Sweet liking phenotype, alcohol craving and response to naltrexone treatment in alcohol dependence

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.

Prospective Associations between Attitudes toward Sweet Foods, Sugar Consumption, and Cravings for Alcohol and Sweets in Early Recovery from Alcohol Use Disorders

Sweet liking (heightened preference for highly-sweet solutions) is linked to Alcohol Use Disorder (AUD) and relapse, as well as attitudes towards sweet foods - use of sugar to cope with negative affect (sweet-cope), and impaired control over sweets consumption (sweet-control). This prospective analysis of individuals with AUD (N=26) participating in an Alcohol and Drug partial hospitalization program observed increases in self-reported sugar consumption and sweet craving from Time 1 (T1) to Time 2 (T2; 4 weeks later). Sweet-cope (T1) predicted T2 sweet craving. In an exploratory cross-lagged panel model, sweet-cope predicted sugar consumption and sweet craving at T1 and T2, and alcohol craving at T2. This pattern of results suggests the hypothesis that use of sugar to regulate negative affect may prove a novel, modifiable risk mechanism of the association between sweet liking and relapse. Sweet-cope may also prove an intervention target for improving nutrition and weight-related factors in early recovery. Future research in larger sample sizes is needed.

Preoperative liking and wanting for sweet beverages as predictors of body weight loss after Roux-en-Y gastric bypass and sleeve gastrectomy

Background/objectives:

Patients who receive Roux-en-Y gastric bypass (RYGB) lose more weight than those who receive vertical sleeve gastrectomy (VSG). RYGB and VSG alter hedonic responses to sweet flavor, but whether baseline differences in hedonic responses modulate weight loss after RYGB or VSG remains untested.

Participants/methods:

Male and female candidates (n=66) for RYGB or VSG were recruited and tested for their subjective liking and wanting ratings of sucrose solutions and flavored beverages sweetened with aspartame. Participants were classified by unsupervised hierarchical clustering for their liking and wanting ratings of sucrose and aspartame. Participant liking ratings were also used in a supervised classification using pre-established categories of liking ratings (liker, disliker, and inverted u-shape). Effects of categories obtained from unsupervised or supervised classification on body weight loss and their interaction with surgery type were analyzed separately at 3 and 12 months after surgery using linear models corrected for sex and age.

Results:

RYGB participants lost more body weight compared to VSG participants at 3 and 12 months after surgery (P < 0.001 for both time points). Unsupervised clustering analysis identified clusters corresponding to high and low wanting or liking ratings for sucrose or aspartame. RYGB participants in high-wanting clusters based on sucrose, but not aspartame, lost more weight than VSG at both 3 (P = 0.01) and 12 months (P = 0.03), yielding a significant cluster by surgery interaction. Categories based on supervised classification using liking ratings for sucrose or aspartame showed no significant effects on body weight loss between RYGB and VSG participants.

Conclusions:

Classification of patients into high/low wanting ratings for sucrose before surgery can predict differential body weight loss after RYGB or VSG in adults and could be used to advise on surgery type.

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.

Spicy Food Preference and Risk for Alcohol Dependence in Korean

OBJECTIVE

Previous studies have reported that both preference for spicy food and drinking behavior are associated with the activity of the opioid system in the central nervous system. The relationship between the preference for spicy food and the risk of alcohol dependence by comparing spicy food preference in alcohol-dependent patients vs. healthy controls was investigated. Also the association between the preference for spicy food and OPRM1 A118G was studied.

METHODS

A total of 150 Korean male patients with alcohol dependence and 100 normal male control subjects were included in this study. Preference for spicy food was measured using the Food Preference Scale (FPS). DNA analysis was conducted to detect the A118G polymorphism.

RESULTS

The mean FPS score was significantly higher in the alcohol-dependent patients (61.2±24.2) than in the normal control subjects (53.0±22.0). FPS scores differed significantly between alcohol-dependent patients and normal control subjects who had the G allele in OPRM1 A118G, but not between the two groups with the AA genotype.

CONCLUSION

A strong preference for spicy food can be assumed to be a risk factor for alcohol dependence, particularly in those carrying the G allele in OPRM1 A118G.

