Can delay discounting deliver on the promise of RDoC?

Positive autobiographical memory recall does not influence temporal discounting: an internal meta-analysis of experimental studies

People tend to discount the value of future rewards as the delay to receiving them increases. This phenomenon, known as temporal discounting, may underlie many impulsive behaviors, such as drug abuse and overeating. Given the potential role of temporal discounting in maladaptive behaviors, many efforts have been made to find experimental manipulations that reduce temporal discounting. One class of manipulations that has held some promise involves recalling positive autobiographical memories prior to making intertemporal choices. Just as imagining positive future events has been shown to reduce temporal discounting, a few studies have shown that recalling positive past events reduces temporal discounting, especially if memory retrieval evokes positive affective states, such as gratitude and nostalgia. However, we failed to replicate these findings. Here we present an internal meta-analysis combining data from 14 studies (n = 758) that involved within-subjects positive memory recall-based manipulations. In each study, temporal discounting was assessed using a monetary intertemporal choice task. The average effect size was not significantly different from zero. This finding helps elucidate the neurocognitive mechanisms of temporal discounting; whereas engaging the episodic memory system to imagine future events might promote more patience, engaging the episodic memory system to imagine past events does not.

Temporal discounting predicts procrastination in the real world

People procrastinate, but why? One long-standing hypothesis is that temporal discounting drives procrastination: in a task with a distant future reward, the discounted future reward fails to provide sufficient motivation to initiate work early. However, empirical evidence for this hypothesis has been lacking. Here, we used a long-term real-world task and a novel measure of procrastination to examine the association between temporal discounting and real-world procrastination. To measure procrastination, we critically measured the entire time course of the work progress instead of a single endpoint, such as task completion day. This approach allowed us to compute a fine-grained metric of procrastination. We found a positive correlation between individuals' degree of future reward discounting and their level of procrastination, suggesting that temporal discounting is a cognitive mechanism underlying procrastination. We found no evidence of a correlation when we, instead, measured procrastination by task completion day or by survey. This association between temporal discounting and procrastination offers empirical support for targeted interventions that could mitigate procrastination, such as modifying incentive systems to reduce the delay to a reward and lowering discount rates.

Association of temporal discounting with transdiagnostic symptom dimensions

Temporal discounting (TD), the tendency to devalue future rewards as a function of delay until receipt, is aberrant in many mental disorders. Identifying symptom patterns and transdiagnostic dimensions associated with TD could elucidate mechanisms responsible for clinically impaired decision-making and facilitate identifying intervention targets. Here, we tested in a general population sample (N = 731) the extent to which TD was related to different symptom patterns and whether effects of time framing (dates/delay units) and monetary magnitude (large/small) had particularly strong effects in people scoring higher on specific symptom patterns. Analyses revealed that TD was related to symptom patterns loading on anxious-depression and inattention-impulsivity-overactivity dimensions. Moreover, TD was lower in the date than the delay version and with higher magnitudes, especially in people scoring higher on the inattention-impulsivity-overactivity dimension. Overall, this study provides evidence for TD as a transdiagnostic process across affective and impulsivity-related dimensions. Future studies should test framing interventions in clinical populations characterized by impulsivity.Preregistration: This research was preregistered at https://osf.io/fg9sc .

Approaching future rewards or waiting for them to arrive: Spatial representations of time and intertemporal choice

Our mental representation of the passage of time is structured by concepts of spatial motion, including an ego-moving perspective in which the self is perceived as approaching future events and a time-moving perspective in which future events are perceived as approaching the self. While previous research has found that processing spatial information in one's environment can preferentially activate either an ego-moving or time-moving temporal perspective, potential downstream impacts on everyday decision-making have received less empirical attention. Based on the idea people may feel closer to positive events they see themselves as actively approaching rather than passively waiting for, in this pre-registered study we tested the hypothesis that spatial primes corresponding to an ego-moving (vs. time-moving) perspective would attenuate temporal discounting by making future rewards feel more proximal. 599 participants were randomly assigned to one of three spatial prime conditions (ego-moving, time-moving, control) resembling map-based tasks people may engage with on digital devices, before completing measures of temporal perspective, perceived wait time, perceived control over time, and temporal discounting. Partly consistent with previous research, the results indicated that the time-moving prime successfully activated the intended temporal perspective-though the ego-moving prime did not. Contrary to our primary hypotheses, the spatial primes had no effect on either perceived wait time or temporal discounting. Processing spatial information in a map-based task therefore appears to influence how people conceptualise the passage of time, but there was no evidence for downstream effects on intertemporal preferences. Additionally, exploratory analysis indicated that greater perceived control over time was associated with lower temporal discounting, mediated by a reduction in perceived wait time, suggesting a possible area for future research into individual differences and interventions in intertemporal decision-making.

The impact of past temporal discounting on mental health: Opposite effects of positive and negative event aftertastes over time: Aftertaste and time

Background

Time frees people from bereavement, but also fades childhood happiness, these dynamics can be understood through the framework of past temporal discounting (PTD), which refers to the gradual decrease in affect intensity elicited by recalling positive or negative events over time. Despite its importance, measuring PTD has been challenging, and its impact on real-life outcomes, such as mental health remains unknown.

Method

Here, we employed a longitudinal tracking approach to measure PTD in healthy participants (N = 210) across eight time points. We recorded changes in affect intensity for positive and negative events and examined the impact of PTD on mental health outcomes, including general mental well-being, depression, stress sensitivity, and etc.

Results

The results of Bayesian multilevel modeling indicated that the affect intensity for positive and negative events discounted over time at a gradually decelerating rate. Furthermore, we found that maintaining good mental health heavily depended on rapid PTD of negative events and slow PTD of positive events.

Conclusions

These results provide a comprehensive characterization PTD and demonstrate its importance in maintaining mental health.

Differences in Discounting Behavior and Brain Responses for Food and Money Reward

Most neuroeconomic research seeks to understand how value influences decision-making. The influence of reward type is less well understood. We used functional magnetic resonance imaging (fMRI) to investigate delay discounting of primary (i.e., food) and secondary rewards (i.e., money) in 28 healthy, normal-weighted participants (mean age = 26.77; 18 females). To decipher differences in discounting behavior between reward types, we compared how well-different option-based statistical models (exponential, hyperbolic discounting) and attribute-wise heuristic choice models (intertemporal choice heuristic, dual reasoning and implicit framework theory, trade-off model) captured the reward-specific discounting behavior. Contrary to our hypothesis of different strategies for different rewards, we observed comparable discounting behavior for money and food (i.e., exponential discounting). Higher k values for food discounting suggest that individuals decide more impulsive if confronted with food. The fMRI revealed that money discounting was associated with enhanced activity in the right dorsolateral prefrontal cortex, involved in executive control; the right dorsal striatum, associated with reward processing; and the left hippocampus, involved in memory encoding/retrieval. Food discounting, instead, was associated with higher activity in the left temporoparietal junction suggesting social reinforcement of food decisions. Although our findings do not confirm our hypothesis of different discounting strategies for different reward types, they are in line with the notion that reward types have a significant influence on impulsivity with primary rewards leading to more impulsive choices.

Developmental deviation in delay discounting as a transdiagnostic indicator of risk for child psychopathology

BACKGROUND

The tendency to prefer smaller, immediate rewards over larger, delayed rewards is known as delay discounting (DD). Developmental deviations in DD may be key in characterizing psychiatric and neurodevelopmental disorders. Recent work empirically supported DD as a transdiagnostic process in various psychiatric disorders. Yet, there is a lack of research relating developmental changes in DD from mid-childhood to adolescence to psychiatric and neurodevelopmental disorders. Additionally, examining the interplay between socioeconomic status/total household income (THI) and psychiatric symptoms is vital for a more comprehensive understanding of pediatric pathology and its complex relationship with DD.

METHODS

The current study addresses this gap in a robust psychiatric sample of 1843 children and adolescents aged 5-18 (M = 10.6, SD = 3.17; 1,219 males, 624 females). General additive models (GAMs) characterized the shape of age-related changes in monetary and food reward discounting for nine psychiatric disorders compared with neurotypical youth (NT; n = 123). Over 40% of our sample possessed a minimum of at least three psychiatric or neurodevelopmental disorders. We used bootstrap-enhanced Louvain community detection to map DD-related comorbidity patterns. We derived five subtypes based on diagnostic categories present in our sample. DD patterns were then compared across each of the subtypes. Further, we evaluated the effect of cognitive ability, emotional and behavioral problems, and THI in relation to DD across development.

