Alcohol sensitivity and smoking history in men and women

Hypermethylation of the OPRM1 and ALDH2 promoter regions in Chinese Han males with alcohol use disorder in Yunnan Province

BACKGROUND

Alcohol use disorder (AUD) is one of the most serious public health problems worldwide. The OPRM1 and ALDH2 genes are important factors in the reward and alcohol metabolism pathways, and their DNA methylation patterns are closely related to AUD and are population-specific. Chinese Han people are the most populous ethnic group in the world, and this group experiences severe AUD. No epigenetic study on OPRM1 and ALDH2 has been performed in Chinese Han patients with AUD.

OBJECTIVES

To investigate whether methylation patterns of OPRM1 and ALDH2 are associated with susceptibility to AUD in Chinese Han males.

METHODS

DNA methylation of the OPRM1 and ALDH2 promoters was studied in Chinese Han males with AUD in Yunnan Province (N = 50 controls, N = 90 individuals with AUD) using the bisulfite pyrosequencing method.

RESULTS

In the AUD group, compared with the control group, OPRM1 was hypermethylated(p < .01) but there was no significant difference in the methylation level of ALDH2 (p > .05). 9 CpG sites of OPRM1 (p < .05) and 2 CpG sites of ALDH2 (p > .01) were hypermethylated. Smoking promoted AUD-mediated hypermethylation of OPRM1, in which 3 CpG sites showed significant hypermethylation (p < .01). Age had no significant effect on the DNA methylation levels of these two genes.

CONCLUSIONS

Our study demonstrates that DNA hypermethylation of the OPRM1 and ALDH2 promoter regions is associated with an increased risk of AUD, which may help to explain the pathogenesis and progression of AUD.

Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in “Heavy Drinking Smokers”

Aims

Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45–50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders.

Methods

We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions.

Results

The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders.

Conclusions

Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in ‘heavy drinking smokers.’

Psychiatric comorbidities in alcohol use disorder

Alcohol use disorder is a major contributor to the morbidity and mortality burden worldwide. It often coexists with other psychiatric disorders; however, the nature of this comorbidity is still a matter of debate. In this Series paper, we examine the main psychiatric disorders associated with alcohol use disorder, including the prevalence of co-occurring disorders, the temporal nature of the relationship, and mechanisms that might explain comorbidity across the lifespan. Overall, this disorder co-occurs with a wide range of other psychiatric disorders, especially those disorders involving substance use and violent or aggressive behaviour. The causal pathways between alcohol use disorder and other psychiatric disorders are heterogeneous. Hypotheses explaining these relationships include reciprocal direct causal associations, shared genetic and environmental causes, and shared psychopathological characteristics of broader diagnostic entities (eg, externalising disorders). Efforts to untangle the associations between alcohol use disorder and other disorders across the lifespan remain a crucial avenue of research.

Psychopharmacology of Tobacco and Alcohol Comorbidity: a Review of Current Evidence

Purpose of the Review

Comorbidity of alcohol and tobacco use is highly prevalent and may exacerbate the health effects of either substance alone. However, the mechanisms underlying this comorbidity are not well understood. This review will examine the evidence for shared neurobiological mechanisms of alcohol and nicotine comorbidity and experimental studies of the behavioural consequences of these interactions.

Recent Findings

Studies examining the shared neurobiology of alcohol and nicotine have identified two main mechanisms of comorbidity: (1) cross-reinforcement via the mesolimbic dopamine pathway and (2) cross-tolerance via shared genetic and nAChR interaction. Animal and human psychopharmacological studies demonstrate support for these two mechanisms of comorbidity.

Summary

Human behavioural studies indicate that (1) alcohol and tobacco potentiate each other’s rewarding effects and (2) nicotine reduces the sedative and intoxication effects of alcohol. Together, these findings provide a strong evidence base to support the role of the cross-reinforcement and cross-tolerance as mechanisms underlying the comorbidity of alcohol and tobacco use. Methodological concerns in the literature and recommendations for future studies are discussed alongside implications for treatment of comorbid alcohol and tobacco use.

Alcohol and nicotine codependence-associated DNA methylation changes in promoter regions of addiction-related genes

Altered DNA methylation in addiction-related genes may modify the susceptibility to alcohol or drug dependence (AD or ND). We profiled peripheral blood DNA methylation levels of 384 CpGs in promoter regions of 82 addiction-related genes in 256 African Americans (AAs) (117 cases with AD-ND codependence and 139 controls) and 196 European Americans (103 cases with AD-ND codependence and 93 controls) using Illumina's GoldenGate DNA methylation array assays. AD-ND codependence-associated DNA methylation changes were analyzed using linear mixed-effects models with consideration of batch effects and covariates age, sex, and ancestry proportions. Seventy CpGs (in 41 genes) showed nominally significant associations (P < 0.05) with AD-ND codependence in both AAs and EAs. One CpG (HTR2B cg27531267) was hypomethylated in AA cases (P = 7.2 × 10^-5), while 17 CpGs in 16 genes (including HTR2B cg27531267) were hypermethylated in EA cases (5.6 × 10^-9 ≤ P ≤ 9.5 × 10^-5). Nevertheless, 13 single nucleotide polymorphisms (SNPs) nearby HTR2B cg27531267 and the interaction of these SNPs and cg27531267 did not show significant effects on AD-ND codependence in either AAs or EAs. Our study demonstrated that DNA methylation changes in addiction-related genes could be potential biomarkers for AD-ND co-dependence. Future studies need to explore whether DNA methylation alterations influence the risk of AD-ND codependence or the other way around.

The hangover: an ambiguous concept in workplace alcohol policy

Because hangovers have been shown to affect cognitive functions and physical performance such as pilot maneuvers, they represent a threat to productivity and safety in the workplace. This article discusses why hangovers are rarely addressed by policies concerning alcohol and intoxication in the workplace. Following a review of relevant research on hangovers with implications for work impairment, the article considers ways in which otherwise well-defined alcohol policies may fail to guide supervisors’ responses to employee hangovers. Measurement problems and biological, psychological, and culturally shaped differences in the experience of hangovers thwart the formulation of simple worktime-hangover policies. The article concludes that further research on the nature and effects of hangovers would strengthen the formulation of policy and educational efforts to prevent them from causing injuries, productivity loss, or conflicts in the workplace.

An overview of alcohol and tobacco/nicotine interactions in the human laboratory

BACKGROUND

Alcohol use disorders and tobacco use contribute significant risk to the global burden of disease, and each are major public health concerns. Together, alcohol and tobacco use are highly comorbid and have multiplicative health risks when used concurrently, underscoring the importance of examining alcohol-tobacco interactions in the human laboratory.

OBJECTIVE

The aims of this review were to summarize the state of research examining alcohol-tobacco interactions in the human laboratory.

METHODS

We reviewed human laboratory evidence for alcohol and tobacco/nicotine interactions, including 1) craving in drinkers and smokers exposed to smoking or drinking cues, 2) fixed-dosing of alcohol or nicotine in smokers and drinkers, and 3) smoking and alcohol influences on self-administration behaviors. The interactive effects of tobacco/nicotine with other drugs of abuse are also briefly discussed.

RESULTS

Overall, results identified that alcohol and tobacco have reciprocal influences on potentiating craving, subjective responses to fixed-dose alcohol or nicotine administration, and self-administration. The literature identified that alcohol increases craving to smoke, decreases time to initiate smoking, and increases smoking self-administration. Similarly, tobacco and nicotine increase alcohol craving, decrease subjective effects of alcohol, and increase alcohol consumption.

