Delay discounting as a mediator of the relationship between perceived stress and cigarette smoking status in adolescents

Stress and episodic future thinking: Effects on temporal window and alcohol demand

BACKGROUND

Stress maintains problematic alcohol use, so it is particularly important to identify interventions that effectively reduce the desire for alcohol even in the context of high stress. Reinforcer Pathology Theory suggests that stress increases alcohol demand by inducing short-term thinking. One intervention that targets this mechanism is episodic future thinking (EFT), which involves vividly imagining personal future events and has been shown to reduce short-term thinking and accompanying preferences for immediate rewards like alcohol. These shared mechanisms suggest that EFT may be particularly effective at reducing alcohol demand in the context of higher stress. This study first assessed the relationship of stress with preference for immediate rewards and alcohol demand, and the impact of EFT on preference for immediate rewards and alcohol demand. This study then tested whether EFT may be particularly effective in the context of higher stress.

METHODS

One hundred thirty-nine adults with problematic alcohol use completed an online survey through Amazon Mechanical Turk (MTurk), including self-report measures of past month stress and baseline momentary stress, an EFT or episodic recent thinking (ERT) procedure, a delay-discounting task, and an alcohol purchase task. Univariate correlations assessed the relationship of stress with delay discounting and alcohol demand intensity. Path analyses assessed hypothesized models relating EFT/ERT, stress, delay discounting, and demand intensity.

RESULTS

Consistent with Reinforcer Pathology Theory, higher baseline momentary stress was correlated with increased preference for immediate rewards. EFT intervention increased preference for delayed rewards, which contributed to decreased alcohol demand. However, the effect of EFT on delay discounting was not moderated by stress.

CONCLUSIONS

EFT does not appear uniquely effective at reducing desire for alcohol in the context of higher stress, but equally, EFT's efficacy was not significantly affected by stress level. Findings emphasize the opposing roles of state stress and EFT in the behavioral economics underlying problematic alcohol use.

No effects of acute stress on monetary delay discounting: A systematic literature review and meta-analysis

Many everyday decisions, including those concerning our health, finances and the environment, involve choosing between a smaller but imminent reward (e.g., €20 now) and a later but larger reward (e.g., €40 in a month). The extent to which an individual prefers smaller imminent rewards over larger delayed rewards can be measured using delay discounting tasks. Acute stress induces a cascade of biological and psychological responses with potential consequences for how individuals think about the future, process rewards, and make decisions, all of which can impact delay discounting. Several studies have shown that individuals focus more on imminent rewards under stress. These findings have been used to explain why individuals make detrimental choices under acute stress. Yet, the evidence linking acute stress to delay discounting is equivocal. To address this uncertainty, we conducted a meta-analysis of 11 studies (14 effects) to systematically quantify the effects of acute stress on monetary delay discounting. Overall, we find no effect of acute stress on delay discounting, compared to control conditions (SMD = -0.18, 95% CI [-0.57, 0.20], p = 0.32). We also find that neither the gender/sex of the participants, the type of stressor (e.g., physical vs. psychosocial) nor whether monetary decisions were hypothetical or incentivized (i.e. monetary decisions were actually paid out) moderated the impact of acute stress on monetary delay discounting. We argue that establishing the effects of acute stress on the separate processes involved in delay discounting, such as reward valuation and prospection, will help to resolve the inconsistencies in the field.

Validation of the Sexual Discounting Task for Use in Adolescents

The Sexual Discounting Task (SDT) was developed to evaluate the effects of delay on decision making as it relates to sexual risk-taking behaviors. Though previously validated with other populations, including urban emerging adults, the current study sought to validate the SDT with adolescents. A sample of adolescents (N = 155; 61% female) between ages 14 and 21 (Mage = 19.5 years) was recruited to complete the SDT (involving choices between immediate unprotected sex and delayed sex with a condom with hypothetical sexual partners) and the Delay Discounting Task (a delay discounting task for money outcomes). Additionally, they completed several self-report measures assessing demographics, sexual behavior, and sexual history. If the condom was readily available, respondents were more likely to use a condom for partners who were judged "most likely to have an STI" and for those that participants were "least likely to have sex with." Moreover, when a condom was not immediately available, greater self-reported sexual risk-taking was related to greater sexual discounting (i.e., greater effects of delay on decreasing condom use). Furthermore, sexual discounting was greater among partners deemed more desirable and those judged "least likely to have an STI." Differences in sexual discounting were significant after controlling for immediately available condom use. Findings from the current study suggest that the SDT is clinically meaningful for adolescents and is sensitive to factors that influence real-world decisions to use condoms. Future treatment and prevention should consider delay discounting as an important variable affecting sexual risk behavior.

Early life adversity and substance use: The mediating role of mood and the moderating role of impulsivity

INTRODUCTION

Early life adversity (ELA) is a risk factor for substance use and misuse, and multiple factors mediate and moderate this association. We examined whether moods mediate the relationships between ELA and nicotine use, cannabis use, and co-use, and whether these mediation effects varied as a function of delay discounting.

METHODS

A total of 2555 adults completed a delay discounting task and responded to questions related to demographics, ELA, mood, and substance use. Data were analyzed using Pearson correlations and moderated mediation using Hayes' PROCESS macro (V3.4, Model 15).

RESULTS

ELA was positively associated with cannabis use, nicotine use, co-use of both substances, depressed and stressed moods, and it was negatively associated with positive mood. While cannabis use was associated negatively with stressed and depressed moods and positively with positive mood, nicotine use was associated negatively with positive mood. Moderated mediation analyses indicated that positive mood mediated the relationship between ELA and cannabis use for those with average and above average delay discounting. Positive mood also mediated the relationship between ELA and co-use among those with above average delay discounting.

CONCLUSION

The results suggest that ELA's associations with cannabis use and cannabis-nicotine co-use may be partially attributable to ELA's effects on positive mood among those who are predisposed to moderately to highly impulsive decision making.

