Latent class typology of nicotine withdrawal: genetic contributions and association with failed smoking cessation and psychiatric disorders

Genetic Associations with Smoking Relapse and Proportion of Follow-up in Smoking Relapse throughout Adulthood in Pre- and Postmenopausal Women

PREVENTION RELEVANCE

This study is the first to quantify genetic associations with smoking relapse among female smokers throughout adulthood. These findings could inform precision medicine approaches to improve long-term smoking relapse prevention to reduce smoking attributable cancer morbidity and mortality.

Effects of Genetic Variants in the Nicotine Metabolism Pathway on Smoking Cessation

Background

We aimed to investigate the associations of various genetic variants in the nicotine metabolism pathway with smoking cessation (SC) in the Chinese Han population.

Method

A case-control study was conducted where 363 successful smoking quitters were referred to as cases, and 345 failed smoking quitters were referred to as controls. A total of 42 genetic variants in 10 genes were selectedand genotyped. The weighted gene score was applied to analyze the whole gene effect. Logistic regression was used to explore associations of each genetic variant and gene score with smoking cessation.

Results

Our study found that the variants CYP2A6∗4, rs11726322, rs12233719, and rs3100 were associated with a higher probability of quitting smoking, while rs3760657 was associated with a lower probability of quitting smoking. Moreover, the gene scores of CYP2D6, FMO3, UGT2B10, UGT1A9, UGT2B7, and UGT2B15 were shown to exert a positive effect, while the gene score of CYP2B6 was detected to exert a negative effect on successful smoking cessation.

Conclusion

This study revealed that genetic variants in the nicotine metabolic pathway were associated with smoking cessation in the Chinese Han population.

Differential Experience of Interdose Withdrawal During Long-Term Opioid Therapy and its Association With Patient and Treatment Characteristics: A Latent Class Analysis in Chronic Pain Population

Opioid withdrawal is characterized by a set of physical and psychological symptoms that depend on both opioid and patient specific characteristics. The present study aims to identify different latent classes of chronic pain patients according to the type of opioid withdrawal symptoms experienced, and to analyze the relationships between the classes and demographic, opioid therapy, psychological and substance use variables. This cross-sectional descriptive study included 391 chronic pain patients on long-term opioid therapy. A Latent Class Analysis (LCA) identified 3 classes (BIC = 7051.89, entropy = .87, LRTs P < .01). The mild withdrawal class showed low probabilities of presenting physical and psychological symptoms, the moderate withdrawal class was characterized by experiencing psychological symptoms, and the severe withdrawal class stood out for high probabilities of presenting both types of symptoms. The classes differed from each other, with higher rates of moderate-severe POUD, opioid misuse, anxiety, depression, and greater pain intensity and interference in more severe withdrawal classes (P < .05). The multinomial logistic regression showed that moderate-severe POUD and anxiety were the strongest variables related to moderate (OR_POUD = 3.34, OR_Anxiety = 2.58) and severe withdrawal classes (OR_POUD = 4.26, OR_Anxiety = 5.15). Considering that POUD and anxiety were strongly related to a more severe withdrawal syndrome, the inclusion of psychological interventions in pain management seems critical in this population. PERSPECTIVE: Although interdose opioid withdrawal is common in chronic pain patients, this study shows 3 different patterns in its experience (mild, moderate, and severe withdrawal). A more severe withdrawal may result in reduced effectiveness of opioids in relieving pain and increased negative consequences, such as higher risk of POUD. Findings that could help improve chronic pain management.

The Association between Trajectories of Anthropometric Variables and Risk of Diabetes among Prediabetic Chinese

In order to explore the association between trajectories of body mass index (BMI) and mid-upper arm circumference (MUAC) and diabetes and to assess the effectiveness of the models to predict diabetes among Chinese prediabetic people, we conducted this study. Using a national longitudinal study, 1529 cases were involved for analyzing the association between diabetes and BMI trajectories or MUAC trajectories. Growth mixture modeling was conducted among the prediabetic Chinese population to explore the trajectories of BMI and MUAC, and logistic regression was applied to evaluate the association between these trajectories and the risk of diabetes. The receiver operating characteristic curve (ROC) and the area under the curve (AUC) were applied to assess the feasibility of prediction. BMI and MUAC were categorized into 4-class trajectories, respectively. Statistically significant associations were observed between diabetes in certain BMI and MUAC trajectories. The AUC for trajectories of BMI and MUAC to predict diabetes was 0.752 (95% CI: 0.690-0.814). A simple cross-validation using logistic regression indicated an acceptable efficiency of the prediction. Diabetes prevention programs should emphasize the significance of body weight control and maintaining skeletal muscle mass and resistance training should be recommended for prediabetes.

Nicotine metabolism predicted by CYP2A6 genotypes in relation to smoking cessation: A systematic review

INTRODUCTION

Identifying genetic factors associated with smoking cessation could inform precision cessation interventions. Of major interest is genetic variation in nicotine metabolism, largely predicted by CYP2A6 variations.

METHODS

We conducted a systematic literature review to summarize the population-based evidence of the association between CYP2A6 and smoking cessation.In the 12 studies meeting the inclusion criteria, the known functional metabolic effect of CYP2A6 variants was used to classify nicotine metabolism as normal (>75% metabolic activity), intermediate (50.1 - 75% activity), slow (25 - 50% activity), and poor (<25% activity). Summary odds ratios of smoking cessation were calculated across metabolic groups, stratified by ancestry and whether participants received pharmacotherapy or placebo/no treatment.

RESULTS

Among untreated people of European ancestry (n = 4 studies), those with CYP2A6 reduced metabolism were more likely to quit smoking than those with normal metabolism [Summary OR = 2.05, 95% CI 1.23 - 3.42] and the likelihood of cessation increased as nicotine metabolism decreased. Nicotine replacement therapy attenuated the association at end-of-treatment, while bupropion modified the association such that intermediate/slow metabolizers were less likely to quit than normal metabolizers [Summary OR = 0.86, 95% CI 0.79 - 0.94]. Among untreated Asian people (n = 3 studies), results differed compared to those with European ancestry: those with slow metabolism were less likely to have quit smoking than normal metabolizers [Summary OR = 0.52, 95% CI 0.38 - 0.71]. Evidence for people of African ancestry (n = 1 study) suggested the CYP2A6 association with cessation may differ compared to those of European ancestry.

IMPLICATIONS

Most studies included in this review were of European ancestry populations; these showed slower nicotine metabolism was associated with increased likelihood of smoking cessation in a dose-related manner. Pharmacotherapy appeared to attenuate or modify this association among people of European ancestry, but it is unclear whether the change in the association remains consistent after treatment ceases. This finding has implications for precision medicine cessation interventions. Based on only a few studies of people of Asian or African ancestry, the association between CYP2A6 variants and cessation may differ from that observed among those of European ancestry, but more evidence is needed.

What Type of Social Support Is Important for Student Resilience During COVID-19? A Latent Profile Analysis

In the face of the sudden outbreak of coronavirus 2019 (COVID-19), some students showed resilience in coping with difficulties while some did not. While different types of students showed different levels of resilience, are there significant characteristics among students with similar levels of resilience? In this study, 3,454 students (aged 15–25 years) were surveyed to understand students' perceived social support-coping modes while investigating the demographic characteristics and mental health status of subclasses of different modes. We found that (1) in the two subgroups of students with extremely low and low levels of perceived social support, the source of students' perceived social support did not have a clear orientation; in the two subgroups with moderate and high levels of perceived social support, the most perceived emotional support was from family and friends, while the least perceived support was companionship from teachers, classmates, and relatives, and problems related to the dependability of friends and communication with family. (2) The degree of social support perceived by students is directly proportional to the coping tendency, i.e., as the degree of perceived social support increases, the proportion of students adopting active coping strategies increases while that of students adopting negative coping strategies decreases; thus, we concluded that high levels of emotional support from family and friends can increase students' tendency of adopting positive strategies to cope with difficulties, while problems related to the dependability of friends and communication with family decrease students' tendency of adopting positive coping strategies. (3) Gender had a significant impact on the extremely low and low levels of perceived social support-negative coping tendencies; these subgroups accounted for 34.6% of the total students. Gender showed no significant influence on other subgroups, a school type had no impact on the distribution of the subgroups. (4) The higher the degree of perceived social support, the lower is the degree of students' general anxiety, and the lower is the degree of impact by the COVID-19 pandemic. The subdivision of student groups allows us to design more targeted support programmes for students with different psychological characteristics to help them alleviate stress during the COVID-19 epidemic.

