Is Risk for Alcoholism Mediated by Individual Differences in Drinking Motivations?

Genetic and environmental etiology of drinking motives in college students

BACKGROUND

Drinking motives are robust proximal predictors of alcohol use behaviors and may mediate distinct etiological pathways in the development of alcohol misuse. However, little is known about the genetic and environmental etiology of drinking motives themselves and their potential utility as endophenotypes.

METHODS

Here, we leverage a longitudinal study of college students from diverse racial/ethnic backgrounds (phenotypic N = 9889, genotypic N = 4855) to investigate the temporal stability and demographic and environmental predictors of four types of drinking motives (enhancement, social, coping, and conformity). Using genome-wide association study (GWAS) and in silico tools, we characterize their associated genes and genetic variants (single nucleotide polymorphisms or SNPs).

RESULTS

Drinking motives were stable across four years of college (ICC >0.74). Some robust environmental predictors of alcohol misuse (parental autonomy granting and peer deviance) were broadly associated with multiple types of drinking motives, while others (e.g., trauma exposure) were type specific. Genome-wide analyses indicated modest SNP-based heritability (14-22%, n.s.) and several suggestive genomic loci that corroborate findings from previous molecular genetic studies (e.g., PECR and SIRT4 genes), indicating possible differences in the genetic etiology of positive versus negative reinforcement drinking motives that align with an internalizing/externalizing typology of alcohol misuse. Coping motives were significantly genetically correlated with alcohol use disorder diagnoses (r_g  = 0.71, p = 0.001). However, results from the genetic analyses were largely underpowered to detect significant associations.

CONCLUSIONS

Drinking motives show promise as endophenotypes but require further investigation in larger samples to further our understanding of the etiology of alcohol misuse.

The neuropeptide Y single-nucleotide polymorphism rs16147:T>C moderates the effect of alcohol dependence on depression in male Chinese Han population

BACKGROUND

Previous studies suggest that alcohol dependence is associated with depression, however, the effect of alcohol dependence varies from individual to individual, which may be due to different genetic backgrounds. The interactions between alcohol dependence and different gene polymorphisms may finally shape the onset of depression. Neuropeptide Y (NPY), which can maintain homeostasis from high-stress stimulation, may protect individuals from the onset of depression. Here, we explored whether the NPY rs16147:T>C has an association with depression in individuals with alcohol dependence during the period of alcohol dependence withdrawal.

METHODS

A total of 455 males with alcohol dependence were recruited. The scale of Michigan Alcoholism Screening Test (MAST) and Self-Depression Scale (SDS) were respectively used to analyze the condition of alcohol dependence and depression. Genomic DNA was extracted from each blood sample and NPY polymorphisms were genotyped. The interaction between NPY rs16147:T>C and alcohol dependence on depression was first analyzed. Then, region of significance analysis was used to confirm which model provided the best fit for the interaction (diathesis-stress or differential susceptibility). Finally, by using internal replication analyses, the accuracy and robustness of the interaction results were improved.

RESULTS

Alcohol dependence was positively correlated with depression. CC homozygotes of NPY rs16147:T>C exhibited less depression when exposed to low alcohol dependence, but more depression when exposed to high alcohol dependence. Individuals with the T allele showed the opposite result.

CONCLUSION

NPY rs16147:T>C might be correlated with susceptibility for depression in males during alcohol dependence withdrawal. The findings support the differential susceptibility model.

Impact of COVID-19 restrictions on alcohol consumption behaviours

BACKGROUND

We aimed to evaluate how coronavirus (COVID-19) restrictions had altered individual's drinking behaviours, including consumption, hangover experiences, and motivations to drink, and changing levels of depression and anxiety.

METHOD

We conducted an online cross-sectional self-report survey. Whole group analysis compared pre- versus post-COVID restrictions. A correlation coefficient matrix evaluated the associations between all outcome scores. Self-report data was compared with Alcohol Use Disorders Identification Test (AUDIT) scores from the 2014 Adult Psychiatric Morbidity Survey. Multiple linear modelling (MLM) was calculated to identify factors associated with increasing AUDIT scores and post-restriction AUDIT scores.

RESULTS

In total, 346 individuals completed the survey, of which 336 reported drinking and were therefore analysed. After COVID-19 restrictions 23.2% of respondents reported an increased AUDIT score, and 60.1% a decreased score. AUDIT score change was positively correlated with change in depression (P < 0.01, r = 0.15), anxiety (P < 0.01, r = 0.15) and drinking to cope scores (P < 0.0001, r = 0.35). MLM revealed that higher AUDIT scores were associated with age, mental illness, lack of a garden, self-employed or furloughed individuals, a confirmed COVID-19 diagnosis and smoking status.

CONCLUSIONS

COVID-19 restrictions decreased alcohol consumption for the majority of individuals in this study. However, a small proportion increased their consumption; this related to drinking to cope and increased depression and anxiety.

Association between polymorphism in gene related to the dopamine circuit and motivations for drinking in patients with alcohol use disorder

The development of alcohol use disorder (AUD) is influenced by genetic, psychological, and social factors. However, the identification of the load of each of these factors and the association between them is still debatable. This study aimed to explore the load of the association between AUD and polymorphisms in genes of the dopaminergic system, as well as with drinking triggers. The study comprised 227 inpatients with AUD and 174 controls. The pattern and motivations for drinking were evaluated using the Alcohol Use Disorders Identification Test (AUDIT) and the Inventory of Drinking Situations (IDS). Analyses of genetic variation in genes encoding dopaminergic were performed using next generation sequencing. We observed an significant association between a polymorphism in DDC (rs11575457) and AUD. Positive reinforcement factors as urges/temptations to drink and pleasant emotion, in isolation, were the significantly related elements to drinking. In addition, negative (physical discomfort) and positive reinforcement factors (testing personal control; pleasant time with others) significantly reinforced the interaction with DDC genetic variant for increased odds of an individual presenting AUD. These results indicated a complex relationship between the dopaminergic system and the drug-seeking behavior profiles.

Explaining the association between anxiety disorders and alcohol use disorder: A twin study

BACKGROUND

It is unknown whether social anxiety disorder (SAD) has a unique association with alcohol use disorder (AUD) over and beyond that of other anxiety disorders, how the associations develop over time, and whether the associations are likely to be causal.

METHODS

Diagnoses of AUD, SAD, generalized anxiety disorder, panic disorder, agoraphobia, and specific phobias were assessed twice using the Composite International Diagnostic Interview among 2,801 adult Norwegian twins. The data were analyzed using logistic regression analyses and multivariate biometric structural equation modeling.

RESULTS

SAD had the strongest association with AUD, and SAD predicted AUD over and above the effect of other anxiety disorders. In addition, SAD was prospectively associated with AUD, whereas other anxiety disorders were not. AUD was associated with a slightly elevated risk of later anxiety disorders other than SAD. Biometric modeling favored a model where SAD influenced AUD compared to models where the relationship was reversed or due to correlated risk factors. Positive associations between AUD and other anxiety disorders were fully explained by shared genetic risk factors.