RESULTS

Higher discounting was found in six of the nine disorders we examined relative to NT. DD was consistently elevated across development for most disorders, except for depressive disorders, with age-specific DD differences compared with NTs. Community detection analyses revealed that one comorbidity subtype consisting primarily of Attention-Deficit/Hyperactivity Disorder (ADHD) Combined Presentation and anxiety disorders displayed the highest overall emotional/behavioral problems and greater DD for the food reward. An additional subtype composed mainly of ADHD, predominantly Inattentive Presentation, learning, and developmental disorders, showed the greatest DD for food and monetary rewards compared with the other subtypes. This subtype had deficits in reasoning ability, evidenced by low cognitive and academic achievement performance. For this ADHD-I and developmental disorders subtype, THI was related to DD across the age span such that participants with high THI showed no differences in DD compared with NTs. In contrast, participants with low THI showed significantly worse DD trajectories than all others. Our results also support prior work showing that DD follows nonlinear developmental patterns.

CONCLUSIONS

We demonstrate preliminary evidence for DD as a transdiagnostic marker of psychiatric and neurodevelopmental disorders in children and adolescents. Comorbidity subtypes illuminate DD heterogeneity, facilitating the identification of high-risk individuals. Importantly, our findings revealed a marked link between DD and intellectual reasoning, with children from lower-income households exhibiting lower reasoning skills and heightened DD. These observations underscore the potential consequences of compromised self-regulation in economically disadvantaged individuals with these disorders, emphasizing the need for tailored interventions and further research to support improved outcomes.

Cognitive and motor impulsivity in the healthy brain, and implications for eating disorders and obesity: A coordinate-based meta-analysis and systematic review

Alterations in the impulse-control balance, and in its neural bases, have been reported in obesity and eating disorders (EDs). Neuroimaging studies suggest a role of fronto-parietal networks in impulsive behaviour, with evaluation and anticipatory processes additionally recruiting meso-limbic regions. However, whether distinct facets of cognitive and motor impulsivity involve common vs. specific neural correlates remains unclear. We addressed this issue through Activation Likelihood Estimation (ALE) meta-analyses of fMRI studies on delay discounting (DD) and go/no-go (GNG) tasks, alongside conjunction and subtraction analyses. We also performed systematic reviews of neuroimaging studies using the same tasks in individuals with obesity or EDs. ALE results showed consistent activations in the striatum, anterior/posterior cingulate cortex, medial/left superior frontal gyrus and left supramarginal gyrus for impulsive choices in DD, while GNG tasks elicited mainly right-lateralized fronto-parietal activations. Conjunction and subtraction analyses showed: i) common bilateral responses in the caudate nucleus; ii) DD-specific responses in the ventral striatum, anterior/posterior cingulate cortex, left supramarginal and medial frontal gyri; iii) GNG-specific activations in the right inferior parietal cortex. Altered fronto-lateral responses to both tasks are suggestive of dysfunctional cortico-striatal balance in obesity and EDs, but these findings are controversial due to the limited number of studies directly comparing patients and controls. Overall, we found evidence for distinctive neural correlates of the motor and cognitive facets of impulsivity: the right inferior parietal lobe underpins action inhibition, whereas fronto-striatal regions and the left supramarginal gyrus are related to impulsive decision-making. While showing that further research on clinical samples is required to better characterize the neural bases of their behavioural changes, these findings help refining neurocognitive model of impulsivity and highlight potential translational implications for EDs and obesity treatment.

Using rodent data to elucidate dopaminergic mechanisms of ADHD: Implications for human personality

An altered behavioral response to positive reinforcement has been proposed to be a core deficit in attention deficit hyperactivity disorder (ADHD). The spontaneously hypertensive rat (SHR), a congenic animal strain, displays a similarly altered response to reinforcement. The presence of this genetically determined phenotype in a rodent model allows experimental investigation of underlying neural mechanisms. Behaviorally, the SHR displays increased preference for immediate reinforcement, increased sensitivity to individual instances of reinforcement relative to integrated reinforcement history, and a steeper delay of reinforcement gradient compared to other rat strains. The SHR also shows less development of incentive to approach sensory stimuli, or cues, that predict reward after repeated cue-reward pairing. We consider the underlying neural mechanisms for these characteristics. It is well known that midbrain dopamine neurons are initially activated by unexpected reward and gradually transfer their responses to reward-predicting cues. This finding has inspired the dopamine transfer deficit (DTD) hypothesis, which predicts certain behavioral effects that would arise from a deficient transfer of dopamine responses from actual rewards to reward-predicting cues. We argue that the DTD predicts the altered responses to reinforcement seen in the SHR and individuals with ADHD. These altered responses to reinforcement in turn predict core symptoms of ADHD. We also suggest that variations in the degree of dopamine transfer may underlie variations in personality dimensions related to altered reinforcement sensitivity. In doing so, we highlight the value of rodent models to the study of human personality.

Patients with episodic migraine without aura have an increased rate of delayed discounting

OBJECTIVE

This study aimed to explore decision-making impulsivity and its neural mechanisms in patients with episodic migraine without aura (EMoA).

BACKGROUND

Previous evidence indicates increased impulsivity and altered reward processing in patients with chronic migraine and medication overuse; however, whether the same holds true for those with EMoA is unclear.

METHODS

Patients newly diagnosed with EMoA (n = 51) and healthy controls (HC, n = 45) were recruited. All participants completed delay discounting task, cognitive assessments, a questionnaire for headache profile, and resting-state function magnetic resonance imaging scans. Resting-state functional connectivity (RSFC) between the regions of interest and the entire brain was explored.

RESULTS

Patients with EMoA showed a steeper subjective discount rate than HCs (F = 4.74, p = .032), which was positively related to a history of migraines (r = .742, p < .001). RSFC among the ventral striatum (vSTR), ventromedial prefrontal cortex, and occipital cortex was lower in patients with EMoA than in control groups, which was correlated with history (r' = .294, p = .036) and subjective discount rate (r' = .380, p = .006). Additionally, discounting rates and RSFC between the vSTR and occipital regions were significantly abnormal in the triptan group than the non-triptan group. Mediating effect analysis indicated a significant mediating effect in the change in RSFC between the vSTR and occipital status, history of triptan use, and subjective discount rate.

CONCLUSION

This study further elucidated that an increase in delayed discounting rate exists in patients with EMoA and is related to the abnormality of the value processing network.

Anhedonia and Delay Discounting: Differing Patterns of Brain-Behavior Relationships in Healthy Control Participants Versus Individuals With Posttraumatic Stress Disorder

BACKGROUND

Anhedonia may contribute to individual differences in delay discounting (DD). In prior work, we found that higher anhedonia was associated with shallower DD in healthy control (HC) participants but steeper DD in individuals with posttraumatic stress disorder (PTSD). In this study, we aimed to directly compare the relationship between anhedonia and DD across groups and to identify functional brain correlates of this interaction.

METHODS

Participants (HC group: n = 23, DSM-5 PTSD group: n = 23) completed a questionnaire assessing anhedonia (Snaith-Hamilton Pleasure Scale [SHAPS]), task-based functional magnetic resonance imaging of decision making including DD, and resting-state functional magnetic resonance imaging. Task-based activity and resting-state functional connectivity were evaluated in reward-related regions that have also been implicated in PTSD (nucleus accumbens [NAcc], right anterior insula).

RESULTS

Higher SHAPS scores were associated with steeper DD in PTSD, but there was no relationship between DD and SHAPS in the HC group. There was a significant group-by-SHAPS interaction for NAcc activity, t31 = 2.92, p = .007: Greater NAcc activity when immediate rewards were chosen was associated with higher SHAPS in the PTSD group but lower SHAPS in the HC group. In resting-state functional connectivity, there was a group-by-SHAPS interaction between the NAcc seed and right parietal and frontal pole clusters.

