohol, cannabis, and illicit drugs) was obtained for 8586 twins who were registered at the Netherlands Twin Register (women: 68.7%; mean ± SD age: 33.5 ± 15.3 y). Participants were categorized as high or low sugar consumers (>1 compared with ≤1 SD above daily consumption in grams) and as high or low substance users (≥2 compared with <2 substances). Through bivariate genetic modeling, genetic and environmental influences on sugar consumption, substance use, and their association were estimated.

RESULTS

Genetic factors explained 48% of the variation in high sugar consumption, whereas unique environmental factors explained 52%. For high substance use, these values were 62% and 38%, respectively. There was a moderate phenotypic association between high sugar consumption and high substance use (r = 0.2), which was explained by genetic factors (59%) and unique environmental factors (41%).

CONCLUSIONS

The positive association between high sugar consumption and high substance use was partly due to unique environmental factors (e.g., social situations). Genetic factors were also of influence, suggesting that neuronal circuits underlying the development of addiction and obesity are related. Further research is needed to identify genes that influence sugar consumption and those that overlap with substance use.

Hemispheric Lateralization of Resting-State Functional Connectivity of the Anterior Insula: Association with Age, Gender, and a Novelty-Seeking Trait

Resting-state functional connectivity (rsFC) is widely used to examine cerebral functional organization. The imaging literature has described lateralization of insula activations during cognitive and affective processing. Evidence appears to support a role of the right-hemispheric insula in attentional orientation to salient stimulus, interoception, and physiological arousal, and a role of the left-hemispheric insula in cognitive and affective control, as well as perspective taking. In this study, in a large data set of healthy adults, we examined lateralization of the rsFC of the anterior insula (AI) by computing a laterality index (LI) of connectivity with 54 regions from the Automated Anatomic Labeling atlas. At a corrected threshold (p < 0.001), the AI is left lateralized in connectivity with the dorsomedial prefrontal cortex, superior frontal gyrus, inferior frontal cortex, and posterior orbital gyrus and right lateralized in connectivity with the postcentral gyrus, supramarginal gyrus, and superior parietal lobule. In gender differences, women, but not men, showed right-lateralized connectivity to the thalamus. Furthermore, in a subgroup of participants assessed by the tridimensional personality questionnaire, novelty seeking is correlated with the extent of left lateralization of AI connectivity to the pallidum and putamen in men and with the extent of right lateralization of AI connectivity to the parahippocampal gyrus in women. These findings support hemispheric functional differentiation of the AI.

Perceptual Qualities of Ethanol Depend on Concentration, and Variation in These Percepts Associates with Drinking Frequency

INTRODUCTION

Ethanol, the pharmaceutically active ingredient in all alcoholic beverages, elicits multiple percepts including sweet, bitter, drying, and burning. However, quality-specific perceptual dose-response functions have not been previously reported. Also, individual differences in ethanol perception may associate with differences in alcoholic beverage use. Here, we describe the chemosensory profile of ethanol across concentrations in a convenience sample of mixed-age adults; secondarily, we explore whether individual differences in various qualities from ethanol associate with alcohol use behaviors.

METHODS

Participants (n=100, 33 men) aged 21 to 55 (mean 33 years) tasted ethanol in water (4, 8, 16, 32, and 48 % v/v) and rated sweetness, bitterness, drying, and burning/tingling on four general Labeled Magnitude Scales. Demographic question and alcohol use measures (years drinking and reported frequency of drinking occasions) were also collected.

RESULTS

Intensity of most qualities increased as a function of ethanol concentration, although the dominant sensation differed with concentration. The dominant sensation for 8 and 16 % ethanol was bitterness (7.4±1.0; 13.5±1.4), whereas for 32 and 48 % ethanol, burning/tingling was the dominant sensation (29.7±2.1; 44.7±2.4). Variation in quality-specific intensities of sampled ethanol explained variability in the reported intake frequency for beer, wine, straight spirits, and number of drinking occasions. The number of years reported drinking (grand mean 10.5±0.8) was not significantly associated with perceptual ratings for sampled ethanol.

CONCLUSIONS

In a convenience sample of mixed-aged adults, the sensations from suprathreshold ethanol varied by concentration: bitterness dominated at lower concentrations, while burn dominated at higher concentrations. Exploratory analyses also suggest that differences in chemosensory responses across participants may associate with measures of alcohol use.

Association of a novel TAS2R38 haplotype with alcohol intake among Mexican-Mestizo population

BACKGROUND

Alcohol intake has been associated with the bitter taste receptor T2R38. TAS2R38 gene expresses two common haplotypes: PAV and AVI. It has been reported that AVI homozygotes consume more alcohol than heterozygotes and PAV homozygotes. The aim of this study was to determine the prevalence of the TAS2R38 haplotypes among Mexican-Mestizo population and to analyze its association with alcohol intake.

MATERIAL AND METHODS

In a cross-sectional study, a total of 375 unrelated Mestizo individuals were genotyped for TAS2R38 polymorphisms (A49P, V262A and I296V) by a Real-Time PCR System (TaqMan). Haplotype frequencies were calculated. Association of TAS2R38 haplotypes with alcohol intake was estimated in drinkers (DRS) and nondrinkers (NDRS).

RESULTS

Two haplotypes accounted for over 96% of all haplotypes(AVV, 60%, and PAI, 36.5%). The frequency of AVV homozygotes was significantly higher in DRS than NDRS(47.2 vs. 32.2%, respectively; p < 0.05). Additionally, the AVV/AVV genotype was associated with alcohol intake when compared with heterozygotes and PAI homozygotes (OR = 1.79, 95% CI 1.13-2.84, p < 0.05 and OR = 2.23, 95% CI 1.11-4.48; p < 0.05, respectively).

