Economic and social deprivation predicts impulsive choice in young children.

Impulsivity is an individual difference in decision-making that is a risk factor for a number of health concerns including addiction and obesity. Although impulsivity has a large heritable component it, the health concerns associated with impulsivity are not uniformly distributed across society. For example, people from poorer backgrounds are more likely to be overweight, and be dependent on tobacco or alcohol. This suggests that the environmental component of impulsivity night be related to economic circumstances and availability of resources. This paper provides evidence that children aged 4 to 12 from the most deprived areas show greater impulsivity in the form of delay discounting than do children from the least deprived areas. The data are discussed with reference to scarcity based models of decision-making and to public health inequalities.

Global Cerebral Ischemia in Male Long Evans Rats Impairs Dopaminergic/ΔFosB Signalling in the Mesocorticolimbic Pathway Without Altering Delay Discounting Rates

Global cerebral ischemia (GCI) in rats has been shown to promote exploration of anxiogenic zones of the Elevated-Plus Maze (EPM) and Open Field Test (OFT). This study investigated changes in impulsive choice and/or defensive responses as possible contributors of heightened anxiogenic exploration observed after ischemia. Impulsivity was assessed using delay discounting (DD) paradigms, while the Predator Odour Test (PO) served to assess changes in defensive responses towards a naturally aversive stimulus. Male Long Evans rats underwent 9 days of autoshaping training and 24 days of DD training prior to GCI or sham surgery (n = 9/group). Post-surgery, rats completed the OFT, EPM, and PO, followed by 6 days of DD sessions. Blood droplets served to evaluate corticosterone secretion associated with PO exposure. With impulsivity being regulated through mesocorticolimbic monoaminergic pathways, we also characterised post-ischemic changes in the expression of dopamine D2 receptors (DRD2), dopamine transporters (DAT), and 1FosB in the basolateral amygdala (BLA), nucleus accumbens core (NAcC) and shell (NAcS), and ventromedial prefrontal cortex (vmPFC) using immunohistofluorescence. Our findings revealed no impact of GCI on delay discounting rates, while PO approach behaviours were minimally affected. Nonetheless, GCI significantly reduced DRD2 and ΔFosB-ir in the NAcS and NAcC, respectively, while DAT-ir was diminished in both NAc subregions. Collectively, our findings refine the understanding of cognitive-behavioural and biochemical responses following stroke or cardiac arrest. They support significant alterations to the dopaminergic mesocorticolimbic pathway after ischemia, which are not associated with altered impulsive choice in a DD task but may influence locomotor exploration of the OFT and EPM.

Reinforcer Quality and Self-Control

<p>Self-control has been extensively studied using procedures in which subjects chose between two reinforcer alternatives. Traditionally, one of those alternatives delivers a small reinforcer after a short delay (SI), the other, a larger reinforcer after a long delay (LD). Choosing the SI is defined as impulsivity as it requires forfeit of the larger reinforcer; and choosing the LD is termed self-control. Four experiments were conducted to examine behaviour using non-human animal analogues of self-control situations. The subjects used for all four experiments were Norway-hooded rats. Experiment 1 used an SI - LD self-control paradigm to examine the effect of manipulating reinforcer quality on response distribution. Findings were that behaviour became more impulsive as the delay ratio became more extreme and this tendency was more systematic when different quality reinforcers were used for the SI and LD alternatives. Experiments 2 and 3 introduced a novel self-control paradigm designed as an analogue of choice situations in which individuals choose between two competing immediately available reinforcers each associated with a different delayed reinforcer. The procedure used was a concurrent-chains schedule that delivered primary reinforcement in the initial and the terminal links. The initial reinforcers were of equal amount and unequal quality; the terminal reinforcers were of unequal amount and equal quality. An impulsive choice was defined as choosing the alternative that delivered the most-valuable reinforcer in the initial link and the least-valued reinforcer in the terminal link. A self-controlled choice was defined as choosing the alternative that delivered the least-valuable reinforcer in the initial link and the most-valuable reinforcer in the terminal link. The results indicated that behaviour was more self-controlled when the terminal reinforcer quality was ethanol solution and increasing the delay between the initial and terminal links increased subjects' responding on the impulsive choice. Behaviour allocation in Experiment 3 was well described by the Contextual Choice Model (Grace, 1994) when the temporal context scaling parameter (k) was allowed to vary. Subjects that were relatively more impulsive had lower derived k values. The final experiment presented the subjects from Experiment 3 with concurrent variable interval (VI) VI schedules in which one alternative delivered plain-sucrose solution and the other ethanol-sucrose solution. Preference measures obtained from Experiment 4 were negatively correlated with the values obtained for the scaling parameter in Experiment 3, indicating that subjects which were more impulsive in the MN - ML paradigm had a stronger preference for ethanol. In summary, findings indicate that reinforcer quality may change the discriminability of reinforcer alternatives; and the influence of reinforcer quality on response allocation is well described by quantitative models based on the Matching Law.</p>