Perceived Stress and Smoking Cessation: The Role of Smoking Urges

Despite the fact that perceived stress is related to abstinence smoking outcomes, no studies have investigated the mediational effect of specific tobacco-related variables on this relationship. This study aimed to explore the indirect effect of perceived stress on abstinence at the end of treatment through smoking urges. The sample comprised 260 treatment-seeking smokers (58.5% female; Mage = 46.00; SD = 11.1) who underwent psychological smoking cessation treatment. The brief version of the Questionnaire of Smoking Urges (QSU) and the Perceived Stress Scale (PSS14) were used. Mediation analyses were conducted in which smoking urges and their dimensions were potential mediators in the relationship between perceived stress and abstinence at the end of treatment. The results showed a non-significant direct effect of perceived stress on abstinence. However, a significant indirect effect was found through smoking urges (QSU-total) and, specifically, through smoking urges associated with the expectation of negative affect relief (QSU-Factor 2). A non-significant indirect effect through smoking urges related to the expectation of tobacco use as a pleasurable experience (QSU-Factor 1) was also found. Analyzing possible mediator variables could contribute to understanding previous conflicting data. These findings point to potential interest in including treatment components targeting perceived stress and smoking urges to improve the effectiveness of smoking cessation treatments.

Hyperbolic discounting rates and risk for problematic alcohol use in youth enrolled in the Adolescent Brain and Cognitive Development study

Adolescence is the peak period for the emergence of substance use, which can lead to long-term psychosocial, occupational and interpersonal complications. Ongoing large-scale, longitudinal, consortium initiatives, such as the Adolescent Brain and Cognitive Development (ABCD) study, offer unprecedented opportunities to elucidate key risk factors for problematic substance use in a well-powered sample and to examine how changes in risk factors relate to symptoms across time. Delay discounting has been proposed as a putative risk marker for early substance-use initiation and other forms of psychopathology. However, the extent to which other factors (e.g., socio-economic status and cognitive ability) influence discounting behaviour in young adolescents is not well established. The present study leverages data from the ABCD study (n = 11 045) to assess associations between core demographic and familial variables and delay discounting in youth-operationalized using hyperbolic discounting rates (k)-before the onset of significant psychopathology. Model estimates revealed significant effects of individual difference factors (e.g., sex and socio-economic status) and alcohol risk status (based on family history) on delay discounting. No significant differences were observed in the primary sample when comparing the presence of parent drug problems or prenatal drug exposures. These effects will require replication in later waves of ABCD. Nonetheless, these results provide support for delay discounting as a potential risk marker for problematic alcohol use and demonstrate a relationship between key demographic variables and adolescent discounting behaviour. Further, these results provide an empirical baseline from which developmental trajectories of delay discounting and substance use may be tracked throughout future waves of ABCD.

Stress and COVID‐19 related behaviours: The mediating role of delay discounting

We examined stress as a predictor of behaviours related to Coronavirus Disease-2019 (COVID-19) through its effects on delay discounting. Adults (N = 3686) completed an online survey with a behavioural measure of delay discounting and questions regarding stress, physical distancing, and stockpiling of food and supplies. Stress was weakly, but positively, correlated with delay discounting (p < 0.01). Delay discounting was positively correlated with stockpiling (p < 0.01); and discounting was negatively correlated with physical distancing (p < 0.01). Mediation models indicated that discounting was a significant mediator of the relationship between stress and physical distancing (-0.003) and stockpiling (0.003); bootstrap 95% CIs (-0.006, -0.001) and (0.001, 0.005), respectively. After accounting for its indirect effects through discounting, stress continued to have a direct effect on these outcomes. This study indicates that delay discounting partially mediates the link between stress and behaviours related to COVID-19. Results suggest that interventions reducing stress and/or delay discounting may be profitable for increasing infection prevention and reducing stockpiling.

Nicotine Inhalation and Suicide: Clinical Correlates and Behavioral Mechanisms

BACKGROUND AND OBJECTIVES

Extensive evidence links smoking and suicide independently of psychiatric diagnoses, but there are questions about the pathophysiology and specificity of this relationship. We examined characteristics of this linkage to identify potential transdiagnostic mechanisms in suicide and its prevention.

METHODS

We reviewed literature that associated suicide with smoking and e-cigarettes, including the temporal sequence of smoking and suicide risk and their shared behavioral risk factors of sensitization and impulsivity.

RESULTS

Smoking is associated with increased suicide across psychiatric diagnoses and in the general population, proportionately to the number of cigarettes smoked per day. Rapid nicotine uptake into the brain through inhalation of conventional cigarettes, electronic cigarettes (e-cigarette), or even second-hand smoke can facilitate long-term sensitization and short-term impulsivity. Both impair action regulation and predispose to negative affect, continued smoking, and suicidal behavior. Intermittent hypoxia, induced by cigarettes or e-cigarettes, synergistically promotes impulsivity and sensitization, exacerbating suicidality. Two other shared behavioral risks also develop negative urgency (combined impulsivity and negative affect) and cross-sensitization to stressors or to other addictive stimuli. Finally, early smoking onset, promoted by e-cigarettes in never-smokers, increases subsequent suicide risk.

CONCLUSION AND SCIENTIFIC SIGNIFICANCE

Prevention or cessation of nicotine inhalation can strategically prevent suicidality and other potentially lethal behavior regardless of psychiatric diagnoses. Medications for reducing smoking and suicidality, especially in younger smokers, should consider the neurobehavioral mechanisms for acute impulsivity and longer-term sensitization, potentially modulated more effectively through glutamate antagonism rather than nicotine substitution. (Am J Addict 2021;30:316-329).