CONCLUSIONS

In conclusion, two TAS2R38 haplotypes(AVV and PAI) prevailed in Mexican-Mestizo population. The novel AVV haplotype was associated with alcohol intake. The high prevalence of this allelic profile in our population could help to explain, at least in part, the preference for alcohol among the Mexicans.

Aggression and increased glutamate in the mPFC during withdrawal from intermittent alcohol in outbred mice

RATIONALE

Disrupted social behavior, including occasional aggressive outbursts, is characteristic of withdrawal from long-term alcohol (EtOH) use. Heavy EtOH use and exaggerated responses during withdrawal may be treated using glutamatergic N-methyl-D-aspartate receptor (NMDAR) antagonists.

OBJECTIVES

The current experiments explore aggression and medial prefrontal cortex (mPFC) glutamate as consequences of withdrawal from intermittent access to EtOH and changes in aggression and mPFC glutamate caused by NMDAR antagonists memantine and ketamine.

METHODS

Swiss male mice underwent withdrawal following 1-8 weeks of intermittent access to 20 % EtOH. Aggressive and nonaggressive behaviors with a conspecific were measured 6-8 h into EtOH withdrawal after memantine or ketamine (0-30 mg/kg, i.p.) administration. In separate mice, extracellular mPFC glutamate after memantine was measured during withdrawal using in vivo microdialysis.

RESULTS

At 6-8 h withdrawal from EtOH, mice exhibited more convulsions and aggression and decreased social contact compared to age-matched water controls. Memantine, but not ketamine, increased withdrawal aggression at the 5-mg/kg dose in mice with a history of 8 weeks of EtOH but not 1 or 4 weeks of EtOH or in water drinkers. Tonic mPFC glutamate was higher during withdrawal after 8 weeks of EtOH compared to 1 week of EtOH or 8 weeks of water. Five milligrams per kilogram of memantine increased glutamate in 8-week EtOH mice, but also in 1-week EtOH and water drinkers.

CONCLUSIONS

These studies reveal aggressive behavior as a novel symptom of EtOH withdrawal in outbred mice and confirm a role of NMDARs during withdrawal aggression and for disrupted social behavior.

Impulsive choice predicts anxiety-like behavior, but not alcohol or sucrose consumption, in male Long-Evans rats

BACKGROUND

Prior human research indicates robust, positive relations between impulsive choice (i.e., preference for smaller, immediate over larger, delayed rewards) and alcohol use disorders. However, varied findings in the nonhuman literature reveal a relatively ambiguous relation between impulsive choice and alcohol consumption in rodents. In addition, few rodent studies have investigated potential relations between impulsive choice and common covariates of alcohol consumption (e.g., avidity for sweet substances or anxiety-like behavior).

METHODS

Ninety-two male Long-Evans rats completed an impulsive-choice task. From this larger sample, extreme high- and low-impulsive groups (n = 30 each) were retained for further testing. In separate tests, subsequent open-field behavior and consumption of oral alcohol (12% w/v) and isocaloric sucrose were examined. Impulsive choice was then retested to examine whether behavior remained stable over the course of the experiment.

RESULTS

No significant relations emerged between impulsive choice and either alcohol or sucrose consumption. However, impulsive choice predicted greater anxiety-like behavior (avoidance of the center field, defecation) in the open-field test. In turn, greater anxiety predicted lower alcohol and sucrose consumption. Finally, choice remained generally stable across the experiment, although high-impulsive rats tended toward less impulsive choice in the retest.

CONCLUSIONS

Although impulsive choice and alcohol consumption appear to share some variance with anxiety-like behavior, the present data offer no support for a relation between impulsive choice and alcohol consumption in Long-Evans rats. Together with mixed rodent data from prior reports, these findings attenuate cross-species comparisons to human relations between impulsive choice and alcohol use disorders.

Differential phosphorylation of NMDAR1-CaMKII-MAPKs in the rat nucleus accumbens following chronic ethanol exposure

Previous studies suggest that the nucleus accumbens shell (AcbSh) and core (AcbC) regions may have distinct roles in ethanol consumption. N-Methyl-d-aspartate receptor 1 (NMDAR1), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-regulated kinases (ERKs) have been demonstrated to contribute to and possibly interact in the molecular mechanism underlying ethanol dependence and relapse. However, little is known regarding the mechanisms underlying the effects of ethanol exposure, withdrawal, and re-exposure, particularly with regard to NMDAR1-CaMKII-ERK signaling in accumbens subregions. In the present study, rats were provided with a 6% ethanol solution as their only drinking source. We found that ethanol exerted locomotor stimulant and anxiolytic effects in open field behaviors. Phosphorylation of NMDAR1, CaMKII and ERK was significantly decreased in the AcbSh and AcbC following chronic ethanol exposure. Ethanol withdrawal increased phospho-NMDAR1 and phospho-CaMKII expression in the AcbSh. Ethanol withdrawal also induced an increase of phospho-ERK1/2 in both the AcbSh and AcbC, while ethanol re-exposure decreased phospho-ERK in the AcbSh. These results indicated that the activation of NMDAR1-CaMKII-ERK signaling in the AcbSh but not the AcbC would contribute more to ethanol drinking and chronic ethanol-related negative emotional states.

Sociodemographic, psychological, and lifestyle characteristics are associated with a liking for salty and sweet tastes in French adults

BACKGROUND

Various studies have shown that sensory liking influences dietary behavior and that individual characteristics are related to food intake and weight status, but little is known about individual profiles associated with salt and sweet liking.