The Association between Blood Pressure Trajectories and Risk of Cardiovascular Diseases among Non-Hypertensive Chinese Population: A Population-Based Cohort Study

Although previous studies have discussed the association between trajectories of blood pressure (BP) and risk of cardiovascular diseases (CVDs), the association among the non-hypertensive general population of youth and middle age has not been elucidated. We used the growth mixture model to explore the trajectories of BP among the non-hypertensive Chinese population and applied Cox regression to evaluate the association between trajectories of BP and the risk of stroke or myocardial infarction (MI). Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were categorized into three classes, respectively. Statistically significant associations were observed between SBP trajectories and stroke (range of adjusted hazard ratios (aHR): 1.369-3.837) or MI (rang of aHR = 6.047-13.017). Association between DBP trajectories and stroke (aHR: 3.685) or MI (range of aHR = 1.312-2.821) were also observed, although they did not reach statistical significance. Trajectories of SBP were more important risk factors than that of DBP in stroke and MI in our study population. BP management is important among pre-hypertensive adults to prevent stroke and MI when they age. Well-designed research with a larger sample size is required to confirm our findings and develop efficient methods to prevent CVDs.

Sociocultural Adaptation Profiles of Ethnic Minority Senior High School Students in Mainland China: A Latent Class Analysis

This study aimed to quantitatively determine the sociocultural adaptation profiles of ethnic minority senior high school students in mainland China. A large-scale questionnaire survey of 1873 Grade 12 students from 31 interior ethnic boarding schools throughout China was conducted. Through exploratory and confirmatory factor analyses, the underlying structure of the sociocultural adaptation questionnaire was uncovered as consisting of three domains and six factors: General adaptation (daily life and school management), academic adaption (learning strategies and learning self-efficacy), and interaction adaptation (interethnic contact and cultural identity). By performing latent class analysis, four distinct sociocultural adaptation profiles of students were distinguished: The well-adapted group (28.0%), the general adaptation group (31.0%), the interaction adaptation group (24.4%), and the maladaptation group (16.6%). The results of chi-squared and variance analyses showed that the sociocultural adaptation profiles of ethnic minority senior high school students were significantly related to sociodemographic variables, such as ethnicity, class organization, hometown location, and family socioeconomic status. These profiles can be used to evaluate changes in ethnic minority students’ sociocultural adaptation and will contribute to the perfection of the ethnic minority boarding school system and the ultimate realization of inclusive and equitable quality education in China.

Momentary precipitants connecting stress and smoking lapse during a quit attempt

OBJECTIVE

Most attempts at smoking cessation are unsuccessful, and stress is frequently characterized both as a momentary precipitant of smoking lapse and a predictor of subsequent changes in other key precipitants of lapse. The current study examined longitudinal associations among stress, multiple precipitants of lapse, and lapse among smokers attempting to quit.

METHOD

Ecological momentary assessments (EMAs) were gathered from a multiethnic, gender-balanced sample of 370 adults enrolled in a smoking cessation program. EMAs (N = 32,563) assessed smoking lapse and precipitants of lapse, including stress, negative affect, smoking urge, abstinence self-efficacy, motivation to quit, difficulty concentrating, coping outcome expectancies, and smoking outcome expectancies. A multilevel structural equation model simultaneously estimated within-subject paths from stress to multiple precipitants and subsequent smoking lapse. Indirect effects of stress to smoking lapse through precipitants were computed.

RESULTS

Results indicated that increased stress was significantly associated with all precipitants of lapse, consistent with a greater risk for lapse (i.e., increased negative affect, smoking urge, difficulty concentrating, and smoking outcome expectancies and reduced abstinence self-efficacy, motivation to quit, and coping outcome expectancies). All precipitants were significantly associated with subsequent lapse. Indirect effects indicated that stress was uniquely connected to lapse through negative affect, smoking urge, abstinence self-efficacy, coping outcome expectancies, and smoking outcome expectancies.

CONCLUSIONS

Results of this study highlight the broad importance of stress for smoking lapse during a quit attempt. Smoking cessation programs should pay close attention to the role of stress in exacerbating key precipitants of lapse to improve cessation success rates. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Nicotine metabolite ratio and smoking outcomes using nicotine replacement therapy and varenicline among smokers with and without psychiatric illness

INTRODUCTION

It has been suggested that the effectiveness of nicotine replacement smoking cessation pharmacotherapy may be enhanced by assessing rates of nicotine metabolism using the nicotine metabolite ratio - which reflects differences in the activity of the CYP2A6 hepatic enzyme - and titrating doses appropriately. To date, supporting evidence is equivocal, with little information regarding the assessment and effectiveness of the nicotine metabolite ratio among smokers with psychiatric conditions.

METHODS

The nicotine metabolite ratio of 499 smokers from the FLEX trial was determined using urine samples obtained at baseline. They were randomized to receive either: standard transdermal nicotine (nicotine replacement therapy); extended nicotine replacement therapy + adjunct nicotine agent; or varenicline. Primary cessation outcomes were seven-day point prevalence at 5, 10, 22, and 52 weeks post-target quit date, comparing across treatment and psychiatric status. Our principal analysis employed logistic regression (outcome: abstinence), using slow metabolizers as the reference category.

RESULTS

No differences were observed by nicotine metabolite ratio classification (slow, moderate, fast) with respect to any demographic or smoking-related variables. Nicotine metabolite ratio class did not predict smoking cessation in either the overall sample, or by treatment condition at any time-point (week 52 moderate metabolizers: odds ratio 1.34, 95% confidence interval (0.68-2.63), p=0.394; fast metabolizers: odds ratio 1.04 (0.56-1.91), p=0. 906).

CONCLUSION

Our results did not find any associations between nicotine metabolite ratio and cessation outcomes among smokers using nicotine replacement therapy or varenicline with and without lifetime psychiatric conditions.

Prolonged cannabis withdrawal in young adults with lifetime psychiatric illness

Young adults with psychiatric illnesses are more likely to use cannabis and experience problems from use. It is not known whether those with a lifetime psychiatric illness experience a prolonged cannabis withdrawal syndrome with abstinence. Participants were fifty young adults, aged 18-25, recruited from the Boston-area in 2015-2016, who used cannabis at least weekly, completed the Structured Clinical Interview for DSM-IV to identify Axis I psychiatric diagnoses (PD+ vs PD-), and attained cannabis abstinence with a four-week contingency management protocol. Withdrawal symptom severity was assessed at baseline and at four weekly abstinent visits using the Cannabis Withdrawal Scale. Cannabis dependence, age of initiation, and rate of abstinence were similar in PD+ and PD- groups. There was a diagnostic group by abstinent week interaction, suggesting a difference in time course for resolution of withdrawal symptoms by group, F(4,46)=3.8, p=0.009, controlling for sex, baseline depressive and anxiety symptoms, and frequency of cannabis use in the prior 90days. In post hoc analyses, there was a difference in time-course of cannabis withdrawal. PD- had significantly reduced withdrawal symptom severity in abstinent week one [t(46)=-2.2, p=0.03], while PD+ did not report improved withdrawal symptoms until the second abstinent week [t(46)=-4.1, p=0.0002]. Cannabis withdrawal symptoms improved over four weeks in young people with and without a lifetime psychiatric diagnosis. However, those with a psychiatric illness reported one week delayed improvement in withdrawal symptom severity. Longer duration of cannabis withdrawal may be a risk factor for cannabis dependence and difficulty quitting.

