Delayed Reward Discounting as a Prognostic Factor for Smoking Cessation Treatment Outcome: A Systematic Review

Longitudinal characterization of impulsivity phenotypes boosts signal for genomic correlates and heritability

Genomic correlates of impulsivity have been identified in several genome-wide association studies (GWAS) using cross-sectional designs, but no studies have investigated the molecular genetic correlates of impulsivity phenotypes using longitudinally constructed traits. In 3860 unrelated European participants in the Avon Longitudinal Study of Parents and Children (ALSPAC), we constructed longitudinal phenotypes for delay discounting and impulsive personality traits (as measured by the UPPS-P impulsive behavior scales) via assessment at ages 24, 26, and 28. We conducted GWASs of impulsivity using both cross-sectional and longitudinal phenotypes, estimated heritability and their phenotypic and genetic correlations, and evaluated their association with recently-developed polygenic risk scores (PRSs) for the impulsivity indicators themselves and also related psychiatric conditions. Latent growth curve modeling revealed a stable intercept over time for all impulsivity phenotypes. High genetic correlation of cross-sectional measures over time suggested a stable genetic component for delay discounting (rg = 0.53-0.99) and sensation seeking (rg = 0.99). Heritability estimates of the stable longitudinal phenotypes substantively improved as compared to their cross-sectional counterparts, revealing a significant SNP-heritability for delay discounting (0.22; p = 0.03) and sensation seeking (0.35; p = 0.0007). Consistent with previous reports, GWAS and gene-based analyses revealed associations between specific longitudinal impulsivity indicators and CADM2 and NCAM1 genes. The PRSs for the impulsivity indicators and disorders related to self-regulation were also significantly associated with longitudinal impulsivity traits. Finally, we validated the associations between longitudinal impulsivity phenotypes and their PRSs in an independent 13-wave longitudinal study (n = 1019) and the benefit of longitudinal phenotypes in simulation studies. In this first longitudinal genetic study of impulsivity traits, the results revealed stable genomic correlates of delay discounting and sensation seeking over time and further validated the utility of recently-developed PRSs, both in relation to the observed traits and in connecting them to psychiatric disorders. More generally, these findings support using latent intercepts as novel longitudinal phenotypes to boost signal for heritability and genomic correlates of mechanisms contributing to psychiatric disease liability.

Differential Responses to Cigarette Package Labeling Alternatives Among Adults Who Smoke: Results From a Randomized Trial

INTRODUCTION

Little experimental research has evaluated whether the effects of cigarette package inserts with efficacy messages and/or pictorial health warning labels (PHWLs) differ across key subgroups of adults who smoke.

AIMS AND METHODS

Adults who reported currently smoking (n = 367) were randomly assigned to one of four groups: Small text-only HWLs on pack sides (control); inserts with efficacy messages and small HWLs (inserts-only); PHWLs showing harms of smoking (PHWLs-only); both (inserts + PHWLs). Participants received a 14-day supply of cigarettes labeled to reflect their group. Every evening over 2 weeks, participants reported forgoing and stubbing out cigarettes before they finished smoking over the prior 24 hours, combined into a binary indicator of either behavior (eg, forgoing/stubbing). Separate mixed-effects logistic models were estimated to evaluate moderation of labeling group contrasts (ie, PHWLs vs not; inserts vs. not; inserts-only vs. inserts + PHWLs; PHWLs-only vs. inserts + PHWLs) by baseline covariates (self-efficacy to quit, intention to quit, education, health literacy, and time discounting), predicting day-level forgoing/stubbing.

RESULTS

Education moderated PHWL effects, with PHWLs predicting more forgoing/stubbing only among those with low education (OR = 4.68, p < .001). Time discounting moderated insert effects, with inserts promoting forgoing/stubbing only among those with low time discounting (ie, lower impulsivity; OR = 4.35, p < .001).

