Integrating behavioral economics and behavioral genetics: delayed reward discounting as an endophenotype for addictive disorders

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.

The Influence of Genetic Polymorphic Variability of the Catechol-O-methyltransferase Gene in a Group of Patients with a Diagnosis of Behavioural Addiction, including Personality Traits

Gambling Disorder (GD) is characterised by a harmful, enduring, and recurrent involvement in betting-related behaviours. Therefore, GD shares similar biological mechanisms and symptoms to substance use disorders (SUD). Therefore, in this study, we chose the behavioural addictions group. During the examination and recruitment to the study, it turned out that all the people undergoing treatment for gambling addiction were also addicted to amphetamines, which is consistent with the biological mechanism related to cerebral neurotransmission. The aim of the study was to investigate the association of the COMT gene polymorphism with behavioral addiction. The study group consisted of 307 participants: 107 men with gambling disorder and amphetamine dependency (mean age = 27.51, SD = 5.25) and 200 non-addicted, nor dependent, free from neuro-psychiatric disorders control group men (mean age = 20.20, SD = 4.51). Both groups were subjected to psychometric evaluation using the State-Trait Anxiety Inventory and the NEO Five-Factor Personality Inventory. Genomic DNA was extracted from venous blood following standard protocols. Determination of the rs4680 polymorphism in the COMT gene was performed using the real-time PCR technique. Statistically significant differences in the frequency of rs4680 genotypes were found in the tested sample of subjects compared with the control group (p = 0.03543). Subjects with gambling disorder and amphetamine use disorder compared to the control group obtained higher scores in the assessment of the STAI trait scale (p = 0.0019), state scale (p < 0.0000), and NEO-FFI Neuroticism scale (p < 0.0000). Significantly lower results were obtained for the NEO-FFI Agreeability scale (p < 0.0000). Additionally, a significant statistical impact of gambling disorder and amphetamine use disorder, and the COMT rs4680 genotype was demonstrated for the score of the STAI trait (p = 0.0351) and state (p = 0.0343) and the NEO-FFI Conscientiousness scale (p = 0.0018). We conclude that COMT and its polymorphic variant influence the development of addiction. Still, considering its multifactorial and polygenic nature, it should be combined with other factors such as personality.

Can delay discounting predict vaccine hesitancy 4-years later? A study among US young adults

Despite being a major threat to health, vaccine hesitancy (i.e., refusal or reluctance to vaccinate despite vaccine availability) is on the rise. Using a longitudinal cohort of young adults (N = 1260) from Los Angeles County, California we investigated the neurobehavioral mechanisms underlying COVID-19 vaccine hesitancy. Data were collected at two time points: during adolescence (12th grade; fall 2016; average age = 16.96 (±0.42)) and during young adulthood (spring 2021; average age = 21.33 (±0.49)). Main outcomes and measures were delay discounting (DD; fall 2016) and tendency to act rashly when experiencing positive and negative emotions (UPPS-P; fall 2016); self-reported vaccine hesitancy and vaccine beliefs/knowledge (spring 2021). A principal components analysis determined four COVID-19 vaccine beliefs/knowledge themes: Collective Responsibility, Confidence and Risk Calculation, Complacency, and Convenience. Significant relationships were found between themes, COVID-19 vaccine hesitancy, and DD. Collective Responsibility (β = -1.158[-1.213,-1.102]) and Convenience (β = -0.132[-0.185,-0.078]) scores were negatively associated, while Confidence and Risk Calculation (β = 0.283[0.230,0.337]) and Complacency (β = 0.412[0.358,0.466]) scores were positively associated with COVID-19 vaccine hesitancy. Additionally, Collective Responsibility (β = -0.060[-0.101,-0.018]) was negatively associated, and Complacency (β = -0.063[0.021,0.105]) was positively associated with DD from fall 2016. Mediation analysis revealed immediacy bias during adolescence, measured by DD, predicted vaccine hesitancy 4 years later while being mediated by two types of vaccine beliefs/knowledge: Collective Responsibility (β = 0.069[0.022,0.116]) and Complacency (β = 0.026[0.008,0.044]). These findings provide a further understanding of individual vaccine-related decision-making among young adults and inform public health messaging to increase vaccination acceptance.

Brain response in heavy drinkers during cross-commodity alcohol and money discounting with potentially real rewards: A preliminary study

Background

Alcohol use disorder (AUD) is associated with exaggerated preference for immediate rewards, a candidate endophenotype for use disorders. Addiction symptomology is often well-described by the preference for immediate intoxication over other delayed prosocial rewards. We measured brain activation in AUD-implicated regions during a cross-commodity delay discounting (CCD) task with choices for immediate alcohol and delayed money.

Methods

Heavy drinkers (n=24) experienced a brief intravenous alcohol infusion prime, regained sobriety, then chose between 'One Shot' and delayed money in an adjusting delay CCD task (sober and intoxicated); also during fMRI (sober). Participants also performed a behavioral sensation seeking task and completed self-report inventories of other risk factors. We assessed brain activation to choices representing immediate intoxication versus delayed money rewards in a priori regions of interest defined within the framework of Addictions NeuroImaging Assessment.

Results

Activation to CCD choice versus control trials activated paralimbic and ventral frontal cortical regions, including orbital and medial prefrontal cortex, posterior cingulate/retrosplenial cortex, angular and superior frontal gyri. We detected no differences between immediate or delayed choices. Left medial orbitofrontal cortex activation correlated with alcohol-induced wanting for alcohol; females showed greater activation than males. Behavioral sensation seeking correlated with right nucleus accumbens task engagement.

Conclusions

Alcohol decision-making elicited activation in regions governing reward, introspection, and executive decision-making in heavy drinkers, demonstrating the utility of laboratory tasks designed to better model real-world choice. Our findings suggest that the brain processes subserving immediate and delayed choices are mostly overlapping, even with varied commodities.

Leveraging related health phenotypes for polygenic prediction of impulsive choice, impulsive action, and impulsive personality traits in 1534 European ancestry community adults

Impulsivity refers to a number of conceptually related phenotypes reflecting self-regulatory capacity that are considered promising endophenotypes for mental and physical health. Measures of impulsivity can be broadly grouped into three domains, namely, impulsive choice, impulsive action, and impulsive personality traits. In a community-based sample of ancestral Europeans (n = 1534), we conducted genome-wide association studies (GWASs) of impulsive choice (delay discounting), impulsive action (behavioral inhibition), and impulsive personality traits (UPPS-P), and evaluated 11 polygenic risk scores (PRSs) of phenotypes previously linked to self-regulation. Although there were no individual genome-wide significant hits, the neuroticism PRS was positively associated with negative urgency (adjusted R²  = 1.61%, p = 3.6 × 10^-7 ) and the educational attainment PRS was inversely associated with delay discounting (adjusted R²  = 1.68%, p = 2.2 × 10^-7 ). There was also evidence implicating PRSs of attention-deficit/hyperactivity disorder, externalizing, risk-taking, smoking cessation, smoking initiation, and body mass index with one or more impulsivity phenotypes (adjusted R² s: 0.35%-1.07%; FDR adjusted ps = 0.05-0.0006). These significant associations between PRSs and impulsivity phenotypes are consistent with established genetic correlations. The combined PRS explained 0.91%-2.46% of the phenotypic variance for individual impulsivity measures, corresponding to 8.7%-32.5% of their reported single-nucleotide polymorphism (SNP)-based heritability, suggesting a non-negligible portion of the SNP-based heritability can be recovered by PRSs. These results support the predictive validity and utility of PRSs, even derived from related phenotypes, to inform the genetics of impulsivity phenotypes.

Delay discounting and alcohol consumption correlate with dorsal anterior insula activation during choice in nontreatment-seeking heavy drinkers

BACKGROUND

The anterior insular cortex (AIC), a prominent salience network node, integrates interoceptive information and emotional states into decision making. While AIC activation during delay discounting (DD) in alcohol use disorder (AUD) has been previously reported, the associations between AIC activation, impulsive choice, alcohol consumption, and connectivity remain unknown. We therefore tested AIC brain responses during DD in heavy drinkers and their association with DD performance, alcohol drinking, and task-based connectivity.

METHODS

Twenty-nine heavy drinkers (12 females; mean (SD) age=31.5 ± 6.1 years; mean (SD)=40.8 ± 23.4 drinks/week) completed a DD task during functional MRI. Regions activated during DD decision making were tested for correlation with DD behavior and alcohol drinking. Psychophysiological interaction (PPI) models assessed the task-dependent functional connectivity (FC) of activation during choice.