A protocadherin gene cluster regulatory variant is associated with nicotine withdrawal and the urge to smoke

Nicotine withdrawal symptoms contribute to relapse in smokers, thereby prolonging the harm caused by smoking. To investigate the molecular basis for this phenomenon, we conducted a genome-wide association study of DSM-IV nicotine withdrawal in a sample of African American (AA) and European American (EA) smokers. A combined AA and EA meta-analysis (n=8021) identified three highly correlated single nucleotide polymorphisms (SNPs) in the protocadherin (PCDH)-α, -β and -γ gene cluster on chromosome 5 that were associated with nicotine withdrawal (P<5 × 10^-8). We then studied one of the SNPs, rs31746, in an independent sample of smokers who participated in an intravenous nicotine infusion study that followed overnight smoking abstinence. After nicotine infusion, abstinent smokers with the withdrawal risk allele experienced greater alleviation of their urges to smoke, as assessed by the Brief Questionnaire on Smoking Urges (BQSU). Prior work has shown that the PCDH-α, -β and -γ genes are expressed in neurons in a highly organized manner. We found that rs31746 mapped to a long-range neuron-specific enhancer element shown previously to regulate PCDH-α, -β and -γ gene expression. Using Braincloud mRNA expression data, we identified a robust and specific association between rs31746 and PCDH-β8 mRNA expression in frontal cortex tissue (P<1 × 10^-5). We conclude that PCDH-α, -β and -γ gene cluster regulatory variation influences the severity of nicotine withdrawal. Further studies on the PCDH-α, -β and -γ genes and their role in nicotine withdrawal may inform the development of novel smoking cessation treatments and reduce the harm caused by tobacco smoking.

What a difference a day makes: differences in initial abstinence response during a smoking cessation attempt

AIMS

To (1) identify distinct classes of smokers based on quit day withdrawal symptoms and (2) explore the relations between withdrawal classes and demographics, tobacco dependence, treatment and smoking outcomes.

DESIGN

Secondary data analysis of participants (n = 1504) in a randomized double-blind placebo-controlled multi-site smoking cessation trial who provided ecological momentary assessments of withdrawal symptoms on their quit day. Participants received smoking cessation counseling and were randomized to receive placebo or one of five active pharmacotherapies.

SETTING

Research offices in Madison and Milwaukee, Wisconsin, USA.

PARTICIPANTS

Adult smokers (n = 1236; 58% female, 86% white), recruited from the community via advertisements, who abstained on their quit day.

MEASUREMENTS

Demographics and tobacco dependence were assessed at baseline and participants carried palmtop computers to record withdrawal symptoms (craving, negative affect, difficulty concentrating, hunger and anhedonia) on their quit day. Point-prevalence abstinence and latency to relapse were assessed at 8 weeks and 6 months post-quit.

FINDINGS

Latent class analysis identified four withdrawal classes [Akaike information criterion (AIC) = 70.09]: Moderate withdrawal (64% of sample), high craving-anhedonia (8% of sample), affective withdrawal (13% of sample) and hunger (15% of sample). The high craving-anhedonia class reported significantly higher dependence (P < 0.01), were less likely to have received combination nicotine replacement, reported lower week 8 abstinence rates and relapsed sooner than those in the moderate withdrawal class (P < 0.05). The affective withdrawal class reported higher levels of baseline negative affect and life-time psychopathology (P < 0.05) and relapsed more quickly than the moderate withdrawal class (P < 0.01).

CONCLUSIONS

While the majority of smokers report typical levels of withdrawal symptoms on their quit day, more than one-third report extreme craving or extreme negative affective or extreme hunger responses to initial abstinence. These distinct quit-day withdrawal symptom patterns are related to baseline characteristics, treatment and cessation success.

Determining non-cigarette tobacco, alcohol, and substance use typologies across menthol and non-menthol smokers using latent class analysis

Background

Substance use and mental health are robustly associated with smoking and poor cessation outcomes, but not often examined in combination with menthol cigarette smoking, which is also associated with lower quit rates. This study identified classes of Black and White menthol and non-menthol cigarette smokers based on demographics, alcohol, drug, and other tobacco use behaviors.

Methods

Using screening data from two studies, latent class analysis (LCA) was conducted to classify n = 1177 menthol and non-menthol cigarette smokers on demographic characteristics, heavy smoking, alcohol and drug use, desire to quit smoking, other tobacco product use, and use of psychotropic medication.

Results

Three latent classes were identified that differentiated smokers on substance use, menthol cigarette smoking, and other tobacco use behavior. One class consisted primarily of young adults who used a wide array of other tobacco products, reported the highest prevalence of other drug use, and showed the lowest desire to quit smoking cigarettes in the next 6-months. Class 2 comprised primarily of Black male menthol smokers, all of whom used cigarillos in addition to cigarettes, and who displayed moderate drug use. The third class was categorized as primarily older cigarette smokers, who engaged in very little other tobacco use or drug use, but who were most likely to self-report being prescribed psychotropic medication.

Conclusions

LCA allowed for the identification of distinct classes of smokers based on factors related to poor cessation outcomes, including menthol use, that have not previously been examined in combination. Interventions should target specific groups of smokers, rather than take a “one size fits all” approach.

Correlates of nicotine withdrawal severity in smokers during a smoke-free psychiatric hospitalization

Psychiatric hospitals are increasingly adopting smoke-free policies. Tobacco use is common among persons with mental illness, and nicotine withdrawal (NW), which includes symptoms of depression, anxiety, anger/irritability, and sleep disturbance, may confound psychiatric assessment and treatment in the inpatient setting. This study aimed to characterize NW and correlates of NW severity in a sample of smokers hospitalized for treatment of mental illness in California. Participants (N=754) were enrolled between 2009 and 2013, and averaged 17 (SD=10) cigarettes/day prior to hospitalization. Though most (70%) received nicotine replacement therapy (NRT) during hospitalization, a majority (65%) reported experiencing moderate to severe NW. In a general linear regression model, NW symptoms were more severe for women, African American patients, and polysubstance abusers. Though invariant by psychiatric diagnostic category, greater NW was associated with more severe overall psychopathology and greater cigarette dependence. The full model explained 46% of the total variation in NW symptom severity (F [19, 470]=23.03 p<0.001). A minority of participants (13%) refused NRT during hospitalization. Those who refused NRT reported milder cigarette dependence and stated no prior use of NRT. Among smokers hospitalized for mental illness, NW severity appears multidetermined, related to cigarette dependence, demographic variables, psychiatric symptom severity, and other substance use. Assessment and treatment of NW in the psychiatric hospital is clinically warranted and with extra attention to groups that may be more vulnerable or naïve to cessation pharmacotherapy.

Effectiveness of Varenicline in Psychiatric Patients with Co-Morbid Polysubstance Dependence

Introduction: Individuals with substance use disorders (SUDs) and mental health disorders (MHDs) have greater prevalence of smoking and suffer greater tobacco-related morbidity and mortality. Varenicline is the latest FDA-approved smoking-cessation agent and few studies have investigated the use of varenicline in this difficult-to-treat population.

Aims: This study examines the smoking cessation outcomes and tolerability of varenicline when used to help quit smoking in 16 patients enroled in both psychiatric and substance abuse programme.

Methods: A retrospective chart review was conducted on 16 patient charts. Patient demographics, psychiatric disorder diagnoses, substance use history, dosing, side effects, number of cigarettes used pre/post varenicline use and the number of complete smoking cessation outcomes were tabulated.

Results: After varenicline intervention, 25% of those who completed treatment completely quit smoking. Thirty-one per cent were able to substantially cut back the amount that they smoked to one cigarette per day. The average reduction in cigarettes was 16 per day (64%), and all but one patient tolerated varenicline.

Conclusions: The authors observed reasonable clinical benefit when varenicline was used to help quit smoking in patients with comorbid SUDs and MHDs. Better-controlled future studies with larger sample sizes will help further determine clinical utility of varenicline in this difficult-to-treat nicotine-dependent population.