CONCLUSIONS

Unlike other anxiety disorders, SAD plausibly has a direct effect on AUD. Interventions aimed at prevention or treatment of SAD may have an additional beneficial effect of preventing AUD, whereas interventions aimed at other anxiety disorders are unlikely to have a similar sequential effect on AUD.

Alcoholism gender differences in brain responsivity to emotional stimuli

Men and women may use alcohol to regulate emotions differently, with corresponding differences in neural responses. We explored how the viewing of different types of emotionally salient stimuli impacted brain activity observed through functional magnetic resonance imaging (fMRI) from 42 long-term abstinent alcoholic (25 women) and 46 nonalcoholic (24 women) participants. Analyses revealed blunted brain responsivity in alcoholic compared to nonalcoholic groups, as well as gender differences in those activation patterns. Brain activation in alcoholic men (ALCM) was significantly lower than in nonalcoholic men (NCM) in regions including rostral middle and superior frontal cortex, precentral gyrus, and inferior parietal cortex, whereas activation was higher in alcoholic women (ALCW) than in nonalcoholic women (NCW) in superior frontal and supramarginal cortical regions. The reduced brain reactivity of ALCM, and increases for ALCW, highlighted divergent brain regions and gender effects, suggesting possible differences in the underlying basis for development of alcohol use disorders.

Is family history of alcohol dependence a risk factor for disturbed sleep in alcohol dependent subjects?

BACKGROUND

Disturbed sleep and a family history of alcohol dependence (AD) are risk factors for developing AD, yet the underlying relationship between them is unclear among individuals with AD. Understanding these inherited associations will help us not only identify risk for development of these comorbid disorders, but also individualize treatment at this interface. We evaluated whether a first-degree family history of AD (FH+) was a risk factor for sleep continuity disturbance in patients with AD. We also evaluated whether alcohol use or mood disturbance moderated the relationship between FH and sleep.

METHODS

We analyzed cross-sectional baseline data from an alcohol clinical trial in a sample of individuals with AD (N = 280). Their family history of AD among nuclear family members, sleep complaints, alcohol use (over the last 90 days), and mood disturbance were assessed using the Family History Interview for Substance and Mood Disorders, Medical Outcomes Study Sleep Scale, Time Line Follow-Back Interview, and Profile of Mood States-Short Form, respectively.

RESULTS

A FH + status (65% of subjects) was significantly associated with lower model estimated mean sleep adequacy (β = - 7.05, p = 0.02) and sleep duration (β = - 0.38, p = 0.04) scale scores. FH was not associated with sleep disturbance scale. No significant moderating effect involving alcohol use or mood disturbance was seen.

CONCLUSION

Family history of AD is a unique risk factor for sleep complaints in AD. Non-restorative sleep and sleep duration may be noteworthy phenotypes to help probe for underlying genotypic polymorphisms in these comorbid disorders.

Interaction between the ADH1B*3 allele and drinking motives on alcohol use among Black college students

BACKGROUND

Black young adults have lower rates of alcohol use than other racial groups. Genetic factors may protect against drinking. Specifically, the ADH1B*3 allele is present almost exclusively in Black populations and has been protective against alcohol use and alcohol use disorder. The protective effects of the ADH1B*3 allele, however, may differ as a function of alcohol-promoting cognitions.

OBJECTIVES

The current study examined whether ADH1B*3 moderated relations of drinking motives with alcohol consumption among Black college drinkers.

METHODS

Participants were 241 undergraduate students of self-identified Black race (mean age = 20 years; 66% female) who reported consuming alcohol at least once in the past 30 days.

RESULTS

ADH1B*3 was not significantly associated with drinking motives or drinking behaviors. However, significant, albeit small, interaction effects of ADH1B*3 with drinking motives on drinking behavior were found; the presence of an ADH1B*3 allele protected against greater drinking quantity among students with high social motives (incidence rate ratio [IRR] = 0.95, 95% CI [0.92, 0.99]) and against frequent drinking among students with low coping motives (IRR = 1.06, 95% CI [1.01, 1.11]).

CONCLUSION

These findings represent a novel demonstration of genetic modulation of alcohol-related cognitions within Black college drinkers, although replication is needed. Results represent an initial step toward better characterizing individual differences in associations of drinking motives with drinking behavior, with potential implications for interventions aimed at motivational processes in alcohol use.

Alcohol misuse in emerging adulthood: Association of dopamine and serotonin receptor genes with impulsivity-related cognition

Impulsivity predicts alcohol misuse and risk for alcohol use disorder. Cognition mediates much of this association. Genes also account for a large amount of variance in alcohol misuse, with dopamine and serotonin receptor genes of particular interest, because of their role in motivated behavior. The precise psychological mechanisms through which such genes confer risk is unclear. Trait impulsivity conveys risk for alcohol misuse by influencing two distinct domains of cognition: beliefs about the reinforcing effects of alcohol consumption (positive alcohol expectancy) and the perceived ability to resist it (drinking refusal self-efficacy). This study investigated the effect of the dopamine-related polymorphism in the DRD2/ANKK1 gene (rs1800497) and a serotonin-related polymorphism in the HTR2A gene (rs6313) on associations between impulsivity, cognition, and alcohol misuse in 120 emerging adults (18-21years). HTR2A predicted lower positive alcohol expectancy, higher refusal self-efficacy, and lower alcohol misuse. However, neither polymorphism moderated the linkages between impulsivity, cognition, and alcohol misuse. This is the first report of an association between HTR2A and alcohol-related cognition. Theoretically-driven biopsychosocial models have potential to elucidate the specific cognitive mechanisms through which distal risk factors like genes and temperament affect alcohol misuse in emerging adulthood.

A developmental model for alcohol use disorders in Swedish men

BACKGROUND

Alcohol use disorder (AUD) is a classic multifactorial syndrome and it is critical to understand the diversity of the relevant risk factors and how they inter-relate over development.

METHOD

We examined 21 risk factors for AUD in four developmental tiers reflecting (i) birth, (ii) childhood and early adolescence, (iii) late adolescence, and (iv) early adulthood in 47 414 Swedish men of whom 3907 (8.2%) were registered for AUD at or after age 25 with a mean length of follow-up of 33.9 (6.6) years. Structural equational model fitting was performed using Mplus.

RESULTS

The best-fitting model provided a good fit to the data and explained 23.4% of the variance in AUD. The five strongest predictors were: externalizing behaviors, criminal behavior, father's alcohol consumption, genetic risk, and low educational attainment. Two developmentally early familial/genetic risk factors had substantial direct paths to AUD: father's alcohol consumption and genetic liability. Other broad developmental pathways to risk for AUD were evident: externalizing, psychosocial and internalizing. Overall, the externalizing pathway to AUD was the strongest. However, these pathways were substantially interwoven over time such that risk factors from one domain were commonly predicted by and/or predicted risk factors from the other broad domains of risk.

CONCLUSION

AUD in men is an etiologically complex syndrome influenced by familial-genetic, psychosocial, internalizing, and especially externalizing risk factors that act and interact over development and have complicated mediational pathways.