RESULTS

Delay discounting choice activated bilateral anterior insular cortex, anterior cingulate cortex, and left precentral gyrus. Right dorsal (d) AIC activation during choice negatively correlated withdiscounting of delayed rewards and alcohol consumption. PPI analysis revealed FC of the right dAIC to both the anterior and posterior cingulate cortices-key nodes in the midline default mode network.

CONCLUSIONS

Greater dAIC involvement in intertemporal choice may confer more adaptive behavior (lower impulsivity and alcohol consumption). Moreover, salience network processes governing discounting may require midline default mode (precuneus/posterior cingulate cortex) recruitment. These findings supporta key adaptive role for right dAIC in decision making involving future rewards and risky drinking.

Future thinking to decrease real-world drinking in alcohol use disorder: Repairing reinforcer pathology in a randomized proof-of-concept trial

Reinforcer Pathology theory proposes that expanding the temporal window of reinforcement (i.e., reducing delay discounting) using episodic future thinking (EFT) would decrease alcohol consumption. However, evidence of effectiveness in real-world settings is lacking. Using a randomized proof-of-concept field trial, the current study examined the effect of expanding the temporal window of reinforcement, using remotely delivered EFT, on decreasing real-world alcohol consumption among individuals with alcohol use disorder (AUD). Fifty-two individuals (9 females) aged 18-65 years who met the DSM-5 criteria for moderate or severe AUD and aimed to drink in moderation or abstain from drinking completed the study and were included in analysis. EFT significantly (p = .031) reduced alcohol consumption (mean change of consumption pre-post intervention = -2.18 drinks/day) compared to control episodic recent thinking (ERT; mean change of -0.52 drinks/day). Changes in discounting rates pre-post intervention significantly predicted changes in alcohol consumption (coef. = .424, 95% CI [.043-.813], p = .030) even after controlling for age, gender, race, income, education, marital status, and family history of addiction. Overall satisfaction across groups was rated as 3.92 on a 1 to 5-point scale, suggesting that the current remote approach is feasible and acceptable. The current findings were congruent with the theory, Reinforcer Pathology, that EFT expands the temporal window and decreases alcohol consumption, and the remote approach was considered feasible and acceptable. We believe the present study contributes new knowledge with tangible benefits for scientifically understanding and better defining novel interventions that may be clinically deployed to improve treatment outcomes. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Brain responses during delay discounting in youth at high-risk for substance use disorders

Offspring of parents with substance use disorders (SUD) discount future rewards at a steeper rate on the monetary delay discounting task (DD) than typically developing youth. However, brain activation during DD has yet to be studied in drug naïve youth with a family history (FH) of SUD. Here, we investigate brain activation differences in high-risk youth during DD. We recruited substance naïve youth, aged 11-12, into three groups to compare brain activation during DD: (1) High-risk youth (n = 35) with a FH of SUD and externalizing psychiatric disorders, (2) psychiatric controls (n = 25) who had no FH of SUD, but with equivalent externalizing psychiatric disorders as high-risk youth, and (3) a healthy control group (n = 24) with no FH of SUD and minimal psychopathology. A whole-brain voxel wise analysis of the [Delay > Baseline], [Immediate > Baseline], and [Control > Baseline] contrasts identified functional regions of interest, from which extracted parameter estimates were tested for significant group differences. Relative to control youth, high-risk youth showed stronger activation in the left posterior insula and thalamus when making delayed choices, and stronger activation of the parahippocampal gyrus when making both delayed and control choices (ps < 0.05). Activation in the left posterior insula negatively correlated with both subscales of the Emotion Regulation Checklist, and positively correlated with the Stroop interference effect (ps < 0.05). Our findings suggest possible heritable SUD risk neural markers that distinguish drug naïve high-risk youth from psychiatric and healthy controls.

A systematic review and meta-analysis of delay discounting and cannabis use

Delay discounting reflects the systematic reduction in the value of a consequence by delay to delivery. Theoretical and empirical work suggests that delay discounting is a key behavioral mechanism underlying substance use disorder. Existing work on cannabis use, however, is mixed with many studies reporting null results. The purpose of this review was to provide an in-depth assessment of the association between delay discounting and cannabis use. We conducted metaregression analyses to determine the omnibus correlation between delay discounting and cannabis use, and to evaluate task-based and sample-based moderators. Studies included evaluated an association between delay discounting and cannabis quantity-frequency or severity measures in human participants (27 studies, 61 effect sizes, 24,782 participants). A robust variance estimation method was used to account for dependence among effect sizes. A significant, but small, omnibus effect was observed (r = .082) in which greater cannabis use frequency or severity was associated with greater discounting. Incentive structure and outcome type were each significant moderators in a multiple moderator model such that incentivized tasks correlated with severity measures showed stronger associations (r = .234) than hypothetical tasks correlated with quantity-frequency measures (r = .029). Comparisons to historic effect size data supported the hypothesis that, at present, the relationship between cannabis use and delay discounting appears empirically smaller than for other substances. Future work should explore theoretical rationales explaining this modest relationship involving cannabis use and delay discounting, such as reflecting the smaller magnitude of perceived long-term clinical outcomes associated with cannabis compared to other substances. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Increasing Physical Activity among Breast Cancer Survivors by Modulating Temporal Orientation with rTMS: Feasibility and Potential Efficacy

Maintaining adequate amounts of physical activity is a critical component of survivorship care for women with breast cancer. Increased physical activity is associated with increases in well-being, quality of life, and longevity, but women with cancer face unique, cancer-related factors that might affect physical activity. Consistent with the Competing Neurobehavioral Decision Systems model of decision making, we proposed to decrease delay discounting and increase physical activity by stimulating the executive function system via high-frequency repetitive transcranial magnetic stimulation (HF rTMS) of the left dorsolateral prefrontal cortex (LDLPFC). This randomized, sham-controlled, double-blinded trial examined the feasibility and potential efficacy of this approach to increase physical activity in breast cancer survivors. We hypothesized that active rTMS would significantly increase the mean number of steps per day and decrease delay discounting. Participants (n = 30) were primarily middle-aged (M = 53.7, SD = 7.9) and white with a mean BMI and body mass indices below 40. Indicators of feasibility and limited efficacy testing were positive. Although repeated-measures ANOVA revealed no significant changes in delay discounting, generalized estimating equations (GEE) found that participants in the active condition increased their mean daily steps by 400 steps per day, while those in the sham condition decreased this by nearly 600 steps per day. These findings indicate that the continued investigation of HF rTMS for increasing physical activity among women with breast cancer is justified.

Neural Modulation in Approach-Avoidance Conflicts in Externalizing Psychopathology

Externalizing psychopathology (EXT) is characterized by poor decision-making in situations that involve simultaneous cues for approach and avoidance behavior (i.e. approach-avoidance conflicts). Previous studies of EXT have examined these deficits primarily using tasks involving decisions between positive reward and negative punishment, suggesting that EXT is characterized by a general bias towards high salience (e.g. temporally proximal or reward) cues relative to low salience (e.g. temporally distal or loss) cues. However, in order to better characterize decision-making in approach-avoidance conflicts, the present study utilized a novel task to examine neural activation in contexts involving both positive reward and negative punishment as well as positive punishment and negative reward by manipulating physical proximity of affective cues. Neuroimaging results indicated that EXT was associated with deficits related to cue prioritization based on salience, suggesting that failure to differentiate relevant from less relevant information contributes to poor decision-making among individuals with EXT.

Individual Differences in Intertemporal Choice

Intertemporal choice involves deciding between smaller, sooner and larger, later rewards. People tend to prefer smaller rewards that are available earlier to larger rewards available later, a phenomenon referred to as temporal or delay discounting. Despite its ubiquity in human and non-human animals, temporal discounting is subject to considerable individual differences. Here, we provide a critical narrative review of this literature and make suggestions for future work. We conclude that temporal discounting is associated with key socio-economic and health-related variables. Regarding personality, large-scale studies have found steeper temporal discounting to be associated with higher levels of self-reported impulsivity and extraversion; however, effect sizes are small. Temporal discounting correlates negatively with future-oriented cognitive styles and inhibitory control, again with small effect sizes. There are consistent associations between steeper temporal discounting and lower intelligence, with effect sizes exceeding those of personality or cognitive variables, although socio-demographic moderator variables may play a role. Neuroimaging evidence of brain structural and functional correlates is not yet consistent, neither with regard to areas nor directions of effects. Finally, following early candidate gene studies, recent Genome Wide Association Study (GWAS) approaches have revealed the molecular genetic architecture of temporal discounting to be more complex than initially thought. Overall, the study of individual differences in temporal discounting is a maturing field that has produced some replicable findings. Effect sizes are small-to-medium, necessitating future hypothesis-driven work that prioritizes large samples with adequate power calculations. More research is also needed regarding the neural origins of individual differences in temporal discounting as well as the mediating neural mechanisms of associations of temporal discounting with personality and cognitive variables.