OBJECTIVE

The aim of the present study was to investigate the association between a liking for salty and sweet tastes (i.e., a liking for foods rich in salt or sugar and preferred amounts of salt or sugar seasoning in foods) and sociodemographic, psychological, and lifestyle characteristics in a large sample.

METHODS

Individual factors and liking scores were collected by validated questionnaires from 37,181 French adults participating in the NutriNet-Santé study, a large web-based observational cohort launched in 2009 that studies relations between nutrition and health. The associations were assessed by multivariable multinomial logistic regression models adjusted for socioeconomic, anthropometric, and health variables.

RESULTS

In both genders, with increasing age, individuals were more likely to have a high salt liking (men, OR: 1.24; 95% CI: 1.18, 1.30; women, OR: 1.14, 95% CI: 1.09, 1.19), whereas they were less likely to have a strong sweet liking (men, OR: 0.87; 95% CI: 0.83, 0.91; women, OR: 0.66; 95% CI: 0.64, 0.68). Current smokers (men, OR: 2.30; 95% CI: 1.90, 2.78; women, OR: 1.50; 95% CI: 1.36, 1.66) and heavy drinkers (men, OR: 2.92; 95% CI: 2.37, 3.58; women, OR: 2.57, 95% CI: 2.22, 2.98) were more likely to like salt than nonsmokers and alcohol abstainers. Regarding the sweet taste, women smokers were less likely to like sweets (OR: 0.80; 95% CI: 0.72, 0.89). Highly uncontrolled eaters [men, OR: 2.39; 95% CI: 2.04, 2.80; women, OR: 2.22; 95% CI: 1.99, 2.47) and highly emotional women (OR: 1.35; 95% CI: 1.18, 1.55) were more likely to have a high liking for sweets than slightly uncontrolled eaters and nonemotional eaters, whereas those with high cognitive restraint (men, OR: 0.39; 95% CI: 0.33, 0.46; women, OR: 0.55; 95% CI: 0.50, 0.60) and former weight-loss dieters (men, OR: 0.60; 95% CI: 0.52, 0.70; women, OR: 0.68; 95% CI: 0.62, 0.73) were less likely to have a strong sweet liking compared with those with low cognitive restraint and never-dieters.

CONCLUSION

An unhealthy lifestyle that includes smoking and alcohol consumption may influence salt liking, and eating behavior may have an impact on sweet liking. Further research is needed to study the influence of individual factors and sensory liking on dietary intake and weight status. This study was registered at the European Clinical Trials Database as 2013-000929-31.

Evolutionary and neuropsychological perspectives on addictive behaviors and addictive substances: relevance to the "food addiction" construct

It has been argued that food cannot be "addictive", unlike conventional drugs of abuse, because it is an essential part of life. In this paper, evidence is reviewed, largely from an evolutionary psychobiological perspective, that plant-based psychoactive drugs (such as those derived from the opium poppy and the coca leaf) and gambling-related behaviors were once adaptive for human health and survival in a similar manner as energy-based foods were for nourishment. "Evolutionary mismatch" viewpoints contend that certain behaviors were enhanced during the hunter-gatherer lifestyle - from which our genetic endowment had its origins - because they bestowed both survival and reproductive advantages to the species. However, in the context of advanced technology and other rapid environmental changes, these same behaviors have tended to become maladaptive and greatly overexpressed. Similar to the manufactured purification of psychotropic plant-based substances, the reward impact of processed and hyperpalatable foods, with their high levels of sugar, fat, and salt, is much increased from foods produced in nature. It is concluded therefore that what was once beneficial and necessary for our survival has been altered and ultraprocessed into edible products that may be disadvantageous and potentially addictive.

Cross-sectional survey of prevalence and personality characteristics of college students with internet addiction in Wenzhou, China

Background

Internet addiction can seriously affect the social functioning and studies of college students in China but measures for addressing this problem have not yet been developed or tested.

Objective

Assess the personality characteristics of college students with internet addiction.

Methods

Two self-report scales, the Tridimensional Personality Questionnaire (TPQ) and the Chen Internet Addiction Scale (CIAS), were administered to a stratified random sample of 697 college students from colleges and vocational schools in Wenzhou, China. The characteristics of 48 subjects who meet Chen's criteria for internet addiction (score of 64 or greater out of 100 on the CIAS) were compared to those of 649 subjects who did not meet criteria for internet addiction.

Results

The prevalence of internet addiction in the sample was 6.9% (95% CI=5.1-9.1%). Compared to students without internet addiction, those with internet addiction were more likely to be male, of Han ethnicity, to have a history of substance use (primarily tobacco and alcohol), and to be a student at a technical college. Students with internet addiction had higher mean (sd) scores on the novelty-seeking subscale of the TPQ [17.9 (1.2) v. 13.0 (1.6), t=16.75 p<0.001] and on the harm-avoidance subscale [17.2 (1.9) v. 14.6 (1.1), t=15.14, p<0.001] but lower scores on the reward-dependence subscale [14.6 (1.4) v. 18.3 (1.7), t=-7.64, p<0.001]. Logistic regression found that the most important independent predictors of internet addiction were Han ethnicity (OR= 5.52, 95% CI=2.00-15.32), male gender (4.40, 1.97-9.81), and substance use (1.08, 1.02-1.15). After adjustment for other variables personality measures were not significantly associated with internet addiction.

Conclusion

The prevalence of internet addiction among college students in Wenzhou is similar to that in other parts of China. Significant differences in the personality characteristics assessed by the TPQ between university students with and without internet addiction become non-significant after controlling for gender, ethnicity and substance use patterns.