CONCLUSION

Future studies should continue to focus on alcohol and tobacco/nicotine interactions in individuals with a wide scope of drinking and smoking histories, different states of alcohol and nicotine deprivation, and influences of either drug on craving, subjective responses, and consumption over the course of the blood alcohol curve. This work could have important implications for the impact of alcohol-tobacco interactions on guiding clinical practice, as well as in the changing landscape of addiction.

Current insights into the mechanisms and development of treatments for heavy drinking cigarette smokers

There is a strong association between cigarette smoking and alcohol use at the epidemiological, behavioral, and molecular levels, and this co-use creates substantial impediments to smoking cessation among smokers who are also heavy drinkers. Compared with individuals who only smoke, those who both drink and smoke heavily experience more severe health consequences and have greater difficulty in quitting smoking. During smoking abstinence, greater alcohol use is associated with decreased odds of smoking cessation, and smokers are substantially more likely to experience a smoking lapse during drinking episodes. As heavy drinking smokers are less responsive to the currently available pharmacological treatments, this subgroup of high-risk substance users possesses a unique clinical profile and treatment needs. Thus, treatment development for heavy drinking smokers represents a significant and understudied research area within the field of smoking cessation. This review will briefly describe findings from epidemiological, behavioral, and molecular studies illustrating alcohol and tobacco co-use and identify how the behavioral and neurobiological mechanisms underlying the interaction of alcohol and nicotine may inform the development of targeted treatments for this unique population of smokers.

Negative affect is associated with alcohol, but not cigarette use in heavy drinking smokers

Co-use of alcohol and cigarettes is highly prevalent, and heavy drinking smokers represent a large and difficult-to-treat subgroup of smokers. Negative affect, including anxiety and depressive symptomatology, has been associated with both cigarette and alcohol use independently, but less is known about the role of negative affect in heavy drinking smokers. Furthermore, while some studies have shown negative affect to precede substance use, a precise biobehavioral mechanism has not been established. The aims of the present study were twofold. First, to test whether negative affect is associated with alcohol and cigarette use in a large community sample of heavy drinking smokers (n=461). And second, to examine craving as a plausible statistical mediator of the association between negative affect and alcohol and/or cigarette use. Hypothesis testing was conducted using a structural equation modeling approach with cross-sectional data. Analysis revealed a significant main effect of negative affect on alcohol use (β=0.210, p<0.05), but not cigarette use (β=0.131, p>0.10) in this sample. Mediational analysis revealed that alcohol craving was a full statistical mediator of this association (p<0.05), such that there was no direct association between negative affect and alcohol use after accounting for alcohol craving. These results are consistent with a negative reinforcement and relief craving models of alcohol use insofar as the experience of negative affect was associated with increased alcohol use, and the relationship was statistically mediated by alcohol craving, presumably to alleviate negative affect. Further longitudinal or experimental studies are warranted to enhance the causal inferences of this mediated effect.

Nicotine interactions with low-dose alcohol: pharmacological influences on smoking and drinking motivation

An extensive literature documents a close association between cigarette and alcohol use. The joint pharmacological effects of alcohol and nicotine on smoking and drinking motivation may help explain this relationship. This experiment was designed to test the separate and combined pharmacological effects of nicotine and a low dose of alcohol (equivalent to 1-2 standard drinks) on substance use motivation using a double-blind and fully crossed within-subjects design. Participants (N = 87) with a wide range of smoking and drinking patterns completed 4 counterbalanced experimental sessions during which they consumed an alcohol (male: 0.3g/kg; female: 0.27g/kg) or placebo beverage and smoked a nicotine (.6 mg) or placebo cigarette. Outcome measures assessed the impact of drug administration (alcohol or nicotine) on craving to smoke, craving to drink, affect, and liking of the beverage and cigarette. Results indicated that combined administration produced higher cravings to smoke for the entire sample, as well as higher cravings to drink among women and lighter drinkers. Heavier users of either alcohol or cigarettes also exhibited enhanced sensitivity to the effects of either drug in isolation. Separate, but not interactive, effects of alcohol and nicotine on mood were observed as well as both same-drug and cross-drug effects on beverage and cigarette liking. Together, these findings support the notion that the interactive pharmacological effects of nicotine and low doses of alcohol play an important role in motivating contemporaneous use and suggest roles for cross-reinforcement and cross-tolerance in the development and maintenance of alcohol and nicotine use and dependence.

Role of tobacco smoking in hangover symptoms among university students

OBJECTIVE

Although hangover results from excessive alcohol consumption, the specific pathways through which hangover symptoms arise have not been elucidated. Research on predictors of hangover sensitivity may provide clues about such mechanisms. The present study investigated whether tobacco smoking on days of heavy drinking affects next-day hangover incidence and severity.

METHOD

The study drew on diary data from a study on smoking and drinking among 113 students at a midwestern university in the United States. Participants completed a daily, web-based, 26-item survey for 8 weeks to assess prior-day alcohol and tobacco use as well as current-day hangover symptoms. Hierarchical linear modeling was used to test the hypothesis that amount of smoking is related to hangover, controlling for amount of alcohol consumed, sex, and other individual characteristics. Analyses were conducted after selecting only days with alcohol consumption levels that typically elicit hangover, then repeated on lighter drinking days for comparison. Validity of the hangover items was checked by comparing reports after such heavy drinking days with days of lighter drinking.

RESULTS

Across all possible person-days, 92% of daily reports were obtained. When selecting only events where an estimated blood alcohol concentration of 110 mg/dl was attained, smoking significantly increased the odds of hangover incidence and hangover severity while controlling for number of drinks consumed and sex. Additional analyses controlling for age first smoked regularly, frequency of drug use, type of drug involvement, or smoking status resulted in findings that were unchanged.

CONCLUSIONS

Smoking more on heavy drinking days affects hangover sensitivity and severity, possibly because of acute pharmacological effects.

How can we use our knowledge of alcohol-tobacco interactions to reduce alcohol use?

Currently, 8.5% of the US population meets criteria for alcohol use disorders, with a total cost to the US economy estimated at $234 billion per year. Alcohol and tobacco use share a high degree of comorbidity and interact across many levels of analysis. This review begins by highlighting alcohol and tobacco comorbidity and presenting evidence that tobacco increases the risk for alcohol misuse and likely has a causal role in this relationship. We then discuss how knowledge of alcohol and tobacco interactions can be used to reduce alcohol use, focusing on whether (a) smoking status can be used as a clinical indicator for alcohol misuse, (b) tobacco policies reduce alcohol use, and (c) nicotinic-based medications can be used to treat alcohol use disorders.

Responses to alcohol and cigarette use during ecologically assessed drinking episodes

RATIONALE

Tobacco and alcohol are frequently used together, and this may be partly explained by a distinct profile of subjective effects associated with co-administration. Ecological momentary assessment studies have examined effects of naturally occurring co-use, but, to date, have not assessed differing effects as alcohol levels rise and fall.

OBJECTIVES

The objective of the study was to describe subjective states and appraisals of cigarette and alcohol effects reported during the entirety of real-world drinking episodes.

METHODS

Currently-smoking frequent drinkers (N = 255) carried electronic diaries for 21 days. Analyses focused on reports made during 2,046 drinking episodes. Signaled prompts intensively oversampled moments in the hours following consumption of the first drink in an episode. Multilevel regression analyses were used to predict ratings of buzz, dizziness, excitement, and sluggishness as a function of person-level and contextual covariates, estimated blood alcohol concentration (eBAC) level, ascending vs. descending eBAC, smoking, and their interactions. Appraisals of cigarette and alcohol effects were also examined within this framework.