CONCLUSIONS

Inserts with efficacy messages appear effective mostly among people with low time discounting, whereas PHWLs appear most effective among those with low education, suggesting their potential to address education-related disparities. Labeling strategies appeared equally effective across subgroups defined by self-efficacy to quit, quit intention, and health literacy. Combining inserts with PHWLs did not appear to mitigate moderation effects.

IMPLICATIONS

This randomized trial with adults who smoke suggests that cigarette packs with inserts describing cessation benefits and tips can promote cessation-related behaviors (ie, forgoing or stubbing out cigarettes) among those with low-time discounting (ie, low impulsivity). Alternative interventions may be needed for people with high-time discounting, as found in cessation trials. PHWLs appear most effective among those with low education, potentially addressing education-related disparities. No differential effects were found for those with different levels of self-efficacy to quit, quit intentions, or health literacy. Combining inserts and PHWLs may not be more effective than either alone.

Ecological momentary assessment of delay discounting, reward valuation, and craving in very light cigarette users

Heightened delay discounting has been linked to adverse smoking cessation outcomes, including among light cigarette users. Few studies have evaluated delay discounting's proposed mechanism, preference reversal (concurrent increases in valuation of/craving for desired objects), and none have done so in naturalistic settings. We examined how person-level delay discounting moderated the within-person association between cigarette valuation and craving among very light daily cigarette users who were financially incentivized to abstain. Forty participants completed a baseline delay-discounting task and intermittent ratings of cigarette valuation and craving during the incentivized abstinence attempt. Subjects earned monetary rewards for abstinence on a descending schedule (e.g., $20 on Days 1 and 2 and $2.50 on Days 9 and 10). Consistent with preference reversals, there was a positive association between cigarette valuation and craving. This relation was moderated by delay discounting (stronger among those with low discounting rates) and by monetary reinforcement amount (stronger on days with low reinforcement). Additionally, subjects were more likely to report stronger cravings on days with high monetary reinforcement, with this effect moderated by delay discounting (stronger among those with low discounting rates). The results suggest that heightened delay discounting may not confer risk for preference reversal among very light daily cigarette users who are attempting abstinence.

Recovery from alcohol use disorder: Reinforcer pathology theory, measurement, and methods

Recovery from alcohol use disorder (AUD) is a dynamic process that often entails periods of drinking but has been defined primarily by abstinence. Recently, a broader interpretation of recovery was developed, including meeting the Diagnostic and Statistical Manual of Mental Disorders (DSM) remission criteria and improved psychosocial functioning. This new understanding of recovery has facilitated the development of novel theories and methodologies. This paper reviews a new theoretical perspective of recovery, Reinforcer Pathology, and two novel methodological approaches in light of this broader view of recovery. Using this theoretical framework as a foundation, we propose an alternative perspective to explain the recovery process as it relates to environmental factors and valuation of the future; we suggest that changing the environment in which substances are available (e.g., increasing non-alcohol-related activities) and extending one's temporal window are associated with improved recovery outcomes (e.g., remission and quality of life). In this review, we discuss two novel methodological approaches. The first uses latent profile analysis to show that using a measure of Relative Reinforcement Value of Alcohol-Free Activities is associated with a greater likelihood of belonging to a high functioning/infrequent heavy drinking recovery profile. The second developed an online national sample and used an accelerated longitudinal design to study longer-term recovery of up to 12 years over a 5-year study period. Reinforcer Pathology theory, novel methods, and measures may further our understanding of recovery and begin to address critical questions for future studies. Subsequent randomized clinical trials should examine whether the suggested targets and interventions based on the theoretical model improve recovery outcomes prospectively. Measuring and promoting alcohol-free activity engagement may facilitate improved recovery outcomes, while novel methodologies permit an understanding of returning to use or remission across different recovery durations.