Gray matter volume correlates of global positive alcohol expectancy in non-dependent adult drinkers

Alcohol use and misuse is known to involve structural brain changes. Numerous imaging studies have examined changes in gray matter (GM) volumes in dependent drinkers, but there is little information on whether non-dependent drinking is associated with structural changes and whether these changes are related to psychological factors-such as alcohol expectancy-that influence drinking behavior. We used voxel-based morphometry (VBM) to examine whether the global positive scale of alcohol expectancy, as measured by the Alcohol Expectancy Questionnaire-3, is associated with specific structural markers and whether such markers are associated with drinking behavior in 113 adult non-dependent drinkers (66 women). Alcohol expectancy is positively correlated with GM volume of left precentral gyrus (PCG) in men and women combined and bilateral superior frontal gyri (SFG) in women, and negatively correlated with GM volume of the right ventral putamen in men. Furthermore, mediation analyses showed that the GM volume of PCG mediate the correlation of alcohol expectancy and the average number of drinks consumed per occasion and monthly total number of drinks in the past year. When recent drinking was directly accounted for in multiple regressions, GM volume of bilateral dorsolateral prefrontal cortices correlated positively with alcohol expectancy in the combined sample. To our knowledge, these results are the first to identify the structural brain correlates of alcohol expectancy and its mediation of drinking behaviors. These findings suggest that more studies are needed to investigate increased GM volume in the frontal cortices as a neural correlate of alcohol expectancy.

Sweet-liking is associated with transformation of heavy drinking into alcohol-related problems in young adults with high novelty seeking

BACKGROUND

We tested the hypothesis that high novelty seeking (NS) (a trait that promotes experimentation) and sweet-liking (SL) (a phenotype that may reflect processing of hedonic stimuli) act independently and synergistically to increase the risk of having alcohol-related problems in young adults.

METHODS

A sample of 163 young adults, ages 18 to 26, was recruited and balanced for gender and evidence for presence of alcohol problems to yield 150 evaluable participants. NS was evaluated using the Tridimensional Personality Questionnaire. Pleasurable response to sweet taste was tested to identify sweet-likers and sweet-dislikers. Alcohol use and problems were assessed by the Alcohol Use Disorders Identification Test and the Rutgers Alcohol Problem Index.

RESULTS

NS, but not SL, was positively and significantly associated with alcohol consumption and alcohol problems; however, the effect of NS on alcohol problems was significantly enhanced in the presence of the SL phenotype, thus showing a strong synergistic interaction. The combination of SL and high NS was associated with increased odds of having alcohol problems -20.64 (95% CI: -89.98, 4.74) compared to those with low NS and sweet-disliking. Other combinations did not produce such odds ratios. SL and low NS showed OR = 1.88 (95% CI 0.44, 7.99), and sweet-dislikers and high novelty seekers had OR = 4.07 (95%, CI 1.01, 16.46).

CONCLUSIONS

These results support and extend our hypothesis that as clinically distinct phenotypes, high NS and the SL phenotype are associated with risk of alcohol-related problems. High NS is associated with the use of alcohol, and the presence of the SL phenotype appears to bias an individual to alcohol problems once alcohol use is initiated. Understanding the biology and phenomenology of these phenotypes will allow a more complete picture of the processes that lead to alcohol problems.

Drinking of flavored solutions by high preferring (WHP) and low preferring (WLP) alcohol-drinking rats

BACKGROUND

Selective breeding alcohol-preferring (P) and alcohol-nonpreferring (NP) rats showed a strong preference for the sucrose solutions, whereas P rats intake greater amounts than NP rats. The aim of this study was the estimation of selectively bred ethanol-preferring (WHP - Warsaw High Preferring) and ethanol-nonpreferring (WLP - Warsaw Low Preferring) rats for their preference for various tastes.

METHODS

The oral drinking of the following substances was studied at a range of concentrations: sucrose (0.5-64.0 g/100 ml), NaCl (0.025-3.2 g/100 ml), citric acid (0.008-2.048 g/l), and sucrose octaacetate (0.002-0.512 g/l) solutions. Separate groups of 7-8 rats from each line were investigated of each of the four tastes. The investigated solutions were presented continuously keeping water and food always available. Concentrations of the various flavors were doubled every 48 h.

RESULTS

Rats from WHP and WLP lines clearly revealed the preference for the sucrose solution and the highest preference was at the 4.0 and 8.0 g/100ml sucrose concentration. Similar to sucrose, both lines exposed strong preference for the NaCl solution and this preference enhanced together with the increase of the NaCl concentration. Nevertheless their preference for the NaCl solutions decreased when the concentration of NaCl reached 1.600 g/100 ml. Both lines of rats did not differ in citric acid or sucrose octaacetate intake at any of the concentrations studied.

CONCLUSION

Selective breeding of rats (WHP) for high and rats (WLP) for low ethanol drinking is favorably correlated with the drinking of sweet and salty solutions and negatively correlated with the consumption of sour and bitter tastes.

Difference of the naltrexone's effects in social drinkers by spicy food preference

The purpose of this study was to investigate the differences in subjective acute effects of alcohol and naltrexone among those who prefer spicy food to varying degrees. Acute biphasic alcohol effects scale (BAES), visual analogue scale for craving (VAS-C), blood alcohol concentration (BAC) and food preference scale were measured in 26 men. Repeated measures ANOVA (2 preference groups×4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in naltrexone condition (N+) (P<0.001), but not in non-naltrexone condition (N-). Furthermore, repeated measures ANOVA (2 drug groups×4 time blocks) on the stimulative subscale of BAES revealed a significant group by block interaction in strong preference for spicy food (SP) (P<0.001), but not in lesser preference for spicy food (LP). The paired t-test revealed that significant suppression of the stimulative subscale of BAES was observed at 15 min (P<0.001) and 30 min (P<0.001) after drinking when N+ compared with N- in SP. For those who prefer spicy food, the stimulative effect of acute alcohol administration was suppressed by naltrexone. This result suggests that the effect of naltrexone may vary according to spicy food preference.