RESULTS

Buzz, excitement, and pleasure from alcohol and cigarettes were prominent features of real-world drinking episodes. Smoking was associated with enhanced buzz and excitement when eBAC was high and descending. Smoking slightly accentuated the relation between eBAC and ratings of drinking pleasure among women, but this relation was somewhat weakened by smoking among men.

CONCLUSIONS

Smoking during drinking episodes may be partly explained by a persistence of stimulant alcohol effects beyond the blood alcohol concentration peak. Acute effects of nicotine and tobacco use on the descending limb deserve further scrutiny in experimental alcohol challenge research.

Cigarette smoke exposure greatly increases alcohol consumption in adolescent C57BL/6 mice

BACKGROUND

Alcohol and tobacco are often used together, and alcoholism is much more common among smokers compared with nonsmokers. Studies in humans suggest that nicotine (an active ingredient in cigarette smoke) can increase the consumption of alcohol. Research on rats and mice demonstrated mixed results; some studies report that nicotine increases alcohol consumption, while others show a decrease in drinking. Because cigarette smoke includes many other chemicals, these also may play a significant role in alcohol consumption. For example, 2 of these other constituents, monoamine oxidase inhibitors and acetaldehyde, increase alcohol tolerance and/or alcohol consumption in rodents. This study was designed to investigate how cigarette smoke from tobacco may modify self-administration of alcohol in adolescent C57BL/6 mice, a critical time when adolescent humans begin abusing drugs.

METHODS

C57BL/6 male mice (4 to 5 weeks old) were acclimated for 3 weeks to consume a 10% (w/v) alcohol solution during a 2-hour daily access in the dark. Subsequently, half the animals were exposed to cigarette smoke for 6 h/d for 16 days. The remaining animals (control) were placed in a smoke-free adjacent chamber. Immediately following the 6-hour period in the chambers, the control and smoke-exposed mice were given access to the 10% alcohol solution for 2 hours.

RESULTS

Animals exposed to cigarette smoke for 6 h/d consumed approximately 3- to 5-fold more alcohol than the mice in the control group throughout the 16-day study. The mice in the smoke group had a blood alcohol concentration that was nearly 4-fold that of the control mice.

CONCLUSIONS

Cigarette smoke increases alcohol consumption several fold higher than reported studies using nicotine treatment alone in adolescent rodents. Thus, this model should be useful to determine the roles of other bioactive components in cigarette smoke that may be important in the high co-abuse of smoking and alcohol consumption.

An Integrative Approach for Studying the Etiology of Alcoholism and Other Addictions

Studies of alcoholism etiology often focus on genetic or psy-chosocial approaches, but not both. Greater understanding of the etiology of alcohol, tobacco and other addictions will come from integration of these research traditions. A research approach is outlined to test three models for the etiology of addictions — behavioral undercontrol, pharmacologic vulnerability, negative affect regulation — addressing key questions including (i) mediators of genetic effects, (ii) genotype-environment correlation effects, (iii) genotype x environment interaction effects, (iv) the developmental unfolding of genetic and environmental effects, (v) subtyping including identification of distinct trajectories of substance involvement, (vi) identification of individual genes that contribute to risk, and (vii) the consequences of excessive use. By using coordinated research designs, including prospective assessment of adolescent twins and their siblings and parents; of adult substance dependent and control twins and their MZ and DZ cotwins, the spouses of these pairs, and their adolescent offspring; and of regular families; by selecting for gene-mapping approaches sibships screened for extreme concordance or discordance on quantitative indices of substance use; and by using experimental (drug challenge) as well as survey approaches, a number of key questions concerning addiction etiology can be addressed. We discuss complementary strengths and weaknesses of different sampling strategies, as well as methods to implement such an integrated approach illustrated for the study of alcoholism etiology. A coordinated program of twin and family studies will allow a comprehensive dissection of the interplay of genetic and environmental risk-factors in the etiology of alcoholism and other addictions.

Glypican Gene GPC5 Participates in the Behavioral Response to Ethanol: Evidence from Humans, Mice, and Fruit Flies

Alcohol use disorders are influenced by many interacting genetic and environmental factors. Highlighting this complexity is the observation that large genome-wide association experiments have implicated many genes with weak statistical support. Experimental model systems, cell culture and animal, have identified many genes and pathways involved in ethanol response, but their applicability to the development of alcohol use disorders in humans is undetermined. To overcome the limitations of any single experimental system, the analytical strategy used here was to identify genes that exert common phenotypic effects across multiple experimental systems. Specifically, we (1) performed a mouse linkage analysis to identify quantitative trait loci that influence ethanol-induced ataxia; (2) performed a human genetic association analysis of the mouse-identified loci against ethanol-induced body sway, a phenotype that is not only comparable to the mouse ethanol-ataxia phenotype but is also a genetically influenced endophenotype of alcohol use disorders; (3) performed behavioral genetic experiments in Drosophila showing that fly homologs of GPC5, the member of the glypican gene family implicated by both the human and mouse genetic analyses, influence the fly's response to ethanol; and (4) discovered data from the literature demonstrating that the genetically implicated gene's expression is not only temporally and spatially consistent with involvement in ethanol-induced behaviors but is also modulated by ethanol. The convergence of these data provides strong support to the hypothesis that GPC5 is involved in cellular and organismal ethanol response and the etiology of alcohol use disorders in humans.

Interviews with "vapers": implications for future research with electronic cigarettes

INTRODUCTION

Awareness and use of electronic cigarettes (e-cigs) has increased dramatically. Electronic Nicotine Delivery Devices deliver an aerosol comprised usually of water, propylene glycol and/or glycerin, nicotine, and flavorings. Scant research exists to evaluate the efficacy and safety of such devices, and only one quantitative survey of European users (N = 81) has been published. This qualitative study explores e-cig users' ("vapers") experiences.

METHODS

Participants attended a convention or club meeting in St. Louis, MO, and were interviewed individually or in small groups. Qualitative methods were used to analyze interview data for both deductive and emergent themes to broad research questions.

RESULTS

Even with a relatively small sample of formal participants (N = 15), there were pervasive themes including the language and culture of vaping; social and informational support among vapers and their use of Internet resources (learning about e-cigs); the learning curve to using e-cigs and the numerous modifications ("mods") available for e-cigs and personal vaporizers; motives and perceived benefits of using e-cigs versus cigarettes including cigarette-like enjoyment, cost, restored sense of taste and smell, and improved breathing and exercise tolerance; rapidly reduced nicotine tolerance and dependence; and a strong interest in e-cig-related research and policy.

CONCLUSIONS

The learning curve to using e-cigs has important implications for laboratory tests of these devices with novice users. Similarly, the multiple e-cig options and the use of "mods" create challenges for researchers and policy makers. Transdisciplinary research is urgently needed, and experienced "vapers" are very interested and willing research participants.