Promising vulnerability markers of substance use and misuse: A review of human neurobehavioral studies

Substance use often begins, and noticeably escalates, during adolescence. Identifying predictive neurobehavioral vulnerability markers of substance use and related problems may improve targeted prevention and early intervention initiatives. This review synthesizes 44 longitudinal studies and explores the utility of developmental imbalance models and neurobehavioral addiction frameworks in predicting neural and cognitive patterns that are associated with prospective substance use initiation and escalation among young people. A total of 234 effect sizes were calculated and compared. Findings suggest that aberrant neural structure and function of regions implicated in reward processing, cognitive control, and impulsivity can predate substance use initiation, escalation, and disorder. Functional vulnerability markers of substance use include hyperactivation during reward feedback and risk evaluation in prefrontal and ventral striatal regions, fronto-parietal hypoactivation during working memory, distinctive neural patterns during successful (fronto-parietal hyperactivation) and failed response inhibition (frontal hypoactivation), and related cognitive deficits. Structurally, smaller fronto-parietal and amygdala volume and larger ventral striatal volume predicts prospective substance misuse. Taken together, the findings of this review suggest that neurobehavioral data can be useful in predicting future substance use behaviors. Notably, little to no research has empirically tested the underlying assumptions of widely used theoretical frameworks. To improve the reliability and utility of neurobehavioral data in predicting future substance use behaviors, recommendations for future research are provided. This article is part of the special issue on 'Vulnerabilities to Substance Abuse.'

The relationship between delay discounting and Internet addiction: A systematic review and meta-analysis

AIMS

To estimate the difference in delay discounting (DD) between subjects with Internet addiction (IA) and those without as well as to identify significant variables involved in DD.

METHODS

Using the keywords related to IA (e.g., "excessive Internet use", "Internet dependence") AND "delayed reward discounting" OR "delay discounting" OR "temporal discounting" OR "delayed gratification" OR time discounting OR intertemporal choice OR impulsive choice, the PubMed, Embase, and PsycINFO databases were searched from inception to June 2020 for English articles with comparison between subjects with IA and those without. Effect sizes were calculated by group means from the k value or area under the curve (AUC). The random-effects models were used.

RESULTS

Fourteen studies in total were eligible for the current meta-analysis that involved 696 subjects with IA (mean age = 22.71) and 2,394 subjects without (mean age = 21.91). Subjects with IA had a steeper DD rate (g = 1.10, 95% CI: 0.57-1.64; p ≤ 0.01) compared with that in those without. Regarding DD data, the difference between k value and AUC was significant (p < 0.01; AUC > k). Additionally, the estimation of DD by the paper-and-pencil task was larger than that by the computerized task (p < 0.01). Significant difference in the DD rate was also noted between subjects with Internet gaming disorder (IGD) and those with unspecified IA (p = 0.00; IGD > IA). The percentage of men and task variables were significantly associated with the DD rate (all p < 0.01), suggesting impaired DD in subjects with IA.

CONCLUSIONS

Our results suggested the feasibility of utilizing the DD rate as a therapeutic index for cognitive control in IA. Nevertheless, judicious use is recommended taking into consideration the significant difference between k value and AUC.

Delay discounting rate by a surrogate decision maker depends on the smoking status of the recipient

The tendency to devalue future rewards is known as delay discounting. Discounting is measured using a series of intertemporal choices between smaller, sooner outcomes and larger, later outcomes. We used a surrogate delay discounting task to explore whether such choices would differ if a hypothetical recipient was a smoker or was an individual with good health habits. Across three studies, the descriptions of the recipient included only information about smoking status (n = 66), smoking status and equal annual income (n = 47), and smoking status and equal weekly expenditures (n = 42). Higher rates of delay discounting for the smoker recipient compared to the nonsmoker recipient were observed across all three studies. These results parallel previous findings showing group differences in discounting between actual smokers and nonsmokers. We discuss the similarities between the present results and previous studies in light of an extension of Bem's (1967) self-perception theory, which posits that choices in laboratory-based delay discounting tasks are informed by observation of real-world intertemporal choice. The theory asserts that there is no fundamental difference between a first-person account of such knowledge and a third-person account. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Intoxication Effects on Impulsive Alcohol Choice in Heavy Drinkers: Correlation With Sensation Seeking and Differential Effects by Commodity

BACKGROUND

The preference for immediate rewards and high sensation seeking are both potent risk factors for alcohol use disorder (AUD), but how they interact during intoxication is poorly understood. To model decision making linked to AUD risk, we tested heavy drinkers for impulsive choice (delay discounting with alcohol:money or money:money) and behavioral sensation seeking using a novel odor choice task. Laboratory tasks measured actual behavior with real contingencies. Our goals were to determine, in heavy drinkers, (i) alcohol's effects on delay discounting, and (ii) how AUD risk factors relate to delay discounting, and (iii) how delay discounting with alcohol choices compares with strictly monetary choices.

METHODS

Thirty-five heavy drinkers (≥2 binges per month; age = 22.8 ± 2.2; 20 male; 5.8 ± 2.3 drinks/drinking day) performed cross-commodity discounting (CCD) of immediate alcohol vs. delayed money, a monetary delay discounting (DD), and behavioral sensation-seeking tasks. CCD and DD were performed while sober and during controlled alcohol infusion targeting 0.08 g/dl. The behavioral sensation-seeking task presented binary choices of odorants varying in intensity and novelty, and the risk of exposure to a malodorant.

RESULTS

CCD and DD behaviors were highly correlated across conditions, mean r = 0.64. Alcohol increased delayed reward preference in DD, p = 0.001, but did not alter mean CCD, p > 0.16. However, alcohol-induced changes in CCD correlated with behavioral sensation seeking, such that higher sensation seekers' immediate alcohol preference increased when intoxicated, p = 0.042; self-reported sensation seeking was uncorrelated, ps > 0.08. Behavioral sensation seeking also correlated with "want" alcohol following a priming dose targeting 0.035 g/dl, p = 0.021. CCD and DD did not correlate with self-reported drinking problems or other personality risk traits.

CONCLUSIONS

Alcohol increased impulsive alcohol choice in high sensation seekers, suggesting an interaction that may underlie impaired control of drinking, at least in a subset of heavy drinkers-consistent with models highlighting high novelty/sensation-seeking AUD subtypes. Discounting behavior overall appears to be a generalized process, and relatively stable across methods, repeated testing, and intoxication. These findings further support the utility of behavioral tasks in uncovering key behavioral phenotypes in AUD.

Steep Discounting of Future Rewards as an Impulsivity Phenotype: A Concise Review

This chapter provides an overview over the behavioral economic index of impulsivity known as delay discounting. Specifically, delay discounting refers to an individual's preference for smaller immediate rewards over a larger delayed rewards. The more precipitously an individual discounts future rewards, the more impulsive they are considered to be. First, the chapter reviews the nature of delay discounting as a psychological process and juxtaposes it with nominally similar processes, including other facets of impulsivity. Second, the chapter reviews the links between delay discounting and numerous health behaviors, including addiction, attention deficit/hyperactivity disorder, and obesity. Third, the determinants of individual variation in delay discounting are discussed, including both genetic and environmental contributions. Finally, the chapter evaluates delay discounting as a potentially modifiable risk factor and the status of clinical interventions designed to reduce delay discounting to address deficits in self-control in a variety of maladaptive behaviors.

Behavioral processes and risk for problem substance use in adolescents

This narrative review examines associations of delay discounting, response inhibition, sensation-seeking, and urgency with adolescent problem substance use. Each of these processes is linked to adult substance use disorders, is associated with conditions linked to increased risk for adolescent problem substance use, and predicts problem substance use. Notably, all processes are linked to early life adversity (ELA) exposure and most appear to help explain links between ELA exposure and problem substance use. These findings are consistent with a growing body of literature indicating ELA interferes with the development of neural circuits crucial to cognitive functioning and emotion regulation. Further, developmental trajectories of these processes generally align with maturational imbalance hypotheses of adolescent risk. Ongoing and pending large longitudinal studies may be essential for better understanding how ELA and other influences shapes these processes and the role of these processes in risk for problem substance use in adolescence and beyond. Finally it is possible that risk-related processes may be useful metrics in the context of implementing and evaluating strategies to prevent problem substance use in adolescence.