Intact Hedonic Responses to Sweet Tastes in Autism Spectrum Disorder

The Sweet Taste Test (STT) is a standardized measure designed to index the ability to detect differences in sweet tastes (sweet taste sensitivity) and hedonic responses to sweet tastes (sweet taste liking). Profiles of response on the STT suggest enhanced hedonic responses to sweet tastes in psychiatric disorders characterized by dysfunctional reward processing systems, including binge-eating disorders and substance use disorders, and a putative mechanism governing STT responses is the brain opioid system. The present study examined STT responses in 20 adults with autism spectrum disorder (ASD) and 38 healthy control adults. There were no differences in sweet taste sensitivity or hedonic response to sweet tastes between the ASD and control groups. Within the ASD sample, ASD symptom severity was associated with sweet taste sensitivity, but not hedonic response to sweet taste. Results may ultimately shed light on brain opioid system functioning in ASD.

Error-related functional connectivity of the thalamus in cocaine dependence

Error processing is a critical component of cognitive control, an executive function that has been widely implicated in substance misuse. In previous studies we showed that error related activations of the thalamus predicted relapse to drug use in cocaine addicted individuals (Luo et al., 2013). Here, we investigated whether the error-related functional connectivity of the thalamus is altered in cocaine dependent patients (PCD, n = 54) as compared to demographically matched healthy individuals (HC, n = 54). The results of a generalized psychophysiological interaction analysis showed negative thalamic connectivity with the ventral medial prefrontal cortex (vmPFC), in the area of perigenual and subgenual anterior cingulate cortex, in HC but not PCD (p < 0.05, corrected, two-sample t test). This difference in functional connectivity was not observed for task-residual signals, suggesting that it is specific to task-related processes during cognitive control. Further, the thalamic-vmPFC connectivity is positively correlated with the amount of cocaine use in the prior month for female but not for male PCD. These findings add to recent literature and provide additional evidence for circuit-level biomarkers of cocaine dependence.

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Error-related thalamic-vmPFC connectivity is altered in cocaine misuse.

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This altered connectivity is associated with impaired self control.

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This deficit is associated with recent cocaine use in women but not men.

Prenatal ethanol increases sucrose reinforcement, an effect strengthened by postnatal association of ethanol and sucrose

Late prenatal exposure to ethanol recruits sensory processing of the drug and of its motivational properties, an experience that leads to heightened ethanol affinity. Recent studies indicate common sensory and neurobiological substrates between this drug and sweet tastants. Using a recently developed operant conditioning technique for infant rats, we examined the effects of prenatal ethanol history upon sucrose self-administration (postnatal days, PDs 14-17). Prior to the last conditioning session, a low (0.5 g/kg) or a high (2.5 g/kg) ethanol dose were paired with sucrose. The intention was to determine if ethanol would inflate or devalue the reinforcing capability of the tastant and if these effects are dependent upon prenatal ethanol history. Male and female pups prenatally exposed to ethanol (2.0 g/kg) responded more when reinforced with sucrose than pups lacking this antenatal experience. Independently of prenatal status, a low ethanol dose (0.5 g/kg) enhanced the reinforcing capability of sucrose while the highest dose (2.5 g/kg) seemed to ameliorate the motivational properties of the tastant. During extinction (PD 18), two factors were critical in determining persistence of responding despite reinforcement omission. Pups prenatally exposed to ethanol that subsequently experienced the low ethanol dose paired with sucrose, showed higher resistance to extinction. The effects here reported were not associated with differential blood alcohol levels across prenatal treatments. These results indicate that fetal ethanol experience promotes affinity for a natural sweet reinforcer and that low doses of ethanol are also capable of enhancing the positive motivational consequences of sucrose when ethanol and sucrose are paired during infancy.

Ventromedial prefrontal cortex response to concentrated sucrose reflects liking rather than sweet quality coding

The perception of the pleasantness of sweet tastes varies widely across individuals. Here, we exploit these differences to isolate brain response to sweet-taste pleasantness while controlling for intensity, quality, and physiological significance. Thirty subjects participated in functional MRI scanning while consuming individually calibrated weak and strong sucrose solutions. All subjects found the weak sweet taste to be neutral in pleasantness, but half of the subjects found strong sweet taste pleasant (likers), whereas half found strong sweet taste unpleasant (dislikers). Greater response was observed in the ventromedial prefrontal cortex (vmPFC) to the sucrose when it was rated pleasant versus neutral compared with unpleasant versus neutral. This suggests that response in the vmPFC underlies sweet-taste preference, this region is preferentially sensitive to affectively positive tastes, and it is the positive value rather than physiological significance, quality, or intensity that drives responses here. Likers versus dislikers did not differ in their diet, alcohol use, body weight, gender, or taq1A allele status, but likers were more likely to report emotional eating. None of these factors influenced response in the vmPFC.