Role of mouse cerebellar nicotinic acetylcholine receptor (nAChR) α(4)β(2)- and α(7) subtypes in the behavioral cross-tolerance between nicotine and ethanol-induced ataxia

We have demonstrated that nicotine attenuated ethanol-induced ataxia via nicotinic-acetylcholine-receptor (nAChR) subtypes α(4)β(2) and α(7). In the present study, ethanol (2g/kg; i.p.)-induced ataxia was assessed by Rotorod performance following repeated intracerebellar infusion of α(4)β(2)- and α(7)-selective agonists. Localization of α(4)β(2) and α(7) nAChRs was confirmed immunohistochemically. Cerebellar NO(x) (nitrite+nitrate) was determined flurometrically. Repeated intracerebellar microinfusion of the α(4)β(2)-selective agonist, RJR-2403 (for 1, 2, 3, 5 or 7 days) or the α(7)-selective agonist, PNU-282987 (1, 2, 3 or 5 days), dose-dependently attenuated ethanol-induced ataxia. These results suggest the development of cross-tolerance between ethanol-induced ataxia and α(4)β(2) and α(7) nAChR agonists. With RJR-2403, the cross-tolerance was maximal after a 5-day treatment and lasted 48h. Cross-tolerance was maximal after a 1-day treatment with PNU-282987 and lasted 72h. Pretreatment with α(4)β(2)- and α(7)-selective antagonists, dihydro-β-erythroidine and methyllycaconitine, respectively, prevented the development of cross-tolerance confirming α(4)β(2) and α(7) involvement. Repeated agonist infusions elevated cerebellar NO(x) 16h after the last treatment while acute ethanol exposure decreased it. Pretreatment with repeated RJR-2403 or PNU-282987 reversed ethanol-induced decrease in NOx. The NO(x) data suggests the involvement of the nitric oxide (NO)-cGMP signaling pathway in the cross-tolerance that develops between α(4)β(2)- and α(7)-selective agonists and ethanol ataxia. Both α(4)β(2) and α(7) subtypes exhibited high immunoreactivity in Purkinje but sparse expression in molecular and granular cell layers. Our results support a role for α(4)β(2) and α(7) nAChR subtypes in the development of cross-tolerance between nicotine and ethanol with the NO signaling pathway as a potential mechanism.

Genome-wide association study of alcohol dependence

CONTEXT

Alcohol dependence is a serious and common public health problem. It is well established that genetic factors play a major role in the development of this disorder. Identification of genes that contribute to alcohol dependence will improve our understanding of the mechanisms that underlie this disorder.

OBJECTIVE

To identify susceptibility genes for alcohol dependence through a genome-wide association study (GWAS) and a follow-up study in a population of German male inpatients with an early age at onset.

DESIGN

The GWAS tested 524,396 single-nucleotide polymorphisms (SNPs). All SNPs with P < 10(-4) were subjected to the follow-up study. In addition, nominally significant SNPs from genes that had also shown expression changes in rat brains after long-term alcohol consumption were selected for the follow-up step.

SETTING

Five university hospitals in southern and central Germany.

PARTICIPANTS

The GWAS included 487 male inpatients with alcohol dependence as defined by the DSM-IV and an age at onset younger than 28 years and 1358 population-based control individuals. The follow-up study included 1024 male inpatients and 996 age-matched male controls. All the participants were of German descent.

MAIN OUTCOME MEASURES

Significant association findings in the GWAS and follow-up study with the same alleles.

RESULTS

The GWAS produced 121 SNPs with nominal P < 10(-4). These, together with 19 additional SNPs from homologues of rat genes showing differential expression, were genotyped in the follow-up sample. Fifteen SNPs showed significant association with the same allele as in the GWAS. In the combined analysis, 2 closely linked intergenic SNPs met genome-wide significance (rs7590720, P = 9.72 x 10(-9); rs1344694, P = 1.69 x 10(-8)). They are located on chromosome region 2q35, which has been implicated in linkage studies for alcohol phenotypes. Nine SNPs were located in genes, including the CDH13 and ADH1C genes, that have been reported to be associated with alcohol dependence.

CONCLUSIONS

This is the first GWAS and follow-up study to identify a genome-wide significant association in alcohol dependence. Further independent studies are required to confirm these findings.

Discriminative stimulus effects of nicotine in humans

Behavioral discrimination procedures clearly demonstrate that nicotine elicits interoceptive stimulus effects in humans that are malleable by various pharmacological manipulations as well as by some behavioral manipulations. The parameters of nicotine discrimination and both chronic and acute factors that may alter discrimination behavior are addressed in this chapter, which emphasizes research by the author involving nicotine delivered by nasal spray. Human discrimination of nicotine is centrally mediated, as the central and peripheral nicotine antagonist mecamylamine blocks discrimination but the peripheral antagonist trimethaphan does not. The threshold dose for discrimination of nicotine via spray appears to be very low in smokers as well as nonsmokers. Because smoked tobacco delivers nicotine more rapidly than spray, the threshold dose of nicotine via smoking is probably even lower. In terms of individual differences, smokers may become tolerant to the discriminative stimulus effects of higher nicotine doses but not of low doses. Men may be more sensitive than women to nicotine's discriminative stimulus effects, consistent with other research suggesting that nicotine is more reinforcing in men than in women. Other potential individual differences in nicotine discrimination have not been clearly tested, but may include genetics, obesity, and dependence on other drugs. Acute environmental factors that alter nicotine discrimination include the specific training and testing conditions, pointing to the need for careful control over such conditions during research. Other factors, such as concurrent acute use of alcohol or caffeine, do not appear to alter nicotine discrimination, suggesting that changes in nicotine discrimination are not likely explanations for the association of smoking behavior with use of those drugs. Concurrent physical activity also does not appear to alter nicotine discrimination, indicating that results from studies of discrimination in subjects at quiet rest, the standard approach in this research, generalize well to discrimination in subjects engaged in various activities, as often occurs in the natural environment. Future research should more clearly examine the potential role of nicotine's discriminative stimulus effects in nicotine reinforcement and determine the generalizability of these findings to nicotine delivered by other means, particularly tobacco smoking.

Variability in initial nicotine sensitivity due to sex, history of other drug use, and parental smoking

Initial sensitivity to nicotine's effects during early exposure to tobacco may relate to dependence vulnerability. We examined the association of initial nicotine sensitivity with individual difference factors of sex, other drug use history (i.e. cross-tolerance or cross-sensitization), and parental smoking status in young adult nonsmokers (N=131). Participants engaged in 4 sessions, the first 3 to assess the dose-response effects of nasal spray nicotine (0, 5, 10 microg/kg) on rewarding, mood, physiological, sensory processing, and performance effects, and the fourth to assess nicotine reinforcement using a choice procedure. Men had greater initial sensitivity than women to some self-reported effects of nicotine related to reward and incentive salience and to impairment in sensory processing, but men and women did not differ on most other effects. Prior marijuana use was associated with greater nicotine reward, nicotine reinforcement was greater in men versus women among those with prior marijuana use, and having parents who smoked was related to increased incentive salience. However, history of other drug use and parental smoking were not otherwise associated with initial nicotine sensitivity. These findings warrant replication with other methods of nicotine administration, especially cigarette smoking, and in more diverse samples of subjects naïve to nicotine. Yet, they suggest that sex differences in initial sensitivity to nicotine reward occur before the onset of dependence. They also suggest that parental smoking may not increase risk of nicotine dependence in offspring by altering initial nicotine sensitivity, and that cross-tolerance between other drugs and nicotine may not be robust in humans.