Behavioral economic demand as a unifying language for addiction science: Promoting collaboration and integration of animal and human models

The intersection of pharmacological, psychological, and economic theory within behavioral economics has helped advance an understanding of substance use disorder. A notable contribution of this approach is the conceptualization of reinforcement from a behavioral economic demand perspective. Demand analyses provide a multidimensional view of reinforcement in which distinct behavioral mechanisms are measured that impact decision making and drug consumption. This review describes the state of research on behavioral economic demand as a common language for addiction science researchers across varied model systems and stages of a translational continuum. We first provide an overview of the theoretical concepts and procedures used to evaluate demand in animal and human models. The potential for demand to serve as a common language for diverse research groups in psychopharmacology and addiction science (e.g., those evaluating neurobehavioral outcomes, medications development, clinical practice) is then described. An overview is also provided of existing empirical studies that, while small in number, suggest good linguistic and conceptual overlap between animal and human demand models when studying biological, environmental, and pharmacological individual difference vulnerabilities underlying drug-taking behavior. Refinement of methodological procedures and incorporation of more nuanced environmental features should help improve correspondence between animal and human demand studies as well as clinical translation of such findings. Our hope is that this review and commentary ultimately serves as inspiration for new collaborative efforts involving behavioral economic demand between animal and human researchers who share a common goal of improving substance use treatment outcomes and broader psychological wellbeing. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Working memory and decision making in children with ADHD: an analysis of delay discounting with the use of the dual-task paradigm

BACKGROUND

Deficits in working memory tasks have been widely documented in Attention Deficit Hyperactivity Disorder (ADHD) studies. The aim of this study is to evaluate the effects of working memory load in impulsivity during decision-making processes. A delayed discounting (DD) paradigm was used, comparing children with ADHD and age-matched controls.

METHOD

Thirty-two children equally divided between typically developing and ADHD, from 8 to 10 years of age were assigned to sessions of a dual-task paradigm. In the primary task the child has to choose between two different amounts of money at different time delays, while in the secondary task the child has to repeat a random series of digits with different lengths. The experiment was conducted in a school setting.

RESULTS

Compared to peers with typical development, delayed discounting was significantly stronger in children with ADHD and discounting rates increased in both groups for heavier memory loads. Furthermore, the memory load impact on frequency of immediate rewards was stronger in children with ADHD compared to typically developing children.

DISCUSSION

Results are discussed in terms of the relation between working memory load and decision-making processes, their impact on impulsive behaviour in ADHD and the need for future research to understand possible neurocognitive correlates and use that information to develop better inclusive policies.

Persisting on the past: Cross-sectional and prospective associations between sunk cost propensity and cannabis use

Prevalence of cannabis use in the United States continues to rise, and 30% of cannabis users eventually meet criteria for Cannabis Use Disorder (CUD). One response to this problem is to develop decision-making constructs that indicate vulnerability to CUD that might not be gleaned from diagnostic criteria. Unfortunately, there is limited evidence that decision-making constructs consistently relate to cannabis use. Interestingly, those who exhibit the sunk cost bias, an overgeneralized tendency to persist based on past investment, and those who use cannabis, both tend to focus on the past and perseverate more than their counterparts. Despite this overlap, no studies have assessed whether the sunk cost bias is positively associated with cannabis use. In 2 experiments with undergraduates, relations between cannabis use and the propensity to engage in the sunk cost bias were examined using negative binomial models. Experiment 1 (n = 46) evaluated the association between sunk cost bias propensity (using hypothetical costs and rewards) and frequency of cannabis use over the past 30 days. Greater sunk cost propensity was associated with more frequent cannabis use after controlling for demographics and alcohol use. In Experiment 2 (n = 103), more frequent cannabis use during a 6-week follow-up period was predicted by greater sunk cost propensity at baseline (using a real cost and reward-based task), independently and after controlling for mental health symptoms, alcohol use, and demographics. These findings provide preliminary evidence that a propensity to exhibit the sunk cost bias may be an important feature associated with cannabis use. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Neurocognitive and Psychiatric Markers for Addiction: Common vs. Specific Endophenotypes for Heroin and Amphetamine Dependence

BACKGROUND

The differential utility of neurocognitive impulsivity and externalizing/ internalizing traits as putative endophenotypes for dependence on heroin vs. amphetamine is unclear.

OBJECTIVE

This exploratory study aims to determine: (1) whether neurocognitive impulsivity dimensions and externalizing/internalizing traits are correlated between siblings discordant for heroin and amphetamine dependence; and (2) which of these associations are common across substances and which are substance- specific.

METHODS

Pearson correlations between individuals with 'pure' heroin and amphetamine dependence and their unaffected biological siblings (n = 37 heroin sibling pairs; n = 30 amphetamine sibling pairs) were run on 10 neurocognitive measures, 6 externalizing measures, and 5 internalizing measures. Sibling pair effects were further examined using regression.

RESULTS

Siblings discordant for heroin dependence were significantly correlated on delay aversion on the Cambridge Gambling Task, risk-taking on the Balloon Analogue Risk Task, sensation seeking, and hopelessness. Siblings discordant for amphetamine dependence were significantly correlated on the quality of decision-making on the Cambridge Gambling Task, discriminability on the Immediate Memory Task, commission errors on the Go/No Go Task, trait impulsivity, ADHD and anxiety sensitivity.

CONCLUSION

Dimensions of impulsivity and externalizing/internalizing traits appear to aggregate among siblings discordant for substance dependence. Risk-taking propensity, sensation seeking and hopelessness were specific for heroin sibling pairs. Motor/action impulsivity, trait impulsivity, and anxiety sensitivity were specific to amphetamine sibling pairs. Decisional/choice impulsivity was common across both heroin and amphetamine sibling pairs. These findings provide preliminary evidence for the utility of neurocognitive impulsivity and externalizing/ internalizing traits as candidate endophenotypes for substance dependence in general and for substance-specific dependencies.

Greater delay discounting and cannabis coping motives are associated with more frequent cannabis use in a large sample of adult cannabis users

BACKGROUND

Self-regulation deficits expressed through a decreased ability to value future rewards (delay discounting (DD)) and impaired emotion regulation (negative urgency (NU), cannabis coping motives (CCM), and anxiety sensitivity (AS)) relate to more frequent or problematic cannabis use. However, there is a need to better understand how self-regulation and emotion regulation constructs reflect competition between deliberative and reactive systems that drive individual differences in cannabis use patterns. Further, few studies assess frequency of cannabis use within and across days of use, which may obscure differentiation of individual differences.

METHODS

In a large national sample of 2545 cannabis users, Latent Class Analysis was used to derive participant sub-classes based on two frequency indices, self-reported cannabis use days and times cannabis was used per day. Three classes emerged: Low (1-9 days/month, 1 time/day; 23 %), moderate (10-29 days/month, 2-3 times/day; 41 %), and high (30 days/month, ≥4 times/day; 36 %). Relationships among frequency classes and emotional regulation and impulsivity were assessed with a multinomial logistic regression.

RESULTS

Higher frequency use was associated with greater DD (χ2 = 6.0, p = .05), greater CCM (χ2 = 73.3, p < .001), and lower cognitive AS (χ2 = 12.1, p = .002), when controlling for demographics, tobacco use, and number of cannabis administration methods. Frequency class and NU were not significantly associated.

CONCLUSIONS

Identifying meaningful patterns of cannabis use may improve our understanding of individual differences that increase risk of frequent or problematic cannabis use. Excessive delay discounting and using cannabis to cope with negative affect may be relevant targets for treatments designed to reduce cannabis use.

Neural correlates of reward magnitude and delay during a probabilistic delay discounting task in alcohol use disorder

RATIONALE

Alcohol-use disorder (AUD) is associated with the propensity to choose smaller sooner options on the delay discounting task. It is unclear, however, how inherent risk underlies delay discounting behavior. As impulsive choice is a hallmark feature in AUD, it is important to understand the neural response to reward and delay while accounting for risk in impulsive decision-making.

OBJECTIVE

This study examined activation associated with delay and reward magnitude, while controlling for risk in a probabilistic delay discounting task in AUD and examined if differences in activation were associated with treatment outcomes.

METHODS

Thirty-nine recently abstinent alcohol-dependent volunteers and 46 controls completed a probabilistic delay discounting task paired with functional magnetic resonance imaging. Alcohol use was collected using a self-report journal for 3 months following baseline scan.

RESULTS

During delay stimulus presentations, Controls exhibited greater activation compared to the Alcohol group notably in the anterior insula, middle/dorsal anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (PFC), and inferior parietal lobule. For magnitude, the Alcohol group exhibited greater activation than Controls primarily in medial PFC, rostral ACC, left posterior parietal cortex, and right precuneus. Within the Alcohol group, alcohol craving severity negatively correlated with right lateral PFC activation during reward magnitude in individuals who completed the 3-month study without relapse, while non-completers showed the opposite relationship.