Limitations of lifetime alcohol use disorder assessments: A criterion-validation study

The goal of the present study was to compare etiologically and clinically relevant correlates of lifetime AUD (e.g., alcohol consumption, personality traits, psychiatric disorders) based on a single assessment compared to a cumulative, prospective assessment of lifetime AUD. Data were drawn from the Alcohol, Health and Behavior (AHB; baseline N=489) study, which consisted of a prospective cohort of college students assessed seven times over a 16-year period ([M(SD) age at baseline=18.56 (.97)] and [M(SD) age at final assessment=34.33 (.82)]). The participants were assessed using the Diagnostic Interview Schedule (DIS) for DSM-III at Waves 1-7 and for DSM-IV at Waves 6-7. A single assessment and cumulative assessments of DSM-III lifetime AUD at Wave 6 (M[SD] age=28.98 [1.03]) were used to predict past-year alcohol related variables (e.g., alcohol consumption, drinking motives, drinking expectancies), personality variables, general functioning, lifetime substance use, and lifetime psychiatric disorders at Wave 7. Significantly larger correlations were found between the cumulative assessment and eight of the 25 etiologically relevant correlates of AUD compared to the single assessment. Further, significant incremental validity of cumulative assessment over single, retrospective assessment was observed for 16 of the 25 covariates. Overall, this study provides further support for the value of using prospective data with multiple assessments when determining lifetime history of disorder.

Drinking experience uncovers genetic influences on alcohol expectancies across adolescence

AIMS

To test whether drinking onset moderates genetic and environmental contributions to individual differences in the etiology of alcohol expectancies across adolescence.

DESIGN

Longitudinal twin design.

SETTING

Community sample from Los Angeles, CA, USA.

PARTICIPANTS

A total of 1292 male and female twins, aged 11–18years, were assessed at 1 (n = 440), 2 (n = 587) or 3 (n = 265) occasions as part of the risk factors for the Antisocial Behavior Twin Study.

MEASUREMENTS

Social behavioral (SB) alcohol expectancies were measured using an abbreviated version of the Social Behavioral subscale from the Alcohol Expectancy Questionnaire for adolescents (AEQ-A). Drinking onset was defined as >1 full drink of alcohol.

FINDINGS

Alcohol expectancies increased over age and the increase became more rapid following onset of drinking. The importance of genetic and environmental influences on SB scores varied with age and drinking status, such that variation prior to drinking onset was attributed solely to environmental influences, whereas all post-onset variation was attributed to genetic influences. Results did not differ significantly by sex.

CONCLUSION

Only environmental factors explain beliefs about the social and behavioral consequences of alcohol use prior to drinking onset,whereas genetic factors explain an increasing proportion of the variance in these beliefs after drinking onset.

Peer deviance, alcohol expectancies, and adolescent alcohol use: explaining shared and nonshared environmental effects using an adoptive sibling pair design

Previous research suggests adolescent alcohol use is largely influenced by environmental factors, yet little is known about the specific nature of this influence. We hypothesized that peer deviance and alcohol expectancies would be sources of environmental influence because both have been consistently and strongly correlated with adolescent alcohol use. The sample included 206 genetically related and 407 genetically unrelated sibling pairs assessed in mid-to-late adolescence. The heritability of adolescent alcohol use (e.g., frequency, quantity last 12 months) was minimal and not significantly different from zero. The associations among peer deviance, alcohol expectancies, and alcohol use were primarily due to shared environmental factors. Of special note, alcohol expectancies also significantly explained nonshared environmental influence on alcohol use. This study is one of few that have identified specific environmental variants of adolescent alcohol use while controlling for genetic influence.

A behavioral genetic investigation of weekend drinking among an adult sample

This study examined common and unique genetic and environmental influences on weekend drinking and weekday drinking reported by US male and female adult participants (mean age = 43.9). Data from 96 monozygotic and 82 dizygotic twin pairs were used to estimate bivariate biometric models of daily levels of weekend and weekday drinking volume. Weekend and weekday drinking volume scores were calculated from end-of-day reports of drinking across eight days. As expected, more drinking occurred during weekends. Biometric models provided evidence of significant additive genetic and nonshared environmental influences on both weekend and weekday drinking. Shared environmental influences were nonsignificant. Genetic influences accounted for a greater proportion of drinking variance during weekdays than weekends (0.36 compared to 0.17). However, these apparent differences in heritability-proportion of total variance accounted for by genetic variance-were due to increased nonshared environmental influences on weekend days, rather than greater genetic influences. The study's limitations are noted. Funded by National Institutes of Health/National Institute of Aging and John D. and Catherine T. MacArthur Foundation.

Patterns of alcohol expectancies and alcohol use across age and gender

AIMS

To investigate the relationship between alcohol expectancies and alcohol use in a community sample as a function of age and gender.

METHODS

The study is based on a national probability sample of 6467 German adults. Respondents were grouped into five age groups ranging from 18 to 59 years. A brief version of the Comprehensive Alcohol Expectancy Questionnaire was used to assess alcohol expectancies. Alcohol use was assessed by the number of drinking days during the past month and the number of drinks on an average drinking day.

RESULTS

Prior to conducting group comparisons, measurement invariance across age and gender was established. Latent mean level comparisons showed that the endorsement of both positive and negative expectancies almost linearly decreased with increasing age. However, this decrease was not reflected in alcohol consumption patterns. Structural analysis of the expectancy factors and drinking variables showed that the predictive power of expectancies varied by age and gender. Particularly, expectancies related to social assertiveness and sexual enhancement were strong predictors only in younger, but not in older respondents. Conversely, expectancies related to tension reduction and impairment were the most important predictors of drinking in respondents older than 30 years, but not in younger age groups. Additionally, the onset and course of age-related changes in expectancies was moderated by gender.

CONCLUSIONS

The present study demonstrates substantial age-related changes in the relationship between alcohol expectancies and alcohol use. Moreover, the profile of alcohol expectancies appears to be more important than their absolute strength.

Shared genetic contributions to early-onset drinking and drinking to cope motives

INTRODUCTION

Recent evidence from empirical studies indicates that individuals who begin drinking at an early age may be more likely to use alcohol to cope with negative mood states and stress; however, the mechanisms underlying this association are unclear. One possibility is that early drinking directly increases risk for drinking to cope (DTC). Alternatively, the association between early drinking and DTC may be indirect, attributable to overlapping genetic or environmental factors. No prior genetically informative study has investigated the sources of covariation underlying the early-onset drinking-DTC association.

METHOD

Early-onset drinking (before age 15) was assessed using structured clinical interviews in a sample of 7130 male and female participants aged 19-56 years from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders (VATSPSUD, Kendler & Prescott, 2006). DTC was assessed using the mood management scale of the alcohol use inventory (Horn & Wanberg, 1983). The sources of the covariation between early first drink and DTC were estimated using bivariate twin modeling.