Effectiveness and feasibility of the self-administered and repeated episodic future thinking exercises in smoking cessation

Delay discounting (DD) is associated with smoking behavior and relapses. Episodic future thinking (EFT) is one of the leading interventions shown to reduce DD. The 1-month follow-up study with 60 participants that employed EFT as active intervention and episodic recent thinking (ERT) as control intervention was conducted in participants receiving smoking cessation treatment. In EFT group, there was significant decrease in DD rates from pre-intervention to post-intervention (p = 0.009), whereas no significant change was observed in ERT group (p = 0.497). DD rates in EFT group did not change significantly over 1 month (p = 0.059), while decrease was detected in ERT group (p = 0.011). Smoking cessation rates between groups were similar (p = 0.486). Adherence with completing follow-up evaluation forms and performing relevant exercises was higher in EFT group (p = 0.038, p = 0.006). Adding EFT to usual smoking cessation treatment did not increase smoking cessation rates, however feasibility of the self-administered exercises needs to be improved to clarify clinical effects.

Art-delivered episodic future thinking reduces delay discounting: A phase IIa proof-of-concept trial

INTRODUCTION

High rates of delay discounting (DD), or the preference for immediate rewards over delayed rewards, is associated with substance use disorder (SUD). Lower rates of DD predict better treatment outcomes, and thus strategies that reduce DD may support SUD recovery. The process of vividly imagining a future event, known as episodic future thinking (EFT), may be a particularly viable approach to reduce DD. Some limited research has examined delivery of EFT in treatment settings, using verbal prompts that are typical of studies in non-treatment settings. We propose that the creation of visual art represents a unique alignment of the purpose of EFT with an innovative delivery modality in treatment settings.

METHODS

This single arm, proof-of-concept trial evaluated art-delivered EFT (ArtEFT) to reduce DD in a sample of women (N = 39) in a residential SUD treatment center. Participants engaged in a single, 1-h ArtEFT session during which they engaged in EFT and created a visual representation using art materials. The study collected DD measures for hypothetical money ($50 and $1000 magnitude conditions) before and after ArtEFT.

RESULTS

Using area-under-the-curve (AUCord) as the index of DD, the study observed predicted changes following the ArtEFT session. The ANOVA revealed statistically significant main effects of both magnitude [F(1,38) = 11.184, p = .002] and time [F(1. 38) = 4.731, p = .036], with a non-significant interaction [F(1,38) = 3.821, p = .058].

CONCLUSION

This study reveals promising preliminary indicators that art may be an effective modality to deliver EFT, with particular advantages for implementation given the popularity of art programming in SUD treatment programs.

Delay discounting demonstrates lower impulsivity linked to a higher likelihood of succeeding at smoking cessation

Sixty-eight percent of smokers want to quit, but only one in 10 are successful at smoking cessation. Recently, impulsivity has been studied in relation to smoking cessation with measures like the delay discounting task (DDT). We aimed to build on the robust literature that has already revealed the association between impulsivity and smoking cessation, as well as look at the differences between sexes for which there is conflicting evidence. We hypothesized that lower impulsivity would be positively associated with cessation success. In the parent cessation trial, participants were randomized to 12 weeks of progesterone or placebo. Participants were asked to quit smoking, and their smoking status was monitored via expired carbon monoxide throughout the study. Participants completed a DDT at screening, week 4, and week 8 using the 27-item Monetary Choice Questionnaire, where participants decided between a small immediate reward or a larger delayed reward (LDR). The effective delay 50 (ED50), which is the delay at which the LDR loses half its value, was analyzed. To estimate the association between ED50 and cessation, a logistic mixed model with a participant random intercept was fit, controlling for study week, randomization, sex, and age. For the 181 participants, a doubling of the ED50 was associated with an 18% increase in the odds of tobacco cessation (95% confidence interval: 0.2-38% increase; p=0.05). In agreement with our hypothesis, lower impulsivity correlated to greater tobacco cessation success. Our study also showed no evidence of sex differences in the association between ED50 and smoking cessation.