CONCLUSIONS

The results of this study extend previous findings that alcohol use disorder is associated with differences in activation during an immediate or delayed choice by delineating activation associated with the parameters of impulsive choice.

Association between impulsivity and neural activation to alcohol cues in heavy drinkers

This study examines associations between two measures of impulsivity and brain response to alcohol taste cues. Impulsivity is both a risk factor for and a consequence of alcohol use and misuse. Frontostriatal circuits are linked to both impulsivity and addiction-related behaviors, including response to alcohol cues. Non-treatment-seeking heavy drinkers (n = 55) completed (i) an fMRI alcohol taste cue-reactivity paradigm; (ii) the monetary choice questionnaire (MCQ), a measure of choice impulsivity where participants choose between smaller, sooner rewards and larger, delayed rewards; (iii) and the UPPS-P Impulsive Behavior Scale, a self-report measure assessing five impulsivity factors. General linear models identified associations between neural alcohol taste cue-reactivity and impulsivity, adjusting for age, gender, and smoking status. Self-reported sensation seeking was positively associated with alcohol taste cue-elicited activation in frontostriatal regions, such that individuals who reported higher sensation seeking displayed greater neural response to alcohol taste cues. Conversely, delay discounting was negatively associated with activation in frontoparietal regions, such that individuals who reported greater discounting showed less cue-elicited activation. There were no significant associations between other self-reported impulsivity subscales and alcohol taste cue-reactivity. These results indicate that sensation seeking is associated with reward responsivity, while delay discounting is associated with recruitment of self-control circuitry.

DRD2/ANKK1 TaqI A1 polymorphism associates with overconsumption of unhealthy foods and biochemical abnormalities in a Mexican population

PURPOSE

The dopamine receptor 2/ankyrin repeat domain and content kinase 1 (DRD2/ANKK1) TaqIA polymorphism (rs1800497) has been associated with rewarding behaviors. This study aimed to investigate the association of DRD2/ANKK1 TaqIA polymorphism with the dietary intake, the intake frequency of food groups and biochemical profile in Mexican mestizo subjects.

METHODS

A cross-sectional/analytical study with 276 Mexican subjects was performed. Dietary intake was assessed with a 24-h recall and a food frequency questionnaire (FFQ). An allelic discrimination assay evaluated DRD2/ANKK1 TaqIA genotypes. Anthropometric and biochemical data were evaluated.

RESULTS

Genotype frequencies were A1A1 (18.48%), A1A2 (45.29%) and A2A2 (36.23%). TaqI A1 allele carriers had a higher intake of carbohydrates (p = 0.038), meats (p = 0.005), fried dishes (p = 0.039), and sugars (p = 0.009). Male TaqI A1 carriers consumed more carbohydrates (p = 0.009) and meats (p = 0.018) while females consumed fewer legumes (p = 0.005). TaqI A1 carriers had glucose (p = 0.037) and triglycerides (p = 0.011) abnormalities. TaqI A1 was associated with higher risk of consumption of unhealthy foods such as fried dishes (OR 3.79, 95% CI 1.53-9.35, p = 0.002) and meats (OR 2.31, 95% CI 1.32-4.05, p = 0.003), and lower healthy foods (OR 1.89, 95% CI 1.04-3.29, p = 0.038). TaqI A1 allele was associated with risk of abnormal glucose, triglycerides, and VLDL levels (OR 2.148, 95% CI 1.068-4.322, p = 0.036; OR 1.999, 95% CI 1.194-3.348, p = 0.011; OR 2.021, 95% CI 1.203-3.392, p = 0.007), respectively.

CONCLUSIONS

The presence of the TaqI A1 allele in Mexicans is a genetic risk factor for detrimental dietary quality that may predispose to metabolic disturbances.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

The neurobiology of impulsivity and substance use disorders: implications for treatment

Impulsivity is strongly associated with substance use disorders (SUDs). Our review discusses impulsivity as an underlying vulnerability marker for SUDs, and treatment of co-occurring impulsivity in SUDs. Three factors should be considered for the complex relationship between impulsivity and a SUD: (1) the trait effect of impulsivity, centering on decreased cognitive and response inhibition, (2) the state effect resulting from either acute or chronic substance use on brain structure and function, and (3) the genetic and environmental factors (e.g., age and sex) may influence impulsive behavior associated with SUDs. Both subjective and objective measures are used to assess impulsivity. Together, treatment developments (pharmacological, behavioral, and neurophysiological) should consider these clinically relevant dimensions assessed by a variety of measures, which have implications for treatment matching in individuals with SUD. Despite its heterogeneity, impulsivity is a marker associated with SUDs and may be understood as an imbalance of bottom-up and top-down neural systems. Further investigation of these relationships may lead to more effective SUD treatments.

Early life adversity and increased delay discounting: Findings from the Family Health Patterns project

Increased discounting (devaluing) of delayed rewards is associated with nearly all types of substance use disorders (SUDs) and is also present in individuals with family histories of SUDs. Early life adversity (ELA) likely contributes to these findings as it is common in both individuals with SUDs and their children and is linked to increased delay discounting and other neurocognitive impairments in human and animal studies. Here we examined data from 1192 healthy young adults (average age 23.6 years old) with (SUDs+) and without (SUDs-) histories of SUDs and with (FH+) and without (FH-) family histories of SUDs. A 2-way ANOVA was conducted to examine the effects of SUDs (SUDs-, SUDs+) and FH (FH-, FH+) on delay discounting followed by an examination of the effects of adding ELA to the model. First, we replicated findings that SUDs+ and FH+ participants had increased rates of delay discounting. After taking ELA into account, the effect of SUDs and FH on delay discounting were both reduced but still significant. The association of ELA and delay discounting was similar in magnitude among both SUDs+ and SUDs- participants and FH+ and FH- participants; those with higher levels of ELA had increased delay discounting. Collectively, these findings indicate that increased ELA is closely associated with the increased delay discounting seen in SUDs+ and FH+ individuals and suggests ELA may be contributing to the increased delay discounting seen in these populations. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Social and delay discounting in autism spectrum disorder

Current literature is divided over whether and how processes such as perspective taking and reward sensitivity differ between individuals with autism spectrum disorder (ASD) versus neurotypical individuals. Discounting tasks may provide novel insight into how these processes operate. In delay discounting tasks, participants choose between smaller immediate rewards and larger delayed rewards, and in social discounting tasks, participants choose between a smaller monetary rewards for themselves versus a larger reward for partners of varied social distance (e.g., a close friend vs. an acquaintance). Delay and social discounting tasks thus implicitly measure the subjective value of rewards given to one's future self and to others, capturing constructs such as perspective taking, reward processing, and social closeness, all of which have been discussed as core cognitive mechanisms underlying ASD. Despite extensive research on discounting in other clinical populations, few studies have examined delay discounting in ASD and no research has examined social discounting in ASD. The goal of the current study was to assess delay and social discounting for monetary rewards in a single sample of adolescents and adults with ASD compared to a matched neurotypical sample. Overall, adults and adolescents with ASD valued both future rewards and rewards given to others less than their typical counterparts did, but rates of discounting were not significantly correlated across temporal and social domains. These results extend an important behavioral paradigm for understanding both perspective taking and reward processing to autism. Autism Res 2019, 12: 870-877. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Discounting tasks-which experimentally measure the subjective value of different rewards-have been used with a variety of clinical populations, but are underexplored in ASD. We found that compared to neurotypical individuals, individuals with ASD showed diminished subjective value for future rewards (compared to immediate rewards) and rewards for others (compared to rewards for self). This finding has implications for understanding perspective taking, reward processing, and social closeness in ASD.