Error processing and gender-shared and -specific neural predictors of relapse in cocaine dependence

Deficits in cognitive control are implicated in cocaine dependence. Previously, combining functional magnetic resonance imaging and a stop signal task, we demonstrated altered cognitive control in cocaine-dependent individuals. However, the clinical implications of these cross-sectional findings and, in particular, whether the changes were associated with relapse to drug use, were not clear. In a prospective study, we recruited 97 treatment-seeking individuals with cocaine dependence to perform the stop signal task during functional magnetic resonance imaging and participate in follow-up assessments for 3 months, during which time cocaine use was evaluated with timeline follow back and ascertained by urine toxicology tests. Functional magnetic resonance imaging data were analysed using general linear models as implemented in Statistical Parametric Mapping 8, with the contrast 'stop error greater than stop success trials' to index error processing. Using voxelwise analysis with logistic and Cox regressions, we identified brain activations of error processing that predict relapse and time to relapse. In females, decreased error-related activations of the thalamus and dorsal anterior cingulate cortex predicted relapse and an earlier time to relapse. In males, decreased error-related activations of the dorsal anterior cingulate cortex and left insula predicted relapse and an earlier time to relapse. These regional activations were validated with data resampling and predicted relapse with an average area under the curve of 0.849 in receiver operating characteristic analyses. These findings provide direct evidence linking deficits in cognitive control to clinical outcome in a moderate-sized cohort of cocaine-dependent individuals. These results may provide a useful basis for future studies to examine how psychosocial factors interact with cognitive control to determine drug use and to evaluate the efficacy of pharmacological or behavioural treatment in remediating deficits of cognitive control in cocaine addicts.

Histamine and motivation

Brain histamine may affect a variety of different behavioral and physiological functions; however, its role in promoting wakefulness has overshadowed its other important functions. Here, we review evidence indicating that brain histamine plays a central role in motivation and emphasize its differential involvement in the appetitive and consummatory phases of motivated behaviors. We discuss the inputs that control histaminergic neurons of the tuberomamillary nucleus (TMN) of the hypothalamus, which determine the distinct role of these neurons in appetitive behavior, sleep/wake cycles, and food anticipatory responses. Moreover, we review evidence supporting the dysfunction of histaminergic neurons and the cortical input of histamine in regulating specific forms of decreased motivation (apathy). In addition, we discuss the relationship between the histamine system and drug addiction in the context of motivation.

[Drug Abuse Comorbidity in Bipolar Disorder]

INTRODUCTION

Drug use among patients with bipolar disorder is greater than the one observed in the general population; psychotic episodes are likely to occur after consumption. This has implications in the prevention, etiology, management, and treatment of the disease. Bipolar disorder pathology is likely to have positive response to pharmacological treatment. Therefore, identifying the strategies with better results to be applied in these patients is fundamental for psychiatrists and primary care physicians.

OBJECTIVE

Review literature in order to determine the prevalence and characteristics of drug abuse in patients with bipolar disorder and establish the pharmacological strategies that have produced better results.

METHODOLOGY

Literature review.

RESULTS

A great variety of studies demonstrate the relationship between bipolar disorder and drug use disorder. These patients are hospitalized more frequently, have an earlier onset of the disease, and present a larger number of depressive episodes and suicide attempts which affect the course of the disease. The drug with better results in the treatment of these patients is Divalproate. Satisfactory results have been also obtained with other mood stabilizers such as carbamazepine, lamotrigine, and the antipsychotic aripiprazole.

CONCLUSIONS

Substance abuse is present in a large number of patients with bipolar disorder. The Divalproate is the drug that has shown better results in the studies.

Depot naltrexone decreases rewarding properties of sugar in patients with opioid dependence

BACKGROUND

Opioid neurotransmission mediates hedonic value of sweet tastants; their intake may be exaggerated by the consumption of exogenous opioids (e.g., opioid dependence). Sweet Taste Test (STT) is a validated quantitative instrument assessing taste perception and hedonic features of sugar (sucrose) using a randomized and double-blind administration at five different sucrose concentrations ranging from 0.05 to 0.83 M.

METHODS

The STT and cue-induced craving procedure were administered to opioid-dependent patients (n = 15) before and 1 week after the injection of a long-acting depot naltrexone (XRNT) preparation.

RESULTS

Analyses of covariance, employing sucrose concentration and its perceived taste as covariates, showed that XRNT therapy significantly reduced the self-reported hedonic and motivational characteristics of sucrose. Greater reductions in both these characteristics were associated with more diminution in the cue-induced opioid craving.

CONCLUSIONS

Opioid antagonism in opioid-dependent subjects leads to a smaller sweet taste reward, which, in turn, may be proportional to decreased opioid craving. These pilot results support the heuristic value of the STT as a potential marker of the XRNT treatment response and call for further inquiry into potential clinical applications of the test.

Drug use is associated with elevated food consumption in college students

Higher food consumption, particularly of sweets, has been reported by substance-dependent persons in various stages of treatment but no investigation of substance use and actual food consumption has been conducted in non-dependent persons. Sixty-two male and female college students completed the Core Alcohol and Drug Survey and the amount of each of six snack foods (including both sweet and savory items) they consumed were measured. Participants also rated appetite before and after eating and rated the pleasantness of and desire to eat each food. Hierarchical multivariate regression revealed that, while controlling for the influence of BMI and intermeal interval, frequency and breadth of substance use significantly predicted elevated food consumption and elevated ratings of hunger and desire to eat. Furthermore, the link between breadth of drug use and food consumption was mediated by higher desire to eat and not by pleasantness of the food. The relationship between substance use and eating behavior may not be restricted only to those in recovery or treatment for persons diagnosed with substance use disorders.