Chromosome 15q25.1 genetic markers associated with level of response to alcohol in humans

As with other genetically complex common psychiatric and medical conditions, multiple genetic and environmental components contribute to alcohol use disorders (AUDs), which can confound attempts to identify genetic components. Intermediate phenotypes are often more closely correlated with underlying biology and have often proven invaluable in genetic studies. Level of response (LR) to alcohol is an intermediate phenotype for AUDs, and individuals with a low LR are at increased risk. A high rate of concurrent alcohol and nicotine use and dependence suggests that these conditions may share biochemical and genetic mechanisms. Genetic association studies indicate that a genetic locus, which includes the CHRNA5-CHRNA3-CHRNB4 gene cluster, plays a role in nicotine consumption and dependence. Genetic association with alcohol dependence was also recently shown. We show here that two of the markers from the nicotine studies also show an association (multiple testing corrected P < 0.025) with several LR phenotypes in a sample of 367 siblings. Additional markers in the region were analyzed and shown to be located in a 250-kb expanse of high linkage disequilibrium containing three additional genes. These findings indicate that LR intermediate phenotypes have utility in genetic approaches to AUDs and will prove valuable in the identification of other genetic loci conferring susceptibility to AUDs.

Long-term stability and heritability of telephone interview measures of alcohol consumption and dependence

Alcohol dependence symptoms and consumption measures were examined for stability and heritability. Data were collected from 12,045 individuals (5376 twin pairs, 1293 single twins) aged 19 to 90 years in telephone interviews conducted in three collection phases. Phases 1 and 2 were independent samples, but Phase 3 targeted families of smokers and drinkers from the Phase 1 and 2 samples. The stability of dependence symptoms and consumption was examined for 1158 individuals interviewed in both Phases 1 and 3 (mean interval = 11.0 years). For 1818 individuals interviewed in Phases 2 and 3 (mean interval = 5.5 years) the stability of consumption was examined. Heritability was examined for each collection phase and retest samples from the selected Phase 3 collection. The measures examined were a dependence score, based on DSM-IIIR and DSM-IV criteria for substance dependence, and a quantity x frequency measure. Measures were moderately stable, with test-retest correlations ranging from .58 to .61 for dependence and from .55 to .64 for consumption. However, the pattern of changes over time for dependence suggested that the measure may more strongly reflect recent than lifetime experience. Similar to previous findings, heritabilities ranged from .42 to .51 for dependence and from .31 to .51 for consumption. Consumption was significantly less heritable in the younger Phase 2 cohort (23-39 years) compared to the older Phase 1 cohort (28-90 years).

Restraint stress and exogenous corticosterone differentially alter sensitivity to the sedative-hypnotic effects of ethanol in inbred long-sleep and inbred short-sleep mice

Decreased sensitivity to ethanol is a genetically mediated trait implicated in susceptibility to developing alcoholism. Here, we explore genotype by environment differences in ethanol sensitivity. The relationship between acute- and repeated-restraint stress, corticosterone (CORT) levels, and sensitivity to sedative-hypnotic properties of ethanol was explored using inbred long-sleep (ILS) and inbred short-sleep (ISS) mice. In ILS mice, acute restraint decreased ethanol sensitivity at a 4.1g/kg dose, as measured by a decrease in the duration of loss of the righting reflex (LORE) and an increase in blood ethanol concentration at regain of the righting response (BECRR). Repeated restraint also decreased LORE duration, but had no effect on BECRR. In the ISS mice, there was no effect of acute restraint on either LORE duration or BECRR. However, repeated restraint increased ethanol sensitivity at a 4.1g/kg dose; with an increase in LORE duration, but a decrease in BECRR. Differences in hypothalamic-pituitary-adrenal (HPA) axis responsiveness to restraint stress (as measured by plasma CORT) were also examined between genotypes. ILS mice displayed habituation to repeated restraint, whereas ISS mice did not. Lastly, the effect of enhanced CORT levels independent of psychological stress was examined for its effects on the sedative-hypnotic effects of ethanol. There were no effects of CORT pretreatment on LORE duration or BECRR in ILS mice compared to saline- or noninjected littermates. In contrast, ISS mice injected with CORT showed a decreased duration of LORE, but no effects on BECRR. These findings suggest that in addition to genetic susceptibility, environmental factors (e.g., restraint stress, exogenous CORT administration) also influence sensitivity to the sedative effects of ethanol through alteration of central nervous system sensitivity and pharmacokinetic parameters, and do so in a genotype-dependent manner.

Effect of transdermal nicotine replacement on alcohol responses and alcohol self-administration

RATIONALE

Nicotine replacement is commonly used to treat tobacco use in heavy-drinking smokers. However, few studies have examined the effect of nicotine replacement on subjective and physiological responses to alcohol and alcohol drinking behavior.

OBJECTIVE

The primary aim of this within-subject, double-blind study was to examine whether transdermal nicotine replacement (0 mg vs 21 mg/day) altered response to a low-dose priming drink and subsequent ad libitum drinking behavior.

MATERIALS AND METHODS

Subjects (n=19) were non-treatment-seeking, non-dependent heavy drinkers who were daily smokers. Six hours after transdermal patch application, subjective and physiological responses to a priming drink [designed to raise blood alcohol levels (BALs) to 0.03 g/dl] were assessed. This was followed by a 2-h self-administration period where subjects could choose to consume up to eight additional drinks (each designed to raise BALs by 0.015 g/dl) or to receive monetary reinforcement for drinks not consumed.

RESULTS

We found that 6 h after patch application, tobacco craving associated with withdrawal relief was decreased, and systolic blood pressure and heart rate were increased in the active patch condition compared to the placebo patch condition. Subjective intoxication in response to the priming drink was attenuated in the active nicotine patch condition compared to 6 h of nicotine deprivation (i.e., placebo patch). During the self-administration period, subjects had longer latencies to start drinking and consequently appeared to consume fewer drinks when administered the active patch compared to the placebo patch.

CONCLUSIONS

In heavy drinkers, transdermal nicotine replacement compared to mild nicotine deprivation attenuated subjective and physiological alcohol responses and delayed the initiation of drinking.

Interactive effects of ethanol and nicotine on learning in C57BL/6J mice depend on both dose and duration of treatment

OBJECTIVE AND RATIONALE

Alcohol and nicotine are commonly co-abused; one possible explanation for co-abuse is that each drug ameliorates the aversive effects of the other. Both drugs have dose-dependent effects on learning and memory. Thus, this study examined the interactive effects of acute ethanol and acute, chronic, or withdrawal from chronic nicotine on fear conditioning in C57BL/6J mice.

MATERIALS AND METHODS

Conditioning consisted of auditory conditioned stimulus-foot-shock unconditioned stimulus pairings. For acute studies, saline or ethanol, then saline or nicotine was administered before training, and saline or nicotine was also administered before testing. For chronic and withdrawal studies, saline or nicotine was administered chronically, and ethanol or saline was administered before training.

RESULTS

Acute nicotine (0.09 mg/kg) reversed ethanol-induced deficits (1.0 and 1.5 g/kg) in contextual and cued fear conditioning, whereas a low dose of ethanol (0.25 g/kg) reversed nicotine (6.3 mg kg(-1) day(-1)) withdrawal-induced deficits in contextual conditioning. Tolerance developed for the effects of nicotine on ethanol-induced deficits in conditioning and cross-tolerance between chronic nicotine and acute ethanol was seen for the enhancing effects of ethanol on conditioning.

CONCLUSIONS

The complex and sometimes polar actions of ethanol and nicotine on behavior may contribute to co-abuse of these drugs. Specifically, smoking may initially reduce the aversive effects of ethanol, but tolerance develops for this effect. In addition, low doses of alcohol may lessen nicotine withdrawal symptoms.

Alcohol history and smoking cessation in nicotine replacement therapy, bupropion sustained release and varenicline trials: a review

AIMS

We conducted a review of published reports of smoking cessation pharmacotherapy trials in order to address the following: (i) the generalizability of findings to smokers with a history of alcohol problems; (ii) the extent to which alcohol use affects smoking cessation overall and the efficacy of pharmacotherapy specifically and (iii) the effect of smoking cessation on alcohol use.