RESULTS

Early drinking onset was reported by 28% of males and 16% of females and was associated with significantly higher DTC scores (phenotypic correlation: males = .19, females = .22). Results from bivariate twin models indicated that the association between early-onset drinking and DTC was completely attributable to shared genetic factors that contribute to both behaviors.

CONCLUSIONS

Greater DTC among early-onset drinkers may not reflect a direct causal process, as shared biological pathways may explain vulnerability to stress-related drinking seen among early-onset drinkers.

Development and preliminary validation of a behavioral task of negative reinforcement underlying risk-taking and its relation to problem alcohol use in college freshmen

BACKGROUND

A long line of theoretical and empirical evidence implicates negative reinforcement as a process underlying the etiology and maintenance of risky alcohol use behaviors from adolescence through emerging adulthood. However, the bulk of this literature has relied on self-report measures, and there is a notable absence of behavioral modes of assessments of negative reinforcement-based alcohol-related risk-taking. To address this clear gap in the literature, the current study presents the first published data on the reliability and validity of the Maryland Resource for the Behavioral Utilization of the Reinforcement of Negative Stimuli (MRBURNS), which is a modified version of the positive reinforcement-based Balloon Analogue Risk Task (BART).

METHODS

Participants included a convenience sample of 116 college freshmen ever regular drinkers (aged 18 to 19) who completed both behavioral tasks; self-report measures of negative reinforcement/avoidance constructs and of positive reinforcement/appetitive constructs to examine convergent validity and discriminant validity, respectively; and self-report measures of alcohol use, problems, and motives to examine criterion validity.

RESULTS

The MRBURNS evidenced sound experimental properties and reliability across task trials. In support of convergent validity, risk-taking on the MRBURNS correlated significantly with negative urgency, difficulties in emotion regulation, and depressive and anxiety-related symptoms. In support of discriminant validity, performance on the MRBURNS was unrelated to risk-taking on the BART, sensation seeking, and trait impulsivity. Finally, pertaining to criterion validity, risk-taking on the MRBURNS was related to alcohol-related problems but not heavy episodic alcohol use. Notably, risk-taking on the MRBURNS was associated with negative reinforcement-based but not with positive reinforcement-based drinking motives.

CONCLUSIONS

Data from this initial investigation suggest the utility of the MRBURNS as a behavioral measure of negative reinforcement-based risk-taking that can provide a useful complement to existing self-report measures to improve our understanding of the relationship between avoidant reinforcement processes and risky alcohol use.

The effects of age at drinking onset and stressful life events on alcohol use in adulthood: a replication and extension using a population-based twin sample

BACKGROUND

A study by Dawson and colleagues (Alcohol Clin Exp Res 2007; 31:69) using data from National Epidemiologic Survey on Alcohol and Related Condition found earlier drinking onset age, and higher levels of past-year stressful life events (SLE) were associated with higher past-year alcohol consumption. The aims of our study were as follows: (i) to attempt to replicate this interaction; (ii) to extend it by examining sex and event dependence as potential moderators of the effect; and (iii) to estimate the roles of genetic and environmental factors in mediating the overlap of early drinking onset and SLE in their relations with alcohol consumption.

METHODS

Data were from 1,382 female and 2,218 male drinkers interviewed as part of the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders. Regression models were used to evaluate the main and interactive effects of early drinking onset and moderate or severe past-year SLE on past-year drinking density (PYDD), a weighted quantity-frequency measure of alcohol consumption. Analyses adjusted for demographic covariates and were stratified by sex and whether SLE were independent or dependent on the person's actions, as rated by interviewers. Structural twin models were used to estimate the degree to which early drinking onset, SLE, and their interaction accounted for additive genetic, common environmental and individual-specific variance in PYDD.

RESULTS

We replicated the prior finding of a main effect of higher alcohol consumption among individuals reporting earlier drinking onset. Age at drinking onset accounted for about 5% of the variation in PYDD, and this association was mostly attributable to overlapping genetic influences. Evidence for an interaction between onset age and SLE was generally weak, possibly because of lower power and other methodological differences from Dawson and colleagues' study. However, there was some evidence consistent with an interaction of higher PYDD among early drinking men who experienced independent SLE and early drinking women with dependent SLE.

CONCLUSIONS

We confirmed prior findings of an association between early age at drinking onset with higher past-year drinking among young- and middle-aged adults and found limited evidence supporting a replication for higher stress-related drinking among early-onset drinkers. The association is consistent with early onset and stress-related drinking being attributable to overlapping genetic liability. Among early drinkers, our results suggest sex differences in consumption with regard to event dependence.

The relationship between rs3779084 in the dopa decarboxylase (DDC) gene and alcohol consumption is mediated by drinking motives in regular smokers

BACKGROUND

Motivational models of alcohol use propose that the motivation to consume alcohol is the final common pathway to its use. Both alcohol consumption and drinking motives are influenced by latent genetic factors that partially overlap. This study investigated whether drinking motives mediate the associations between alcohol consumption and 2 single-nucleotide polymorphisms (SNPs) from genes involved in serotonin (TPH2; rs1386496) and dopamine synthesis (DDC; rs3779084). Based on earlier work showing that enhancement and coping motives were heritable in regular smokers but not in nonregular smokers, we hypothesized these motives would mediate the relationships between alcohol consumption and these SNPs in regular smokers.

METHODS

Drinking motives data were available from 830 young adult female twins (n = 344 regular smokers and n = 486 never/nonregular smokers). We used confirmatory factor analyses to model enhancement, coping, and alcohol consumption factors and to conduct mediation analyses in the regular smoker and never/nonregular smoker groups.

RESULTS

Our hypothesis was partially supported. The relationship between alcohol consumption and rs1386496 was not mediated by drinking motives in either group. However, in the regular smokers, the relationship between alcohol consumption and rs3779084 was mediated by enhancement and coping motives. Carriers of the rs3779084 minor allele who were regular smokers reported more motivation to consume alcohol. Given this pattern of results was absent in the never/nonregular smokers, our results are consistent with a gene × smoking status interaction.

CONCLUSIONS

In regular smokers, variability at the locus marked by rs3779084 in the DDC gene appears to index biologically based individual differences in the motivation to consume alcohol to attain or improve a positive affective state or to relieve a negative one. These results could be because of increased sensitivity to the reinforcing effects of alcohol among minor allele carriers who smoke, which might be due to structural or functional differences in mesorticolimic dopamine "reward" circuitry.

Validation of a nine-dimensional measure of drinking motives for use in clinical applications: the desired effects of drinking scale

The Desired Effects of Drinking (DEOD) is a 36-item, 9-subscale, self-report measure assessing reasons for drinking, concerning three general motives for alcohol use: Coping, Social, and Enhancement. These subscales include Negative Feelings, Self-esteem, Relief, Positive Feelings, Social Facilitation, Assertion, Drug Effects, Sexual Enhancement, and Mental effects. As part of the COMBINE study, scores from the nine DEOD subscales, along with additional information about alcohol consumption and consequences, were incorporated into personalized client feedback as part of a motivational enhancement intervention and as a guide for the development of a plan for treatment and change. With responses from a clinical sample of 572 individuals seeking alcohol treatment, the 9-subscale structure of the instrument was substantiated through a second-order confirmatory factor analysis, revealing moderately large to large factor loadings and good indices of model fit. A third-order factor analysis indicated these nine subscales adequately represented the three drinking motives. It is suggested these three general motives for alcohol use, which may be more distinctly delineated into the nine dimensions reflected in the DEOD structure, can be used clinically to help plan appropriate interventions and facilitate behavior change.