CONCLUSIONS

These results extend prior findings that anhedonia is associated with steeper DD in PTSD and demonstrate that this behavioral finding occurs in the context of NAcc hyperactivity to immediate rewards and hyperconnectivity in anhedonic individuals with PTSD.

Multi-timescale reinforcement learning in the brain

To thrive in complex environments, animals and artificial agents must learn to act adaptively to maximize fitness and rewards. Such adaptive behavior can be learned through reinforcement learning1, a class of algorithms that has been successful at training artificial agents2-6 and at characterizing the firing of dopamine neurons in the midbrain7-9. In classical reinforcement learning, agents discount future rewards exponentially according to a single time scale, controlled by the discount factor. Here, we explore the presence of multiple timescales in biological reinforcement learning. We first show that reinforcement agents learning at a multitude of timescales possess distinct computational benefits. Next, we report that dopamine neurons in mice performing two behavioral tasks encode reward prediction error with a diversity of discount time constants. Our model explains the heterogeneity of temporal discounting in both cue-evoked transient responses and slower timescale fluctuations known as dopamine ramps. Crucially, the measured discount factor of individual neurons is correlated across the two tasks suggesting that it is a cell-specific property. Together, our results provide a new paradigm to understand functional heterogeneity in dopamine neurons, a mechanistic basis for the empirical observation that humans and animals use non-exponential discounts in many situations10-14, and open new avenues for the design of more efficient reinforcement learning algorithms.

Selective chemogenetic inactivation of corticoaccumbal projections disrupts trait choice impulsivity

Impulsive choice has enduring trait-like characteristics and is defined by preference for small immediate rewards over larger delayed ones. Importantly, it is a determining factor in the development and persistence of substance use disorder (SUD). Emerging evidence from human and animal studies suggests frontal cortical regions exert influence over striatal reward processing areas during decision-making in impulsive choice or delay discounting (DD) tasks. The goal of this study was to examine how these circuits are involved in decision-making in animals with defined trait impulsivity. To this end, we trained adolescent male rats to stable behavior on a DD procedure and then re-trained them in adulthood to assess trait-like, conserved impulsive choice across development. We then used chemogenetic tools to selectively and reversibly target corticostriatal projections during performance of the DD task. The prelimbic region of the medial prefrontal cortex (mPFC) was injected with a viral vector expressing inhibitory designer receptors exclusively activated by designer drugs (Gi-DREADD), and then mPFC projections to the nucleus accumbens core (NAc) were selectively suppressed by intra-NAc administration of the Gi-DREADD actuator clozapine-n-oxide (CNO). Inactivation of the mPFC-NAc projection elicited a robust increase in impulsive choice in rats with lower vs. higher baseline impulsivity. This demonstrates a fundamental role for mPFC afferents to the NAc during choice impulsivity and suggests that maladaptive hypofrontality may underlie decreased executive control in animals with higher levels of choice impulsivity. Results such as these may have important implications for the pathophysiology and treatment of impulse control, SUDs, and related psychiatric disorders.

Chronic Deep Brain Stimulation of the Human Nucleus Accumbens Region Disrupts the Stability of Intertemporal Preferences

When choosing between rewards that differ in temporal proximity (intertemporal choice), human preferences are typically stable, constituting a clinically relevant transdiagnostic trait. Here we show, in female and male human patients undergoing deep brain stimulation (DBS) of the anterior limb of the internal capsule/NAcc region for treatment-resistant obsessive-compulsive disorder, that long-term chronic (but not phasic) DBS disrupts intertemporal preferences. Hierarchical Bayesian modeling accounting for temporal discounting behavior across multiple time points allowed us to assess both short-term and long-term reliability of intertemporal choice. In controls, temporal discounting was highly reliable, both long-term (6 months) and short-term (1 week). In contrast, in patients undergoing DBS, short-term reliability was high, but long-term reliability (6 months) was severely disrupted. Control analyses confirmed that this effect was not because of range restriction, the presence of obsessive-compulsive disorder symptoms or group differences in choice stochasticity. Model-agnostic between- and within-subject analyses confirmed this effect. These findings provide initial evidence for long-term modulation of cognitive function via DBS and highlight a potential contribution of the human NAcc region to intertemporal preference stability over time.SIGNIFICANCE STATEMENT Choosing between rewards that differ in temporal proximity is in part a stable trait with relevance for many mental disorders, and depends on prefrontal regions and regions of the dopamine system. Here we show that chronic deep brain stimulation of the human anterior limb of the internal capsule/NAcc region for treatment-resistant obsessive-compulsive disorder disrupts the stability of intertemporal preferences. These findings show that chronic stimulation of one of the brain's central motivational hubs can disrupt preferences thought to depend on this circuit.

Mouse-cursor trajectories reveal reduced contextual influence on decision conflict during delay discounting in anorexia nervosa

OBJECTIVE

The capacity of individuals with anorexia nervosa (AN) to forgo immediate food rewards in their long-term pursuit of thinness is thought to reflect elevated self-control and/or abnormal reward sensitivity. Prior research attempted to capture an increased tendency to delay gratification in AN using delay-discounting tasks that assess how rapidly the subjective value of rewards decreases as a function of time until receipt. However, significant effects were mostly subtle or absent. Here, we tested whether the process leading to such decisions might be altered in AN.

METHOD

We recorded mouse-cursor movement trajectories leading to the final choice in a computerized delay-discounting task (238 trials) in 55 acutely underweight females with AN and pairwise age-matched female healthy controls (HC). We tested for group differences in deviations from a direct choice path, a measure of conflict strength in decision making, and whether group moderated the effect of several predictors of conflict strength (e.g., choice difficulty, consistency). We also explored reaction times and changes in trajectory directions (X-flips).

RESULTS

No group differences in delay-discounting parameters or movement trajectories were detected. However, the effect of the aforementioned predictors on deviations (and to a lesser extent reaction times) was reduced in AN.

DISCUSSION

These findings suggest that while delay discounting and conflict strength in decision making are generally unaltered in AN, conflict strength was more stable across different decisions in the disorder. This might enable individuals with AN to pursue (maladaptive) long-term body-weight goals, because particularly conflicting choices may not be experienced as such.

PUBLIC SIGNIFICANCE

The deviations from a direct path of mouse-cursor movements during a computerized delay-discounting task varied less in people with anorexia nervosa. Assuming such deviations measure decision conflict, we speculate that this increased stability might help people with anorexia nervosa achieve their long-term weight goals, as for them the struggle with the decision to eat high-calorie meals when hungry will be milder, so they would be more likely to skip them.

Assessing the utility of a novel cortical marker of delay discounting (C-DD) in two independent samples of early adolescents: Links with externalizing pathology

Delay discounting is a well-established risk factor for risky behaviors and the development of externalizing spectrum disorders. Building upon recent work that developed a novel cortical marker of delay discounting (C-DD) in adult samples, the objective of this study was to test whether the C-DD relates to delay discounting and subsequently externalizing pathology in adolescent samples. The current study used two samples: 9992 early adolescents participating in the ABCD study (Mage = 9.93 years old, 48.7% female), and 56 early adolescents recruited from the community (Mage = 12.27 years old, 55.4% female). Cortical thickness was estimated using the FreeSurfer standard pipeline, and the cortical marker of delay discounting (C-DD) was calculated based on procedures outlined by the initial validation study. All data are cross-sectional in nature. As expected, C-DD was positively related to delay discounting in the ABCD sample, even after accounting for age, biological sex, collection site and data quality indicators. Moreover, results showed that C-DD was discriminately associated with externalizing, but not internalizing, symptoms in both samples of young adolescents. Findings replicate those found in adult samples, suggestive that C-DD may be a useful neuroanatomical marker of youth delay discounting. Replication of findings in other samples will be needed to determine whether C-DD has translational relevance to understanding externalizing psychopathology in adolescent samples.

Gender difference in network relationship between inter-temporal decisions and prefrontal activation levels in internet gaming disorder

Background

Impulsivity and decision-making are key factors in addiction. However, little is known about how gender and time sensitivity affect impulsivity in internet gaming disorder (IGD).

Objective

To investigate the gender difference of impulsive decision-making and relevant brain responses in IGD.