METHODS

We located published reports of nicotine replacement therapy (NRT), bupropion sustained release (SR) and varenicline clinical trials using an approach based on prior Cochrane reviews. The reports were searched for alcohol-related inclusion/exclusion criteria and for findings related to alcohol.

RESULTS

The present review included 212 published reports from 149 trials. Alcohol-related exclusion criteria appeared frequently (41.6% of trials)--45/125 NRT trials (36%), 15/22 bupropion SR trials (68.2%) and 3/3 varenicline trials--and most commonly involved exclusion of participants with either current or recent alcohol problems. Most studies failed to provide any baseline alcohol-related characteristics. Eleven trials reported on the relationship between alcohol history and likelihood of smoking cessation. In the majority of these studies, smokers with a past history of alcohol problems were not at a disadvantage, although contrary findings exist. Only two studies examined the potential influence of smoking cessation on alcohol use.

CONCLUSIONS

Smokers with alcohol problems, particularly those with current or recent problems, are underrepresented in studies of approved pharmacotherapy for smoking cessation. Future trials should assess alcohol use at baseline and during treatment and examine reciprocal influences between alcohol consumption and smoking cessation.

Enhanced sensitivity to the euphoric effects of alcohol in schizophrenia

The purpose of this study was to determine whether schizophrenia was associated with alterations in alcohol response that might explain the elevated risk for AUDs in this population. In a randomized, double-blind, placebo-controlled, counter-balanced 3 test day laboratory study, the effects of alcohol were compared in 23 subjects with schizophrenia (without any previous alcohol use disorder (AUD) but with some alcohol exposure) and in 14 healthy subjects matched for age, gender, education, and lifetime exposure to alcohol. Standard alcohol drinks in a scheduled design were administered to produce blood alcohol levels of 0, 0.02-0.04 mg%, or 0.06-0.08 mg%. Schizophrenia symptoms, perceptual alterations, stimulant and depressant subjective effects of alcohol, and 'high' were measured before alcohol administration and at several post-drug time points. Verbal learning and recall, vigilance and distractibility, and motor function were assessed once per test day. Relative to healthy subjects, subjects with schizophrenia reported greater euphoria and stimulatory effects in response to alcohol. Alcohol produced small transient increases in positive psychotic symptoms and perceptual alterations without affecting negative symptoms. Alcohol also impaired several aspects of immediate and delayed recall, and vigilance, and distractibility. Schizophrenia patients showed increased euphoric and stimulatory responses to alcohol. These exaggerated positive responses to alcohol doses may contribute to the increased risk for AUDs associated with schizophrenia. The absence of 'beneficial' effects of alcohol does not support a self-medication hypothesis of alcohol use in schizophrenia.

Smoking comorbidity in alcoholism: neurobiological and neurocognitive consequences

Considerable research attests to the adverse effects of chronic smoking on cardiac, pulmonary, and vascular function as well as on increased risk for various cancers. However, comparatively little is known about the effects of chronic smoking on brain function. Although smoking rates have decreased in the developed world (they have increased in the developing world), smoking rates have been at a persistently high level in individuals with alcohol use disorders. Despite the high prevalence of comorbid chronic smoking and alcohol dependence, very few studies have addressed the separate and interactive effects that smoking and alcoholic drinking may have on neurobiology and brain function. This symposium, which took place at the annual meeting of the Research Society on Alcoholism in Santa Barbara, California, on June 29, 2005, postulates that the neurobiologic and neurocognitive abnormalities commonly described in studies of alcohol-dependent individuals are modulated by concurrent abuse of tobacco products and that brain recovery in abstinent alcoholic individuals is affected by chronic smoking. Four expert speakers and a discussant from different research disciplines focus in this symposium on the description of neurobiological and neurobehavioral effects because of concomitant drinking and smoking. Understanding the potential separate effects and interactions of chronic nicotine/smoking and alcohol consumption promotes a better understanding of specific mechanisms and neurocognitive consequences of brain injury and brain recovery with abstinence. The material presented contributes useful information to ongoing discussions about treatment strategies for these comorbid disorders and valuable educational material that can be used to affect public perception about smoking and perhaps health policy.

Association of DNA polymorphisms in the synaptic vesicular amine transporter gene (SLC18A2) with alcohol and nicotine dependence

The brain synaptic vesicular amine transporter SLCA18A2 is a key component for the uptake of monoamines like dopamine or serotonin into vesicles. We have analyzed seven DNA polymorphisms located in the genomic region of SLC18A2 for association with alcohol- and nicotine dependence, using a family-based design. Our sample comprised 131 families with alcohol-dependent offspring and 96 families with at least one nicotine-dependent offspring. For the alcohol-dependent sample, we found statistical significant association for two single markers (rs363387, P=0.03; rs363333, P=0.0066) as well as for several haplotypes (minimal P=0.0038). When the sample with alcohol dependence was stratified according to gender, we observed increased association for the male subgroup (rs363387, P=0.0011). None of the markers showed association in the sample of families with nicotine dependence. However, analysis of a combined sample of alcohol and nicotine-dependent families resulted in single markers as well as several haplotypes showing statistical significant association with substance dependence (minimal P=0.0044). We conclude that DNA polymorphisms located in SLC18A2 might contribute to the development of substance dependence.

Nicotine addiction and comorbidity with alcohol abuse and mental illness

The World Health Organization estimates that one-third of the global adult population smokes. Because tobacco use is on the rise in developing countries, death resulting from tobacco use continues to rise. Nicotine, the main addictive component of tobacco, initiates synaptic and cellular changes that underlie the motivational and behavioral alterations that culminate in addiction. Nicotine addiction progresses rapidly in adolescents and is most highly expressed in vulnerable people who have psychiatric illness or other substance abuse problems.

Norepinephrine Transporter: A Candidate Gene for Initial Ethanol Sensitivity in Inbred Long-Sleep and Short-Sleep Mice

BACKGROUND

Altered noradrenergic neurotransmission is associated with depression and may contribute to drug abuse and alcoholism. Differential initial sensitivity to ethanol is an important predictor of risk for future alcoholism, making the inbred long-sleep (ILS) and inbred short-sleep (ISS) mice a useful model for identifying genes that may contribute to alcoholism.

METHODS

In this study, molecular biological, neurochemical, and behavioral approaches were used to test the hypothesis that the norepinephrine transporter (NET) contributes to the differences in ethanol-induced loss of righting reflex (LORR) in ILS and ISS mice.

RESULTS

We used these mice to investigate the NET as a candidate gene contributing to this phenotype. The ILS and ISS mice carry different DNA haplotypes for NET, showing eight silent differences between allelic coding regions. Only the ILS haplotype is found in other mouse strains thus far sequenced. Brain regional analyses revealed that ILS mice have 30 to 50% lower [3H]NE uptake, NET binding, and NET mRNA levels than ISS mice. Maximal [3H]NE uptake and NET number were reduced, with no change in affinity, in the ILS mice. These neurobiological changes were associated with significant influences on the behavioral phenotype of these mice, as demonstrated by (1) a differential response in the duration of ethanol-induced LORR in ILS and ISS mice pretreated with a NET inhibitor and (2) increased ethanol-induced LORR in LXS recombinant inbred (RI) strains, homozygous for ILS in the NET chromosomal region (44-47 cM), compared with ISS homozygous strains.