Beer promotes high levels of alcohol intake in adolescent and adult alcohol-preferring rats

Previous studies suggest that high levels of alcohol consumption can be obtained in laboratory rats by using beer as a test solution. The present study extended these observations to examine the intake of beer and equivalent dilute ethanol solutions with an inbred line of alcohol-preferring P rats. In Experiment 1, male adolescent P rats and age-matched Wistar rats had access to either beer or equivalent ethanol solutions for 1h daily in a custom-built lickometer apparatus. In subsequent experiments, adolescent (Experiment 2) and adult (Experiment 3) male P rats were given continuous 24-h home cage access to beer or dilute ethanol solutions, with concomitant access to lab chow and water. In each experiment, the alcohol content of the beer and dilute ethanol solutions was gradually increased from 0.4, 1.4, 2.4, 3.4, 4.4, 5 to 10% EtOH (vol/vol). All three experiments showed a major augmentation of alcohol intake when rats were given beer compared with equivalent ethanol solutions. In Experiment 1, the overall intake of beer was higher in P rats compared with Wistar rats, but no strain difference was found during the 1-h sessions with plain ethanol consumption. Experiment 1 also showed that an alcohol deprivation effect was more readily obtained in rats with a history of consuming beer rather than plain ethanol solutions. In Experiments 2 and 3, voluntary beer intake in P rats represented ethanol intake of 10-15 g/kg/day, among the highest reported in any study with rats. This excessive consumption was most apparent in adolescent rats. Beer consumption markedly exceeded plain ethanol intake in these experiments except at the highest alcohol concentration (10%) tested. The advantage of using beer rather than dilute ethanol solutions in both selected and nonselected rat strains is therefore confirmed. Our findings encourage the use of beer with alcohol-preferring rats in future research that seeks to obtain high levels of alcohol self-administration.

Genetics of sweet taste preferences

Sweet taste is a powerful factor influencing food acceptance. There is considerable variation in sweet taste perception and preferences within and among species. Although learning and homeostatic mechanisms contribute to this variation in sweet taste, much of it is genetically determined. Recent studies have shown that variation in the T1R genes contributes to within- and between-species differences in sweet taste. In addition, our ongoing studies using the mouse model demonstrate that a significant portion of variation in sweetener preferences depends on genes that are not involved in peripheral taste processing. These genes are likely involved in central mechanisms of sweet taste processing, reward and/or motivation. Genetic variation in sweet taste not only influences food choice and intake, but is also associated with proclivity to drink alcohol. Both peripheral and central mechanisms of sweet taste underlie correlation between sweet-liking and alcohol consumption in animal models and humans. All these data illustrate complex genetics of sweet taste preferences and its impact on human nutrition and health. Identification of genes responsible for within- and between-species variation in sweet taste can provide tools to better control food acceptance in humans and other animals.

Long-term exogenous melatonin treatment modulates overall feed efficiency and protects ovarian tissue against injuries caused by ethanol-induced oxidative stress in adult UChB rats

BACKGROUND

Chronic ethanol intake leads to reproductive damage including reactive oxygen species formation, which accelerates the oxidative process. Melatonin is known to regulate the reproductive cycle, food/liquid intake, and it may also act as a potent antioxidant indoleamine. The aim of this study was to verify the effects of alcoholism and melatonin treatment on overall feed efficiency and to analyze its protective role against the oxidative stress in the ovarian tissue of UChB rats (submitted to 10% [v/v] voluntary ethanol consumption).

METHODS

Forty adult female rats (n = 10/group) were finally selected for this study: UChB Co: drinking water only; and UChB EtOH: drinking ethanol at 2 to 6 ml/100 g/d + water, both receiving 0.9% NaCl + 95% ethanol 0.04 ml as vehicle. Concomitantly, UChB Co + M and UChB EtOH + M groups were infused with vehicle + melatonin (100 μg/100 g body weight/d) intraperitoneally over 60 days. All animals were euthanized by decapitation during the morning estrus (4 am).

RESULTS

Body weight gain was reduced with ethanol plus melatonin after 40 days of treatment. In both melatonin-treated groups, it was observed a reduction in food-derived calories and liquid intake toward the end of treatment. The amount of consumed ethanol dropped during the treatment. Estrous cycle was longer in rats that received both ethanol and melatonin, with prolonged diestrus. Following to oxidative status, lipid hydroperoxide levels were higher in the ovaries of ethanol-preferring rats and decreased after melatonin treatment. Additionally, antioxidant activities of superoxide dismutase, glutathione peroxidase activity, and glutathione reductase activity were increased in melatonin-treated groups.

CONCLUSIONS

We suggest that melatonin is able to affect feed efficiency and, conversely, it protects the ovaries against the oxidative stress arising from ethanol consumption.

The ghrelin signalling system is involved in the consumption of sweets

The gastric-derived orexigenic peptide ghrelin affects brain circuits involved in energy balance as well as in reward. Indeed, ghrelin activates an important reward circuit involved in natural- as well as drug-induced reward, the cholinergic-dopaminergic reward link. It has been hypothesized that there is a common reward mechanism for alcohol and sweet substances in both animals and humans. Alcohol dependent individuals have higher craving for sweets than do healthy controls and the hedonic response to sweet taste may, at least in part, depend on genetic factors. Rat selectively bred for high sucrose intake have higher alcohol consumption than non-sucrose preferring rats and vice versa. In the present study a group of alcohol-consuming individuals selected from a population cohort was investigated for genetic variants of the ghrelin signalling system in relation to both their alcohol and sucrose consumption. Moreover, the effects of GHS-R1A antagonism on voluntary sucrose-intake and operant self-administration, as well as saccharin intake were investigated in preclinical studies using rodents. The effects of peripheral grelin administration on sucrose intake were also examined. Here we found associations with the ghrelin gene haplotypes and increased sucrose consumption, and a trend for the same association was seen in the high alcohol consumers. The preclinical data show that a GHS-R1A antagonist reduces the intake and self-administration of sucrose in rats as well as saccharin intake in mice. Further, ghrelin increases the intake of sucrose in rats. Collectively, our data provide a clear indication that the GHS-R1A antagonists reduces and ghrelin increases the intake of rewarding substances and hence, the central ghrelin signalling system provides a novel target for the development of drug strategies to treat addictive behaviours.