The discounted future: Relationship between temporal discounting and future thinking in Alzheimer's disease

Temporal discounting refers to the tendency to prefer smaller sooner rewards over larger later rewards. Prior research has reported temporal discounting in Alzheimer's disease (AD). We thus investigated, in this study, the relationship between temporal discounting and future thinking in AD. The study included 40 patients with AD and 42 control participants. We invited participants, on a temporal discounting task, to choose between an immediate but smaller or a delayed but larger amount of money (e.g. "would you prefer 10 dollars today or 50 dollars after one month?"). We also invited the participants to imagine events that may happen in the future, a task known as future thinking. Analysis demonstrated a bias toward immediate rewards (i.e. temporal discounting) as well as difficulties to imagine specific future events in patients with AD. Critically, temporal discounting and future thinking in AD were significantly correlated. Generally speaking, a lack of thinking about the future may lead to impulsive behavior. More specifically, decline in future thinking in AD may limit the ability of patients to project themselves in time to consider outcomes of their decisions, resulting in a tendency to devaluate future rewards in favor of more imminent ones (i.e. temporal discounting).

Behavioral trainings and manipulations to reduce delay discounting: A systematic review

In everyday decision-making, individuals make trade-offs between short-term and long-term benefits or costs. Depending on many factors, individuals may choose to wait for larger delayed reward, yet in other situations they may prefer the smaller, immediate reward. In addition to within-subject variation in the short-term versus long-term reward trade-off, there are also interindividual differences in delay discounting (DD), which have been shown to be quite stable. The extent to which individuals discount the value of delayed rewards turns out to be associated with important health and disorder-related outcomes: the more discounting, the more unhealthy or problematic choices. This has led to the hypothesis that DD can be conceptualized as trans-disease process. The current systematic review presents an overview of behavioral trainings and manipulations that have been developed to reduce DD in human participants aged 12 years or older. Manipulation studies mostly contain one session and measure DD directly after the manipulation. Training studies add a multiple session training component that is not per se related to DD, in between two DD task measurements. Ninety-eight studies (151 experiments) were identified that tested behavioral trainings and manipulations to decrease DD. Overall, results indicated that DD can be decreased, showing that DD is profoundly context dependent and changeable. Most promising avenues to pursue in future research seem to be acceptance-based/mindfulness-based trainings, and even more so manipulations involving a future orientation. Limitations and recommendations are discussed to identify the mechanistic processes that allow for changes in discount rate and behavior accordingly.

Improving Self-Control: The Influence of Role Models on Intertemporal Choices

The ability to delay rewards is one of the most useful qualities one may wish to develop. People who possess this quality achieve more successful careers, display better interpersonal skills and are less vulnerable to psychopathology, obesity or addictions. In the present online studies, we investigated the extent to which delay-of-reward behaviors in female participants can be improved by observing others mastering it. We developed an intertemporal choice (IC) paradigm in which participants had to make fictitious choices between sooner smaller rewards and later bigger ones (e.g., $150 in 1 week vs. $170 in 4 weeks). In Study 1 (N = 186), we found that participants who delayed more had higher socioeconomic statuses and were less likely to procrastinate, smoke or develop obesity. In Study 2 (N = 178), we exposed female participants to a role model who, faced with ICs, chose most of the time the delayed option. Results showed that, although participants were only asked to memorize the model's decisions, they tended to choose the delayed option more often after than before exposure to the model. In Study 3 (N = 148), we found that the direction of the influence depended on the model's behavior: our female participants delayed more after having seen a high delay than a low delay model. In Study 4 (N = 370), we confirmed the effect of modeling on ICs in comparison to a control condition and showed that this effect was still significant 3 months after exposure to the model. Altogether, these results speak in favor of a high efficacy of modeling to develop self-control in women.

Intergenerational transmission of delay discounting: The mediating role of household chaos

INTRODUCTION

Adolescence is a period when impulsive decision making may be especially vulnerable to environmental influences. Impulsive decision making is often assessed using a delay discounting paradigm, which measures the preference for smaller rewards sooner over larger rewards with a delay. Research is needed to clarify the relationship between parents' and adolescents' delay discounting and to identify related environmental processes that might facilitate the intergenerational transmission of delay discounting. The current prospective longitudinal study examined the competing mediating processes of household chaos and harsh parenting in the intergenerational transmission of delay discounting between parents and adolescents.

METHODS

Participants included 167 adolescents (mean age = 14.07 years at Time 1; 53% male) and their parents (mean age = 41.98 years at Time 1; 87% female) recruited from the southeast United States. Parents' delay discounting was collected at Time 1, and adolescents' delay discounting was collected both at Time 1 and at Time 3 via a computerized delay discounting task. Parents and adolescents reported household chaos and harsh parenting at Time 2.

RESULTS

A parallel mediation model indicated that parents' delay discounting at Time 1 indirectly predicted adolescents' delay discounting Time 3 residualized change scores (regressing Time 3 delay discounting onto baseline delay discounting) through household chaos but not through harsh parenting at Time 2.

CONCLUSIONS

These results underline the importance of household chaos in facilitating the intergenerational transmission of delay discounting between parents and adolescents. Furthermore, our findings point to household chaos as a potential environmental target for interrupting intergenerational impulsivity.

Early life adversity and health-risk behaviors: proposed psychological and neural mechanisms

Early life adversity (ELA) is associated with poorer health in adulthood, an association explained, at least in part, by increased engagement in health-risk behaviors (HRBs). In this review, we make the case that ELA influences brain development in ways that increase the likelihood of engaging in HRBs. We argue that ELA alters neural circuitry underpinning cognitive control as well as emotional processing, including networks involved in processing threat and reward. These neural changes are associated psychologically and behaviorally with heightened emotional reactivity, blunted reward responsivity, poorer emotion regulation, and greater delay discounting. We then demonstrate that these adaptations to ELA are associated with an increased risk of smoking cigarettes, drinking alcohol, and eating high-fat, high-sugar foods. Furthermore, we explore how HRBs affect the brain in ways that reinforce addiction and further explain clustering of HRBs.