CONCLUSIONS

This is the first report to suggest that the NET gene is one of many possible genetic factors influencing ethanol sensitivity in ILS, ISS, and LXS RI mouse strains.

No Association between Gastroesophageal Reflux and Cancers of the Larynx and Pharynx

PURPOSE

To examine the proposed relation between gastroesophageal reflux disease and cancers of the larynx and pharynx.

EXPERIMENTAL DESIGN

A cohort of 66,965 patients with discharge diagnoses of heartburn, hiatal hernia, or esophagitis was identified in the Swedish Inpatient Register. We observed a total of 376,622 person-years in the cohort. Identification of laryngeal and pharyngeal cancers was achieved through the Swedish Cancer Register. Standardized incidence ratios, the ratio of the observed to the expected number of cancers, derived from the general Swedish population and adjusted for sex, age, and calendar year, was used to estimate the relative risk.

RESULTS

During follow-up, 30 cases of laryngeal and 31 cases of pharyngeal cancer were detected in the cohort. Slightly increased risks of laryngeal [relative risk, 1.6; 95% confidence interval (CI), 1.1-2.2] and pharyngeal carcinomas (relative risk, 1.9; 95% CI, 1.3-2.8) were observed in the total reflux cohort. After stratification to exclude cohort members with a diagnosis of alcoholism, no significant increase in the risk of laryngeal (relative risk, 1.3; 95% CI, 0.8-2.0) or pharyngeal carcinomas (relative risk, 1.0; 95% CI, 0.5-1.6) was found compared with the general population. Furthermore, there were no dose-response patterns of the risk for laryngeal and pharyngeal cancers with years of cohort follow-up, indicators of reflux severity, or specificity of reflux diagnosis.

CONCLUSION

This study provides no evidence in support of the proposed association between gastroesophageal reflux disease and cancers of the larynx or pharynx.

Permissive nicotine regulation as a complement to traditional tobacco control

BACKGROUND

Cigarette smoking takes a staggering toll on human health and attracts considerable public health attention, yet real solutions seem distant. The 2004 Family Smoking Prevention and Tobacco Control Act (US Senate bill S2461) would have given the US Food and Drug Administration limited authority to regulate cigarettes to "protect the public health." However, such legislation is unlikely to substantially reduce smoking or related deaths.

DISCUSSION

The past 500 years of tobacco control efforts demonstrate that nicotine prohibition is a practical impossibility for numerous reasons, state revenue being one of the most ominous. The FDA already has regulatory authority over pharmaceutical grade nicotine products, and requires pharmacists to dispense the most addictive of these only with prescriptions. Meanwhile, every corner store can sell far more addictive and dangerous cigarettes to any adult. The FDA could immediately increase competition between cigarettes and clean nicotine products by approving available nicotine products for over-the-counter sales to adults. Similarly permissive regulation of cigarettes and addictive nicotine products will reduce tobacco use and improve smokers' health, but increase nicotine use in the population. Fortunately, restricted youth access and accurate labeling of nicotine's absolute risks will dissuade many non-smokers from experimenting with it, while accurate depiction of its risks relative to cigarette smoking will encourage many smokers to switch. The FDA could take a series of small steps that might ultimately replace a large proportion of cigarette smoking with equally addictive nicotine products, without risking serious public health setbacks. Vaccine, methadone, and injury prevention policies establish relevant public health precedents.

SUMMARY

Cigarettes, or an equally addictive alternative, will be a permanent and common product in most societies. Regulations restricting only the safest addictive nicotine products are hard to justify. Addictive nicotine compliments other tobacco control strategies. Modern tobacco control policies are applicable to addictive nicotine. Controlled trials and test market studies are urgently needed to evaluate addictive nicotine as an alternative to smoking. Meanwhile, legislators should preserve the Food and Drug Administration's option to permit non-prescription sales of addictive nicotine.

Smoking cessation and alcohol consumption in individuals in treatment for alcohol use disorders

Most individuals with alcohol use disorders are dependent on both alcohol and nicotine, and combined use of both substances is more damaging to health than use of either alone. Although research indicates that alcoholics can quit smoking, discrepant results have been reported regarding whether smoking cessation is associated with increased risk of alcohol relapse. The purpose of this paper was to examine the relationship between smoking cessation and alcohol consumption using data from Project MATCH. Of the 1,307 participants who smoked at any point during the study, 160 (12%) quit. Quitters consumed less alcohol than those who continued smoking. In addition, quitters demonstrated a significant reduction in alcohol consumption at the time of smoking cessation, which was sustained for six months post-cessation. These findings suggest that individuals in treatment for alcohol use disorders who are motivated to stop smoking can safely be encouraged to do so without jeopardizing their sobriety.

A genomic scan for habitual smoking in families of alcoholics: common and specific genetic factors in substance dependence

Smoking is a highly heritable, addictive disorder that commonly co-occurs with alcohol dependence. The purpose of this study is to perform a genomic screen for habitual smoking and comorbid habitual smoking and alcohol dependence in families from the Collaborative Study on the Genetics of Alcoholism (COGA). Subjects were assessed using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) to evaluate alcohol dependence and habitual smoking (smoking one pack per day or more for at least 6 months). Sixty seven multi-generational families with 154 independent sibling pairs affected with habitual smoking were genotyped in a screening sample. Analyses on 79 multi-generational families with 173 independent sibling pairs were repeated in a replication sample. Sibpair analyses were performed using ASPEX. Four chromosomal regions in the screening sample had increased allele sharing among sibling pairs for habitual smoking with a LOD score greater than 1 (chromosomes 5, 9, 11, and 21). The highest LOD score was on chromosome 9 (LOD = 2.02; allele sharing 58.9%). Four chromosomal regions also had modest evidence for linkage to the comorbid phenotype habitual smoking and alcohol dependence (chromosomes 1, 2, 11, 15); and the strongest finding was on chromosome 2 (LOD = 3.30; allele sharing 69.1%). Previously identified areas (chromosomes 1 and 7) implicated in the development of alcohol dependence in this same data set did not provide evidence for linkage to habitual smoking in the screening sample. In the replication data set, there continued to be increased allele sharing near peaks identified in the screening sample on chromosomes 2 and 9, but the results were modest. An area on chromosome 7, approximately 60 cM from a location previously identified in linkage analysis with alcohol dependence, had increased allele sharing for the comorbid habitual smoking and alcohol dependence. These data provide evidence of specific genetic regions involved in the development of habitual smoking and not alcohol dependence. Conversely, genetic regions that influence the development of alcohol dependence do not appear to contribute to the development of habitual smoking. Finally, there is also evidence of an area on chromosome 2 that may reflect a common genetic vulnerability locus to both habitual smoking and alcohol dependence.

Alcoholism risk, tobacco smoking, and P300 event-related potential

OBJECTIVE

The P300 event-related potential (ERP) is sometimes larger for individuals at low- compared to high-risk for alcoholism. These effects are inconsistent, and how P300 is affected by tobacco smoking in the context of alcoholism risk is unknown. The present study used P300 to examine the inter-relationship between alcoholism heritability and smoking status.

METHODS

P300 was elicited with a visual discrimination task from young adults at low- and high-risk for alcoholism. Half of the subjects in each risk category reported that they did not smoke cigarettes, and the other half reported that they smoked regularly, with equal numbers of male and female subjects assessed. ERPs were recorded, and subjects were instructed to respond only to an infrequently presented target stimulus that occurred in a series of standard and distracter stimuli.