Does variance in drinking motives explain the genetic overlap between personality and alcohol use disorder symptoms? A twin study of young women

BACKGROUND

Genetic risk for alcohol dependence has been shown to overlap with genetic factors contributing to variation in dimensions of personality. Although drinking motives have been posited as important mediators of the alcohol-personality relation, the extent to which the genetic covariance between alcohol use disorder (AUD) symptoms (i.e., abuse and dependence criteria) and personality is explained by genetic factors contributing to variation in drinking motives remains unclear.

METHODS

Using data from 2,904 young adult female twins, the phenotypic and genetic associations between personality dimensions (constraint [measured by the Multidimensional Personality Questionnaire; Tellegen A, 1982 unpublished data], conscientiousness, neuroticism, and agreeableness [measured by the NEO-PI; Costa and McCrae, 1985]), internal drinking motives (enhancement and coping motives [measured by the Drinking Motive Questionnaire; Cooper, 1994]), and AUD symptoms were tested.

RESULTS

Significant genetic associations were found between all personality measures and AUD symptoms. Coping motives showed significant genetic overlap with AUD symptoms and most personality measures, whereas enhancement motives were not significantly heritable. Adjusting for coping motives, genetic correlations between AUD symptoms and traits of neuroticism and agreeableness were no longer statistically significant.

CONCLUSIONS

Findings suggest that genetic variation in drinking to cope might account for a considerable proportion of the genetic covariance between specific personality dimensions and AUD symptoms.

Toward a comprehensive developmental model for alcohol use disorders in men

The multiple risk factors for alcohol use (AU) and alcohol use disorders (AUDs) are interrelated through poorly understood pathways, many of which begin in childhood. In this report, the authors seek to develop an empirical, broad-based developmental model for the etiology of AU and AUDs in men. We assessed 15 risk factors in four developmental tiers in 1,794 adult male twins from the Virginia population based twin registry. The best fitting model explained 39% of the variance in late adolescent AU, and 30% of the liability to lifetime symptoms of AUD. AU and AUDs can be best understood as arising from the action and interaction of two pathways reflecting externalizing genetic/temperamental and familial/social factors. Peer group deviance was important in each pathway. Internalizing symptoms played a more minor role. Familial/social factors were especially important influences on AU, while genetic/temperamental factors were more critical for AUDs. We conclude that AU and AUDs in men are complex traits influenced by genetic, family, temperamental, and social factors, acting and interacting over developmental time.

The enduring influence of drinking motives on alcohol consumption after fateful trauma

OBJECTIVE

Drinking motives predict later levels of alcohol consumption and development of alcohol dependence, but their effects on stress-related drinking are less clear. Proximity to the terrorist attack on the World Trade Center (WTC) on 9/11/01 was significantly associated with alcohol consumption 1 and 16 weeks after 9/11/01. We investigated the relationship between drinking motives measured a decade earlier, proximity to the WTC, and drinking after 9/11/01. This event constitutes a natural experiment for studying the effects of previously measured drinking motives on alcohol consumption after fateful trauma.

METHODS

Adult drinkers (N = 644) residing in a New Jersey county were evaluated for four drinking motives: coping with negative affect, for enjoyment, for social facilitation and social pressure. After 9/11/01, their exposure to the WTC attack and subsequent drinking were assessed. Poisson regression was used to assess the relationships between proximity to the WTC, drinking motives and post-9/11/01 drinking; models were adjusted for alcohol dependence, age, gender and race.

RESULTS

Drinking to cope with negative affect predicted alcohol consumption 1 week after 9/11/01 (p = 0.04) and drinking for enjoyment predicted drinking 1 and 16 weeks after 9/11/01 (p = 0.001 and 0.01, respectively). The associations were independent of proximity to the WTC. No interactions were observed between drinking motives, proximity to the WTC or lifetime alcohol dependence.

CONCLUSION

Drinking motives a decade earlier predicted higher alcohol consumption after fateful trauma independently from proximity to the WTC on 9/11/01. Results suggest that drinking motives constitute a robust, enduring influence on drinking behavior, including after traumatic experiences.

Risky alcohol use in adolescence: the role of genetics (DRD2, SLC6A4) and coping motives

BACKGROUND

Drinking to cope (i.e., drinking to forget or alleviate negative feelings) has been found to be associated with adolescents' heavy drinking and alcohol-related problems. Additionally, it is widely accepted that genetic factors are involved in alcohol use and dependence. Studies are only beginning to reveal, however, which specific genotypes are related to drinking behaviors, and it is unknown whether they may interact with coping motives in predicting adolescents' risky drinking. The aim of this study was to examine relationships between the dopamine D2 receptor gene (DRD2) Taq1A polymorphism (rs1800497), a serotonin transporter gene (SLC6A4) polymorphism (5-HTTLPR), coping motives, and adolescents' binge drinking and alcohol-related problems.

METHODS

Participants in this cross-sectional study were 282 Dutch adolescents (mean age 17.4, 47% men) who had consumed alcohol at least once in their life.

RESULTS

Coping motives were positively related to both binge drinking and alcohol-related problems, while DRD2 and SLC6A4 genotypes were not. DRD2, but not the SLC6A4 genotype, interacted with coping motives. The link between coping motives and alcohol outcomes was stronger among those carrying the DRD2 risk (A1) allele.

CONCLUSIONS

This study extends the present literature by providing additional insight into the etiological factors of adolescent drinking behavior. An interaction between a vulnerability gene (DRD2) and a cognitive factor (coping drinking) was found to be related to adolescents' binge drinking and alcohol-related problems.

A systematic evaluation and validation of subtypes of adolescent alcohol use motives: genetic and environmental contributions

BACKGROUND

Alcohol use motives are closely associated with specific profiles of alcohol use and reflect a subjectively derived decisional framework based on a motivational style of responding. Adult twin studies typically estimate the heritability of alcohol use motives to be between 7 and 42%, although relatively little is known about genetic and environmental influences upon alcohol use motives in adolescence.

METHODS

Latent class analysis (LCA) models containing 1 through 5 classes were fitted to the data derived from 1,422 adolescent twin and siblings self-reported alcohol use motives. Using twin models, we estimated the genetic, shared, and nonshared environmental influences to the class membership data derived from the LCA.

RESULTS

Four drinking motives classes were identified (family-oriented, social, enhancement/social, and coping/social). The coping/social and enhancement/social classes were differentiated from the social class on measures of depression, delinquency, and aggressive behavior. Analyses indicated that nonadditive genetic factors accounted for 76% of the variance in the coping/social motives class and additive genetic influences accounted for 66% of the variance in the social motives class. There was a moderate contribution of genetic factors and shared environmental factors influencing class membership of enhancement/social motivated drinkers (28 and 20% explained variance, respectively). Substantial shared environmental influences were revealed for membership of the family-oriented class (75%).