Paths to tobacco abstinence: A repeated-measures latent class analysis

OBJECTIVE

Knowledge of smoking change processes may be enhanced by identifying pathways to stable abstinence. We sought to identify latent classes of smokers based on their day-to-day smoking status in the first weeks of a cessation attempt. We examined treatment effects on class membership and compared classes on baseline individual differences and 6-month abstinence rates.

METHOD

In this secondary analysis of a double-blind randomized placebo-controlled clinical trial (N = 1,433) of 5 smoking cessation pharmacotherapies (nicotine patch, nicotine lozenge, bupropion SR, patch and lozenge, or bupropion SR and lozenge), we conducted repeated-measures latent class analysis of daily smoking status (any smoking vs. none) for the first 27 days of a quit attempt. Treatment and covariate relations with latent class membership were examined. Distal outcome analysis compared confirmed 6-month abstinence rates among the latent classes.

RESULTS

A 5-class solution was selected. Three-quarters of smokers were in stable smoking or abstinent classes, but 25% were in classes with unstable abstinence probabilities over time. Active treatment (compared to placebo), and particularly the patch and lozenge combination, promoted early quitting. Latent classes differed in 6-month abstinence rates and on several baseline variables, including nicotine dependence, quitting history, self-efficacy, sleep disturbance, and minority status.

CONCLUSIONS

Repeated-measures latent class analysis identified latent classes of smoking change patterns affected by treatment, related to known risk factors, and predictive of distal outcomes. Tracking behavior early in a change attempt may identify prognostic patterns of change and facilitate adaptive treatment planning.

Psychological symptoms, smoking lapse behavior, and the mediating effects of nicotine withdrawal symptoms: A laboratory study

The influence of psychological symptoms on smoking-lapse behavior is critical to understand. However, this relationship is obscured by comorbidity across multiple forms of psychological symptoms and their overlap with nicotine withdrawal. To address these challenges, we constructed a structural model of latent factors underlying 9 manifest scales of affective and behavioral symptoms and tested relations between latent factors and manifest scale residuals with nicotine withdrawal and smoking lapse in a laboratory analog task. Adult daily smokers (N = 286) completed a baseline session at which several forms of affective and behavioral symptoms were assessed and 2 experimental sessions (i.e., following 16 hr of smoking abstinence and following regular smoking), during which withdrawal symptoms and delay of smoking in exchange for monetary reinforcement, as an analogue for lapse propensity, were measured. A single second-order factor of general psychological maladjustment associated with more severe withdrawal-like symptoms, which in turn associated with shorter delay of smoking. The first-order factors, which tapped qualitatively unique domains of psychological symptoms (low positive affect, negative affect, disinhibition), and the manifest scale residuals provided little predictive power beyond the second-order factor with regard to lapse behavior. Relations among general psychological maladjustment, withdrawal-like symptoms, and lapse were significant in both abstinent and nonabstinent conditions, suggesting that psychological maladjustment, and not nicotine withdrawal per se, accounted for the relation with lapse. These results highlight the potential for smoking-cessation strategies that target general psychological maladjustment processes and have implications for addressing withdrawal-like symptoms among individuals with psychological symptoms.

Nicotine withdrawal

An aversive abstinence syndrome manifests 4-24 h following cessation of chronic use of nicotine-containing products. Symptoms peak on approximately the 3rd day and taper off over the course of the following 3-4 weeks. While the severity of withdrawal symptoms is largely determined by how nicotine is consumed, certain short nucleotide polymorphisms (SNPs) have been shown to predispose individuals to consume larger amounts of nicotine more frequently--as well as to more severe symptoms of withdrawal when trying to quit. Additionally, rodent behavioral models and transgenic mouse models have revealed that specific nicotinic acetylcholine receptor (nAChR) subunits, cellular components, and neuronal circuits are critical to the expression of withdrawal symptoms. Consequently, by continuing to map neuronal circuits and nAChR subpopulations that underlie the nicotine withdrawal syndrome--and by continuing to enumerate genes that predispose carriers to nicotine addiction and exacerbated withdrawal symptoms--it will be possible to pursue personalized therapeutics that more effectively treat nicotine addiction.

Association between nicotine withdrawal and reward responsiveness in humans and rats

IMPORTANCE

Reward-related disturbances after withdrawal from nicotine are hypothesized to contribute to relapse to tobacco smoking but mechanisms underlying and linking such processes remain largely unknown.

OBJECTIVE

To determine whether withdrawal from nicotine affects reward responsiveness (ie, the propensity to modulate behavior as a function of prior reinforcement experience) across species using translational behavioral assessments in humans and rats.

DESIGN, SETTING, PARTICIPANTS

Experimental studies used analogous reward responsiveness tasks in both humans and rats to examine whether reward responsiveness varied in (1) an ad libitum smoking condition compared with a 24-hour acute nicotine abstinence condition in 31 human smokers with (n = 17) or without (n = 14) a history of depression; (2) rats 24 hours after withdrawal from chronic nicotine (n = 19) or saline (n = 20); and (3) rats following acute nicotine exposure after withdrawal from either chronic nicotine or saline administration.

MAIN OUTCOMES AND MEASURES

Performance on a reward responsiveness task under nicotine and nonnicotine conditions.

RESULTS

In both human smokers and nicotine-treated rats, reward responsiveness was significantly reduced after 24-hour withdrawal from nicotine (P < .05). In humans, withdrawal-induced deficits in reward responsiveness were greater in those with a history of depression. In rats previously exposed to chronic nicotine, acute nicotine reexposure long after withdrawal potentiated reward responsiveness (P < .05).

CONCLUSIONS AND RELEVANCE

These findings across species converge in suggesting that organisms have diminished ability to modulate behavior as a function of reward during withdrawal of nicotine. This blunting may contribute to relapse to tobacco smoking, particularly in depression-vulnerable individuals, to reinstate responsiveness to natural rewards and to experience potentiated nicotine-induced reward responsiveness. Moreover, demonstration of behavioral homology across humans and rodents provides a strong translational framework for the investigation and development of clinical treatments targeting reward responsiveness deficits during early withdrawal of nicotine.

Effect Size, Statistical Power and Sample Size Requirements for the Bootstrap Likelihood Ratio Test in Latent Class Analysis

Selecting the number of different classes which will be assumed to exist in the population is an important step in latent class analysis (LCA). The bootstrap likelihood ratio test (BLRT) provides a data-driven way to evaluate the relative adequacy of a (K -1)-class model compared to a K-class model. However, very little is known about how to predict the power or the required sample size for the BLRT in LCA. Based on extensive Monte Carlo simulations, we provide practical effect size measures and power curves which can be used to predict power for the BLRT in LCA given a proposed sample size and a set of hypothesized population parameters. Estimated power curves and tables provide guidance for researchers wishing to size a study to have sufficient power to detect hypothesized underlying latent classes.

Anxiety and depressive symptoms and affective patterns of tobacco withdrawal

BACKGROUND

The complex concordance and discordance across and within anxiety and depressive symptoms complicates understanding of the relation between emotional symptoms and manifestations of tobacco withdrawal. The goal of this study was to parse the broad variation in anxiety and depressive symptoms into conceptually discrete components and explore their relative predictive influence on affective patterns of acute tobacco withdrawal.

METHODS

We employed a within-participant experimentally manipulated tobacco abstinence design involving: (i) a baseline visit at which past-week depression and anxiety symptoms were assessed and (ii) two counterbalanced experimental visits-one after ad lib smoking and one after 16-h of tobacco abstinence-at which state affect was assessed. Participants were community-dwelling adults (N=187) smoking 10+ cig/day for at least two years without an active mood disorder.

RESULTS

Anxiety-related general distress symptoms (e.g., tension, nervousness) predicted greater abstinence-induced increases in various negative affective states but not changes in positive affect (βs .17-.33). Depression-related general distress symptoms (e.g., sadness, worthlessness) predicted greater abstinence-induced increases in acute depressed affect only (βs .24-.25). Anhedonic symptoms (e.g., diminished interest, lack of pleasure) predicted larger abstinence-induced decreases in acute positive affect only (βs .17-.20). Anxious Arousal symptoms (e.g., shakiness, heart racing) predicted larger abstinence-induced increases in fatigue and depressive affect (βs .15-.24).