RESULTS

P300 amplitude from the target stimuli was larger for the low-risk compared to high-risk subjects overall. However, smoking status demonstrated even stronger effects, with non-smokers producing consistently larger component amplitudes than smokers and accounting for more variance than alcoholism risk. These group factors also significantly affected P300 scalp topography. No reliable alcoholism risk or smoking group effects were obtained for the ERPs from the other stimuli.

CONCLUSIONS

The findings suggest that P300 measures of alcoholism risk in young adults are moderated by smoking status. Theoretical implications are discussed.

Genetics and drug use as a complex phenotype

Drug use is a complex behavior influenced by multiple biological, family, and sociocultural factors. The concurrent use/misuse of multiple drugs is often seen and drug use also co-occurs with other psychiatric conditions. Behavior and molecular genetic studies support an important posited role of genes in drug use. This posited genetic risk does not appear to be conferred by one or two major genes manifesting large effects, but rather by a number of genes manifesting smaller effects. Genetic factors explain, on average, only about half of the total variability in drug use, with the remaining variability influenced by environmental factors. Also, genetic risk may be differentially expressed in the presence vs. absence of particular environmental conditions. Thus, investigation of environmental factors and their interaction with genetic risk is a necessary component of genetic research. While the full potential of genetic investigations for the prevention of drug misuse has yet to be realized, an example of the impact of risk factor modification under various conditions of gene-environment interaction is provided, and the implications for use of genetic information in drug-misuse prevention are discussed. The multifactorial nature of drug use necessitates coordinated investigation from multiple disciplines and timely dissemination of scientific findings. In addition, this work demands adherence to the highest standards of confidentiality and ethical use of genetic information to best inform future prevention efforts.

Adolescent alcohol and tobacco use: onset, persistence and trajectories of use across two samples

AIMS

We examined the alcohol-tobacco relationship using two prospective, ethnically diverse samples. Trajectories of alcohol and tobacco use are portrayed overall and by sex and ethnicity. Using prospective analyses, we examine directional influences between alcohol and tobacco use, and we characterize initiation versus persistence of drinking and smoking as a function of use of the other substance.

DESIGN, SETTING

Data were from the National Longitudinal Study of Adolescent Health (AddHealth) and the Adolescent Health Risk Study (AHRS). Follow-up intervals for AddHealth and AHRS were 1 and 5 years, respectively.

PARTICIPANTS

AddHealth respondents (n = 4831) were on average 14.8 years old (48% male, 23% black, 61% white) and AHRS respondents (n = 1814) were on average 16.7 years old (47% male, 44% black, 49% white).

MEASUREMENTS

Two alcohol consumption variables and two smoking variables were used: drinking frequency and heavy drinking frequency, and regular (current) smoking and daily number of cigarettes.

FINDINGS

Alcohol and tobacco use exhibited monotonic increases over adolescence and young adulthood. Men and white respondents reported more use than women and black respondents. Alcohol and tobacco were moderately associated at both times. Analyses revealed that prior alcohol use predicted tobacco use more strongly than the converse. Initiation of smoking was a function of prior drinking; to a lesser extent, initiation of drinking was a function of prior smoking. Persistence of smoking was a function of prior drinking and persistence of drinking was a function of prior smoking.

CONCLUSIONS

Provisional support exists for the claim that alcohol use predicts tobacco use more strongly than the converse. For both drinking and smoking, onset and persistence are predicted by prior use of the other substance, and these associations were robust across sex and ethnicity.

Potential regulation of nicotine and ethanol actions by alpha4-containing nicotinic receptors

A restriction fragment length polymorphism (RFLP) associated with a major nicotinic receptor subunit (i.e., alpha4) has been identified in two mouse lines that were selectively bred for differences in sensitivity to ethanol. These mice, referred to as Long-Sleep (LS) and Short-Sleep (SS) mice, also differ in sensitivity to several effects of nicotine. The potential role of the alpha4 RFLP in regulating several responses to nicotine and ethanol was evaluated by using the LSxSS-derived recombinant inbred (RI) strains. Those RI strains that carried the LS-like alpha4 RFLP were more sensitive to the depressant effects of nicotine on Y-maze crossing and rearing activities and ethanol-induced increases in Y-maze crossing activity than were those RI strains that carry the SS-like alpha4 RFLP. The LS-like RI strains were also more sensitive to nicotine-induced hypothermia. The RFLP was not associated with strain differences in ethanol-induced body temperature or sleep time. The potential role of the RFLP in regulating ethanol and nicotine consumption was evaluated in heterogeneous stock (HS) mice. An association was found between the alpha4 RFLP and variation in ethanol consumption, but not in nicotine consumption, as measured in a four-bottle choice test. Recent studies of ethanol and tobacco abuse by human beings suggest that common genes may influence these two forms of substance abuse. The results of the studies reported here suggest that the alpha4 nicotinic receptor gene should be evaluated for its potential role in regulating ethanol and tobacco abuse in human beings.

Reevaluation of the confounding effect of cigarette smoking on the relationship between alcohol use and lung cancer risk, with larynx cancer used as a positive control

BACKGROUND

The effect of smoking on lung cancer risk has been well documented, while the effect of alcohol remains controversial. We examined the hypothesis that the apparent association between alcohol intake and lung cancer risk is fully due to the confounding effect of cigarette smoke.

METHODS

Our sample of hospitalized patients included 2,953 male and 1,622 female lung cancer cases; 521 male and 159 female larynx cancers cases; and 8,169 male and 4,154 female controls, admitted to participating hospitals between 1981 and 1994. All controls had been diagnosed with non-smoking-related diseases. Larynx cancer was used as a positive control for lung cancer. Relative risks were estimated through odds ratios, adjusted through multiple logistic regression.

RESULTS

Although the odds ratios for alcohol had been significantly elevated prior to adjustment for smoking (OR = 2.4, 95% CI = 2.0-2.8), alcohol had no effect on lung cancer following this adjustment (OR = 1.2, 95% CI = 1.0-1.4). By contrast, the effect of alcohol on larynx cancer remained high even after adjustment for smoking (OR = 5.6, 95% CI = 3.7-8.6).

CONCLUSION

The often-reported association between alcohol and lung cancer risk can be fully explained by the confounding effect of cigarette use.

Addictive behaviors and depression among African Americans residing in a public housing community

Numerous studies have indicated that there is an association between cigarette smoking, alcohol use, and depression. However, little attention has been devoted to understanding how demographic factors, such as socioeconomic status and ethnicity, influence these relationships. To address this gap in the literature, cigarette and alcohol use were examined in a sample of African Americans from an urban area. A single public-housing community in Washington, DC was selected for complete ascertainment of the adult population. A total of 126 African American subjects were recruited. Semi-structured interviews were conducted to assess depressive symptoms and to characterize cigarette and alcohol use patterns. Cigarette smoking was not related to the severity of depressive symptoms. By contrast, increased symptoms of depression were related to alcohol use patterns. Light drinkers had a mean score of 5.77 on the Centers for Epidemiologic Studies Depression Scale, compared to a mean of 8.30 for abstainers and 10.07 for heavy drinkers (F = 4.968, p < .003). An analysis of patterns of substance use revealed that subjects were more likely to either abstain from both substances (30.2%) or to use both substances (32.5%) (chi2 = 8.516, df = 1. p < .004). It is unclear which specific processes work to link alcohol use and depressive symptoms in this group of urban African Americans from a low-income community. What is clear is that alcohol use is clearly related to depressive symptoms in the sample. It is hypothesized that both self-medicating processes and substance-induced depressive symptoms may be responsible for these findings. Important factors to consider in developing effective intervention programs that target this specific population are discussed.