CONCLUSIONS

Heritable influences may predispose individuals to drink to cope with negative affect, for social reasons, and to a lesser extent for enhancement. Familial environmental influences shape family-oriented motives for drinking in adolescents.

Drinking motives in female smokers: factor structure, alcohol dependence, and genetic influences

BACKGROUND

Alcohol and tobacco use often co-occur. Human and animal studies indicate that nicotine increases alcohol's rewarding effects and the motivation to consume it. The aims of this study were to examine whether the factorial architecture of self-reported motivations to consume alcohol differed between regular and nonregular cigarette smokers while taking into account the lifetime history of alcohol dependence and psychopathology, and to estimate the genetic and environmental influences on the motivations.

METHODS

Using data on 2,189 monozygotic and dizygotic female twins, we examined the factorial structure (item thresholds and factor loadings, means, and variances) of the items from the Drinking Motives Questionnaire (DMQ) in regular and nonregular smokers. Post hoc tests examined the association between the latent drinking motives factors and alcohol dependence in both groups. Twin models were fitted to the latent drinking motives factors, testing for variations in the magnitude of additive genetic, shared, and nonshared environmental influences between the groups.

RESULTS

The 4 DMQ factors (social, conformity, coping, and enhancement) were recovered in both groups, and their measurement structure was consistent across the groups. Regular smokers reported higher levels of coping, enhancement, and social motives while nonregular smokers reported higher conformity motives. Alcohol dependence was associated with higher scores on all motives in both groups; however, in a regression analysis that included all of the motives as predictor variables, only coping was significantly related to alcohol dependence. While twin models revealed evidence for substantially greater genetic influences on enhancement (h² = 0.40), coping (h² = 0.35) and social (h² = 0.37) drinking motives in regular compared to nonregular smokers, the power to statistically distinguish the 2 groups was low.

CONCLUSIONS

While the measurement structure of the drinking motive factors appears to be similar across regular and nonregular smokers, regular smokers report more motivation to drink for internal affect-related reasons and to obtain social reward. Of all the motives, coping was the most robust predictor of alcohol dependence in both the regular and the nonregular smokers. Further, genetic influences might play a larger role in drinking motives among regular smokers, which provides tentative evidence for latent genetic × smoking status interactions.

Evaluating a cognitive model of ALDH2 and drinking behavior

BACKGROUND

Despite evidence for genetic influences on alcohol use and alcohol-related cognitions, genetic factors and endophenotypes are rarely incorporated in cognitive models of drinking behavior. This study evaluated a model of ALDH2 and drinking behavior stipulating cognitive factors and alcohol sensitivity as accounting for genetic influences on drinking outcomes.

METHODS

Participants were Asian-American young adults (n = 171) who completed measures of alcohol cognitions (drinking motives, drinking refusal self-efficacy, and alcohol expectancies), alcohol sensitivity, drinking behavior, and alcohol-related problems as part of a prospective study. Structural equation modeling (SEM) evaluated a model of drinking behavior that stipulated indirect effects of ALDH2 on drinking outcomes through cognitive variables and alcohol sensitivity.

RESULTS

The full model provided an adequate fit to the observed data, with the measurement model explaining 63% of the variance in baseline heavy drinking and 50% of the variance in alcohol-related problems at follow-up. Associations of ALDH2 with cognitive factors and alcohol sensitivity were significant, whereas the association of ALDH2 with drinking was not significant with these factors included in the model. Mediation tests indicated significant indirect effects of ALDH2 through drinking motives, drinking refusal self-efficacy, and alcohol sensitivity.

CONCLUSIONS

Results are consistent with the perspective that genetic influences on drinking behavior can be partly explained by learning mechanisms and implicate cognitive factors as important for characterizing associations of ALDH2 with drinking.

The Multiple, Distinct Ways that Personality Contributes to Alcohol Use Disorders

There is little question of whether personality is associated with problematic alcohol involvement (such as alcohol use disorders; AUDs); it clearly is. However, the question remains: how or why is personality related to risky drinking and AUDs? To address this question, theoretical models have been posited regarding the causal effects of personality on alcohol use and related problems. In this article, several of these models are summarized and reviewed. Future research directions are discussed, including possible frameworks that serve to integrate various models of the personality-AUD relation.

Consilient research approaches in studying gene x environment interactions in alcohol research

This review article discusses the importance of identifying gene-environment interactions for understanding the etiology and course of alcohol use disorders and related conditions. A number of critical challenges are discussed, including the fact that there is no organizing typology for classifying different types of environmental exposures, many key human environmental risk factors for alcohol dependence have no clear equivalents in other species, much of the genetic variance of alcohol dependence in human is not 'alcohol specific', and the potential range of gene-environment interactions that could be considered is so vast that maintaining statistical control of Type 1 errors is a daunting task. Despite these and other challenges, there appears to be a number of promising approaches that could be taken in order to achieve consilience and ecologically valid translation between human alcohol dependence and animal models. Foremost among these is to distinguish environmental exposures that are thought to have enduring effects on alcohol use motivation (and self-regulation) from situational environmental exposures that facilitate the expression of such motivations but do not, by themselves, have enduring effects. In order to enhance consilience, various domains of human approach motivation should be considered so that relevant environmental exposures can be sampled, as well as the appropriate species to study them in (i.e. where such motivations are ecologically relevant). Foremost among these are social environments, which are central to the initiation and escalation of human alcohol consumption. The value of twin studies, human laboratory studies and pharmacogenetic studies is also highlighted.

Initial evidence of an association between OPRM1 and adolescent alcohol misuse

BACKGROUND

Considerable research efforts have attempted to identify genes associated with alcoholism among adults, yet few studies have examined adolescents. Identifying genes associated with alcohol misuse in youth is important given that the relative contribution of genetic and environmental influences on alcoholism varies across development. The purpose of this study was to examine the association between a polymorphism of the mu-opioid receptor gene (OPRM1) and alcohol misuse in a sample of youth and to test whether heightened sensitivity to the reinforcing effects of alcohol mediated this relationship.

METHODS

Adolescents (n = 187; mean age = 15.4 years; 47.6% female) were genotyped for A118G (rs1799971), a single-nucleotide polymorphism (SNP) of the OPRM1 gene, and assessed for alcohol use disorder (AUD) diagnoses and other psychopathology. Alcohol misuse was also measured continuously to maximize detection of drinking problems in youth. Drinking motives were used to capture the extent to which youth consumed alcohol to enhance positive affect.

RESULTS

AUD groups differed significantly in terms of allelic distributions of the A118G SNP, such that 51.9% of youth with an AUD carried at least one copy of the G allele compared to 16.3% of non-AUD controls. Those who carried the G allele endorsed drinking to enhance positive affect more strongly than those who were homozygous for the A allele and drinking to enhance positive affect mediated the association between OPRM1 and alcohol-related problems.