Methods

We conducted a functional magnetic resonance imaging (fMRI) study with 123 participants, including 59 IGD individuals (26 females) and 64 matched recreational game users (RGUs, 23 females). Participants performed a delay-discounting task during fMRI scanning. We examined gender-by-group effects on behavioral and neural measures to explore the preference for immediate over delayed rewards and the associated brain activity. We also investigated the network correlations between addiction severity and behavioral and neural measures, and analyzed the mediating role of brain activity in the link between delay discounting parameters and IGD severity.

Results

We found significant gender-by-group interactions. The imaging results revealed gender-by-group interactions in the dorsolateral prefrontal cortex, medial frontal gyrus, and inferior frontal gyrus (IFG). Post hoc analysis indicated that, for females, RGUs showed higher activity than IGD individuals in these brain regions, while for males IGD individuals exhibited higher activity than RGUs. The activation in the left IFG mediated the relation between Internet Addiction Test score and discount rate in females. In males, the activation in the right dlPFC mediated the relation between IAT score and time sensitivity.

Discussion

Our findings imply that male IGD participants demonstrate impaired intertemporal decisions associated with neural dysfunction. Influencing factors for impulsive decision-making in IGD diverge between males (time sensitivity) and females (discount rate). These findings augment our comprehension of the neural underpinnings of gender differences in IGD and bear significant implications for devising effective intervention strategies for treating people with IGD.

Dopamine D2 receptors in nucleus accumbens cholinergic interneurons increase impulsive choice

Impulsive choice, often characterized by excessive preference for small, short-term rewards over larger, long-term rewards, is a prominent feature of substance use and other neuropsychiatric disorders. The neural mechanisms underlying impulsive choice are not well understood, but growing evidence implicates nucleus accumbens (NAc) dopamine and its actions on dopamine D2 receptors (D2Rs). Because several NAc cell types and afferents express D2Rs, it has been difficult to determine the specific neural mechanisms linking NAc D2Rs to impulsive choice. Of these cell types, cholinergic interneurons (CINs) of the NAc, which express D2Rs, have emerged as key regulators of striatal output and local dopamine release. Despite these relevant functions, whether D2Rs expressed specifically in these neurons contribute to impulsive choice behavior is unknown. Here, we show that D2R upregulation in CINs of the mouse NAc increases impulsive choice as measured in a delay discounting task without affecting reward magnitude sensitivity or interval timing. Conversely, mice lacking D2Rs in CINs showed decreased delay discounting. Furthermore, CIN D2R manipulations did not affect probabilistic discounting, which measures a different form of impulsive choice. Together, these findings suggest that CIN D2Rs regulate impulsive decision-making involving delay costs, providing new insight into the mechanisms by which NAc dopamine influences impulsive behavior.

Integrating aspects of affect, reward, and cognition to develop more comprehensive models of binge-eating pathology

Reward-related processes are an increasing focus of eating disorders research. Although evidence suggests that numerous distinct reward processes may contribute to eating pathology (e.g., reward learning and delay discounting), existing etiological models of reward dysfunction tend to focus on only a limited number of reward processes, and frequently lack specificity when identifying the individual reward processes hypothesized to contribute to dysregulated eating behavior. Moreover, existing theories have been limited in their integration of reward-related processes with other demonstrated risk and maintenance factors for eating disorders (e.g., affect and cognition), potentially contributing to underdeveloped models of eating pathology. In this article, we highlight five distinct reward processes with theorized or demonstrated relevance to eating disorders involving binge-eating, followed by a review of two well-established risk/maintenance factors for binge-eating pathology. We then introduce two novel models of binge eating onset and maintenance that integrate these factors (i.e., the Affect, Reward, Cognition models), and discuss methods for testing each of the models in future research. Ultimately, we hope that the proposed models provide a springboard for the continued evolution of more precise and comprehensive theories of reward dysfunction in the eating disorders, as well as the development of novel intervention approaches. PUBLIC SIGNIFICANCE STATEMENT: Eating disorders are associated with abnormalities in multiple domains of reward functioning. However, models of reward dysfunction within the eating disorders have not been well-integrated with prominent models of affect and cognition. This article presents two novel models of onset and maintenance for binge-eating pathology, which attempt to integrate observed reward abnormalities with other affective and cognitive processes implicated in binge-type eating disorders.

Individual differences in delay discounting are associated with dorsal prefrontal cortex connectivity in children, adolescents, and adults

Delay discounting is a measure of impulsive choice relevant in adolescence as it predicts many real-life outcomes, including obesity and academic achievement. However, resting-state functional networks underlying individual differences in delay discounting during youth remain incompletely described. Here we investigate the association between multivariate patterns of functional connectivity and individual differences in impulsive choice in a large sample of children, adolescents, and adults. A total of 293 participants (9-23 years) completed a delay discounting task and underwent 3T resting-state fMRI. A connectome-wide analysis using multivariate distance-based matrix regression was used to examine whole-brain relationships between delay discounting and functional connectivity. These analyses revealed that individual differences in delay discounting were associated with patterns of connectivity emanating from the left dorsal prefrontal cortex, a default mode network hub. Greater delay discounting was associated with greater functional connectivity between the dorsal prefrontal cortex and other default mode network regions, but reduced connectivity with regions in the dorsal and ventral attention networks. These results suggest delay discounting in children, adolescents, and adults is associated with individual differences in relationships both within the default mode network and between the default mode and networks involved in attentional and cognitive control.

"Switching" between fast and slow processes is just reward-based branching

Shortcuts to goals are rewarded by faster attainment and punished by more frequent failure, so selection of the various kinds - heuristics, cached sequences (habits or macros), gut instincts - depends on reward history just like other kinds of choice. The speeds of shortcuts lie on continua along with speeds of deliberation, and these continua have no obvious separation points.

The intracortical myelin content of impulsive choices: results from T1- and T2-weighted MRI myelin mapping

Delay discounting (DD) refers to a phenomenon that humans tend to choose small-sooner over large-later rewards during intertemporal choices. Steep discounting of delayed outcome is related to a variety of maladaptive behaviors and is considered as a transdiagnostic process across psychiatric disorders. Previous studies have investigated the association between brain structure (e.g. gray matter volume) and DD; however, it is unclear whether the intracortical myelin (ICM) influences DD. Here, based on a sample of 951 healthy young adults drawn from the Human Connectome Project, we examined the relationship between ICM, which was measured by the contrast of T1w and T2w images, and DD and further tested whether the identified associations were mediated by the regional homogeneity (ReHo) of brain spontaneous activity. Vertex-wise regression analyses revealed that steeper DD was significantly associated with lower ICM in the left temporoparietal junction (TPJ) and right middle-posterior cingulate cortex. Region-of-interest analysis revealed that the ReHo values in the left TPJ partially mediated the association of its myelin content with DD. Our findings provide the first evidence that cortical myelination is linked with individual differences in decision impulsivity and suggest that the myelin content affects cognitive performances partially through altered local brain synchrony.

Age differences in intertemporal choice among children, adolescents, and adults

When choosing between sooner-smaller and later-larger rewards (i.e., intertemporal choices), adults typically prefer later-larger rewards more often than children. Intertemporal choice preferences have been implicated in various impulsivity-related psychopathologies, making it important to understand the underlying mechanisms not only in terms of how reward magnitude and delay affect choice but also in terms of how these mechanisms develop across age. We administered an intertemporal choice paradigm to 60 children (8-11 years), 79 adolescents (14-16 years), and 60 young adults (18-23 years). The paradigm systematically varied amounts and delays of the available rewards, allowing us to identify mechanisms underlying age-related differences in patience. Compared with young adults, both children and adolescents made fewer later-larger choices. In terms of underlying mechanisms, variation in delays, absolute reward magnitudes, and relative amount differences affected choice in each age group, indicating that children showed sensitivity to the same choice-relevant factors as young adults. Sensitivity to both absolute reward magnitude and relative amount differences showed a further monotonic age-related increase, whereas no change in delay sensitivity occurred. Lastly, adolescents and young adults weakly displayed a present bias (i.e., overvaluing immediate vs. future rewards; nonsignificant and trend, respectively), whereas children showed a nonsignificant but opposite pattern, possibly indicating that specifically dealing with future rewards changed with age. These findings shed light on the underlying mechanisms that contribute to the development of patience. By decomposing overt choices, our results suggest that the age-related increase in patience may be driven specifically by stronger sensitivity to amount differences with age.