CONCLUSION

Different components of anxiety and depressive symptoms are associated with unique affective patterns of acute tobacco withdrawal. These results provide insight into the affective mechanisms underlying tobacco dependence and could inform smoking cessation treatment approaches tailored to individuals with emotional distress.

A Latent Class Analysis of DSM-III-R Pathological Gambling Criteria in Middle-Aged Men: Association with Psychiatric Disorders

PURPOSE

: This study was designed to empirically derive latent classes based on PG criteria and to assess the association between nongambling psychiatric disorders and specific classes.

METHODS

: A total of 8138 community-based middle-aged men were surveyed, and 2720 were assessed for Diagnostic Interview Schedule, Version 3, Revised (DIS-III-R) pathologic gambling (PG). Latent class analysis (LCA) was applied to Diagnostic and Statistical Manual Version 3, Revised (DSM-III-R) criteria to identify gambling classes. χ and logistic regression models evaluated the association between gambling classes and lifetime psychiatric disorders.

RESULTS

: The final model included 4 classes: class 0 (ie, 5418 individuals who never gambled 25 or more times per year) and classes 1-3 (identified by the LCA and comprising 2720 respondents assessed for PG). For the 9 individual criteria of PG, endorsement percentages ranged from 2%-6%, 4%-58%, and 53%-100% for classes 1-3, respectively. Nongambling psychiatric disorders were differentially associated with the 4 gambling classes, and psychopathology was more common in groups more frequently acknowledging PG criteria.

CONCLUSIONS

: Empirical support is provided for distinct classes of gambling behaviors demonstrating differential associations with individual PG criteria and nongambling psychiatric disorders. The data-driven categorization of gambling behaviors provides direction for research on defining, preventing, and treating syndromal and subsyndromal PG.

Pharmacogenetics of smoking cessation: role of nicotine target and metabolism genes

Many smokers attempt to quit smoking but few are successful in the long term. The heritability of nicotine addiction and smoking relapse have been documented, and research is focused on identifying specific genetic influences on the ability to quit smoking and response to specific medications. Research in genetically modified cell lines and mice has identified nicotine acetylcholine receptor subtypes that mediate the pharmacological and behavioral effects of nicotine sensitivity and withdrawal. Human genetic association studies have identified single nucleotide polymorphisms (SNPs) in genes encoding nicotine acetylcholine receptor subunits and nicotine metabolizing enzymes that influence smoking cessation phenotypes. There is initial promising evidence for a role in smoking cessation for SNPs in the β2 and α5/α3/β4 nAChR subunit genes; however, effects are small and not consistently replicated. There are reproducible and clinically significant associations of genotypic and phenotypic measures of CYP2A6 enzyme activity and nicotine metabolic rate with smoking cessation as well as response to nicotine replacement therapies and bupropion. Prospective clinical trials to identify associations of genetic variants and gene-gene interactions on smoking cessation are needed to generate the evidence base for both medication development and targeted therapy approaches based on genotype.

Genetics of schizophrenia and smoking: an approach to studying their comorbidity based on epidemiological findings

The association between schizophrenia and tobacco smoking has been described in more than 1,000 articles, many with inadequate methodology. The studies on this association can focus on: (1) current smoking, ever smoking or smoking cessation; (2) non-psychiatric controls or controls with severe mental illness (e.g., bipolar disorder); and (3) higher smoking frequency or greater usage in smokers. The association with the most potential for genetic studies is that between ever daily smoking and schizophrenia; it may reflect a shared genetic vulnerability. To reduce the number of false-positive genes, we propose a three-stage approach derived from epidemiological knowledge. In the first stage, only genetic variations associated with ever daily smoking that are simultaneously significant within the non-psychiatric controls, the bipolar disorder controls and the schizophrenia cases will be selected. Only those genetic variations that are simultaneously significant in the three hypothesis tests will be tested in the second stage, where the prevalence of the genes must be significantly higher in schizophrenia than in bipolar disorder, and significantly higher in bipolar disorder than in controls. The genes simultaneously significant in the second stage will be included in a third stage where the gene variations must be significantly more frequent in schizophrenia patients who did not start smoking daily until their 20s (late start) versus those who had an early start. Any genetic approach to psychiatric disorders may fail if attention is not given to comorbidity and epidemiological studies that suggest which comorbidities are likely to be explained by genetics and which are not. Our approach, which examines the results of epidemiological studies on comorbidities and then looks for genes that simultaneously satisfy epidemiologically suggested sets of hypotheses, may also apply to the study of other major illnesses.

Profiles of importance, readiness and confidence in quitting tobacco use

OBJECTIVE

This study examined whether rulers of importance, readiness and confidence (IRC) in quitting smoking could be used to identify subgroups of smokers, with the future goal of potentially tailoring interventions to specific readiness profiles.

METHODS

Consecutive emergency department patients ≥18 years old were considered for enrolment. Participants provided information on their tobacco use and motivation to quit smoking using 10-point IRC rulers. We used latent profile analysis on the IRC rulers to identify subgroups of smokers and examined associations between profile membership and participant's nicotine dependence and demographics.

RESULTS

A total of 1549 patients were screened, yielding a sample of 609 tobacco users. According to statistical fit indices, a four-profile solution fits best: 32% displayed maximum importance and readiness with strong confidence, 43% of the sample displayed relatively average levels of all three variables, 17% displayed below average importance with least favourable readiness and confidence and 7% displayed least favourable importance and readiness but relatively high confidence. Profiles were then shown to differ on nicotine dependence and educational level.

CONCLUSIONS

Four distinct profiles of IRC responses were observed. Identifying and describing these patterns has the potential to enhance future targeted intervention efforts and has implications for theory development.

Developmental trajectories in toddlers' self-restraint predict individual differences in executive functions 14 years later: a behavioral genetic analysis

We examined whether self-restraint in early childhood predicted individual differences in 3 executive functions (EFs; inhibiting prepotent responses, updating working memory, and shifting task sets) in late adolescence in a sample of approximately 950 twins. At ages 14, 20, 24, and 36 months, the children were shown an attractive toy and told not to touch it for 30 s. Latency to touch the toy increased with age, and latent class growth modeling distinguished 2 groups of children that differed in their latencies to touch the toy at all 4 time points. Using confirmatory factor analysis, we decomposed the 3 EFs (measured with latent variables at age 17 years) into a Common EF factor (isomorphic to response inhibition ability) and 2 factors specific to updating and shifting. Less-restrained children had significantly lower scores on the Common EF factor, equivalent scores on the Updating-Specific factor, and higher scores on the Shifting-Specific factor than did the more-restrained children. The less-restrained group also had lower IQ scores, but this effect was entirely mediated by the EF components. Twin models indicated that the associations were primarily genetic in origin for the Common EF variable but split between genetics and nonshared environment for the Shifting-Specific variable. These results suggest a biological relation between individual differences in self-restraint and EFs, one that begins early in life and persists into late adolescence.

A latent class analysis of DSM-IV and Fagerström (FTND) criteria for nicotine dependence

BACKGROUND

Nicotine dependence is associated with considerable morbidity and mortality. Two predominant classification systems, the Diagnostic and Statistical Manual (DSM-IV) and Fagerström Test for Nicotine Dependence (FTND), have been used to measure liability to nicotine dependence, yet few studies have attempted to simultaneously examine both sets of criteria.

METHODS

Using a sample of 624 regular smoking individuals who are offspring of Vietnam Era Twin fathers ascertained for an offspring of twin study, we applied latent class analysis to the 7 DSM-IV and the 6 FTND criteria to classify individuals by their nicotine dependence symptom profiles. Post-hoc across-class comparisons were conducted using a variety of smoking-related variables and aspects of psychopathology. Whether a single class identified offspring at high genetic and environmental vulnerability was also investigated.