The metabolic syndrome in patients with alcohol dependency: Current research and clinical implications

The relationship between alcohol dependency and disorders such as liver disease and cancer has been thoroughly researched. However, the effects of alcohol on cardiometabolic health remain controversial. Several reports found low to moderate alcohol consumption to be associated with a lower risk for cardiometabolic disorders. In contrast, excessive alcohol consumption has been related to an increased risk. Most of these studies were performed in non-clinical populations, therefore limiting the explanatory power to non-dependent patients. Only a few studies examined cardiovascular disorders and cardiovascular risk factors, in particular the metabolic syndrome (MetS), in alcohol dependent patients. We here present a narrative review of studies performed so far on the MetS in alcohol dependency, and provide current hypotheses on the association of alcohol dependency, appetite regulation and the development of the MetS.

Sweet taste pleasantness is modulated by morphine and naltrexone

BACKGROUND

Rodent models highlight the key role of μ-opioid receptor (MOR) signaling in palatable food consumption. In humans, however, the effects of MOR stimulation on eating and food liking remain unclear.

OBJECTIVES

Here, we tested sweet pleasantness experience in humans following MOR drug manipulations. We hypothesized that behaviors regulated by the endogenous MOR system would be enhanced by MOR agonism and decreased by antagonism. In line with rodent findings, we expected the strongest drug effects for the sweetest (high-calorie) sucrose stimuli. As very sweet stimuli are considered aversive by many people (called sweet dislikers), we also assessed whether MOR manipulations affect pleasantness ratings of sucrose-water stimuli differently depending on subjective and objective value.

METHODS

In a bidirectional psychopharmacological cross-over study, 49 healthy men underwent a sweet taste paradigm following double-blind administration of the MOR agonist morphine, placebo, and the opioid antagonist naltrexone.

RESULTS

As hypothesized, MOR stimulation with morphine increased pleasantness of the sweetest of five sucrose solutions, without enhancing pleasantness of the lower-sucrose solutions. For opioid antagonism, an opposite pattern was observed for the sweetest drink only. The observed drug effects on pleasantness of the sweetest drink did not differ between sweet likers and dislikers.

CONCLUSIONS

The bidirectional effect of agonist and antagonist treatment aligns with rodent findings showing that MOR manipulations most strongly affect the highest-calorie foods. We speculate that the MOR system promotes survival in part by increasing concordance between the objective (caloric) and subjective (hedonic) value of food stimuli, so that feeding behavior becomes more focused on the richest food available.

Tasting profile affects adoption of caloric beverage reduction in a randomized weight loss intervention

Objective

The aim of this study was to examine differences in rates of non‐caloric beverage adoption by participants classified as sweet likers (SLs) or sweet dislikers (measured using a behavioural tasting task).

Methods

Data are a sub‐study from a 6‐month, three‐group, randomized weight loss trial (CHOICE) (body mass index 36.3 ± 5.8 kg m⁻², 84% female, aged 42.2 ± 10.9 years, 53% African‐American) comparing the replacement of caloric beverages with either non‐caloric sweetened beverages (diet) or water (water) compared with a control group. This sub‐study, which included participants within the water (n = 106) and diet (n = 103) groups only, examined whether SLs (n = 33 water; n = 37 diet) varied in their adherence to caloric beverage recommendations compared with sweet dislikers (n = 73 water; n = 76 diet) over the 6‐month study.

Results

Diet intake and sweet‐liking data collected on 190 (3 months) and 169 participants (6 months) were used for analysis. The interaction between SL status and beverage group (diet vs. water) approached significance (P = 0.06) at 3 months but not 6 months. Caloric beverage intake (% energy) at 3 months was significantly higher in SLs within the water group (9.7 ± 1.4%) compared with SLs in the diet group (5.4 ± 1.0%, P = 0.03).

Conclusions

Results suggest that SL status may affect the rate in reduction of caloric beverages when water is the recommended substitution. Future studies should explore tailoring beverage recommendations to tasting profile.

Are Alcohol Anti-relapsing and Alcohol Withdrawal Drugs Useful in Cannabinoid Users?