Rescuing cognitive and emotional regulatory skills to aid smoking prevention in at-risk youth: A randomized trial

Adolescence is a vulnerable period for smoking initiation, with disadvantaged teens particularly at risk. In addition, emotional and cognitive dysregulation is associated with an increased risk of smoking and makes it particularly challenging to benefit from standard substance use prevention interventions. The goal of the current study is to investigate the extent to which interventions designed to improve cognitive (working memory) and emotional (distress tolerance) regulatory processes enhance the effectiveness of a standard smoking prevention informational intervention. We will study adolescents (12-16 years of age) predominantly from racial/ethnic-minority and low-income households. Proximal smoking-risk outcome measures are used to allow testing of prevention models outside a full longitudinal study. We hope to generate new insights and approaches to smoking prevention among adolescents from lower socio-economic status (SES) by documenting the influence of working memory training and distress tolerance (mindfulness) interventions on cognitive/affective targets that place individuals at risk for smoking initiation and maintenance.

CLINICAL TRIALS REGISTRATION

NCT03148652.

A second type of magnitude effect: Reinforcer magnitude differentiates delay discounting between substance users and controls

Basic research on delay discounting, examining preference for smaller-sooner or larger-later reinforcers, has demonstrated a variety of findings of considerable generality. One of these, the magnitude effect, is the observation that individuals tend to exhibit greater preference for the immediate with smaller magnitude reinforcers. Delay discounting has also proved to be a useful marker of addiction, as demonstrated by the highly replicated finding of greater discounting rates in substance users compared to controls. However, some research on delay discounting rates in substance users, particularly research examining discounting of small-magnitude reinforcers, has not found significant differences compared to controls. Here, we hypothesize that the magnitude effect could produce ceiling effects at small magnitudes, thus obscuring differences in delay discounting between groups. We examined differences in discounting between high-risk substance users and controls over a broad range of magnitudes of monetary amounts ($0.10, $1.00, $10.00, $100.00, and $1000.00) in 116 Amazon Mechanical Turk workers. We found no significant differences in discounting rates between users and controls at the smallest reinforcer magnitudes ($0.10 and $1.00) and further found that differences became more pronounced as magnitudes increased. These results provide an understanding of a second form of the magnitude effect: That is, differences in discounting between populations can become more evident as a function of reinforcer magnitude.

Perceived stress and poly-tobacco product use across adolescence: Patterns of association and gender differences

Perceived stress-an endophenotype indicative of the tendency to appraise stress as frequent, unpredictable and unmanageable-is associated with adolescent cigarette smoking. It is unclear whether this association: (1) extends to alternative tobacco products, like electronic cigarettes and hookah (tobacco water pipe), which are increasingly popular among youth, and (2) differs by gender. In this report, data were drawn from a population-based longitudinal cohort of youth in Southern California. Perceived stress was assessed at baseline (7th or 8th grade; 2010). Electronic cigarette, hookah, combustible cigarette, and cigar use were assessed at a 4-year follow-up (11th or 12th grade; 2014). After adjusting for confounders, polytomous logistic regressions showed that a standardized baseline perceived stress score (M = 0, SD = 1) predicted electronic cigarette, hookah, combustible cigarette, and cigar use and a poly-tobacco use index at the 4-year follow-up in the overall sample. Interactions between perceived stress and gender were also observed (Interaction Ps < 0.05), which demonstrated that the association of perceived stress with tobacco product use and poly-use were stronger in females (ORs for current use range: 1.47 to 1.72) than males (ORs range: 0.93 to 1.31). Adjusting for baseline perceived stress, the change in perceived stress from baseline to follow-up was also positively associated with use and poly-use of most tobacco products in females and in males to some extent. In the current era in which teen use of alternative tobacco products is increasingly common, adolescent tobacco use and poly-use research and prevention strategies should address gender-specific origins of tobacco product use risk and consider perceived stress and other emotional endophenotypes in such risk pathways.

Mindfulness-Based Stress Reduction for Adolescents with Functional Somatic Syndromes: A Pilot Cohort Study

OBJECTIVE

To assess the feasibility of a mindfulness-based stress reduction (MBSR) program for adolescents with widespread chronic pain and other functional somatic symptoms and to make preliminary assessments of its clinical utility.

STUDY DESIGN

Three cohorts of subjects completed an 8-week MBSR program. Child- and parent-completed measures were collected at baseline and 8 and 12 weeks later. Measures included the Functional Disability Inventory (FDI), the Fibromyalgia/Symptom Impact Questionnaire-Revised (FIQR/SIQR), the Pediatric Quality of Life Inventory, the Multidimensional Anxiety Scale (MASC2), and the Perceived Stress Scale. Subjects and parents were interviewed following the program to assess feasibility.

RESULTS

Fifteen of 18 subjects (83%) completed the 8-week program. No adverse events occurred. Compared with baseline scores, significant changes were found in mean scores on the FDI (33% improvement, P = .026), FIQR/SIQR (26% improvement, P = .03), and MASC2 (child: 12% improvement, P = .02; parent report: 17% improvement, P = .03) at 8 weeks. MASC2 scores (child and parent) and Perceived Stress Scale scores were significantly improved at 12 weeks. More time spent doing home practice was associated with better outcomes in the FDI and FIQR/SIQR (44% and 26% improvement, respectively). Qualitative interviews indicated that subjects and parents reported social support as a benefit of the MBSR class, as well as a positive impact of MBSR on activities of daily living, and on pain and anxiety.

CONCLUSIONS

MBSR is a feasible and acceptable intervention in adolescents with functional somatic syndromes and has preliminary evidence for improving functional disability, symptom impact, and anxiety, with consistency between parent and child measures.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT02190474.