RESULTS

The cross-diagnosis kappa was .30. A 4-class solution fit these data best. The classes included a low DSM-low FTND class and a high DSM-high FTND class; a moderate DSM-moderate FTND class, which was distinguished by moderate levels of smoking and intermediate levels of comorbid psychopathology; and a light smoking-moderate FTND class consisting primarily of lighter smokers with a more recent onset of regular smoking. High genetic and environmental vulnerability to nicotine dependence was noted in all classes with no statistically significant across-class differences.

CONCLUSIONS

In general, the DSM-IV and FTND criteria performed similarly to define a continuum of risk for nicotine dependence. The emerging class of light smokers should be further investigated to assess whether they transition to another class or remain as such.

Smoking history, nicotine dependence, and changes in craving and mood during short-term smoking abstinence in alcohol dependent vs. control smokers

OBJECTIVE

The goal of this study was to compare lifetime cigarette smoking, severity of nicotine dependence, and subjective effects of short-term tobacco abstinence in abstinent alcohol dependent (AD) and control smokers.

METHOD

AD (n=119) and control (n=55) ever-smokers were compared on tobacco use history and nicotine dependence. Negative affect and craving to smoke were examined in a subsample of currently smoking AD (N=34) and control (N=19) participants during a 6-h period of tobacco abstinence using the Profile of Mood States (POMS) and the Questionnaire on Smoking Urges-Brief (QSU-B).

RESULTS

Although AD smokers did not differ from controls on heaviness of smoking, they were more likely to meet lifetime criteria for nicotine dependence. AD smokers also reported more withdrawal symptoms and were more likely to endorse withdrawal-related depressed mood during past smoking reduction or abstinence periods. During short-term abstinence, AD smokers were more likely to report high craving to smoke for negative affect relief within the first 150 min of tobacco abstinence, but did not differ from controls on overall craving to smoke or withdrawal-related negative affect on the POMS.

CONCLUSIONS

Results support previous findings that AD smokers have a greater prevalence of nicotine dependence and more severe nicotine withdrawal, with a greater propensity toward withdrawal-related depressed mood. These results, along with our novel finding that greater craving to smoke in abstaining smokers with AD is specific to negative affect-related craving, suggest that negative reinforcement may be a particularly salient factor in the maintenance of tobacco use among individuals with AD.

Nicotine withdrawal symptoms in adolescent and adult twins

We examined the variation and heritability of DSM-IV nicotine withdrawal (NW) in adult and adolescent male and female twin cigarette smokers (who reported smoking 100 or more cigarettes lifetime). Telephone diagnostic interviews were completed with 3,112 Australian adult male and female smokers (53% women; age: 24-36) and 702 Missouri adolescent male and female smokers (59% girls; age: 15-21). No gender or cohort differences emerged in rates of meeting criteria for NW (44%). Latent class analyses found that NW symptoms were best conceptualized as a severity continuum (three levels in adults and two levels in adolescents). Across all groups, increasing NW severity was associated with difficulty quitting, impairment following cessation, heavy smoking, depression, anxiety, conduct disorder and problems with alcohol use. NW was also associated with seeking smoking cessation treatment and with smoking persistence in adults. The latent class structure of NW was equally heritable across adult and adolescent smokers with additive genetic influences accounting for 49% of the variance and the remaining 51% of variance accounted for by unique environmental influences. Overall, findings suggest remarkable similarity in the pattern and heritability of NW across adult and adolescent smokers, and highlight the important role of NW in psychiatric comorbidity and the process of smoking cessation across both age groups.

The co-occurrence of cigarette smoking and bipolar disorder: phenomenology and treatment considerations

OBJECTIVES

  Despite recent advances in understanding the causes and treatment of nicotine dependence among individuals with psychiatric disorders, smoking among individuals with bipolar disorder (BD) has received little attention. The goal of this review is to synthesize the literature on the epidemiology, consequences, and treatment of smoking and nicotine dependence among individuals with BD and to delineate a future research agenda.

METHODS

  We conducted a PubMed search of English-language articles using the search terms bipolar disorder, mania, tobacco, nicotine, and smoking, followed by a manual search of the literature cited in the identified articles. Articles were chosen by the authors on the basis of their relevance to the topic areas covered in this selective review.

RESULTS

  Adults with BD are two to three times more likely to have started smoking and, on the basis of epidemiological data, may be less likely to initiate and/or maintain smoking abstinence than individuals without psychiatric disorders. Smoking cessation is achievable for individuals with BD, but challenges such as chronic mood dysregulation, high prevalence of alcohol and drug use, more severe nicotine dependence, and limited social support can make quitting more difficult. Effective treatments for tobacco cessation are available, but no controlled trials in smokers with BD have been conducted.

CONCLUSIONS

  Cigarette smoking is a prevalent and devastating addiction among individuals with BD and should be addressed by mental health providers. Additional research on the mechanisms of, and optimal treatment for, smoking and nicotine dependence in this population is desperately needed.

Motivation to quit smoking among hospitalised individuals with and without mental health disorders

BACKGROUND

Persons with mental health disorders (MHD) have higher rates of smoking and poorer cessation of smoking outcomes than those without MHD. A decreased level of motivation may partially explain lower cessation rates, but there is little information on motivation among inpatients with MHD.

OBJECTIVES

Primary aims were to compare (1) motivation to cease smoking among those hospitalised with MHD or non-MHD, (2) the proportion that attempted smoking cessation, and (3) use of aids to cessation. A secondary aim was to assess cessation up to six months post-discharge.

METHODS

Smokers were recruited at a tertiary hospital in Perth, Western Australia. Surveys were administered upon admission and at 5 and 14 days and 6 months post-discharge.

RESULTS

We recruited 64 MHD inpatients and 43 non-MHD inpatients. At baseline there were no significant differences between the groups on any measures of the five measures of motivation. Significantly more of the MHD sample attempted smoking cessation than those in the non-MHD sample (34 versus 13: chi(2)(1)=5.472, P=0.028). Nicotine replacement therapy (NRT) alone was used by 70% of those attempting to quit but was only provided as part of discharge medication to two people and few persons (<21%) in either group used NRT post-discharge. By 14 days, three (4.7%) of the MHD group and none (0%) of the non-MHD group reported abstinence, at 6-months one from each group reported continuous abstinence since discharge from hospital.

CONCLUSIONS

Motivation to cease smoking among inpatients with MHD was similar to those without MHD, as was use of NRT while hospitalised. The low provision of post-discharge NRT may contribute to the poor cessation of smoking outcomes and does not fulfil evidence based guidelines.

A systematic review of the Diagnostic and Statistical Manual diagnostic criteria for nicotine dependence

The Diagnostic and Statistical Manual diagnostic criteria for nicotine dependence (DSM-ND) are based on the proposition that dependence is a syndrome that can be diagnosed only when a minimum of 3 of the 7 proscribed features are present. The DSM-ND criteria are an accepted research measure, but the validity of these criteria has not been subjected to a systematic evaluation. To systematically review evidence of validity and reliability for the DSM-ND criteria, a literature search was conducted of 16 national and international databases. Each article with original data was independently reviewed by two or more reviewers. In total, 380 potentially relevant articles were examined and 169 were reviewed in depth. The DSM-ND criteria have seen wide use in research settings, but sensitivity and specificity are well below the accepted standards for clinical applications. Predictive validity is generally poor. The 7 DSM-ND criteria are regarded as having face validity, but no data support a 3-symptom ND diagnostic threshold, or a 4-symptom withdrawal syndrome threshold. The DSM incorrectly states that daily smoking is a prerequisite for withdrawal symptoms. The DSM shows poor to modest concurrence with all other measures of nicotine dependence, smoking behaviors and biological measures of tobacco use. The data support the DSM-ND criteria as a valid measure of nicotine dependence severity for research applications. However, the data do not support the central premise of a 3-symptom diagnostic threshold, and no data establish that the DSM-ND criteria provide an accurate diagnosis of nicotine dependence.