Cannabinoids are still classified as illegal psychoactive drugs despite their broad and increasingly acknowledged therapeutic potential. These substances are most famous for their wide recreational use, particularly among young adults to either alter the state of consciousness, intensify pleasure induced by other psychoactive substances or as an alternative to the previously abused drugs. It is important to emphasize that cannabinoids are often taken together with a variety of medications intended for the treatment of alcohol use disorder (AUD) or alcohol withdrawal syndrome (AWS). These medications include disulfiram, acamprosate, and naltrexone. In this paper, we summarize recent advances in the knowledge of possible beneficial effects and interactions between cannabinoids and drugs commonly used for treatment of AUD and AWS either comorbid or existing as a separate disorder.

Changes in Nutrition-Related Behaviors in Alcohol-Dependent Patients After Outpatient Detoxification: The Role of Chocolate

BACKGROUND

Previous studies have reported changes in nutrition-related behaviors in alcohol-dependent patients after alcohol detoxification, but prospective studies assessing the effects of these changes on maintaining abstinence are lacking.

OBJECTIVES

To assess changes in craving and consumption of chocolate and other sweets over time up to six months after outpatient alcohol detoxification treatment and to detect differences in abstinent versus nonabstinent patients.

METHODS

One hundred and fifty alcohol-dependent patients were included in this prospective observational study. Participants completed self-report questionnaires on nutrition-related behaviors and craving before detoxification treatment (baseline, t1), one week (t2), one month (t3), and six months later (t4).

RESULTS

Significant changes in craving for and consumption of chocolate as well as in craving for other sweets were observed over time. Increases were most prominent within the first month. Patients who remained abstinent until t3 consumed three times more chocolate than nonabstainers. One quarter of the patients switched from being rare (t1) to frequent (t3) chocolate eaters, and 84% of these remained abstinent until t3. No significant correlations were found between craving for alcohol and craving for or consumption of chocolate or other sweets.

CONCLUSIONS/IMPORTANCE

In the first month after outpatient alcohol detoxification treatment, significant changes in nutrition-related behaviors were observed. These changes were not associated with alcohol craving. For a subgroup, increasing the frequency of chocolate consumption might be a temporary protective factor with respect to alcohol relapse.

Intracranial self-stimulation reward thresholds during morphine withdrawal in rats bred for high (HiS) and low (LoS) saccharin intake

RATIONALE

Sweet preference is a marker of vulnerability to substance use disorders, and rats selectively bred for high (HiS) vs. low saccharin (LoS) intake display potentiated drug-seeking behaviors. Recent work indicated that LoS rats were more responsive to the negative effects of drugs in several assays.

OBJECTIVE

The current study used the intracranial self-stimulation (ICSS) procedure to investigate the anhedonic component of morphine withdrawal in male HiS and LoS rats.

METHODS

Rats were administered morphine (10mg/kg) or saline for 8 days. To evaluate withdrawal effects, reward thresholds were measured 24 and 28h following the 8th morphine injection (spontaneous withdrawal) and again for 4 days following daily acute morphine and naloxone (1mg/kg) administration (precipitated withdrawal).

RESULTS

24h following the final morphine injection, reward thresholds in LoS rats were significantly elevated compared to reward thresholds in LoS controls, indicating spontaneous withdrawal. This effect was not observed in HiS rats. LoS rats also showed greater elevations of reward thresholds on several days during naloxone-precipitated withdrawal compared to their HiS counterparts.

CONCLUSIONS

LoS rats were more sensitive to morphine withdrawal-mediated elevations in ICSS thresholds than HiS rats. While these differences were generally modest, our data suggest that severity of the negative affective component of opiate withdrawal may be influenced by genotypes related to addiction vulnerability.

Clinical and biological moderators of response to naltrexone in alcohol dependence: a systematic review of the evidence

AIM

The goal of this systematic review was to identify moderators of naltrexone efficacy in the treatment of alcohol dependence.

METHODS

We searched Pubmed, CINHAL, Embase, PsycINFO and the Cochrane Library from 1990 to April 2012 and reference lists of pertinent review articles, which yielded 622 trial, pooled analysis and review articles. Using pre-established eligibility criteria, two reviewers independently determined whether abstracts contained evidence of demographic or biological characteristics, i.e. moderators, influencing naltrexone response in alcohol dependence. We assessed each publication for risk of bias and evaluated the strength of the body of evidence for each moderator.