Reinforcer Quality and Self-Control

<p>Self-control has been extensively studied using procedures in which subjects chose between two reinforcer alternatives. Traditionally, one of those alternatives delivers a small reinforcer after a short delay (SI), the other, a larger reinforcer after a long delay (LD). Choosing the SI is defined as impulsivity as it requires forfeit of the larger reinforcer; and choosing the LD is termed self-control. Four experiments were conducted to examine behaviour using non-human animal analogues of self-control situations. The subjects used for all four experiments were Norway-hooded rats. Experiment 1 used an SI - LD self-control paradigm to examine the effect of manipulating reinforcer quality on response distribution. Findings were that behaviour became more impulsive as the delay ratio became more extreme and this tendency was more systematic when different quality reinforcers were used for the SI and LD alternatives. Experiments 2 and 3 introduced a novel self-control paradigm designed as an analogue of choice situations in which individuals choose between two competing immediately available reinforcers each associated with a different delayed reinforcer. The procedure used was a concurrent-chains schedule that delivered primary reinforcement in the initial and the terminal links. The initial reinforcers were of equal amount and unequal quality; the terminal reinforcers were of unequal amount and equal quality. An impulsive choice was defined as choosing the alternative that delivered the most-valuable reinforcer in the initial link and the least-valued reinforcer in the terminal link. A self-controlled choice was defined as choosing the alternative that delivered the least-valuable reinforcer in the initial link and the most-valuable reinforcer in the terminal link. The results indicated that behaviour was more self-controlled when the terminal reinforcer quality was ethanol solution and increasing the delay between the initial and terminal links increased subjects' responding on the impulsive choice. Behaviour allocation in Experiment 3 was well described by the Contextual Choice Model (Grace, 1994) when the temporal context scaling parameter (k) was allowed to vary. Subjects that were relatively more impulsive had lower derived k values. The final experiment presented the subjects from Experiment 3 with concurrent variable interval (VI) VI schedules in which one alternative delivered plain-sucrose solution and the other ethanol-sucrose solution. Preference measures obtained from Experiment 4 were negatively correlated with the values obtained for the scaling parameter in Experiment 3, indicating that subjects which were more impulsive in the MN - ML paradigm had a stronger preference for ethanol. In summary, findings indicate that reinforcer quality may change the discriminability of reinforcer alternatives; and the influence of reinforcer quality on response allocation is well described by quantitative models based on the Matching Law.</p>

Reward-Related Decision-Making in Current and Past Disordered Gambling: Implications for Impulsive Choice and Risk Preference in the Maintenance of Gambling Disorder

Impulsive reward-related decision-making (RRDM) is robustly associated with gambling disorder (GD), although its role in the development and perpetuation of GD is still being investigated. This project sought to examine the possible roles of impulsive and risky choice, two aspects of RRDM, in the perpetuation of GD. Additionally, the potential moderating role of comorbid substance misuse was considered. A total of 434 participants with symptoms of current GD and symptoms of concurrent substance use disorder (SUD; n = 105), current GD with past SUD (n = 98), past GD with current SUD (n = 53), or past GD with past substance use disorder (SUD; n = 92), and 96 healthy controls were recruited through MTurk. Participants completed a randomly adjusting delay discounting (a measure of impulsive choice) and probabilistic discounting (a measure of risky choice) task and self-report questionnaires of gambling participation, GD and SUD symptomology, and trait impulsivity. Although control participants showed significantly greater delay discounting compared to individuals with a current or history of GD, no significant group differences emerged between individuals with current GD or a history of GD. Individuals with current GD showed significantly less probabilistic discounting compared to individuals with a history of GD and control participants showed the greatest rates of probabilistic discounting. These effects remained after controlling for lifetime gambling symptom severity and trait impulsivity. Overall, these findings suggest a potential maintaining role of risky choice in gambling disorder, but do not support a maintaining role for impulsive choice.

Development of a cortical delay discounting assay: a potential biomarker of externalizing disorders

Background People who tend to impulsively choose smaller, sooner rewards over larger, later rewards are at increased risk for addiction and psychiatric disorders. A neurobiological measure of the tendency to overvalue immediate gratification could facilitate the study of individuals who are susceptible to these mental disorders. The objective of this research was to develop a cortical assay of impulsive choice for immediate rewards. Methods A cortex-based assay of impulsive choice was developed using 1105 healthy adults from the Human Connectome Project, and then cross-validated in two independent samples of adults with elevated rates of psychiatric disorders. Results Study 1: Cortical delay discounting (C-DD) was developed using a multivariate additive model of gray matter thickness across both hemispheres. Higher C-DD corresponded to thinner cortex and greater impulsive choice for immediate rewards. It also predicted cannabis use beyond established risk factors for drug use, including familial substance use, childhood conduct problems, personality traits, and cognitive functioning. Study 2: C-DD replicated the association with delay discounting performance from study 1. Structural equation modeling showed C-DD covaried with symptoms of externalizing, but not internalizing disorders. Study 3: C-DD positively predicted future delay discounting behavior (6–34 months later). Conclusions Across three studies, a cortical assay of impulsive choice evidenced consistent associations with drug use and delay discounting task performance. It was also uniquely associated with psychiatric disorders that share impulsivity as a core feature. Together, findings support the utility of C-DD as a neurobiological assay of impulsive decision-making and a possible biomarker of externalizing disorders.