CONCLUSIONS

These data build on findings from adult studies and provide the first evidence that a polymorphism of the OPRM1 receptor gene is associated with the development of early-onset alcohol-related problems during adolescence, in part, by heightening sensitivity to the reinforcing effects of alcohol.

ALDH2, ADH1B and alcohol expectancies: integrating genetic and learning perspectives

The present study evaluated associations of ALDH2 and ADH1B genotypes with alcohol expectancies and drinking behavior in a sample of Asian American young adults. In addition to assessing global alcohol expectancies, the authors developed a measure of physiological expectancies to evaluate an expectancy phenotype specific to the mechanism by which ALDH2 and ADH1B variations presumably influence drinking behavior. Compared with individuals with the ALDH2*1/*1 genotype, those with the ALDH2*2 allele reported greater negative alcohol expectancies, greater expectancies for physiological effects of alcohol and lower rates of alcohol use. ADH1B was not associated with alcohol expectancies or drinking behavior. Hierarchical models showed that demographic factors, ALDH2 genotype, and expectancy variables explained unique variance in drinking outcomes. Mediation tests showed significant indirect effects of ALDH2 on drinking frequency and peak lifetime consumption through expectancies. These results provide support for influences of genetic factors and alcohol sensitivity on alcohol-related learning and suggest the importance of developing biopsychosocial models of drinking behavior in Asian Americans.

Genetic and non-genetic influences on the development of co-occurring alcohol problem use and internalizing symptomatology in adolescence: a review

AIMS

Alcohol problem use during adolescence has been linked to a variety of adverse consequences, including cigarette and illicit drug use, delinquency, adverse effects on pubertal brain development and increased risk of morbidity and mortality. In addition, heavy alcohol-drinking adolescents are at increased risk of comorbid psychopathology, including internalizing symptomatology (especially depression and anxiety). A range of genetic and non-genetic factors have been implicated in both alcohol problem use as well as internalizing symptomatology. However, to what extent shared risk factors contribute to their comorbidity in adolescence is poorly understood.

DESIGN

We conducted a systematic review on Medline, PsycINFO, Embase and Web of Science to identify epidemiological and molecular genetic studies published between November 1997 and November 2007 that examined risk factors that may be shared in common between alcohol problem use and internalizing symptomatology in adolescence.

FINDINGS

Externalizing disorders, family alcohol problems and stress, as well as the serotonin transporter (5-HTT) S-allele, the monoamine oxidase A (MAOA) low-activity alleles and the dopamine D2 receptor (DDR2) Taq A1 allele have been associated most frequently with both traits. An increasing number of papers are focusing upon the role of gene-gene (epistasis) and gene-environment interactions in the development of comorbid alcohol problem use and internalizing symptomatology.

CONCLUSIONS

Further research in adolescents is warranted; the increasing availability of large longitudinal genetically informative studies will provide the evidence base from which effective prevention and intervention strategies for comorbid alcohol problems and internalizing symptomatology can be developed.

Mood-related drinking motives mediate the familial association between major depression and alcohol dependence

BACKGROUND

Major depression and alcohol dependence co-occur within individuals and families to a higher than expected degree. This study investigated whether mood-related drinking motives mediate the association between major depression and alcohol dependence, and what the genetic and environmental bases are for this relationship.

METHODS

The sample included 5,181 individuals from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders, aged 30 and older. Participants completed a clinical interview which assessed lifetime major depression, alcohol dependence, and mood-related drinking motives.

RESULTS

Mood-related drinking motives significantly explained the depression-alcohol dependence relationship at both the phenotypic and familial levels. Results from twin analyses indicated that for both males and females, the familial factors underlying mood-related drinking motives accounted for virtually all of the familial variance that overlaps between depression and alcohol dependence.

CONCLUSIONS

The results are consistent with an indirect role for mood-related drinking motives in the etiology of depression and alcohol dependence, and suggest that mood-related drinking motives may be a useful index of vulnerability for these conditions.

Adverse childhood experiences predict earlier age of drinking onset: results from a representative US sample of current or former drinkers

OBJECTIVE

Our goal was to determine whether adverse childhood experiences predicted the age at which drinking was initiated and drinking motives in a representative sample of current or former drinkers in the United States.

METHODS

In 2006, a probability sample of 3592 US current or former drinkers aged 18 to 39 were surveyed. Multinomial logistic regression examined whether each of 10 adverse childhood experiences was associated with earlier ages of drinking onset, controlling for demographics, parental alcohol use, parental attitudes toward drinking, and peers' drinking in adolescence. We also examined whether there was a graded relationship between the number of adverse childhood experiences and age of drinking onset and whether adverse childhood experiences were related to self-reported motives for drinking during the first year that respondents drank.

RESULTS

Sixty-six percent of respondents reported >or=1 adverse childhood experiences, and 19% reported experiencing >or=4. The most commonly reported adverse childhood experiences were parental separation/divorce (41.3%), living with a household member who was a problem drinker (28.7%), mental illness of a household member (24.8%), and sexual abuse (19.1%). Of the 10 specific adverse childhood experiences assessed, 5 were significantly associated with initiating drinking at <or=14 years of age (compared with at >or=21 years of age) after adjustment for confounders, including physical abuse, sexual abuse, having a mentally ill household member, substance abuse in the home, and parental discord or divorce. Compared with those without adverse childhood experiences, respondents with adverse childhood experiences were substantially more likely to report that they drank to cope during the first year that they used alcohol.

CONCLUSIONS

Results suggest that children with particular adverse childhood experiences may initiate drinking earlier than their peers and that they may be more likely to drink to cope with problems (rather than for pleasure or to be social).

Adult transition from at-risk drinking to alcohol dependence: the relationship of family history and drinking motives

BACKGROUND

Prospective studies have not previously examined whether a family history of alcoholism and drinking motives conjointly predict a diagnosed DSM-IV alcohol abuse or dependence in adults, despite a large literature that each is associated with alcohol consumption. The focus of this study is the conjoint, prospective examination of these risk factors in a 10-year longitudinal study of adults who were at-risk drinkers at baseline.

METHODS

Prospective, population-based cohort of drinkers aged 18 or older from a Northeastern U.S. area initially evaluated for history of alcohol use disorders and drinking motives in 1991 to 1992. New onset dependence was studied in those who never met the criteria for alcohol dependence at baseline (n = 423), and new onset abuse was studied in those who never met the criteria for alcohol abuse at baseline (n = 301) and who did not develop dependence during the follow-up.

RESULTS

Family history significantly interacted with 2 baseline drinking motives in predicting new onsets of DSM-IV alcohol dependence: drinking to reduce negative affect (OR 3.38; 95% CI 1.05, 10.9) and drinking for social facilitation (OR 3.88; CI 1.21, 12.5). Effects were stronger after conditioning the drinking motives on having a positive family history of alcoholism. In contrast, in predicting new onsets of alcohol abuse, drinking motives did not have direct effects or interact with family history.