Stress-Induced Executive Dysfunction in GDNF-Deficient Mice, A Mouse Model of Parkinsonism

Maladaptive reactivity to stress is linked to improper decision making, impulsivity, and discounting of delayed rewards. Chronic unpredictable stress (CUS) alters dopaminergic function, re-shapes dopaminergic circuits in key areas involved in decision making, and impairs prefrontal-cortex dependent response inhibition and working memory. Glial-derived neurotrophic factor (GDNF) is essential for regulating dopamine (DA) release in the basal ganglia and for the survival of dopaminergic neurons; GDNF-deficient mice are considered an animal model for aging-related Parkinsonism. Recently, GDNF expression in the striatum has been linked to resilience to stress. Here we investigated the effects of CUS on decision making in GDNF-heterozygous (HET) mice and their wild-type littermate controls (WT). Before CUS no differences in temporal discounting (TD) were found between genotypes. However, following CUS GDNF HET mice, having a partial reduction of GDNF levels, showed increased impulsive choice indexed by a reduction in percent Larger-Later (LL) choices in the TD paradigm, and a reduction in area under the TD curve. Moreover, stressed GDNF HET mice, but not their WT controls, showed decreased neuronal activation (number of cFos positive neurons) in the orbitofrontal cortex (OFC), nucleus accumbens (NA) core, and NA shell, suggestive of a maladaptive response to stress. Interestingly, area under the TD curve positively correlated with cFos activation in the NA core, and NA shell, but not with orbitofrontal activity. These results provide further evidence of the differential involvement of the OFC, NA core, and NA shell in impulsive choice, and identify GDNF-deficient mice as a double-hit (gene × environment) model of stress-related executive dysfunction, particularly relevant to substance abuse and Parkinson’s disease (PD).

Gender differences in the association between self-reported stress and cigarette smoking in Korean adolescents

Background

The aim of this study was to examine the relationship between stress and smoking among Korean adolescents, as well as the influence of gender on this relationship.

Methods

A cross-sectional study was conducted using data from 3930 adolescents aged 12–18 years, collected in the 2007–2012 Korea National Health and Nutrition Examination Surveys.

Results

An increased level of self-reported stress was positively associated with increasing levels of smoking in both girls and boys (p for trend < 0.001). After adjusting for age, the odds ratios of smoking among girls and boys reporting very high levels of stress were 15.99 (95 % confidence interval (CI), 4.17–61.30) and 2.34 (95 % CI, 1.07–5.11), respectively, compared with those who reported low levels of stress.

Conclusions

This study found a statistically significant association between stress and smoking among Korean adolescents and this association was stronger in girls than boys. Further research is needed to understand more fully the link between stress and smoking in adolescents, with particular attention to sex differences.

Divergent responses of the amygdala and ventral striatum predict stress-related problem drinking in young adults: possible differential markers of affective and impulsive pathways of risk for alcohol use disorder

Prior work suggests that there may be two distinct pathways of alcohol use disorder (AUD) risk: one associated with positive emotion enhancement and behavioral impulsivity, and another associated with negative emotion relief and coping. We sought to map these two pathways onto individual differences in neural reward and threat processing assessed using blood-oxygen-level-dependent functional magnetic resonance imaging in a sample of 759 undergraduate students (426 women, mean age 19.65±1.24 years) participating in the Duke Neurogenetics Study. We demonstrate that problem drinking is highest in the context of stress and in those with one of two distinct neural phenotypes: (1) a combination of relatively low reward-related activity of the ventral striatum (VS) and high threat-related reactivity of the amygdala; or (2) a combination of relatively high VS activity and low amygdala reactivity. In addition, we demonstrate that the relationship between stress and problem alcohol use is mediated by impulsivity, as reflected in monetary delay discounting rates, for those with high VS-low amygdala reactivity, and by anxious/depressive symptomatology for those with the opposite neural risk phenotype. Across both neural phenotypes, we found that greater divergence between VS and amygdala reactivity predicted greater risk for problem drinking. Finally, for those individuals with the low VS-high amygdala risk phenotype we found that stress not only predicted the presence of AUD diagnosis at the time of neuroimaging but also subsequent problem drinking reported 3 months following study completion. These results offer new insight into the neural basis of AUD risk and suggest novel biological targets for early individualized treatment or prevention.

Sex Differences in Behavioral Dyscontrol: Role in Drug Addiction and Novel Treatments

The purpose of this review is to discuss recent findings related to sex differences in behavioral dyscontrol that lead to drug addiction, and clinical implications for humans are discussed. This review includes research conducted in animals and humans that reveals fundamental aspects of behavioral dyscontrol. The importance of sex differences in aspects of behavioral dyscontrol, such as impulsivity and compulsivity, is discussed as major determinants of drug addiction. Behavioral dyscontrol during adolescence is also an important consideration, as this is the time of onset for drug addiction. These vulnerability factors additively increase drug-abuse vulnerability, and they are integral aspects of addiction that covary and interact with sex differences. Sex differences in treatments for drug addiction are also reviewed in terms of their ability to modify the behavioral dyscontrol that underlies addictive behavior. Customized treatments to reduce behavioral dyscontrol are discussed, such as (1) using natural consequences such as non-drug rewards (e.g., exercise) to maintain abstinence, or using punishment as a consequence for drug use, (2) targeting factors that underlie behavioral dyscontrol, such as impulsivity or anxiety, by repurposing medications to relieve these underlying conditions, and (3) combining two or more novel behavioral or pharmacological treatments to produce additive reductions in drug seeking. Recent published work has indicated that factors contributing to behavioral dyscontrol are an important target for advancing our knowledge on the etiology of drug abuse, intervening with the drug addiction process and developing novel treatments.

A Computational Analysis of Aberrant Delay Discounting in Psychiatric Disorders

Impatience for reward is a facet of many psychiatric disorders. We draw attention to a growing literature finding greater discounting of delayed reward, an important aspect of impatience, across a range of psychiatric disorders. We propose these findings are best understood by considering the goals and motivation for discounting future reward. We characterize these as arising from either the opportunity costs of waiting or the uncertainty associated with delayed reward. We link specific instances of higher discounting in psychiatric disorder to heightened subjective estimates of either of these factors. We propose these costs are learned and represented based either on a flexible cognitive model of the world, an accumulation of previous experience, or through evolutionary specification. Any of these can be considered suboptimal for the individual if the resulting behavior results in impairments in personal and social functioning and/or in distress. By considering the neurochemical and neuroanatomical implementation of these processes, we illustrate how this approach can in principle unite social, psychological and biological conceptions of impulsive choice.