Nicotine withdrawal sensitivity, linkage to chr6q26, and association of OPRM1 SNPs in the SMOking in FAMilies (SMOFAM) sample

BACKGROUND

Nicotine withdrawal symptoms are related to smoking cessation. A Rasch model has been used to develop a unidimensional sensitivity score representing multiple correlated measures of nicotine withdrawal. A previous autosome-wide screen identified a nonparametric linkage (NPL) log-likelihood ratio (LOD) score of 2.7 on chromosome 6q26 for the sum of nine withdrawal symptoms.

METHODS

The objectives of these analyses were to (a) assess the influence of nicotine withdrawal sensitivity on relapse, (b) conduct autosome-wide NPL analysis of nicotine withdrawal sensitivity among 158 pedigrees with 432 individuals with microsatellite genotypes and nicotine withdrawal scores, and (c) explore family-based association of single nucleotide polymorphism (SNP) at the mu opioid receptor candidate gene (OPRM1) with nicotine withdrawal sensitivity in 172 nuclear pedigrees with 419 individuals with both SNP genotypes and nicotine withdrawal scores.

RESULTS

An increased risk for relapse was associated with nicotine withdrawal sensitivity score (odds ratio, 1.25; 95% confidence interval, 1.10-1.42). A maximal NPL LOD score of 3.15, suggestive of significant linkage, was identified at chr6q26 for nicotine withdrawal sensitivity. Evaluation of 18 OPRM1 SNPs via the family-based association test with the nicotine withdrawal sensitivity score identified eight tagging SNPs with global P values <0.05 and false discovery rate Q values <0.06.

CONCLUSION

An increased risk of relapse, suggestive linkage at chr6q26, and nominally significant association with multiple OPRM1 SNPs were found with Rasch-modeled nicotine withdrawal sensitivity scores in a multiplex smoking pedigree sample. Future studies should attempt to replicate these findings and investigate the relationship between nicotine withdrawal symptoms and variation at OPRM1.

Sex heterogeneity in pharmacogenetic smoking cessation clinical trials

Approximately one-quarter of smokers who use treatments for nicotine dependence are able to achieve cessation. However, there is evidence that women do not respond as well to nicotine replacement therapy (NRT) and, perhaps, to bupropion, compared to men. In this contribution to the Special Issue of Drug and Alcohol Dependence concerning Women and Smoking, we begin with a brief overview of data supporting the role of sex in influencing response to NRT and bupropion. Next, we summarize the results of pharmacogenetic smoking cessation clinical trials which assessed sex as a moderator as well. A relatively small number of pharmacogenetic studies of nicotine dependence treatments have been conducted and five studies reported sex effects in these trials. Of these trials, sex moderated the association of genetic variation in drug pharmacokinetics or pharmacodynamics and treatment response. We conclude this paper with a summary and a brief discussion of the major caveats of this literature and priorities for future research.

Association of major depression with subtypes of nicotine dependence found among adult daily smokers: a latent class analysis

Nicotine dependence (ND) and major depression (MD) are highly prevalent disorders that frequently co-occur. Less is known about which aspects of ND are most strongly associated with MD. The present study was designed to determine if subtypes of smokers exist and differ in their risk of MD and lifetime MD symptoms. Latent class analysis was used to identify profiles of DSM-IV ND criteria for 8,842 daily smokers drawn from the larger 2001-2002 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). We found evidence for 4 distinct subtypes of smokers mainly characterized by increasing levels of ND severity, by number of criteria endorsed. We found a dose-response relationship between classes by increasing ND severity and odds of past-year MD and lifetime depression criteria. Class 2 was characterized by higher symptom endorsement probabilities (SEPs) for wider range of ND criteria and a higher odds of MD (OR=3.66) compared to class 3, which was characterized by higher SEPs for physiological ND criteria, higher prevalence of ND (class 2, 71.50% vs. class 3, 81.57%), and a lower odds of MD (OR=2.15). A post hoc contrast showed these two distinct classes of respondents with mild to moderate ND significantly differed in their likelihood of MD comorbidity (F=12.25, 1 df, p=0.0008). ND severity mainly characterized the classes, but unique differences may exist between smokers with mild to moderate ND. Individuals with symptom profiles not characterized by physiological dependence endorse wider range of ND criteria and have a higher likelihood of MD.

Association of tobacco dependence and quit attempt duration with Rasch-modeled withdrawal sensitivity using retrospective measures

AIM

To examine whether Rasch modeling would yield a unidimensional withdrawal sensitivity measure correlating with factors associated with successful smoking cessation.

DESIGN

The psychometric Rasch modeling approach was applied to estimate an underlying latent construct (withdrawal sensitivity) in retrospective responses from 1644 smokers who reported quitting for 3 or more months at least once.

SETTING

Web-based, passcode-controlled self-administered computerized questionnaire.

PARTICIPANTS

Randomly selected convenience sample of 1644 adult members of an e-mail invitation-only web panel drawn from consumer databases.

MEASUREMENTS

Lifetime Tobacco Use Questionnaire, assessing tobacco use across the life-span, including demographics and respondent ratings of the severity of withdrawal symptoms experienced in respondents' first and most recent quit attempts lasting 3 or more months.

FINDINGS

Rasch-modeled withdrawal sensitivity was generally unidimensional and was associated with longer periods of smoking cessation. One latent variable accounted for 74% of the variability in symptom scores. Rasch modeling with a single latent factor fitted withdrawal symptoms well, except for increased appetite, for which the fit was marginal. Demographic variables of education, gender and ethnicity were not related to changes in sensitivity. Correlates of greater withdrawal sensitivity in cessation attempts of at least 3 months included younger age at first quit attempt and indicators of tobacco dependence.

CONCLUSION

The relationship between tobacco dependence symptoms and Rasch-model withdrawal sensitivity defines further the relationship between sensitivity and dependence. The findings demonstrate the utility of modeling to create an individual-specific sensitivity measure as a tool for exploring the relationships among sensitivity, dependence and cessation.

The effect of catechol-O-methyltransferase Met/Val functional polymorphism on smoking cessation: retrospective and prospective analyses in a cohort study

OBJECTIVE

The Met/Val functional polymorphism of the gene-encoding catechol-O-methyltransferase (COMT) is one of the most widely tested variants for association with different phenotypes of addictive behavior, but replication has been inconsistent for smoking status. We investigated the relationship of this COMT single nucleotide polymorphism with smoking cessation in elderly persons in retrospective and prospective analyses.

METHODS

The study is embedded in the population-based Rotterdam Study cohort and included 5,115 persons aged 55 years and more. In the retrospective analyses using logistic regression, current smokers who had smoked 10 or more cigarettes daily for 10 or more years were compared with former smokers. In the prospective analyses, we followed 1,195 current smokers up to 12 years and used Cox proportional hazard model to detect the effect of the COMT single nucleotide polymorphism on self-reported incidence of smoking cessation.

RESULTS

The Val/Val genotype of COMT had a consistent association with smoking cessation as compared with the Met/Met+Met/Val genotypes in retrospective [odds ratio=0.79, 95% confidence interval (CI): 0.66-0.96, P=0.02] and prospective analyses (hazard ratio=0.80, 95% CI: 0.63-1.01, P=0.06). In the pooled analyses of prevalent and incident cessation cases that we compared with persisting smokers, the odds ratio was 0.70 (95% CI: 0.55-0.88, P=0.003). No sex difference and no effect of the COMT polymorphism on smoking initiation were observed.

CONCLUSION

Our results suggest that COMT Met/Val polymorphism is strongly associated with smoking cessation. The Met allele is the risk allele that decreases the likelihood of smoking cessation in men and women.

A testable prognostic model of nicotine dependence

Individuals' dependence on nicotine, primarily through cigarette smoking, is a major source of morbidity and mortality worldwide. Many smokers attempt but fail to quit smoking, motivating researchers to identify the origins of this dependence. Because of the known heritability of nicotine-dependence phenotypes, considerable interest has been focused on discovering the genetic factors underpinning the trait. This goal, however, is not easily attained: no single factor is likely to explain any great proportion of dependence because nicotine dependence is thought to be a complex trait (i.e., the result of many interacting factors). Genomewide association studies are powerful tools in the search for the genomic bases of complex traits, and in this context, novel candidate genes have been identified through single nucleotide polymorphism (SNP) association analyses. Beyond association, however, genetic data can be used to generate predictive models of nicotine dependence. As expected in the context of a complex trait, individual SNPs fail to accurately predict nicotine dependence, demanding the use of multivariate models. Standard approaches, such as logistic regression, are unable to consider large numbers of SNPs given existing sample sizes. However, using Bayesian networks, one can overcome these limitations to generate a multivariate predictive model, which has markedly enhanced predictive accuracy on fitted values relative to that of individual SNPs. This approach, combined with the data being generated by genomewide association studies, promises to shed new light on the common, complex trait nicotine dependence.