Impulsivities and addictions: a multidimensional integrative framework informing assessment and interventions for substance use disorders

Impulse control is becoming a critical survival skill for the twenty-first century. Impulsivity is implicated in virtually all externalizing behaviours and disorders, and figures prominently in the aetiology and long-term sequelae of substance use disorders (SUDs). Despite its robust clinical and predictive validity, the study of impulsivity is complicated by its multidimensional nature, characterized by a variety of trait-like personality dimensions, as well as by more state-dependent neurocognitive dimensions, with variable convergence across measures. This review provides a hierarchical framework for linking self-report and neurocognitive measures to latent constructs of impulsivity and, in turn, to different psychopathology vulnerabilities, including substance-specific addictions and comorbidities. Impulsivity dimensions are presented as novel behavioural targets for prevention and intervention. Novel treatment approaches addressing domains of impulsivity are reviewed and recommendations for future directions in research and clinical interventions for SUDs are offered. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Genetic influences on delayed reward discounting: A genome-wide prioritized subset approach

Delayed reward discounting (DRD) is a behavioral economic measure of impulsivity that has been consistently associated with addiction. It has also been identified as a promising addiction endophenotype, linking specific sources of genetic variation to individual risk. A challenge in the studies to date is that levels of DRD are often confounded with prior drug use, and previous studies have also had limited genomic scope. The current investigation sought to address these issues by studying DRD in healthy young adults with low levels of substance use (N = 986; 62% female, 100% European ancestry) and investigating genetic variation genome-wide. The genome-wide approach used a prioritized subset design, organizing the tests into theoretically and empirically informed categories and apportioning power accordingly. Three subsets were used: (a) a priori loci implicated by previous studies; (b) high-value addiction (HVA) markers from the recently developed SmokeScreen array; and (c) an atheoretical genome-wide scan. Among a priori loci, a nominally significant association was present between DRD and rs521674 in ADRA2A. No significant HVA loci were detected. One statistically significant genome-wide association was detected (rs13395777, p = 2.8 × 10-8), albeit in an intergenic region of unknown function. These findings are generally not supportive of the previous candidate gene studies and suggest that DRD has a complex genetic architecture that will require considerably larger samples to identify genetic associations more definitively. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Life History Theory and Recovery From Substance Use Disorder

Recovery has emerged as an important paradigm in addictions treatment but the field has yet to achieve consensus on how it should be defined and measured. The recovery construct has been extended beyond sustained reductions in use or abstinence to enhancements in global health/well-being and also prosocial community reintegration. However, few studies have included these broader domains in their measurement of recovery and few scientific theories have been advanced to explain why reductions in substance use occasion these broader life changes. This article applies life history theory to recovery for the first time to help define recovery, advance recovery measurement, and explain why broad change across multiple life domains should facilitate sustained recovery progress. We conclude with a discussion of future directions and challenges for future research informed by our life history framework for recovery.

The gene-environmental architecture of the development of adolescent substance use

BACKGROUND

Using a longitudinal twin design and a latent growth curve/autoregressive approach, this study examined the genetic-environmental architecture of substance use across adolescence.

METHODS

Self-reports of substance use (i.e. alcohol, marijuana) were collected at ages 13, 14, 15, and 17 years from 476 twin pairs (475 boys, 477 girls) living in the Province of Quebec, Canada. Substance use increased linearly across the adolescent years.

RESULTS

ACE modeling revealed that genetic, as well as shared and non-shared environmental factors explained the overall level of substance use and that these same factors also partly accounted for growth in substance use from age 13 to 17. Additional genetic factors predicted the growth in substance use. Finally, autoregressive effects revealed age-specific non-shared environmental influences and, to a lesser degree, age-specific genetic influences, which together accounted for the stability of substance use across adolescence.

CONCLUSIONS

The results support and expand the notion that genetic and environmental influences on substance use during adolescence are both developmentally stable and developmentally dynamic.

Peer influence, Frontostriatal connectivity, and delay discounting in African American emerging adults

Prior research has demonstrated the importance of delay discounting in adverse health behaviors, such as addiction, attention deficit hyperactivity disorder, risk taking, and obesity. Nevertheless, the functional connectivity of neural circuitry associated with delay discounting and the ways in which the social environment may influence frontostriatal connectivity remain largely unknown, particularly in African Americans. Building on recent literature implicating frontostriatal connectivity during active delay discounting decision making and at rest, we used functional magnetic resonance imaging to assess the association between delay discounting and frontostriatal resting state connectivity (rsFC). We also examined the capacity of social relationships with parents and peers to longitudinally predict frontostriatal rsFC. The study cohort was composed of 91 rural African American emerging adults followed over a 6-year period. Greater (i.e., more positive) frontostriatal rsFC was associated with decreased delay discounting (i.e., less impulsive decision making). In addition, peer relationships at ages 20 and 21 significantly predicted frontostriatal rsFC at age 25 above and beyond parental influence. A significant indirect effect of peer affiliation on delay discounting through frontostriatal rsFC also emerged. These results indicate a role of frontostriatal connectivity in delay discounting decision making and highlight peers' unique influence on decision making behaviors through frontostriatal rsFC during emerging adulthood.

Neural activation during delay discounting is associated with 6-month change in risky sexual behavior in adolescents

Background

Identifying cognitive and neural mechanisms of decision making in adolescence can enhance understanding of, and interventions to reduce, risky health behaviors in adolescence. Delay discounting, or the propensity to discount the magnitude of temporally distal rewards, has been associated with diverse health risk behaviors, including risky sex. This cognitive process involves recruitment of reward and cognitive control brain regions, which develop on different trajectories in adolescence and are also implicated in real-world risky decision making. However, no extant research has examined how neural activation during delay discounting is associated with adolescents' risky sexual behavior.

Purpose

To determine whether a relationship exists between adolescents' risky sexual behavior and neural activation during delay discounting.

Methods

Adolescent participants completed a delay discounting paradigm during functional magnetic resonance imaging (fMRI) scanning, and they reported risky sexual behavior at baseline, 3-, 6-, 9-, and 12-month follow-up time points. Latent growth curve models were employed to determine relationships between brain activation during delay discounting and change in risky sexual behavior over time.

Results

Greater activation in brain regions associated with reward and cognitive control (caudate, putamen, nucleus accumbens, anterior cingulate, insula, orbitofrontal cortex, inferior frontal gyrus, dorsolateral prefrontal cortex) during delay discounting was associated with lower mean levels of risky sexual behavior but greater growth over the period from baseline to 6 months.

Conclusions

Neural activation during delay discounting is cross-sectionally and prospectively associated with risky sexual behavior in adolescence, highlighting a neural basis of risky decision-making as well as opportunities for early identification and intervention.

Defining the phenotype of young adults with family histories of alcohol and other substance use disorders: Studies from the family health patterns project

Individuals with a family history of alcohol and other drug use disorders (FH+) are at increased risk for developing substance use disorders themselves relative to those with no such histories (FH-). Here we sought to identify key characteristics associated with FH+ status and alcohol and other drug use disorder status in a large cohort of FH+ and FH- young adults. We conducted principal component analyses on demographic, temperament, and cognitive measures differentiating 506 FH+ and 528 FH- young adults. Three principal components were identified, and these component scores were then used to predict the odds of being FH+ and the odds of having an alcohol or other drug use disorder. Component 1 consisted of measures indexing internalizing traits, with higher component scores indicating greater depressive, anxious, and emotional instability tendencies. Component 2 consisted of measures of externalizing traits as well as exposure to early life adversity (ELA), with higher scores indicating less impulse control, more antisocial behavior, and greater ELA exposure. Component 3 consisted of estimated intelligence, delay discounting, and demographic characteristics, with higher scores indicating lower estimated intelligence, greater discounting of delayed rewards, less education, and lower childhood socioeconomic status. For each 1-point increase in the Component 1, 2, and 3 scores, the odds of being classified FH+ increased by 2%, 8%, and 4%, respectively. Similar findings were observed when individuals with alcohol or other drug use disorders were removed from the analyses. Finally, greater Component 2 scores were also associated with increased odds of having an alcohol or other drug use disorder. Collectively, these findings provide a more comprehensive understanding of the FH+ phenotype in young adults and help form a basis for further studies on biological mechanisms underlying risk for substance use disorders. The present findings also provide further support for a prominent role of ELA in promoting risk for problem alcohol and other drug use.

Genome-wide association study of delay discounting in 23,217 adult research participants of European ancestry

Delay discounting (DD), the tendency to discount the value of delayed versus current rewards, is elevated in a constellation of diseases and behavioral conditions. We performed a genome-wide association study of DD using 23,127 research participants of European ancestry. The most significantly associated single-nucleotide polymorphism was rs6528024 (P = 2.40 × 10-8), which is located in an intron of the gene GPM6B. We also showed that 12% of the variance in DD was accounted for by genotype and that the genetic signature of DD overlapped with attention-deficit/hyperactivity disorder, schizophrenia, major depression, smoking, personality, cognition and body weight.

Disruption in time projection and non-adherence to long-term therapies

OBJECTIVE

Patients' non-adherence to medical prescriptions is a crucial issue in contemporary medicine because it can jeopardize care efficacy. Non-adherence is especially frequent in patients with chronic diseases. In this article, we propose that a particular condition, which we call disruption in time projection, is a cause of non-adherence to medication therapies in chronic diseases.

METHODS

A questionnaire was administered to 120 hospitalized people with type 2 diabetes addressing three psychological constructs defining time projection: patience/impatience in a fictive monetary scenario (preferring to receive €1,500 in 1 year or €500 today), magnitude of temporal horizon (greater or lesser ability to imagine future events) and perception of the degree of physical similarity of current self to self at 1 year, 5 years and 10 years from the present. In addition, the questionnaire evaluated adherence to medication, social deprivation and depression.