Disrupting future discounting: a commentary on an underutilised psychological approach for improving adherence to diet and physical activity interventions

Non-communicable diseases (NCD) such as CVD and type 2 diabetes mellitus are major contributors to the burden of disease. NCD are largely driven by modifiable lifestyle factors including poor diet and insufficient physical activity, and consequently, prevention is a public health priority. Although diet and physical activity levels can be improved via lifestyle interventions, long-term adherence to such interventions remains low, which limits their effectiveness. Thus, it is critical to identify the underlying mechanisms that challenge uptake and adherence to such interventions. The current commentary discusses an important, but underexplored, psychological driver of poor adherence to lifestyle interventions, namely, future discounting, which describes the tendency to prefer smaller, short-term rewards over larger, long-term rewards. For example, in the nutrition domain, future discounting refers to valuing the immediate reward of excessive intake of energy-dense, nutrient-poor, discretionary foods high in salt, sugar, and saturated fat, and insufficient intake of low-energy, nutrient-dense, whole foods such as vegetables. Prominent theoretical models propose that excessive future discounting is a major contributor to the development of unhealthy lifestyle behaviours. Furthermore, a vast body of evidence suggests that future discounting plays a key role in risk of NCD. Thus, the evidence to date supports the idea that future discounting is an important multi-behaviour target for supporting lifestyle behaviour change; however, this approach has been largely neglected in preventive health efforts. Furthermore, this commentary discusses promising techniques (e.g. Episodic Future Thinking) for disrupting future discounting to promote improved adherence to lifestyle interventions aimed at reducing NCD risk.

Value-based decision-making network functional connectivity correlates with substance use and delay discounting behaviour among young adults

Substance use disorders are characterized by reduced control over the quantity and frequency of psychoactive substance use and impairments in social and occupational functioning. They are associated with poor treatment compliance and high rates of relapse. Identification of neural susceptibility biomarkers that index risk for developing a substance use disorder can facilitate earlier identification and treatment. Here, we aimed to identify the neurobiological correlates of substance use frequency and severity amongst a sample of 1,200 (652 females) participants aged 22-37 years from the Human Connectome Project. Substance use behaviour across eight classes (alcohol, tobacco, marijuana, sedatives, hallucinogens, cocaine, stimulants, opiates) was measured using the Semi-Structured Assessment for the Genetics of Alcoholism. We explored the latent organization of substance use behaviour using a combination of exploratory structural equation modelling, latent class analysis, and factor mixture modelling to reveal a unidimensional continuum of substance use behaviour. Participants could be rank ordered along a unitary severity spectrum encompassing frequency of use of all eight substance classes, with factor score estimates generated to represent each participant's substance use severity. Factor score estimates and delay discounting scores were compared with functional connectivity in 650 participants with imaging data using the Network-based Statistic. This neuroimaging cohort excludes participants aged 31 and over. We identified brain regions and connections correlated with impulsive decision-making and poly-substance use, with the medial orbitofrontal, lateral prefrontal and posterior parietal cortices emerging as key hubs. Functional connectivity of these networks could serve as susceptibility biomarkers for substance use disorders, informing earlier identification and treatment.

Optogenetic disruption of the prelimbic cortex alters long-term decision strategy but not valuation on a spatial delay discounting task

Rats demonstrate a preference for smaller, immediate rewards over larger, delayed ones, a phenomenon known as delay-discounting (DD). Behavior arises from the interaction of multiple decision-making systems, and the medial prefrontal cortex (mPFC) has been identified as a central component in the mediation between these decision systems. To investigate the role of the prelimbic (PL) subregion of mPFC on decision strategy interaction, we compared two cohorts of rats (ChR2-opsin-expressing 'Active' and opsin-absent 'Control') on a spatial delay-discounting task while delivering in-vivo light stimulation into PL at the choice point of select trials. By analyzing the overall delay-adjustment along with deliberative and procedural behavioral strategy markers, our study revealed differences in the decision strategies used between the active and control animals despite both groups showing similar valuations. Control animals developed the expected shift from deliberative to procedural decision strategy on this task (indicated by reaching delay-stability, particularly during late-session laps); however, active-virus animals repeatedly over-adjusted around their preferred delay throughout the entire session, suggesting a significant deficit in procedural decision-making on this task. Active animals showed a significant decrease in proportion of vicarious trial and error events (VTE, a behavior correlated with deliberative processes) on delay adjustment laps relative to control animals. This points to a more nuanced role for VTE, not just in executing deliberation, but in shifting from deliberative to procedural processes. This opto-induced change in VTE was especially pronounced for late-session adjustment laps. We found no other session-by-session or lap-by-lap effects, leaving a particular role for PL in the long-term development of procedural strategies on this task.

Proof-of-concept trial of Goal Management Training+ to improve executive functions and treatment outcomes in methamphetamine use disorder

BACKGROUND

Deficits in executive function are common in methamphetamine use disorder (MUD), likely contributing to difficulties in sustained treatment success. Cognitive remediation interventions are designed to treat such deficits but have not been adapted to the needs of people with MUD. This study presents a proof-of-concept trial to evaluate a new cognitive remediation program for MUD, Goal Management Training⁺ (GMT⁺).

METHODS

This was a cluster-randomised crossover trial comparing GMT⁺ with a psychoeducation-based control (Brain Health Workshop; BHW). GMT⁺ is a therapist-administered group-based cognitive remediation for executive dysfunction comprising four 90-minute weekly sessions and daily journal activities. BHW is a lifestyle psychoeducation program matched to GMT⁺ for therapist involvement, format, and duration. Participants (n = 36; GMT n = 17; BHW n = 19) were recruited from therapeutic communities in Victoria, Australia. Primary outcomes included intervention acceptability, feasibility, and improvements in self-reported executive function. Secondary outcomes included cognitive tests of executive function, severity of methamphetamine dependence, craving, and quality of life. We performed mixed linear modelling and calculated Hedges' g effect sizes.

RESULTS

GMT⁺ participant ratings and program retention indicated high acceptability. There was no difference between GMT⁺ and BHW on self-reported executive function (g = 0.06). Cognitive tasks suggested benefits of GMT⁺ on information gathering (g = 0.88) and delay-discounting (g = 0.80). Severity of methamphetamine dependence decreased more in GMT⁺ (g = 1.47).

CONCLUSIONS

GMT⁺ was well-accepted but did not improve self-reported executive functioning. Secondary outcomes suggested GMT⁺ was beneficial for objective cognitive performance and severity of dependence.

Altered delay discounting in neurodegeneration: insight into the underlying mechanisms and perspectives for clinical applications

Steeper delay discounting (i.e., the extent to which future rewards are perceived as less valuable than immediate ones) has been proposed as a transdiagnostic process across different health conditions, in particular psychiatric disorders. Impulsive decision-making is a hallmark of different neurodegenerative conditions but little is known about delay discounting in the domain of neurodegenerative conditions. We reviewed studies on delay discounting in patients with Parkinson's disease (PD) and in patients with dementia (Alzheimer's disease / AD or frontotemporal dementia / FTD). We proposed that delay discounting could be an early marker of the neurodegenerative process. We developed the idea that altered delay discounting is associated with overlapping but distinct neurocognitive mechanisms across neurodegenerative diseases: dopaminergic-related disorders of reward processing in PD, memory/projection deficits due to medial temporal atrophy in AD, modified reward processing due to orbitofrontal atrophy in FTD. Neurodegeneration could provide a framework to decipher the neuropsychological mechanisms of value-based decision-making. Further, delay discounting could become a marker of interest in clinical practice, in particular for differential diagnosis.