RESULTS

Twenty-eight publications (on 20 studies) met criteria for data synthesis. These included 26 publications from 12 randomized, placebo-controlled trials, three non-randomized, non-placebo studies and one randomized, non-placebo study. In addition, there were two publications from pooled analyses of four randomized, placebo-controlled trials. Family history of alcohol problems and the Asn40Asp polymorphism of the μ-opioid receptor gene showed a positive association with efficacy in four of five and three of five studies, respectively. Other moderators reported to be associated with efficacy included male sex (two of five studies), pre-treatment drinking (two of two studies) and high craving (two of five studies). However, the overall risk of bias in the published literature is high.

CONCLUSIONS

The identification of naltrexone-responsive alcohol-dependent patients is still in development. Studies to date point to two potential moderators-family history and presence of the OPRM1 Asn40Asp polymorphism-as having the strongest evidence. However, the data to date is still insufficient to recommend that any moderator be used in determining clinical treatment.

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.

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.

Alcohol craving as a predictor of relapse

BACKGROUND AND OBJECTIVES

Alcoholism treatment interventions, both psychosocial and pharmacologic, aim to reduce cravings to drink. Yet, the role of craving in treatment outcomes remains unclear. This study evaluated craving intensity measured with the Penn Alcohol Craving Scale (PACS) at admission and discharge from residential treatment as a predictive factor of relapse after treatment.

METHODS

The study cohort included 314 alcohol-dependent subjects. Associations between relapse after discharge, PACS score, and clinical variables were investigated using time-to-event analyses. The primary analysis, based on the intent-to-treat principle, presumed relapse in those declining follow-up or not responding to contact attempts. Secondary analysis utilized data from 226 subjects successfully contacted after discharge with a median follow-up time of 365 days.

RESULTS

The intent-to-treat analysis demonstrated that relapse was associated with higher level of craving at admission (p= .002) and discharge (p < .001). The analysis of data from patients successfully contacted after discharge led to similar results. A multivariable analysis indicated that relapse rates increased as PACS scores increased, and a higher discharge PACS score was significantly associated with relapse (p= .006) even after adjusting for covariates.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

This study demonstrates that higher PACS scores at the time of admission and discharge are associated with relapse following residential addiction treatment. These data support the role of craving in relapse and the utility of craving measurement as a clinical guide in assessing relapse risk.

Targeted opioid receptor antagonists in the treatment of alcohol use disorders

In 1994, the US Food and Drug Administration approved the μ-opioid receptor antagonist naltrexone to treat alcohol dependence. However, treatments requiring daily administration, such as naltrexone, are inconsistently adhered to in substance abusing populations, and constant medication exposure can increase risk of adverse outcomes, e.g., hepatotoxicity. This has fostered a 'targeted' or 'as needed' approach to opioid receptor antagonist treatment, in which medications are used only in anticipation of or during high-risk situations, including times of intense cravings. Initial studies of the ability of targeted naltrexone to reduce drinking-related outcomes were conducted in problem drinkers and have been extended into larger, multi-site, placebo-controlled investigations with positive results. Another μ-opioid receptor antagonist, nalmefene, has been studied on an 'as-needed' basis to reduce heavy drinking in alcohol-dependent individuals. These studies include three large multi-site trials in Europe of up to 1 year in duration, and serve as the basis for the recent approval of nalmefene by the European Medicines Agency as an 'as-needed' adjunctive treatment for alcohol dependence. We review potential moderators of opioid receptor antagonist treatment response including subjective assessments, objective clinical measures and genetic variants. In sum, the targeted or 'as-needed' approach to treatment with opioid antagonists is an efficacious harm-reduction strategy for problem drinking and alcohol dependence.

Cocaine self-administration punished by i.v. histamine in rat models of high and low drug abuse vulnerability: effects of saccharin preference, impulsivity, and sex

A key feature of substance use disorders is continued drug consumption despite aversive consequences. This has been modeled in the animal laboratory by pairing drug self-administration with electric shock, thereby punishing drug intake (Deroche-Gamonet et al. 2004). In the present experiments, we examined the effects of punishment on i.v. cocaine self-administration by adding histamine to the cocaine solution with three different animal models of high and low vulnerability to drug abuse: rats selectively bred for high (HiS) and low (LoS) saccharin consumption, rats selected for high (HiI) and low (LoI) impulsivity, and sex differences. Animals were allowed to self-administer cocaine (0.4 mg/kg/infusion) to establish a baseline of operant responding. Histamine (4.0mg/kg/infusion) was then added directly into the cocaine solution and its consequent effects on self-administration were compared to baseline. The histamine+cocaine solution was then replaced with a cocaine-only solution, and the rats' operant responding was again compared to baseline. Concurrent histamine exposure was effective in reducing cocaine consumption in all groups of rats; however, LoS and female rats took longer to return to baseline levels of cocaine consumption after histamine was removed compared to HiS and male rats. These data suggest that the reduction of drug self-administration by aversive consequences may differ in groups that vary in drug use vulnerability . Such results may inform pharmacological strategies that enhance the negative aspects of drug consumption.