Predictors of delay discounting among smokers: education level and a Utility Measure of Cigarette Reinforcement Efficacy are better predictors than demographics, smoking characteristics, executive functioning, impulsivity, or time perception

Ninety-four smokers completed the delay discounting procedure for either hypothetical amounts of money, $10 (money) and $1000 (money) or hypothetical amounts of cigarettes ($10 and $1000 worth of cigarettes). We investigated how variables previously found to be related to rates of delay discounting accounted for the observed results. These variables included the following: demographic information, smoking characteristics, executive function abilities, impulsivity, time perception, and the Utility Measure of Cigarette Reinforcing Efficacy (UMCE). Education level and UMCE were each significantly correlated with 3 out of 4 of the discounting measures. Moreover, the largest effect sizes observed were between these two measures and the four discounting measures. All potential discounting predictors were also investigated using step-wise linear regression with Bayesian Information Criterion (BIC) analysis—these BIC models revealed that education level and UMCE accounted for large portions of the variance. We conclude that education level and UMCE were the most consistent predictors of discounting. This data is discussed within the framework of a widely accepted neuroeconomic model that suggests that two brain systems separately assess two separate facets of decision-making, and the interplay between these two systems determines self-control in smokers. We hypothesize that education level and UMCE may serve as surrogate measures of the functionality of these two systems and that discounting may be a sentinel measure of self-control.

Using Behavior Economics to Understand Alcohol Use Disorders: A Concise Review and Identification of Research Priorities

We review recent advances in the application of behavioral economics to alcohol use disorders (AUDs). Specifically, we review individual differences in alcohol demand (i.e., the relative reinforcing value of alcohol) and delayed reward discounting (i.e., impulsive decision making) in relation to AUDs. Additionally, we review the efficacy of reinforcement-based clinical applications. What emerges from the literature is an extensive body of cross-sectional research implicating alcohol demand and delayed reward discounting with alcohol misuse. However, more research is needed to examine these domains across the lifespan in order to understand their longitudinal trajectories. Similarly, clinical research is consistently supportive of reinforcement-based clinical interventions, but the number of randomized controlled trials to date is relatively small and there has been limited examination of the putative mechanisms of behavior change.

The behavioral economics of substance use disorders: reinforcement pathologies and their repair

The field of behavioral economics has made important inroads into the understanding of substance use disorders through the concept of reinforcer pathology. Reinforcer pathology refers to the joint effects of (a) the persistently high valuation of a reinforcer, broadly defined to include tangible commodities and experiences, and/or (b) the excessive preference for the immediate acquisition or consumption of a commodity despite long-term negative outcomes. From this perspective, reinforcer pathology results from the recursive interactions of endogenous person-level variables and exogenous environment-level factors. The current review describes the basic principles of behavioral economics that are central to reinforcer pathology, the processes that engender reinforcer pathology, and the approaches and procedures that can repair reinforcement pathologies. The overall goal of this review is to present a new understanding of substance use disorders as viewed by recent advances in behavioral economics.

Predictive validity of delay discounting behavior in adolescence: a longitudinal twin study

A standard assumption in the delay discounting literature is that individuals who exhibit steeper discounting of hypothetical rewards also experience greater difficulty deferring gratification to real-world rewards. There is ample cross-sectional evidence that delay discounting paradigms reflect a variety of maladaptive psychosocial outcomes, including substance use pathology. We sought to determine whether a computerized assessment of hypothetical delay discounting (HDD) taps into behavioral impulsivity in a community sample of adolescent twins (N = 675). Using a longitudinal design, we hypothesized that greater HDD at age 14-15 predicts real-world impulsive choices and risk for substance use disorders in late adolescence. We also examined the genetic and environmental structure of HDD performance. Individual differences in HDD behavior showed moderate heritability, and were prospectively associated with real-world temporal discounting at age 17-18. Contrary to expectations, HDD was not consistently related to substance use or trait impulsivity. Although a significant association between HDD behavior and past substance use emerged in males, this effect was mediated by cognitive ability. In both sexes, HDD failed to predict a comprehensive index of substance use problems and behavioral disinhibition in late adolescence. In sum, we present some of the first evidence that HDD performance is heritable and predictive of real-world temporal discounting of rewards. Nevertheless, HDD might not serve as a valid marker of substance use disorder risk in younger adolescents, particularly females.

Catecholamine levels and delay discounting forecast drug use among African American youths

AIMS

To test hypotheses about the contributions of the catecholamines epinephrine and norepinephrine [which serve as biological markers of life stress through sympathetic nervous system (SNS) activation], delay discounting and their interaction to the prediction of drug use among young African American adults.

DESIGN

A 1-year prospective study that involved assessment of SNS activity and collection of self-report data involving delay discounting and drug use.

SETTING

Rural communities in the southeastern United States.

PARTICIPANTS

A total of 456 African Americans who were 19 years of age at the beginning of the study.

MEASUREMENTS

At age 19, participants provided overnight urine voids that were assayed for epinephrine and norepinephrine. Participants were also assessed for hyperbolic temporal discounting functions (k) and drug use. At age 20, the participants again reported their drug use.

FINDINGS

Linear regression analyses revealed that (i) catecholamine levels at age 19 forecast increases in drug use [B = 0.087, P < 0.01, 95% confidence interval (CI) = 0.025, 0.148] and (ii) among young men, catecholamine levels interacted positively with delay discounting to forecast increases in drug use (simple slope = 0.113, P < 0.001, 95% CI = 0.074, 0.152).

CONCLUSIONS

Higher urinary catecholamine concentrations in their adulthood predict higher levels of drug use a year later among young African American men in the United States who engage in high, but not low, levels of delay discounting.