Smoking Dependence, Time-Discounting, and Sustained Cessation Behavior: A Longitudinal Study of Predominantly Light Smokers

INTRODUCTION

This study aimed to assess whether two established psychosocial predictors of smoking abstinence, nicotine dependence and time-discounting, also apply to a population of predominantly cigarette light smokers, which is the dominant pattern of smoking in countries like Mexico. Relatively infrequent smoking is increasingly prevalent, yet still harmful, making it important to understand the predictors of cessation in this population.

AIMS AND METHODS

Mexican adult smokers recruited from an online consumer panel were surveyed every 4 months between November 2018 and July 2020. We considered respondents who reported a quit attempt in between surveys (n = 1288). Dependence was measured with a 10-item version of the Wisconsin Inventory of Smoking Dependence Motives (WISDM). Time-discounting was assessed with five branching questions about hypothetical reward scenarios. Logistic models regressed sustained quit attempts (≥30 days of abstinence) at time t + 1 on study variables at time t.

RESULTS

We found strong interitem reliability (α = 0.92) and intraindividual consistency of our brief WISDM (ρ = 0.68), but moderate intraindividual consistency of the time-discounting measure (ρ = 0.48). Forty-eight percent of the sample reported sustained quit attempts, and 79% were non-daily or light daily smokers (≤5 cigarettes per day). Smokers with higher WISDM-10 had lower odds of sustained quitting and this result remained when controlling for smoking frequency and the Heaviness of Smoking Index (adjusted odds ratio [AOR] = 0.768). Time-discounting was unassociated with sustained quitting.

CONCLUSIONS

Our findings suggest that a brief, 10-item multidimensional measure of dependence is useful for predicting sustained quitting in a context of relatively light smoking; time-discounting appears less relevant, although our results are not conclusive because of the low test-retest reliability of our measure.

IMPLICATIONS

Given the increase in non-daily and light daily cigarette smoking in many countries, including in Mexico, and the health risks this still poses, it is important to understand the predictors of cessation among relatively light smokers. The WISDM-10 multidimensional measure seems to be a good instrument to assess dependence and predict successful quitting in this population, and possibly more appropriate than physical dependence measures. As such, it could help design and target more suitable cessation treatments for non-daily and daily light cigarette smokers. While this study did not find time-discounting to be a relevant predictor of smoking abstinence, future studies should explore other measures.

Reliability and validity of behavioral-economic measures: A review and synthesis of discounting and demand

This review sought to synthesize the literature on the reliability and validity of behavioral-economic measures of demand and discounting in human research, introduce behavioral-economic research methodologies for studying addictive behaviors, discuss gaps in the current literature, and review areas for future research. A total of 34 studies was included in this review. The discounting literature showed similar responding regardless of whether hypothetical or actual outcomes were used, though people tended to discount the outcome presented first more steeply, suggesting order effects. Although delay-discounting measures seem to show temporal stability, exceptions were found for probability- and experiential-discounting tasks. The demand literature also demonstrated similar responding regardless of outcome type; however, some demand indices showed exceptions. Randomized price sequences tended to show modest increases in Omax and α and modestly higher rates of inconsistent or nonsystematic responses compared with sequential price sequences. Demand indices generally showed temporal stability, although the stability was weaker the larger the time interval between test sessions. Future studies would benefit by examining addictive commodities beyond alcohol, nicotine, and money; examining temporal stability over longer time intervals; using larger delays in discounting tasks; and using larger sample sizes.

Delay discounting and substance use treatment outcomes: A systematic review focused on treatment outcomes and discounting methodology

INTRODUCTION

Delay discounting-the tendency to choose small, immediate rewards over larger, delayed rewards-is robustly associated with substance use. Delay discounting may present challenges in treatment for substance use disorders, as individuals with elevated discounting may struggle to wait for the long-term rewards that come from abstinence, which may yield poorer treatment outcomes. However, evidence on the role of discounting in treatment outcomes has been inconsistent. The study conducted a systematic review of the literature to characterize the prospective effects of delay discounting measured pre-treatment on substance use treatment outcomes, with a focus on characterizing findings across: 1) type of treatment outcome and 2) methodology used to assess and characterize discounting.