Opiate agonists and antagonists modulate taste perception in opiate-maintained and recently detoxified subjects

Heroin addicts consume large quantities of refined sugars. This study investigated the effect of opiate use and antagonism on sweet taste in opiate-maintained drug users and detoxified former chronic opiate users, using a within-subject design. Seven opiate users received methadone and seven buprenorphine maintenance. Six detoxified subjects received naltrexone. Sucrose recognition thresholds and measurements of pleasantness and intensity were determined before and four hours after 1) a single dose of methadone or buprenorphine or 2) naltrexone. Control data were taken from a cohort of healthy volunteers including smokers. All measures of sweet and salt taste perception were significantly greater in opiate users and recently detoxified subjects compared to control subjects, with the exception of sweet pleasantness, which returned to control level after detoxification. Acute methadone administration reduced salt thresholds and unpleasantness to control levels. Increased sweet thresholds and salt unpleasantness in detoxified subjects were reversed by acute opioid antagonism, returning to control levels. These results suggest that opiate use and antagonism alters taste perception. Some of the alterations reverse on detoxification (sweet pleasantness), and others can be reversed by opioid antagonism (sweet threshold, salt unpleasantness). Changes in taste perception may underlie altered consumption of refined sugars in opiate users.

Craving as a predictor of treatment outcomes in heavy drinkers with comorbid depressed mood

Alcohol and depression comorbidity is high and is associated with poorer outcomes following treatment. The ability to predict likely treatment response would be advantageous for treatment planning. Craving has been widely studied as a potential predictor, but has performed inconsistently. The effect of comorbid depression on craving's predictive performance however, has been largely neglected, despite demonstrated associations between negative affect and craving. The current study examined the performance of craving, measured pre-treatment using the Obsessive subscale of the Obsessive Compulsive Drinking Scale, in predicting 18-week and 12-month post-treatment alcohol use outcomes in a sample of depressed drinkers. Data for the current study were collected during a randomized controlled trial (Baker, Kavanagh, Kay-Lambkin, Hunt, Lewin, Carr, & Connolly, 2010) comparing treatments for comorbid alcohol and depression. A subset of 260 participants from that trial with a Timeline Followback measure of alcohol consumption was analyzed. Pre-treatment craving was a significant predictor of average weekly alcohol consumption at 18 weeks and of frequency of alcohol binges at 18 weeks and 12 months, but pre-treatment depressive mood was not predictive, and effects of Baseline craving were independent of depressive mood. Results suggest a greater ongoing risk from craving than from depressive mood at Baseline.

Bipolar disorder and alcohol use disorder: a review

Bipolar disorder and alcohol use disorder represent a significant comorbid population, which is significantly worse than either diagnosis alone in presentation, duration, co-morbidity, cost, suicide rate, and poor response to treatment. They share some common characteristics in relation to genetic background, neuroimaging findings, and some biochemical findings. They can be treated with separate care, or ideally some form of integrated care. There are a number of pharmacotherapy trials, and psychotherapy trials that can aid program development. Post-treatment prognosis can be influenced by a number of factors including early abstinence, baseline low anxiety, engagement with an aftercare program and female gender. The future development of novel therapies relies upon increased psychiatric and medical awareness of the co-morbidity, and further research into novel therapies for the comorbid group.

Analyses related to the development of DSM-5 criteria for substance use related disorders: 2. Proposed DSM-5 criteria for alcohol, cannabis, cocaine and heroin disorders in 663 substance abuse patients

BACKGROUND

A number of changes have been proposed and investigated in the criteria for substance use disorders in DSM-5. However, although clinical utility of DSM-5 is a high priority, relatively little of the empirical evidence supporting the changes was obtained from samples of substance abuse patients.