RESULTS

In the multivariate analyses, two factors were associated with adherence to medication: patience (P<0.001) and long temporal horizon (P=0.006). Two factors were associated with HbA1c ≥8% (64 mmol/mol): non-adherence to medication (P=0.003) and short temporal horizon (P=0.011). Three factors were associated with long temporal horizon: adherence to medication (P<0.001), patience (P<0.001) and the existence of grandchildren (P=0.002). Social deprivation (P<0.001), non-adherence (P<0.001), female gender (P=0.002) and short temporal horizon (P=0.050) were associated with impatience. Finally, an association of adherence to expected similarity in the future to current self, impatience, short temporal horizon, social deprivation and depression was also shown in a multiple correspondence analysis.

CONCLUSION

What we termed a disruption in time projection may be a unique determinant for non-adherence to long-term therapy and, therefore, may influence the outcome of chronic diseases. We hypothesize that this is involved in both intentional and unintentional non-adherence and that it represents the loss of a protective mechanism. If this novel concept is to be confirmed in other settings and generalized to other chronic diseases, the recognition of its role in disease prognosis may help orient the teaching and practice of medicine.

Revealing Neurocomputational Mechanisms of Reinforcement Learning and Decision-Making With the hBayesDM Package

Reinforcement learning and decision-making (RLDM) provide a quantitative framework and computational theories with which we can disentangle psychiatric conditions into the basic dimensions of neurocognitive functioning. RLDM offer a novel approach to assessing and potentially diagnosing psychiatric patients, and there is growing enthusiasm for both RLDM and computational psychiatry among clinical researchers. Such a framework can also provide insights into the brain substrates of particular RLDM processes, as exemplified by model-based analysis of data from functional magnetic resonance imaging (fMRI) or electroencephalography (EEG). However, researchers often find the approach too technical and have difficulty adopting it for their research. Thus, a critical need remains to develop a user-friendly tool for the wide dissemination of computational psychiatric methods. We introduce an R package called hBayesDM (hierarchical Bayesian modeling of Decision-Making tasks), which offers computational modeling of an array of RLDM tasks and social exchange games. The hBayesDM package offers state-of-the-art hierarchical Bayesian modeling, in which both individual and group parameters (i.e., posterior distributions) are estimated simultaneously in a mutually constraining fashion. At the same time, the package is extremely user-friendly: users can perform computational modeling, output visualization, and Bayesian model comparisons, each with a single line of coding. Users can also extract the trial-by-trial latent variables (e.g., prediction errors) required for model-based fMRI/EEG. With the hBayesDM package, we anticipate that anyone with minimal knowledge of programming can take advantage of cutting-edge computational-modeling approaches to investigate the underlying processes of and interactions between multiple decision-making (e.g., goal-directed, habitual, and Pavlovian) systems. In this way, we expect that the hBayesDM package will contribute to the dissemination of advanced modeling approaches and enable a wide range of researchers to easily perform computational psychiatric research within different populations.

The association between parental history and delay discounting among individuals in recovery from addiction

BACKGROUND

Family history of addiction is a risk factor for substance use disorders. Delay discounting (DD) is associated with the risk of substance use and dependence, and is predictive of the likelihood of successful abstinence and treatment outcomes; thus, we investigated the extent to which having parents with addiction (parental history of addiction) and number of addicted parents affect DD among individuals in recovery from addiction.

METHODS

Data from 177 individuals in recovery from addiction from The International Quit and Recovery Registry (IQRR), an ongoing online data collection program that aims to understand addiction and how people succeed in recovery, were included in the analysis. Participants with no, one, or two parents with addiction were compared on measures of DD using an adjusting-amount task.

RESULTS

Parental history of addiction was significantly associated with delay discounting. After controlling for age and gender, which were significantly different between groups, participants reporting two biological parents with addiction had significantly higher DD rates compared to those reporting one or no parents with addiction.

CONCLUSIONS

Participants with two parents with addiction had significantly higher rates of discounting compared to those with no or only one parent with addiction. This information can serve as a foundation to better identify and target important subgroups that need additional or non-traditional intervention strategies to address their larger degree of impulsivity and help maintain abstinence or achieve better treatment outcomes.

The Role of Working Memory for Cognitive Control in Anorexia Nervosa versus Substance Use Disorder

Prefrontal cortex executive functions, such as working memory (WM) interact with limbic processes to foster impulse control. Such an interaction is referred to in a growing body of publications by terms such as cognitive control, cognitive inhibition, affect regulation, self-regulation, top-down control, and cognitive–emotion interaction. The rising trend of research into cognitive control of impulsivity, using various related terms reflects the importance of research into impulse control, as failure to employ cognitions optimally may eventually result in mental disorder. Against this background, we take a novel approach using an impulse control spectrum model – where anorexia nervosa (AN) and substance use disorder (SUD) are at opposite extremes – to examine the role of WM for cognitive control. With this aim, we first summarize WM processes in the healthy brain in order to frame a systematic review of the neuropsychological, neural and genetic findings of AN and SUD. In our systematic review of WM/cognitive control, we found n = 15 studies of AN with a total of n = 582 AN and n = 365 HC participants; and n = 93 studies of SUD with n = 9106 SUD and n = 3028 HC participants. In particular, we consider how WM load/capacity may support the neural process of excessive epistemic foraging (cognitive sampling of the environment to test predictions about the world) in AN that reduces distraction from salient stimuli. We also consider the link between WM and cognitive control in people with SUD who are prone to ‘jumping to conclusions’ and reduced epistemic foraging. Finally, in light of our review, we consider WM training as a novel research tool and an adjunct to enhance treatment that improves cognitive control of impulsivity.

Neurocognitive dysfunction in addiction: Testing hypotheses of diffuse versus selective phenotypic dysfunction with a classification-based approach

Neurocognitive dysfunctions are frequently identified in the addictions. These dysfunctions may indicate either diffuse dysfunction or may represent separate facets that have differential importance to the addiction phenotype. In a sample (n = 260) of alcohol and/or stimulant users and controls we measured responses across 7 diverse neurocognitive measures. These measures were Continuous Performance, Delay Discounting, Iowa Gambling, Stroop, Tower, Wisconsin Card Sorting, and Letter Number Sequencing. Comparisons were then made between the drug-dependent groups and controls using analysis of variance and also using a machine learning approach to classify participants based on task performance as substance-dependent or controls in 1 tree and as alcohol and/or stimulant users or controls in a second tree. The analysis of variance showed significant differences between groups on the Delay Discounting (p < .001), Iowa Gambling (p < .001), Letter Number Sequencing (p < .001), and Wisconsin Card Sorting (p < .05) tasks. The first classification tree correctly classified between substance-dependent or controls for 88.3% of participants and classified between alcohol and/or stimulant users or controls for 63.9% of participants. Delay discounting was the first split in both trees and in the substance-dependent and control tree. The analysis of variance results largely replicate previous findings. The machine learning classification tree analysis provides evidence to support the hypothesis that different measures of neurocognitive dysfunction represent different processes. Among them, delay discounting was the most robust in categorizing drug dependence. (PsycINFO Database Record

Age and impulsive behavior in drug addiction: A review of past research and future directions

Impulsive behavior is implicated in the initiation, maintenance, and relapse of drug-seeking behaviors involved in drug addiction. Research shows that changes in impulsive behavior across the lifespan contribute to drug use and addiction. The goal of this review is to examine existing research on the relationship between impulsive behavior and drug use across the lifespan and to recommend directions for future research. Three domains of impulsive behavior are explored in this review: impulsive behavior-related personality traits, delay discounting, and prepotent response inhibition. First, we present previous research on these three domains of impulsive behavior and drug use across developmental stages. Then, we discuss how changes in impulsive behavior across the lifespan are implicated in the progression of drug use and addiction. Finally, we discuss the relatively limited attention given to middle-to-older adults in the current literature, consider the validity of the measures used to assess impulsive behavior in middle-to-older adulthood, and suggest recommendations for future research.