Does temporal discounting explain unhealthy behavior? A systematic review and reinforcement learning perspective

The tendency to make unhealthy choices is hypothesized to be related to an individual's temporal discount rate, the theoretical rate at which they devalue delayed rewards. Furthermore, a particular form of temporal discounting, hyperbolic discounting, has been proposed to explain why unhealthy behavior can occur despite healthy intentions. We examine these two hypotheses in turn. We first systematically review studies which investigate whether discount rates can predict unhealthy behavior. These studies reveal that high discount rates for money (and in some instances food or drug rewards) are associated with several unhealthy behaviors and markers of health status, establishing discounting as a promising predictive measure. We secondly examine whether intention-incongruent unhealthy actions are consistent with hyperbolic discounting. We conclude that intention-incongruent actions are often triggered by environmental cues or changes in motivational state, whose effects are not parameterized by hyperbolic discounting. We propose a framework for understanding these state-based effects in terms of the interplay of two distinct reinforcement learning mechanisms: a “model-based” (or goal-directed) system and a “model-free” (or habitual) system. Under this framework, while discounting of delayed health may contribute to the initiation of unhealthy behavior, with repetition, many unhealthy behaviors become habitual; if health goals then change, habitual behavior can still arise in response to environmental cues. We propose that the burgeoning development of computational models of these processes will permit further identification of health decision-making phenotypes.

Delay discounting by depressed and non-depressed adolescent smokers and non-smokers

BACKGROUND

Both delay discounting and depression are risk factors for cigarette smoking during adolescence. However, very little research has explored associations between these variables in adolescent smokers and non-smokers.

METHODS

Eighty adolescents were recruited based on depression status (depressed and non-depressed) and smoking status (smokers and non-smokers) to form four groups (n=20 per group). All participants completed a computerized monetary delay discounting task and a measure of depression.

RESULTS

Delay discounting and depression were significantly correlated. Also, smokers (both depressed and non-depressed) and depressed non-smokers all discounted significantly more than non-smokers who were not depressed. Depressed non-smokers and both groups of smokers did not differ in rate of delay discounting.

CONCLUSIONS

Adolescent non-smokers who are depressed discount similarly to adolescents who smoke and more than non-smokers who are not depressed. Future research should explore the unique versus shared roles of delay discounting and depression as risk factors for smoking during adolescence.

A developmental perspective on neuroeconomic mechanisms of contingency management

This paper provides a developmental overview of relevant theory and research on delay discounting and neuroeconomics, and their implications for contingency management (CM) approaches to treatment. Recent advances in the neuroscience of decision making have the potential to inform treatment development for adolescent substance use in general, and CM treatments in particular. CM interventions may be informed by research on delay discounting, a type of decision making that reflects how individuals value immediate versus delayed rewards. Delay discounting reliably distinguishes substance abusers from nonabusers and is a significant predictor of individual differences in response to substance use treatments. Discounting may also be important in predicting response to CM, as CM attempts to directly influence this decision-making process, shifting the preference from the immediate rewards of use to delayed rewards for choosing not to use. Multiple neural processes underlie decision making, and those processes have implications for adolescent substance abuse. There are significant neurodevelopmental processes that differentiate adolescents from adults. These processes are implicated in delay discounting, suggesting that adolescence may reflect a period of plasticity in temporal decision making. Understanding the neural mechanisms of delay discounting has led to promising working memory interventions directly targeting the executive functions that underlie individual choices. These interventions may be particularly helpful in combination with CM interventions that offer immediate rewards for brief periods of abstinence, and may show particular benefit in adolescence due to the heightened neural plasticity of systems that underlie temporal discounting in adolescence.

Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior

Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control.

The neurobiological effects of stress on adolescent decision making

Relative to other developmental periods, adolescence is characterized by risky decision making, increased perceived stress and heightened reactivity to acute stress. It is also during this time that individuals undergo significant neurodevelopment in brain regions that process decision making and stress. In this review, we summarize what is currently known about stress during adolescence, how it impacts risky decision-making, and how acute stress may exert neurobiological effects on circuitry that subserves decision-making in the developing brain. We conclude by suggesting future research directions that may help the field gain traction on this important, but relatively understudied, question.

Effects of cumulative stress and impulsivity on smoking status

OBJECTIVE

The stress-vulnerability model of addiction predicts that environmental factors, such as cumulative stress, will result in individual adaptations that decrease self-control, increase impulsivity, and increase risk for addiction. Impulsivity and cumulative stress are risk factors for tobacco smoking that are rarely examined simultaneously in research.

METHODS

We examined the indirect and direct effects of cumulative adversity in a community sample consisting of 291 men and women who participated in an assessment of cumulative stress, self-reported impulsivity, and smoking history. Data were analyzed using bootstrapping techniques to estimate indirect effects of stress on smoking via impulsivity.

RESULTS

Cumulative adversity is associated with smoking status via direct effects and indirect effects through impulsivity scores. Additional models examining specific types of stress indicate contributions of traumatic stress and recent life events as well as chronic relationship stressors.

CONCLUSIONS

Overall, cumulative stress is associated with increased risk of smoking via increased impulsivity and via pathways independent of impulsivity. These findings support the stress-vulnerability model and highlight the utility of mediation models in assessing how, and for whom, cumulative stress increases risk of current cigarette smoking. Increasing self-control is a target for interventions with individuals who have experienced cumulative adversity.

Excessive discounting of delayed reinforcers as a trans-disease process contributing to addiction and other disease-related vulnerabilities: emerging evidence

Delay discounting describes the devaluation of a reinforcer as a function of the delay until its receipt. Although all people discount delayed reinforcers, one consistent finding is that substance-dependent individuals tend to discount delayed reinforcers more rapidly than do healthy controls. Moreover, these higher-than-normal discounting rates have been observed in individuals with other behavioral maladies such as pathological gambling, poor health behavior, and overeating. This suggests that high rates of delay discounting may be a trans-disease process (i.e., a process that occurs across a range of disorders, making findings from one disorder relevant to other disorders). In this paper, we argue that delay discounting is a trans-disease process, undergirded by an imbalance between two competing neurobehavioral decision systems. Implications for our understanding of, and treatment for, this trans-disease process are discussed.