METHODS

Proposed changes were examined in 663 patients in treatment for substance use disorders, evaluated by experienced clinicians using the Psychiatric Research Interview for Substance and Mental Disorders (PRISM). Factor and item response theory analysis was used to investigate the dimensionality and psychometric properties of alcohol, cannabis, cocaine and heroin abuse and dependence criteria, and craving.

RESULTS

The seven dependence criteria, three of the abuse criteria (hazardous use; social/interpersonal problems related to use; neglect of roles to use), and craving form a unidimensional latent trait for alcohol, cannabis, cocaine and heroin. Craving did not add significantly to the total information offered by the dependence criteria, but adding the three abuse criteria and craving together did significantly increase total information for the criteria sets associated with alcohol, cannabis and heroin.

CONCLUSION

Among adult patients in treatment for substance disorders, the alcohol, cannabis, cocaine and heroin criteria for dependence, abuse (with the exception of legal problems), and craving measure a single underlying dimension. Results support the proposal to combine abuse and dependence into a single diagnosis in the DSM-5, omitting legal problems. Mixed support was provided for the addition of craving as a new criterion, warranting future studies of this important construct in substance use disorders.

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.

Predictors for the efficacy of naltrexone treatment in alcohol dependence: sweet preference

AIMS

To analyse the possible associations between sweet preference and the efficacy of naltrexone treatment of alcohol dependence.

METHODS

The preference for different concentrations of sucrose was evaluated in 78 participants diagnosed with alcohol dependence after treatment for 32 weeks with naltrexone or placebo without prior detoxification.

RESULTS

A significant difference between naltrexone and placebo groups was found in the association between the preference for higher sucrose concentrations and relapses to heavy drinking. Higher sweet preference was significantly related to successful treatment measures in the naltrexone group but not in the placebo group.

CONCLUSION

Sweet preference has a strong correlation to treatment outcomes with naltrexone, and sweet preference might be used as a predictor for better treatment results in alcoholics. Our study offers one possible new explanation of the clinical observation that naltrexone is not effective for every patient.

Endogenous opiates and behavior: 2009

This paper is the 32nd consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2009 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurologic disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).

Role of feeding-related pathways in alcohol dependence: A focus on sweet preference, NPY, and ghrelin

Converging research evidence suggests that alcohol and food-seeking behaviors share common neural pathways. There is preclinical and clinical evidence linking the consumption of sweets to alcohol intake in both animals and humans. In addition, a growing body of animal and human literature suggests the involvement of "feeding-related" peptides in alcohol-seeking behavior. In particular, both central and peripheral appetitive peptides have shown a possible role in alcohol dependence. The present mini-review will summarize the literature on the link between sweet preference and alcohol dependence, and on the role of feeding-related peptides in alcohol dependence. Specifically, in an attempt to narrow the field, the present mini-review will focus on 2 specific pathways, the central neuropeptide Y and the peripheral gut peptide ghrelin. Although more research is needed, data available suggest that studying feeding-related pathways in alcohol dependence may have theoretic, biologic, diagnostic, and therapeutic implications.

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.

Milk consumption during adolescence decreases alcohol drinking in adulthood

Early onset of alcohol consumption increases the risk for the development of dependence. Whether adolescent consumption of other highly palatable solutions may also affect alcohol drinking in adulthood is not known. The purpose of this study was to determine the effects of adolescent consumption of four solutions: water, sucrose, sucrose-milk and milk on ethanol drinking in adult rats. Rats had limited access to one of the four solutions from day PND 29 to PND 51 and were subsequently trained to consume ethanol (E) using a sucrose (S) fade-out procedure. Adolescent consumption of sucrose and sucrose-milk solutions increased intake of 2.5% E when it was combined with 10% S but it had no effect on the drinking of 10% E alone. Adolescent consumption of milk and sucrose-milk significantly decreased the intake of 10% E when it was combined with 10% S, and milk significantly reduced 10% E consumption alone and when it was combined with 5% S. Adolescent exposure to the sucrose-milk and sucrose solutions was also found to increase sucrose and sucrose-milk consumption. Our findings suggest adolescent exposure to sucrose increases, whereas, exposure to milk reduces ethanol consumption in adult rats. Our results may provide a new theoretical approach to the early prevention of alcoholism.