An fMRI-Based Brain Marker of Individual Differences in Delay Discounting

Individual differences in delay discounting-how much we discount future compared to immediate rewards-are associated with general life outcomes, psychopathology, and obesity. Here, we use machine learning on fMRI activity during an intertemporal choice task to develop a functional brain marker of these individual differences in human adults. Training and cross-validating the marker in one dataset (Study 1, N = 110 male adults) resulted in a significant prediction-outcome correlation (r = 0.49), generalized to predict individual differences in a completely independent dataset (Study 2: N = 145 male and female adults, r = 0.45), and predicted discounting several weeks later. Out-of-sample responses of the functional brain marker, but not discounting behavior itself, differed significantly between overweight and lean individuals in both studies, and predicted fasting-state blood levels of insulin, c-peptide, and leptin in Study 1. Significant predictive weights of the marker were found in cingulate, insula, and frontoparietal areas, among others, suggesting an interplay among regions associated with valuation, conflict processing, and cognitive control. This new functional brain marker is a step toward a generalizable brain model of individual differences in delay discounting. Future studies can evaluate it as a potential transdiagnostic marker of altered decision-making in different clinical and developmental populations.SIGNIFICANCE STATEMENT People differ substantially in how much they prefer smaller sooner rewards or larger later rewards such as spending money now versus saving it for retirement. These individual differences are generally stable over time and have been related to differences in mental and bodily health. What is their neurobiological basis? We applied machine learning to brain-imaging data to identify a novel brain activity pattern that accurately predicts how much people prefer sooner versus later rewards, and which can be used as a new brain-based measure of intertemporal decision-making in future studies. The resulting functional brain marker also predicts overweight and metabolism-related blood markers, providing new insight into the possible links between metabolism and the cognitive and brain processes involved in intertemporal decision-making.

Learned industriousness as a translational mechanism in anorexia nervosa

It remains unexplained why some behaviours persist despite being non-hedonic and ostensibly aversive. This phenomenon is especially baffling when such behaviours are taken to excess in the form of psychopathology. Anorexia nervosa is one psychiatric disorder in which effortful behaviours that most people find unpleasant (suchas restrictive eating) are persistently performed. We propose thatthe social psychology theory of learned industriousness providesa novel mechanistic account for such phenomena. This theoryposits that high-effort behaviour can be conditioned to acquire secondary reinforcing properties through repeated pairing with reward. Accordingly, effort sensations become less aversive andmore appetitive, increasing willingness to engage in effortful behaviour. In this Perspective, we review pre-clinical behaviouraland biological data that support learned industriousness, contrast learned industriousness with other models of non-hedonic persistence (such as habit learning), highlight evidence that supports learned industriousness in individuals with anorexia nervosa and consider implications of the model, including translation to other psychiatric presentations.

Individual Differences in Delay Discounting are Associated with Dorsal Prefrontal Cortex Connectivity in Youth

Delay discounting is a measure of impulsive choice relevant in adolescence as it predicts many real-life outcomes, including substance use disorders, obesity, and academic achievement. However, the functional networks underlying individual differences in delay discounting during youth remain incompletely described. Here we investigate the association between multivariate patterns of functional connectivity and individual differences in impulsive choice in a large sample of youth. A total of 293 youth (9-23 years) completed a delay discounting task and underwent resting-state fMRI at 3T. A connectome-wide analysis using multivariate distance-based matrix regression was used to examine whole-brain relationships between delay discounting and functional connectivity was then performed. These analyses revealed that individual differences in delay discounting were associated with patterns of connectivity emanating from the left dorsal prefrontal cortex, a hub of the default mode network. Delay discounting was associated with greater functional connectivity between the dorsal prefrontal cortex and other parts of the default mode network, and reduced connectivity with regions in the dorsal and ventral attention networks. These results suggest that delay discounting in youth is associated with individual differences in relationships both within the default mode network and between the default mode and networks involved in attentional and cognitive control.

Dopamine D2 receptors in nucleus accumbens cholinergic interneurons increase impulsive choice

Impulsive choice, often characterized by excessive preference for small, short-term rewards over larger, long-term rewards, is a prominent feature of substance use and other neuropsychiatric disorders. The neural mechanisms underlying impulsive choice are not well understood, but growing evidence implicates nucleus accumbens (NAc) dopamine and its actions on dopamine D2 receptors (D2Rs). Because several NAc cell types and afferents express D2Rs, it has been difficult to determine the specific neural mechanisms linking NAc D2Rs to impulsive choice. Of these cell types, cholinergic interneurons (CINs) of the NAc, which express D2Rs, have emerged as key regulators of striatal output and local dopamine release. Despite these relevant functions, whether D2Rs expressed specifically in these neurons contribute to impulsive choice behavior is unknown. Here, we show that D2R upregulation in CINs of the mouse NAc increases impulsive choice as measured in a delay discounting task without affecting reward magnitude sensitivity or interval timing. Conversely, mice lacking D2Rs in CINs showed decreased delay discounting. Furthermore, CIN D2R manipulations did not affect probabilistic discounting, which measures a different form of impulsive choice. Together, these findings suggest that CIN D2Rs regulate impulsive decision-making involving delay costs, providing new insight into the mechanisms by which NAc dopamine influences impulsive behavior.

The catecholamine precursor Tyrosine reduces autonomic arousal and decreases decision thresholds in reinforcement learning and temporal discounting

Supplementation with the catecholamine precursor L-Tyrosine might enhance cognitive performance, but overall findings are mixed. Here, we investigate the effect of a single dose of tyrosine (2g) vs. placebo on two catecholamine-dependent trans-diagnostic traits: model-based control during reinforcement learning (2-step task) and temporal discounting, using a double-blind, placebo-controlled, within-subject design (n = 28 healthy male participants). We leveraged drift diffusion models in a hierarchical Bayesian framework to jointly model participants' choices and response times (RTS) in both tasks. Furthermore, comprehensive autonomic monitoring (heart rate, heart rate variability, pupillometry, spontaneous eye blink rate) was performed both pre- and post-supplementation, to explore potential physiological effects of supplementation. Across tasks, tyrosine consistently reduced participants' RTs without deteriorating task-performance. Diffusion modeling linked this effect to attenuated decision-thresholds in both tasks and further revealed increased model-based control (2-step task) and (if anything) attenuated temporal discounting. On the physiological level, participants' pupil dilation was predictive of the individual degree of temporal discounting. Tyrosine supplementation reduced physiological arousal as revealed by increases in pupil dilation variability and reductions in heart rate. Supplementation-related changes in physiological arousal predicted individual changes in temporal discounting. Our findings provide first evidence that tyrosine supplementation might impact psychophysiological parameters, and suggest that modeling approaches based on sequential sampling models can yield novel insights into latent cognitive processes modulated by amino-acid supplementation.

Intertemporal choice reflects value comparison rather than self-control: insights from confidence judgements

Intertemporal decision-making has long been assumed to measure self-control, with prominent theories treating choices of smaller, sooner rewards as failed attempts to override immediate temptation. If this view is correct, people should be more confident in their intertemporal decisions when they 'successfully' delay gratification than when they do not. In two pre-registered experiments with built-in replication, adult participants (n = 117) made monetary intertemporal choices and rated their confidence in having made the right decisions. Contrary to assumptions of the self-control account, confidence was not higher when participants chose delayed rewards. Rather, participants were more confident in their decisions when possible rewards were further apart in time-discounted subjective value, closer to the present, and larger in magnitude. Demonstrating metacognitive insight, participants were more confident in decisions that better aligned with their separate valuation of possible rewards. Decisions made with less confidence were more prone to changes-of-mind and more susceptible to a patience-enhancing manipulation. Together, our results establish that confidence in intertemporal choice tracks uncertainty in estimating and comparing the value of possible rewards-just as it does in decisions unrelated to self-control. Our findings challenge self-control views and instead cast intertemporal choice as a form of value-based decision-making about future possibilities. This article is part of the theme issue 'Thinking about possibilities: mechanisms, ontogeny, functions and phylogeny'.

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

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

Gambling Environment Exposure Increases Temporal Discounting but Improves Model-Based Control in Regular Slot-Machine Gamblers

Gambling disorder is a behavioral addiction that negatively impacts personal finances, work, relationships and mental health. In this pre-registered study (https://osf.io/5ptz9/) we investigated the impact of real-life gambling environments on two computational markers of addiction, temporal discounting and model-based reinforcement learning. Gambling disorder is associated with increased temporal discounting and reduced model-based learning. Regular gamblers (n = 30, DSM-5 score range 3-9) performed both tasks in a neutral (café) and a gambling-related environment (slot-machine venue) in counterbalanced order. Data were modeled using drift diffusion models for temporal discounting and reinforcement learning via hierarchical Bayesian estimation. Replicating previous findings, gamblers discounted rewards more steeply in the gambling-related context. This effect was positively correlated with gambling related cognitive distortions (pre-registered analysis). In contrast to our pre-registered hypothesis, model-based reinforcement learning was improved in the gambling context. Here we show that temporal discounting and model-based reinforcement learning are modulated in opposite ways by real-life gambling cue exposure. Results challenge aspects of habit theories of addiction, and reveal that laboratory-based computational markers of psychopathology are under substantial contextual control.