Genetic variability in nicotinic acetylcholine receptors and nicotine addiction: converging evidence from human and animal research

Tobacco smoking is a leading preventable cause of death in the United States and produces a major health and economic burden. Although the majority of smokers want to quit, few are successful. These data highlight the need for additional research into the neurobiology of tobacco dependence. Addiction to nicotine, the main psychoactive component of tobacco, is influenced by multiple factors that include individual differences in genetic makeup. Twin studies have demonstrated that genetic factors can influence vulnerability to nicotine addiction, and subsequent research has identified genes that may alter sensitivity to nicotine. In humans, genome-wide and candidate gene association studies have demonstrated that genes encoding nicotinic acetylcholine receptor (nAChR) proteins are associated with multiple smoking phenotypes. Similarly, research in mice has provided evidence that naturally occurring variability in nAChR genes is associated with changes in nicotine sensitivity. Furthermore, the use of genetic knockout mice has allowed researchers to determine the nAChR genes that mediate the effects of nicotine, whereas research with knockin mice has demonstrated that changes to nAChR genes can dramatically alter nicotine sensitivity. This review will examine the genetic factors that alter susceptibility to nicotine addiction, with an emphasis on the genes that encode nAChR proteins.

Effects of smoking abstinence on adult smokers with and without attention deficit hyperactivity disorder: results of a preliminary study

RATIONALE

Individuals with attention deficit hyperactivity disorder (ADHD) smoke at higher rates than the general population; however, little is known about the mechanisms underlying this comorbidity.

OBJECTIVE

This study evaluated the effects of overnight abstinence on withdrawal symptoms and cognitive performance in adult smokers with and without ADHD.

MATERIALS AND METHODS

Individuals smoking > or = 15 cigarettes per day were recruited from the community and underwent an evaluation to establish a diagnosis of ADHD (n = 12) or not (n = 14). Withdrawal symptoms, mood, craving, cognitive performance, and smoking cue reactivity were measured during two laboratory sessions-in a 'Satiated' condition participants smoked up to and during the session while in an 'Abstinent' condition, participants were required to be smoking abstinent overnight and remain abstinent during the session.

RESULTS

The effects of abstinence on ADHD and non-ADHD smokers did not differ for withdrawal symptom severity, mood, craving or cue reactivity. Significant Group x Condition interactions were observed for measures of attention and response inhibition on the Conners' CPT. For reaction time (RT) variability and errors of commission, the ADHD group exhibited greater decrements in performance after overnight abstinence compared to the non-ADHD group. The effects of abstinence on other cognitive measures (e.g., rapid visual information processing task, cued Go/No-Go task) did not differ between the two groups.

CONCLUSION

This preliminary study is the first to systematically evaluate the effects of acute smoking abstinence in adult smokers diagnosed with ADHD. Individuals with the disorder may smoke at higher rates due to greater worsening of attention and response inhibition after abstinence.

Genetics and smoking cessation improving outcomes in smokers at risk

This article reviews evidence supporting the potential utility of a pharmacogenetic approach to the treatment of nicotine dependence. There is substantial evidence that nicotine dependence and smoking persistence are heritable, and are determined by a complex interplay of polygenic and environmental influences. The most robust evidence for specific genetic influences on nicotine dependence is found in studies of genetic variation in nicotine-metabolizing enzymes. Data also support the role of genes in the dopamine and opioid pathways as predictors of dependence and smoking relapse; however, the evidence for genetic associations is not always consistent. Emerging data from pharmacogenetic trials of nicotine-dependence treatment are promising, suggesting that genetic profiles of smokers someday may be used by providers to choose the type, dose, and duration of treatment for individual smokers. However, additional trials including larger and more diverse populations are needed before such data can be translated to practice to reduce smoking prevalence and tobacco-related disease.

Genetics of nicotine dependence and pharmacotherapy

Nicotine dependence is substantially heritable. Several regions across the genome have been implicated in containing genes that confer liability to nicotine dependence and variation in individual genes has been associated with nicotine dependence. Smoking cessation measures are also heritable, and measured genetic variation is associated with nicotine dependence treatment efficacy. Despite significant strides in the understanding of the relative contribution of genetic and environmental factors to nicotine dependence and treatment, emergent challenges necessitate interdisciplinary coordinated effort for effective problem solving. These challenges include refinement of the nicotine dependence phenotype, better understanding of the dynamic interplay between genes and environment in nicotine dependence etiology, application and development of molecular and statistical methodology that can adequately address vast amounts of data, and continuous translational cross-talk.

Nicotine dependence subtypes: association with smoking history, diagnostic criteria and psychiatric disorders in 5440 regular smokers from the Vietnam Era Twin Registry

Studies suggest empirically derived subtypes of nicotine dependence exist in young adult populations with short smoking careers. It is not known if classes of dependence exist in middle aged smokers with longer smoking careers and whether these classes reflect quantitative or qualitative differences. It is not known if psychiatric disorders are associated with classes of nicotine dependence. Nicotine dependence symptoms were obtained from a 1992 administration of the Diagnostic Interview Schedule. Latent Class Analyses (LCA) was computed using data from 5440 members of the Vietnam Era Twin Registry. LCA was used to derive significantly different classes of nicotine dependence, which were assessed for their association with smoking history, nicotine dependence, and other psychiatric disorders. The LCA model which best fit the data was a 4 class solution characterized by severity. Age onset of regular smoking decreased with more severe classes. Cigarette consumption, failed cessation and psychiatric disorders were associated with more severe classes. Empirically derived subtypes of nicotine dependence are mostly characterized by increasing severity. Suggestions for refinement of nicotine dependence diagnostic criteria are discussed.

A comparison of the latent class structure of cannabis problems among adult men and women who have used cannabis repeatedly

BACKGROUND

Little empirical evidence exists to determine if there are alternative classification schemes for cannabis abuse and dependence beyond the definitions provided by Diagnostic and Statistical Manual (DSM) criteria. Current evidence is not conclusive regarding gender differences for cannabis use, abuse and dependence. It is not known if symptom profiles differ by gender.

METHODS

Latent class analysis (LCA) was used to assess whether cannabis abuse and dependence symptom patterns suggest a severity spectrum or distinct subtypes and to test whether symptom patterns differ by gender. Data from 3312 men and 2509 women in the National Longitudinal Alcohol Epidemiologic Survey (NLAES) who had used cannabis 12 + times life-time were included in the present analyses. The comparability of the solutions for men and women was examined through likelihood ratio chi(2) tests.

RESULTS

Based on the Bayesian information criterion and interpretability, a four-class solution was selected, and the classes were labeled as 'unaffected/mild hazardous use', 'hazardous use/abuse', 'abuse/moderate dependence' and 'severe abuse/dependence'. The solutions were generally suggestive of a severity spectrum. Compared to men, women were more likely to be in the 'unaffected/mild hazardous use' class and less likely to be in the 'abuse/moderate dependence' or 'severe abuse/dependence' classes. The results were generally similar for men and women. However, men had consistently and substantially higher endorsements of hazardous use than women, women in the 'abuse/moderate dependence' class had moderately higher rates for four dependence symptoms, and women in two of the classes were more likely to endorse withdrawal.

CONCLUSION

Our findings generally support the severity dimension for DSM-IV cannabis abuse and dependence symptomatology for both men and women. While our results indicate that public health messages may have generic and not gender-specific content, treatment providers should focus more effort on reducing hazardous use in men and alleviating withdrawal in women.