Genes, emotions and gut microbiota: The next frontier for the gastroenterologist

Most medical specialties including the field of gastroenterology are mainly aimed at treating diseases rather than preventing them. Genomic medicine studies the health/disease process based on the interaction of the human genes with the environment. The gastrointestinal (GI) system is an ideal model to analyze the interaction between our genes, emotions and the gut microbiota. Based on the current knowledge, this mini-review aims to provide an integrated synopsis of this interaction to achieve a better understanding of the GI disorders related to bad eating habits and stress-related disease. Since human beings are the result of an evolutionary process, many biological processes such as instincts, emotions and behavior are interconnected to guarantee survival. Nourishment is a physiological need triggered by the instinct of survival to satisfy the body’s energy demands. The brain-gut axis comprises a tightly connected neural-neuroendocrine circuitry between the hunger-satiety center, the dopaminergic reward system involved in the pleasure of eating and the gut microbiota that regulates which food we eat and emotions. However, genetic variations and the consumption of high-sugar and high-fat diets have overridden this energy/pleasure neurocircuitry to the point of addiction of several foodstuffs. Consequently, a gut dysbiosis generates inflammation and a negative emotional state may lead to chronic diseases. Balancing this altered processes to regain health may involve personalized-medicine and genome-based strategies. Thus, an integrated approach based on the understanding of the gene-emotions-gut microbiota interaction is the next frontier that awaits the gastroenterologist to prevent and treat GI disorders associated with obesity and negative emotions.

Impulsivity in rodents with a genetic predisposition for excessive alcohol consumption is associated with a lack of a prospective strategy

Increasing evidence supports the hypothesis that impulsive decision-making is a heritable risk factor for an alcohol use disorder (AUD). Clearly identifying a link between impulsivity and AUD risk, however, is complicated by the fact that both AUDs and impulsivity are heterogeneous constructs. Understanding the link between the two requires identifying the underlying cognitive factors that lead to impulsive choices. Rodent models have established that a family history of excessive drinking can lead to the expression of a transgenerational impulsive phenotype, suggesting heritable alterations in the decision-making process. In the present study, we explored the cognitive processes underlying impulsive choice in a validated, selectively bred rodent model of excessive drinking-the alcohol-preferring ("P") rat. Impulsivity was measured via delay discounting (DD), and P rats exhibited an impulsive phenotype as compared to their outbred foundation strain-Wistar rats. Steeper discounting in P rats was associated with a lack of a prospective behavioral strategy, which was observed in Wistar rats and was directly related to DD. To further explore the underlying cognitive factors mediating these observations, a drift diffusion model of DD was constructed. These simulations supported the hypothesis that prospective memory of the delayed reward guided choice decisions, slowed discounting, and optimized the fit of the model to the experimental data. Collectively, these data suggest that a deficit in forming or maintaining a prospective behavioral plan is a critical intermediary to delaying reward, and by extension, may underlie the inability to delay reward in those with increased AUD risk.

α2A -Adrenergic receptor polymorphisms and mRNA expression levels are associated with delay discounting in cocaine users

Cocaine users characteristically display preferences for smaller immediate rewards over larger delayed rewards, and this delay discounting (DD) has been proposed as an endophenotype of cocaine addiction. Recent evidence suggests that the norepinephrine system and more specifically the α_2A -adrenergic receptor (ADRA2A) are impacted by chronic cocaine use while also being potentially involved in the neural mechanisms underlying DD. Hence, we investigated the effects of ADRA2A polymorphisms and ADRA2A mRNA expression levels on DD of cocaine users and stimulant-naïve controls. Two hundred and twenty-three participants (129 cocaine users and 94 stimulant-naïve healthy controls) completed a computerized DD paradigm and were genotyped for three single nucleotide polymorphisms (SNPs; rs1800544, rs521674 and rs602618) in the ADRA2A gene, while their peripheral ADRA2A mRNA expression was quantified in whole blood samples. The three SNPs were in near-perfect linkage disequilibrium. Accordingly, significant group*genotype interactions were found for all three ADRA2A variants revealing steeper DD in cocaine users (but not in controls) carrying the G-allele of SNP rs1800544, the T-allele of rs521674 and the C-allele of rs602618. Similarly, high ADRA2A mRNA expression levels were significantly associated with a reduced tendency to choose smaller more immediate rewards (over larger delayed rewards) in cocaine users but not in controls. As the relationship between DD and cocaine use was moderated by ADRA2A SNPs and by peripheral ADRA2A gene expression, we propose that the norepinephrine system is involved in DD deficits observed in cocaine using individuals. Consequently, pharmacological compounds targeting ADRA2As might be considered for the symptom-specific treatment of delay aversion in stimulant addiction.

Interrelationships between marijuana demand and discounting of delayed rewards: Convergence in behavioral economic methods

BACKGROUND

Distinct behavioral economic domains, including high perceived drug value (demand) and delay discounting (DD), have been implicated in the initiation of drug use and the progression to dependence. However, it is unclear whether frequent marijuana users conform to a "reinforcer pathology" addiction model wherein marijuana demand and DD jointly increase risk for problematic marijuana use and cannabis dependence (CD).

METHODS

Participants (n=88, 34% female, 14% cannabis dependent) completed a marijuana purchase task at baseline. A delay discounting task was completed following placebo marijuana cigarette (0% THC) administration during a separate experimental session.

RESULTS

Marijuana demand and DD were quantified using area under the curve (AUC). In multiple regression models, demand uniquely predicted frequency of marijuana use while DD did not. In contrast, DD uniquely predicted CD symptom count while demand did not. There were no significant interactions between demand and DD in either model.

CONCLUSIONS

These findings suggest that frequent marijuana users exhibit key constituents of the reinforcer pathology model: high marijuana demand and steep discounting of delayed rewards. However, demand and DD appear to be independent rather than synergistic risk factors for elevated marijuana use and risk for progression to CD. Findings also provide support for using AUC as a singular marijuana demand metric, particularly when also examining other behavioral economic constructs that apply similar statistical approaches, such as DD, to support analytic methodological convergence.

Neural Systems Underlying Individual Differences in Intertemporal Decision-making

Excessively choosing immediate over larger future rewards, or delay discounting (DD), associates with multiple clinical conditions. Individual differences in DD likely depend on variations in the activation of and functional interactions between networks, representing possible endophenotypes for associated disorders, including alcohol use disorders (AUDs). Numerous fMRI studies have probed the neural bases of DD, but investigations of large-scale networks remain scant. We addressed this gap by testing whether activation within large-scale networks during Now/Later decision-making predicts individual differences in DD. To do so, we scanned 95 social drinkers (18-40 years old; 50 women) using fMRI during hypothetical choices between small monetary amounts available "today" or larger amounts available later. We identified neural networks engaged during Now/Later choice using independent component analysis and tested the relationship between component activation and degree of DD. The activity of two components during Now/Later choice correlated with individual DD rates: A temporal lobe network positively correlated with DD, whereas a frontoparietal-striatal network negatively correlated with DD. Activation differences between these networks predicted individual differences in DD, and their negative correlation during Now/Later choice suggests functional competition. A generalized psychophysiological interactions analysis confirmed a decrease in their functional connectivity during decision-making. The functional connectivity of these two networks negatively correlates with alcohol-related harm, potentially implicating these networks in AUDs. These findings provide novel insight into the neural underpinnings of individual differences in impulsive decision-making with potential implications for addiction and related disorders in which impulsivity is a defining feature.

Early Adolescent Trajectories of Impulsiveness and Sensation Seeking in Children of Fathers with Histories of Alcohol and Other Substance Use Disorders

BACKGROUND

Problem substance use often begins in adolescence. This vulnerability likely stems, at least partially, from relatively rapid increases in sensation seeking occurring in early to mid-adolescence and more gradual improvements in impulse control occurring through later adolescence. Better understanding how these processes develop in high-risk youth may lead to enhanced substance use disorder treatment and prevention strategies.

METHODS

We characterized trajectories of self-reported impulsivity and sensation seeking in 305 FH+ youths who at minimum had a father with a history of alcohol or other drug use disorders and 81 youths with no family histories of substance use disorders (FH-). Assessments started at ages 10 to 12 and continued at 6-month intervals for up to 42 months. In addition, a subset of 58 FH+ youths who began alcohol or other drug use before age 15 (FH+ Users) were compared to 58 FH+ propensity-matched adolescents who did not initiate substance use before age 15 (FH+ Non-Users).

RESULTS

Compared to FH- youths at preadolescence, FH+ youths reported higher general impulsivity and higher impulsivity related to poor planning and attention. Over time, there were no differential effects of FH status on changes in impulsivity or sensation seeking across adolescence. FH+ Users had smaller decreases in general impulsivity and impulsivity related to restlessness and fidgeting across adolescence than FH+ Non-Users. FH+ Users also had greater increases in sensation seeking across adolescence than FH+ Non-Users.

CONCLUSIONS

Increased impulsivity in FH+ youths may make them less able to regulate sensation seeking drives that peak in adolescence, which may contribute to their high risk for developing substance use disorders. Additionally, FH+ adolescents who initiate early use may be at increased risk in part due to increased impulsivity coupled with greater increases in sensation seeking.