A method for studying reinforcement factors controlling impulsive choice for use in behavioral neuroscience

Although procedures originating within the experimental analysis of behavior commonly are used in behavioral neuroscience to produce behavioral endpoints, they are used less often to analyze the behavioral processes involved, particularly at the level of individual organisms (see Soto, 2020). Concurrent-chains procedures have been used extensively to study choice and to quantify relations between various dimensions of reinforcement and preference. Unfortunately, parametric analysis of those relations using traditional steady-state, single-subject experimental designs can be time-consuming, often rendering these procedures impractical for use in behavioral neuroscience. The purpose of this paper is to describe how concurrent-chains procedures can be adapted to allow for parametric examination of effects of the reinforcement dimensions involved in impulsive choice (magnitude and delay) within experimental sessions in rats. Data are presented indicating that this procedure can produce relatively consistent within-session estimates of sensitivity to reinforcement in individual subjects, and that these estimates can be modified by neurobiological manipulation (drug administration). These data suggest that this type of procedure offers a promising approach to the study of neurobiological mechanisms of complex behavior in individual organisms, which could facilitate a more fruitful relationship between behavior analysis and behavioral neuroscience.

Additive roles of tobacco and cannabis co-use in relation to delay discounting in a sample of heavy drinkers

RATIONALE

Alcohol use disorder (AUD) is associated with steeper delay discounting rates; however, it is unknown whether substance co-use, particularly cannabis use, has an additive effect on discounting rates among heavy drinkers. Furthermore, it is unclear whether substance co-use and delay discounting are independently associated with AUD severity.

OBJECTIVES

The purpose of this study was to determine whether alcohol, tobacco, and cannabis co-use impacts delay discounting rates. We also sought to determine whether substance co-use and delay discounting were associated with AUD symptom counts.

METHODS

The study sample was culled from several human laboratory studies and consisted of 483 heavy drinking individuals who completed a baseline visit (prior to experimental procedures). Participants were divided into groups based on self-reported alcohol, tobacco, and cannabis use during the past 30 days: alcohol only (n = 184), alcohol + cigarettes (n = 89), alcohol + cannabis (n = 82), and tri-use (n = 128). We examined discounting rates across the 4 groups and used multiple linear regression to test whether co-use and delay discounting were associated with AUD symptoms.

RESULTS

After adjusting for covariates, individuals in the alcohol + cannabis group and the tri-use group had steeper discounting rates relative to the alcohol-only group. In addition, tri-use and delay discounting rates were independently correlated with a greater number of AUD symptoms.

CONCLUSIONS

Delay discounting rates were significantly greater among subgroups reporting cannabis use providing partial support for an additive effect, while also highlighting the importance of co-use substance type. Both tri-use and delay discounting were associated with greater AUD severity, which may provide relevant intervention targets.

Delay Discounting in Gambling Disorder: Implications in Treatment Outcome

Impulsive choice, measured by delay discounting (DD) tasks, has been shown in patients with gambling disorders (GD). However, the impact of DD and treatment outcome has been scarcely explored in GD patients. The aims of this study were: (1) to examine the baseline association between DD and clinical variables in GD patients depending on their age and gambling preferences (strategic vs. non-strategic); and (2) to estimate the predictive role of DD on poorer outcomes of cognitive-behavioral therapy (CBT) when considering also the effect of other clinical variables. 133 treatment-seeking male GD patients were evaluated at baseline with a DD task and measures of GD severity, personality traits and psychopathology. Treatment outcome was measured in terms of dropout from CBT and relapses. Results showed baseline associations between DD and GD severity (correlation coefficient R = 0.408 among strategic gamblers and R = 0.279 among mixed gamblers) and between DD and positive/negative urgency (R = 0.330 for the youngest patients, R = 0.244 for middle age, and around R = 0.35 for gamblers who reported preferences for strategic games). Other personality traits such as high harm avoidance and low cooperativeness were also related to DD at baseline (R = 0.606 among strategic gamblers). Regarding treatment outcome, a steeper discount rate predicted a higher risk of relapses in strategic gamblers (odds ratio OR = 3.01) and middle-age ones (OR = 1.59), and a higher risk of dropout in younger gamblers (OR = 1.89), non-strategic gamblers (OR = 1.70) and mixed gamblers (R = 4.74). GD severity mediated the associations between age, DD, personality traits and poor CBT outcome. In conclusion, impulsive choice affects treatment response in individuals with GD and may interfere with it to a significant extent. Considering DD in GD, patients seeking treatment could help control its impact on treatment adherence and relapses.

Impulsivity and Emotional Dysregulation Predict Choice Behavior During a Mixed-Strategy Game in Adolescents With Borderline Personality Disorder

Impulsivity and emotional dysregulation are two core features of borderline personality disorder (BPD), and the neural mechanisms recruited during mixed-strategy interactions overlap with frontolimbic networks that have been implicated in BPD. We investigated strategic choice patterns during the classic two-player game, Matching Pennies, where the most efficient strategy is to choose each option randomly from trial-to-trial to avoid exploitation by one’s opponent. Twenty-seven female adolescents with BPD (mean age: 16 years) and twenty-seven age-matched female controls (mean age: 16 years) participated in an experiment that explored the relationship between strategic choice behavior and impulsivity in both groups and emotional dysregulation in BPD. Relative to controls, BPD participants showed marginally fewer reinforcement learning biases, particularly decreased lose-shift biases, increased variability in reaction times (coefficient of variation; CV), and a greater percentage of anticipatory decisions. A subset of BPD participants with high levels of impulsivity showed higher overall reward rates, and greater modulation of reaction times by outcome, particularly following loss trials, relative to control and BPD participants with lower levels of impulsivity. Additionally, BPD participants with higher levels of emotional dysregulation showed marginally increased reward rate and increased entropy in choice patterns. Together, our preliminary results suggest that impulsivity and emotional dysregulation may contribute to variability in mixed-strategy decision-making in female adolescents with BPD.

Neurocognition after motor vehicle collision and adverse post-traumatic neuropsychiatric sequelae within 8 weeks: Initial findings from the AURORA study

BACKGROUND

Previous work has indicated that differences in neurocognitive functioning may predict the development of adverse post-traumatic neuropsychiatric sequelae (APNS). Such differences may be vulnerability factors or simply correlates of APNS-related symptoms. Longitudinal studies that measure neurocognitive functioning at the time of trauma are needed to determine whether such differences precede the development of APNS.

METHODS

Here, we present findings from a subsample of 666 ambulatory patients from the AURORA (Advancing Understanding of RecOvery afteR trumA) study. All patients presented to EDs after a motor vehicle collision (MVC). We examined associations of neurocognitive test performance shortly after MVC with peritraumatic symptoms in the ED and APNS (depression, post-traumatic stress, post-concussive symptoms, and pain) 2 weeks and 8 weeks later. Neurocognitive tests assessed processing speed, attention, verbal reasoning, memory, and social perception.

RESULTS

Distress in the ED was associated with poorer processing speed and short-term memory. Poorer short-term memory was also associated with depression at 2 weeks post-MVC, even after controlling for peritraumatic distress. Finally, higher vocabulary scores were associated with pain 2 weeks post-MVC.

LIMITATIONS

Self-selection biases among those who present to the ED and enroll in the study limit generalizability. Also, it is not clear whether observed neurocognitive differences predate MVC exposure or arise in the immediate aftermath of MVC exposure.

CONCLUSIONS

Our results suggest that processing speed and short-term memory may be useful predictors of trauma-related characteristics and the development of some APNS, making such measures clinically-relevant for identifying at-risk individuals.