CONCLUSIONS

Those who drank to reduce negative affect or for social facilitation at baseline were at greater risk of alcohol dependence 10 years later if they also had a family history of alcoholism. These results suggest an at-risk group that can be identified prior to the development of alcohol dependence. Further, the findings suggest utility in investigating the interaction of drinking motives with measured genetic polymorphisms in predicting alcohol dependence.

Drinking expectancies and motives: a genetic study of young adult women

BACKGROUND

Constructs such as drinking expectancies (beliefs regarding the effects of alcohol) and motives (drinking alcohol to achieve a valued end) have been shown to be associated with various stages of alcohol use behaviors. However, little is known of the extent to which genetic and environmental influences contribute to individual differences in expectancies and motives.

METHODS

Using data from 3,656 young adult same-sex female twins, we examined the association between measures of drinking expectancies and motives and drinking behaviors. Using twin models, we estimated the extent to which genetic, shared and non-shared environmental factors influenced individual differences in expectancies and motives and also tested whether the extent of the genetic and environmental contributions on expectancies varied across abstainers and users of alcohol.

RESULTS

Expectancies predicted initiation of alcohol use. Both motives and expectancies were associated with frequency and quantity of alcohol consumption and drinks-to-intoxication. There was no evidence for heritable influences on expectancies and enhancement motives, with familial similarity for these traits being due to shared environment. Heritable influences on social, coping and conformity motives ranged from 11% to 33%. When expectancies were stratified by alcohol use, significant heritable influences (31-39%) were found for cognitive-behavioral impairment and risk-taking/negative self-perception (RT/NSP) in abstainers only, while environmental influences contributed to familial variance for other measures of expectancies in alcohol users.

CONCLUSIONS

Environmental influences (both familial and individual-specific) shape alcohol expectancies, while heritable influences may predispose to motives for drinking. Individual differences in expectancies are moderated by alcohol use, suggesting that sources of individual differences in expectancies may vary in drinkers versus abstainers.

Sex differences in the influence of COMT Val158Met on alcoholism and smoking in plains American Indians

BACKGROUND

Alcoholism and heavy smoking are highly comorbid and are cotransmitted in the general U.S. population; however little is known about comorbidity in American Indians. The catechol-O-methyltransferase (COMT) functional polymorphism, Val158Met, has been associated with alcoholism in Caucasians. The aims of our study were firstly to investigate patterns of alcohol and tobacco consumption and comorbidity between alcoholism and smoking in Plains American Indians and secondly to determine the influence, including sexual dimorphic effects, of COMT Val158Met and COMT haplotypes, on these behaviors.

METHODS

Diagnostic and Statistical Manual-III-R lifetime diagnoses were assigned to 342 community-ascertained Plains American Indians (201 women, 141 men). Lifetime drinking and smoking histories were obtained. Five COMT loci, including Val158Met, were genotyped. Haplotype-based analyses identified 1 block with 3 common haplotypes; 2 included Val158, and 1 had the Met158 allele.

RESULTS

The alcoholics drank heavily (12+/-8 drinks/drinking day) but episodically (max 10+/-8 d/mo). Although 62% of male alcoholics and 40% of female alcoholics were smokers (> or =10 cigarettes/d), only 12% of alcoholic men and 8% of alcoholic women smoked heavily (>20/d). In women, the COMT Val158 allele frequency was maximal in alcoholic smokers (0.85), decreasing to 0.74 in nonalcoholic smokers, 0.67 in alcoholic nonsmokers, and 0.64 in nonalcoholic nonsmokers (chi2 = 11.1, 3 df, p = 0.011). Women showed a main effect of Val158 on smoking (p=0.003). Both male and female alcoholics were more likely to have at least 1 Val158 allele compared with nonalcoholics (0.95 vs 0.88, p < 0.05). Approximately 30% of all participants were long-term, nonaddicted light, social smokers (3.6+/-1.7 cigarettes/d); they had the same Val158Met frequencies as nonsmokers. Haplotype analyses supported the Val158Met findings; however, only 1 of the 2 Val158 haplotypes was implicated.

CONCLUSIONS

Plains Indians have different smoking and drinking patterns and considerably less comorbidity between alcoholism and heavy smoking compared with the general U.S. population. Our COMT Val158Met results suggest that there may be both sex differences in the genetic origins of alcoholism and smoking in this population and overlap in genetic vulnerability to both addictions in women.

Challenges in genetic studies of the etiology of substance use and substance use disorders: introduction to the special issue

Misuse of psychoactive substances is associated with substantial costs to users and to society. A growing literature suggests individual differences in vulnerability to develop substance related problems are influenced to a large degree by genetic factors. We review the evidence from genetic epidemiologic and molecular genetic studies of problematic use of alcohol, tobacco, and other drugs, then discuss the challenges for the next generation of studies of genetic influences on substance use. These challenges are addressed in the remaining papers of this special issue. The papers cover a variety of approaches, substances, and non-human as well as human studies, but are united by their focus on going beyond heritability estimates to address the mechanisms and processes underlying the development of substance use and substance related problems, including measurement, precursors of substance abuse, stages of substance involvement, and specificity of genetic influences.

Genetic analysis of sensation seeking with an extended twin design

The heritability of sensation seeking is investigated in an extended twin design, including mono- and dizygotic twins and their siblings. Besides a comparison of the phenotypic resemblance between monozygotic twins and dizygotic twins, the design allows for an explicit test of the assumption that results from twins may be generalized to the singleton population. Secondly, the design offers the opportunity to investigate to what extent the influence of common environment is the same for males and females and for twins and siblings, i.e. allowing for explicit tests of a special twin environment and of a sex-specific common environment. The results indicate that individual variation in sensation seeking is heritable, with few differences between males and females in heritability estimates for the sensation seeking dimensions. In contrast to prior studies, evidence is found for common environmental influences for thrill and adventure seeking in males, and experience seeking and boredom susceptibility in females. Evidence for a special twin environment was limited to boredom susceptibility in females.

DRINKING AND MOTIVATIONS TO DRINK AMONG ADOLESCENT CHILDREN OF PARENTS WITH ALCOHOL PROBLEMS

AIMS

To study the influences of parental alcohol problems on adolescents' alcohol consumption and motivations to drink alcohol.

METHODS

A community sample of 1744 adolescents from schools in South Wales completed the 6-item Children of Alcoholics Screening Test, Drinking Motives Questionnaire, and survey measures of alcohol consumption.

RESULTS

Children of parents with alcohol problems constituted almost one-fifth of the sample group and were found to drink more frequently, more heavily, and more often alone than children of parents without alcohol problems. Parental alcohol problems were also related to internal motives to drink (e.g. coping) in their adolescent children. Across the entire sample, internal motives to drink interacted with parental alcohol problems in predicting alcohol consumption and drinking frequency.

CONCLUSION

Parental alcohol problems appeared to co-exist with an asocial pattern of alcohol consumption in adolescents that involves drinking alone and drinking to feel intoxicated or to forget about problems. In addition to the external, social motives to drink, which are shared by most adolescents, nearly one in five of the adolescents studied reported salient internal motives to drink that tended to coexist with alcohol problems in their parents.