Personality and Parenting Processes Associated with Problem Behaviors: A Study of Adolescents in Santiago, Chile

Considerable research in the U.S. has established that adolescent antisocial, aggressive, and attention problems have a negative influence on adolescents' ability to become productive members of society. However, although these behaviors appear in other cultures, little is known about the development of these problems among adolescents in countries other than the U.S.. This study contributes to our understanding of personality and parenting factors associated with adolescent problem behaviors using an international sample. Data are from a NIDA-funded study of 884 community-dwelling adolescents in Santiago, Chile (Mean age=14, SD=1.4, 48% females) of mid-to-low socioeconomic status. Results revealed that rule-breaking and aggressive behaviors were both associated with greater levels of adolescent drive but lower levels of parental monitoring and positive parenting by both parents. Adolescents who reported more attention problems were more likely to exhibit driven behavior, more behavioral inhibition, to report lower levels of parental monitoring, and positive parenting by mother and father. Results of interactions revealed that the influences of positive parenting and parental monitoring on adolescent aggressive behaviors varied as a function of the gender of the adolescent. Helping parents build on their parenting skills may result in important reductions in adolescent problem behaviors among U.S. and international adolescents.

Delayed reward discounting and addictive behavior: a meta-analysis

RATIONALE

Delayed reward discounting (DRD) is a behavioral economic index of impulsivity and numerous studies have examined DRD in relation to addictive behavior. To synthesize the findings across the literature, the current review is a meta-analysis of studies comparing DRD between criterion groups exhibiting addictive behavior and control groups.

OBJECTIVES

The meta-analysis sought to characterize the overall patterns of findings, systematic variability by sample and study type, and possible small study (publication) bias.

METHODS

Literature reviews identified 310 candidate articles from which 46 studies reporting 64 comparisons were identified (total N=56,013).

RESULTS

From the total comparisons identified, a small magnitude effect was evident (d= .15; p< .00001) with very high heterogeneity of effect size. Based on systematic observed differences, large studies assessing DRD with a small number of self-report items were removed and an analysis of 57 comparisons (n=3,329) using equivalent methods and exhibiting acceptable heterogeneity revealed a medium magnitude effect (d= .58; p< .00001). Further analyses revealed significantly larger effect sizes for studies using clinical samples (d= .61) compared with studies using nonclinical samples (d=.45). Indices of small study bias among the various comparisons suggested varying levels of influence by unpublished findings, ranging from minimal to moderate.

CONCLUSIONS

These results provide strong evidence of greater DRD in individuals exhibiting addictive behavior in general and particularly in individuals who meet criteria for an addictive disorder. Implications for the assessment of DRD and research priorities are discussed.

A pilot examination of stress-related changes in impulsivity and risk taking as related to smoking status and cessation outcome in adolescents

INTRODUCTION

Psychosocial stress and impulsivity are each associated with smoking in adolescents. There is also evidence that stress can increase impulsive responding, and impulsive adolescent smokers attempting cessation are at greater risk of relapse. We performed a pilot investigation to examine stress-induced changes in response inhibition, inattention, and risk taking as related to smoking status and posttreatment smoking abstinence.

METHODS

Twelve adolescent smokers participating in a smoking cessation intervention and 15 adolescent nonsmokers completed a 2-session protocol assessing stress-related change in response inhibition and inattention (on the Conners' Continuous Performance Test-II), risk taking (on the Balloon Analogue Risk Task), nicotine withdrawal symptoms, and self-reported stress.

RESULTS

At baseline, smokers had greater inattentive responding and risk taking when compared with nonsmokers. Stress exposure led to significant increases in stress, anger, and depression in all participants and also increased nicotine craving (on the Minnesota Nicotine Withdrawal Scale item) and impulsive responding in smokers. After covarying for baseline differences in impulsivity/risk taking, smokers who were not abstinent at the end of treatment experienced greater stress-induced risk taking when compared with those who were abstinent.

CONCLUSIONS

In all, it appears that response inhibition and risk taking may be differentially altered by stress exposure in adolescent smokers and nonsmokers and that adolescent smoking cessation success may be associated with less risk taking in the face of stress.

Interactive effects of cumulative stress and impulsivity on alcohol consumption

BACKGROUND

Alcohol addiction may reflect adaptations to stress, reward, and regulatory brain systems. While extensive research has identified both stress and impulsivity as independent risk factors for drinking, few studies have assessed the interactive relationship between stress and impulsivity in terms of hazardous drinking within a community sample of regular drinkers.

METHODS

One hundred and thirty regular drinkers (56M/74F) from the local community were assessed for hazardous and harmful patterns of alcohol consumption using the Alcohol Use Disorders Identification Test (AUDIT). All participants were also administered the Barratt Impulsiveness Scale (BIS-11) as a measure of trait impulsivity and the Cumulative Stress/Adversity Checklist (CSC) as a comprehensive measure of cumulative adverse life events. Standard multiple regression models were used to ascertain the independent and interactive nature of both overall stress and impulsivity as well as specific types of stress and impulsivity on hazardous and harmful drinking.

RESULTS

Recent life stress, cumulative traumatic stress, overall impulsivity, and nonplanning-related impulsivity as well as cognitive and motor-related impulsivity were all independently predictive of AUDIT scores. However, the interaction between cumulative stress and total impulsivity scores accounted for a significant amount of the variance, indicating that a high to moderate number of adverse events and a high trait impulsivity rating interacted to affect greater AUDIT scores. The subscale of cumulative life trauma accounted for the most variance in AUDIT scores among the stress and impulsivity subscales.

CONCLUSIONS

Findings highlight the interactive relationship between stress and impulsivity with regard to hazardous drinking. The specific importance of cumulative traumatic stress as a marker for problem drinking is also discussed.