METHOD

A systematic literature search identified N = 17 studies that examined the association between delay discounting at treatment entry (pre-treatment) and substance use treatment outcomes. Findings were reported across the following substance use treatment outcomes: abstinence, relapse, use frequency and related problems, and treatment adherence. Findings regarding discounting methodology were reported by type of discounting measure (adjusting choice task, fixed choice task, or experiential task) and parameter used to characterize discounting (k, log transformed k (lnk), and area under the curve).

RESULTS

Delay discounting at treatment entry was not consistently associated with substance use treatment outcomes when examined across all studies overall (47 %) or by treatment outcome (0-40 % for most outcomes). The majority of studies (64 %) that used an adjusting choice, computer-based task reported a significant association between discounting and treatment outcomes, whereas few studies that used a fixed choice or experiential task reported significant associations with treatment outcomes (0-25 %). Most studies (71 %) that used the lnk parameter to characterize discounting reported significant associations between discounting and a range of treatment outcomes. In contrast, few studies that used k or AUC (25-33 %) reported significant associations between discounting and treatment outcomes.

CONCLUSION

When examined overall and by treatment outcome, evidence did not consistently indicate that delay discounting was prospectively associated with substance use treatment outcomes. However, delay discounting at treatment entry was more commonly associated with a variety of poorer treatment outcomes when researchers used more fine-grained methods to characterize discounting.

Predictors of smoking cessation outcomes identified by machine learning: A systematic review

This systematic review aims to characterize the utility of machine learning to identify the predictors of smoking cessation outcomes and identify the machine learning methods applied in this area. In the current study, multiple searches occurred through December 9, 2022 in MEDLINE, Science Citation Index, Social Science Citation Index, EMBASE, CINAHL Plus, APA PsycINFO, PubMed, Cochrane Central Register of Controlled Trials, and the IEEE Xplore were performed. Inclusion criteria included various machine learning techniques, studies reporting cigarette smoking cessation outcomes (smoking status and the number of cigarettes), and various experimental designs (e.g., cross-sectional and longitudinal). Predictors of smoking cessation outcomes were assessed, including behavioral markers, biomarkers, and other predictors. Our systematic review identified 12 papers fitting our inclusion criteria. In this review, we identified gaps in knowledge and innovation opportunities for machine learning research in the field of smoking cessation.

Neuroeconomic predictors of smoking cessation outcomes: A preliminary study of delay discounting in treatment-seeking adult smokers

Large proportions of smokers are unsuccessful in evidence-based smoking cessation treatment and identifying prognostic predictors may inform improvements in treatment. Steep discounting of delayed rewards (delay discounting) is a robust predictor of poor smoking cessation outcome, but the underlying neural predictors have not been investigated. Forty-one treatment-seeking adult smokers completed a functional magnetic resonance imaging (fMRI) delay discounting paradigm prior to initiating a 9-week smoking cessation treatment protocol. Behavioral performance significantly predicted treatment outcomes (verified 7-day abstinence, n = 18; relapse, n = 23). Participants in the relapse group exhibited smaller area under the curve (d = 1.10) and smaller AUC was correlated with fewer days to smoking relapse (r = 0.56, p < 0.001) Neural correlates of discounting included medial and dorsolateral prefrontal cortex, posterior cingulate, precuneus and anterior insula, and interactions between choice type and relapse status were present for the dorsolateral prefrontal cortex, precuneus and the striatum. This initial investigation implicates differential neural activity in regions associated with frontal executive and default mode activity, as well as motivational circuits. Larger samples are needed to improve the resolution in identifying the neural underpinnings linking steep delay discounting to smoking cessation.