Repeated binge ethanol administration during adolescence enhances voluntary sweetened ethanol intake in young adulthood in male and female rats

Binge alcohol consumption is a rising concern in the United States, especially among adolescents. During this developmental period alcohol use is usually initiated and has been shown to cause detrimental effects on brain structure and function as well as cognitive/behavioral impairments in rats. Binge models, where animals are repeatedly administered high doses of ethanol typically over a period of three or four days cause these effects. There has been little work conducted aimed at investigating the long-term behavioral consequences of repeated binge administration during adolescence on later ethanol-induced behavior in young adulthood and adulthood. The repeated four-day binge model may serve as a good approximate for patterns of human adolescent alcohol consumption as this is similar to a "bender" in human alcoholics. The present set of experiments examined the dose-response and sex-related differences induced by repeated binge ethanol administration during adolescence on sweetened ethanol (Experiment 1) or saccharin (Experiment 2) intake in young adulthood. In both experiments, on postnatal days (PND) 28-31, PND 35-38 and PND 42-45, ethanol (1.5, 3.0 or 5.0 g/kg) or water was administered intragastrically to adolescent rats. Rats underwent abstinence from PND 46-59. Subsequently, in young adulthood, ethanol and saccharin intake were assessed. Exposure to any dose of ethanol during adolescence significantly enhanced ethanol intake in adulthood. However, while female rats had higher overall g/kg intake, males appear to be more vulnerable to the impact of adolescent ethanol exposure on subsequently increased ethanol intake in young adulthood. Exposure to ethanol during adolescence did not alter saccharin consumption in young adulthood in male or female rats. Considering that adolescence is the developmental period in which ethanol experimentation and consumption is usually initiated, the present set of experiments demonstrate the importance of elucidating the impact of early binge-pattern ethanol exposure on the subsequent predisposition to drink later in life.

Unipolar depression does not moderate responses to the Sweet Taste Test

BACKGROUND

The Sweet Taste Test (STT) measures hedonic responses to sweet tastes and has been linked to both alcoholism and to a family history of alcoholism. However, STT response profiles in unipolar major depressive disorder (MDD), a disorder characterized by anhedonia, have been minimally investigated.

METHODS

Twelve adults with and 15 adults without MDD participated in two identical STT assessments separated by approximately 12 weeks. Between assessments, MDD outpatients received Behavioral Activation Therapy for Depression, a psychotherapy modality designed to increase engagement with rewarding stimuli and reduce avoidance behaviors. Primary-dependent measures included sensitivity to sucrose, hedonic response to sucrose, and designation as a Sweet-Liker or Sweet-Disliker.

RESULTS

A total of 75% of adults with MDD were treatment responders. There were no significant differences in STT response profiles between groups overall or at either timepoint. Furthermore, STT profiles of MDD participants did not differ after psychotherapy, relative to baseline.

CONCLUSIONS

Findings suggest that although anhedonia is a symptom of MDD, the disorder is not characterized by altered responses to sweet tastes. Implications and future directions are discussed.

Sweet liking and high novelty seeking: independent phenotypes associated with alcohol-related problems

AIM

We tested the hypothesis that high novelty seeking (NS; a trait that promotes experimentation) and hedonic response to sweet taste (a trait that may reflect processing of hedonic stimuli) act independently to increase the risk for having alcohol-related problems in young adults.

METHODS

The study was conducted in 158 healthy subjects (age 20-25 years) with no lifetime history of alcohol and/or drug abuse/dependence. NS was evaluated using the Tridimensional Personality Questionnaire. Pleasurable response to sweet taste was tested, using a sweet taste test to identify sweet likers (SL; those preferring the strongest offered sucrose solution) and sweet dislikers (SDL; those preferring weaker sucrose solutions).

RESULTS

NS score, but not SL/SDL status, was positively correlated with drinks per month (P = 0.0054) and drinks per drinking day (P = 0.021). When tested individually, both NS and SL/SDL status predict having alcohol-related problems (NS: odds ratio [OR] = 5.3, P = 0.0016 and SL/SDL: OR = 5.8, P = 0.0001) with an OR similar to positive family history of alcoholism status (OR = 5.7, P = 0.0007). The combination of SL status and high NS score (greater than gender-specific 70th percentile) greatly increased the estimated odds of having alcohol-related problems (OR 27.5, P < 0.0001).

CONCLUSIONS

These results support the hypothesis that high NS and SL phenotypes are independently associated with risk of alcohol-related problems. The combination of both phenotypes greatly increases the likelihood of alcohol-related problems. Although confirmation is necessary, this suggests that these phenotypes could contribute to improved methods to assess risk for alcohol-related problems and provide additional insight into processes underlying progression to alcohol-related problems.

Effects of a diagnosis or family history of alcoholism on the taste intensity and hedonic value of sucrose

Given inconsistent findings in published studies, we examined whether a personal lifetime history of alcohol dependence (AD) or a parental history of alcoholism affected preference for sweet solutions. Ninety-three alcohol-dependent subjects rated the intensity and hedonic value of five different sucrose solutions, which was compared with similar data from 122 subjects screened to exclude alcohol dependence. The effect of a family history of alcoholism (FH) was examined in the AD group. Neither the diagnosis of AD nor a family history of alcoholism was associated with ratings of sweetness intensity or sweet preference. These findings do not support the hypothesis that sucrose preference is positively associated with either a personal lifetime history of AD or a family history of alcoholism.