Characterizing Clinical Heterogeneity in a Large Inpatient Addiction Treatment Sample: Confirmatory Latent Profile Analysis and Differential Levels of Craving and Impulsivity

BACKGROUND

Individuals with substance use disorders (SUDs) have highly heterogeneous presentations and identifying more homogeneous subgroups may foster more personalized treatment. This study used SUD and other psychiatric indicators to characterize latent subgroups of patients in a large inpatient addiction treatment program. The resulting subgroups were then analyzed with respect to differences on clinically informative motivational mechanisms.

METHODS

Patients (n = 803) were assessed for severity of SUD (ie, alcohol use disorder, drug use disorder), post-traumatic stress disorder, anxiety disorders, and major depressive disorder. Confirmatory latent profile analysis (CLPA) was used to identify latent subgroups, hypothesizing 4 subgroups. Subgroups were then characterized with respect to multiple indicators of impulsivity (ie, delay discounting and impulsive personality traits via the UPPS-P) and craving.

RESULTS

The CLPA confirmed the hypothesized 4-profile solution according to all indicators (eg, entropy = 0.90, all posterior probabilities ⩾.92). Profile 1 (n = 229 [32.2%], 24.9% female, median age in range of 45-49) reflected individuals with high alcohol severity and low psychiatric severity (HAlc/LPsy). Profile 2 (n = 193 [27.1%], 29.3% female, median age in range of 35-39) reflected individuals with high drug and psychiatric severity (HDrug/HPsy). Profile 3 (n = 160 [22.5%], 37.6% female, median age in range of 45-49) reflected individuals with high alcohol severity and psychiatric severity (HAlc/HPsy). Profile 4 (n = 130 [18.3%], 19.4% female, median age in range of 35-39) reflected individuals with high drug severity and low psychiatric severity (HDrug/LPsy). Both high comorbid psychiatric severity subgroups exhibited significantly higher craving and facets of impulsivity.

CONCLUSIONS

The results provide further evidence of 4 latent subgroups among inpatients receiving addiction treatment, varying by alcohol versus other drugs and low versus high psychiatric comorbidity. Furthermore, they reveal the highest craving and impulsivity in the high psychiatric comorbidity groups, suggesting targets for more intensive clinical intervention in these patients.

Chronic tobacco smoking, impaired reward-based decision-making, and role of insular cortex: A comparison between early-onset smokers and late-onset smokers

INTRODUCTION

The literature suggests that tobacco smoking may have a neurotoxic effect on the developing adolescent brain. Particularly, it may impair the decision-making process of early-onset smokers (<16 years), by rendering them more prone to impulsive and risky choices toward rewards, and therefore more prone to smoking relapses, in comparison to late-onset smokers (≥16 years). However, no study has ever investigated reward-based decision-making and structural brain differences between early-onset smokers and late-onset smokers.

METHODS

Computerized measures of reward-based decision-making [Cambridge Gambling Task (CGT); 5-trials adjusting delay discounting task (ADT-5)] were administered to 11 early-onset smokers (mean age at regular smoking initiation = 13.2 years), 17 late-onset smokers (mean age at regular smoking initiation = 18.0 years), and 24 non-smoker controls. Voxel-based morphometry (VBM) was utilized to investigate the gray matter (GM) and white matter (WM) volume differences in fronto-cortical and striatal brain regions between early-onset smokers, late-onset smokers, and non-smokers.

RESULTS

Early-onset smokers displayed a riskier decision-making behavior in comparison to non-smokers as assessed by the CGT (p < 0.01, Cohen's f = 0.48). However, no significant differences (p > 0.05) in reward-based decision-making were detected between early-onset smokers and late-onset smokers. VBM results revealed early-onset smokers to present lower GM volume in the bilateral anterior insular cortex (AI) in comparison to late-onset smokers and lower WM volume in the right AI in comparison to late-onset smokers.

CONCLUSION

Impairments in reward-based decision-making may not be affected by tobacco smoking initiation during early adolescence. Instead, lower GM and WM volume in the AI of early-onset smokers may underline a vulnerability to develop compulsive tobacco seeking and smoking behavior during adulthood.