Beyond Description and Deficits: How Computational Psychiatry Can Enhance an Understanding of Decision-Making in Anorexia Nervosa

PURPOSE OF REVIEW

Despite decades of research, knowledge of the mechanisms maintaining anorexia nervosa (AN) remains incomplete and clearly effective treatments elusive. Novel theoretical frameworks are needed to advance mechanistic and treatment research for this disorder. Here, we argue the utility of engaging a novel lens that differs from existing perspectives in psychiatry. Specifically, we argue the necessity of expanding beyond two historically common perspectives: (1) the descriptive perspective: the tendency to define mechanisms on the basis of surface characteristics and (2) the deficit perspective: the tendency to search for mechanisms associated with under-functioning of decision-making abilities and related circuity, rather than problems of over-functioning, in psychiatric disorders.

RECENT FINDINGS

Computational psychiatry can provide a novel framework for understanding AN because this approach emphasizes the role of computational misalignments (rather than absolute deficits or excesses) between decision-making strategies and environmental demands as the key factors promoting psychiatric illnesses. Informed by this approach, we argue that AN can be understood as a disorder of excess goal pursuit, maintained by over-engagement, rather than disengagement, of executive functioning strategies and circuits. Emerging evidence suggests that this same computational imbalance may constitute an under-investigated phenotype presenting transdiagnostically across psychiatric disorders. A variety of computational models can be used to further elucidate excess goal pursuit in AN. Most traditional psychiatric treatments do not target excess goal pursuit or associated neurocognitive mechanisms. Thus, targeting at the level of computational dysfunction may provide a new avenue for enhancing treatment for AN and related disorders.

A meta-analysis of the effects of episodic future thinking on delay discounting

Delay discounting (DD) refers to the phenomenon in which the subjective value of future rewards is reduced over time. There are individual differences in the DD rate, and increased discounting has been observed in those with various psychiatric disorders. Episodic future thinking (EFT) is the act of vividly imagining events that may happen in the future. Studies have shown that EFT could reduce DD, although inconsistent results have been reported. The aim of this meta-analysis was to clarify the efficacy with which EFT reduces DD and to identify potential moderators. Forty-seven studies (including 63 contrasts) were included in the final analysis. EFT was found to significantly reduce DD (Hedges' g = 0.52). Moderator analysis showed that positive EFT (g = 0.64) was more effective in reducing DD than EFT with the valence not specifically mentioned (g = 0.28) and EFT with neutral or negative valence (g = -0.03). In addition, several factors related to the control task and DD task were related to the efficacy of EFT to reduce DD. These findings have implications for using EFT to reduce DD in the future.

Delay Discounting in Established and Proposed Behavioral Addictions: A Systematic Review and Meta-Analysis

Steep delay discounting, or a greater preference for smaller-immediate rewards over larger-delayed rewards, is a common phenomenon across a range of substance use and psychiatric disorders. Non-substance behavioral addictions (e.g., gambling disorder, internet gaming disorder, food addiction) are of increasing interest in delay discounting research. Individual studies have reported steeper discounting in people exhibiting various behavioral addictions compared to controls or significant correlations between discounting and behavioral addiction scales; however, not all studies have found significant effects. To synthesize the published research in this area and identify priorities for future research, we conducted a pre-registered systematic review and meta-analysis (following PRISMA guidelines) of delay discounting studies across a range of behavioral addiction categories. The final sample included 78 studies, yielding 87 effect sizes for the meta-analysis. For studies with categorical designs, we found statistically significant, medium-to-large effect sizes for gambling disorder (Cohen’s d = 0.82) and IGD (d = 0.89), although the IGD effect size was disproportionately influenced by a single study (adjusted d = 0.53 after removal). Categorical internet/smartphone studies were non-significant (d = 0.16, p = 0.06). Aggregate correlations in dimensional studies were statistically significant, but generally small magnitude for gambling (r = 0.22), internet/smartphone (r = 0.13) and food addiction (r = 0.12). Heterogeneity statistics suggested substantial variability across studies, and publication bias indices indicated moderate impact of unpublished or small sample studies. These findings generally suggest that some behavioral addictions are associated with steeper discounting, with the most robust evidence for gambling disorder. Importantly, this review also highlighted several categories with notably smaller effect sizes or categories with too few studies to be included (e.g., compulsive buying, exercise addiction). Further research on delay discounting in behavioral addictions is warranted, particularly for categories with relatively few studies.

Value-based cognition and drug dependency

Value-based decision-making is thought to play an important role in drug dependency. Achieving elevated levels of euphoria or ameliorating dysphoria/pain may motivate goal-directed drug consumption in both drug-naïve and long-time users. In other words, drugs become viewed as the preferred means of attaining a desired internal state. The bias towards choosing drugs may affect one's cognition. Observed biases in learning, attention and memory systems within the brain gradually focus one's cognitive functions towards drugs and related cues to the exclusion of other stimuli. In this narrative review, the effects of drug use on learning, attention and memory are discussed with a particular focus on changes across brain-wide functional networks and the subsequent impact on behaviour. These cognitive changes are then incorporated into the cycle of addiction, an established model outlining the transition from casual drug use to chronic dependency. If drug use results in the elevated salience of drugs and their cues, the studies highlighted in this review strongly suggest that this salience biases cognitive systems towards the motivated pursuit of addictive drugs. This bias is observed throughout the cycle of addiction, possibly contributing to the persistent hold that addictive drugs have over the dependent. Taken together, the excessive valuation of drugs as the preferred means of achieving a desired internal state affects more than just decision-making, but also learning, attentional and mnemonic systems. This eventually narrows the focus of one's thoughts towards the pursuit and consumption of addictive drugs.

Subjective Time in Dementia: A Critical Review

The capacity for subjective time in humans encompasses the perception of time's unfolding from moment to moment, as well as the ability to traverse larger temporal expanses of past- and future-oriented thought via mental time travel. Disruption in time perception can result in maladaptive outcomes-from the innocuous lapse in timing that leads to a burnt piece of toast, to the grievous miscalculation that produces a traffic accident-while disruption to mental time travel can impact core functions from planning appointments to making long-term decisions. Mounting evidence suggests that disturbances to both time perception and mental time travel are prominent in dementia syndromes. Given that such disruptions can have severe consequences for independent functioning in everyday life, here we aim to provide a comprehensive exposition of subjective timing dysfunction in dementia, with a view to informing the management of such disturbances. We consider the neurocognitive mechanisms underpinning changes to both time perception and mental time travel across different dementia disorders. Moreover, we explicate the functional implications of altered subjective timing by reference to two key and representative adaptive capacities: prospective memory and intertemporal decision-making. Overall, our review sheds light on the transdiagnostic implications of subjective timing disturbances in dementia and highlights the high variability in performance across clinical syndromes and functional domains.

Hippocampal neurogenesis promotes preference for future rewards

Adult hippocampal neurogenesis has been implicated in a number of disorders where reward processing is disrupted but whether new neurons regulate specific aspects of reward-related decision making remains unclear. Given the role of the hippocampus in future-oriented cognition, here we tested whether adult neurogenesis regulates preference for future, advantageous rewards in a delay discounting paradigm for rats. Indeed, blocking neurogenesis caused a profound aversion for delayed rewards, and biased choice behavior toward immediately available, but smaller, rewards. Consistent with a role for the ventral hippocampus in impulsive decision making and future-thinking, neurogenesis-deficient animals displayed reduced activity in the ventral hippocampus. In intact animals, delay-based decision making restructured dendrites and spines in adult-born neurons and specifically activated adult-born neurons in the ventral dentate gyrus, relative to dorsal activation in rats that chose between immediately-available rewards. Putative developmentally-born cells, located in the superficial granule cell layer, did not display task-specific activity. These findings identify a novel and specific role for neurogenesis in decisions about future rewards, thereby implicating newborn neurons in disorders where short-sighted gains are preferred at the expense of long-term health.

Now or Later? Stress-Induced Increase and Decrease in Choice Impulsivity Are Both Associated with Elevated Affective and Endocrine Responses

Exposure to acute stress elicit physiological and psychological responses that can impact decision-making, often expressed as an increased tendency to act in an impulsive manner following stress. Delay discounting (DD) task has emerged as a reliable measure of impulsive behavior in the form of choice impulsivity (CI). Interestingly, studies that examined the effect of acute stress on DD performance reported mixed results. To address this, we conducted a within-subject examination of the impact of acute stress on CI, focusing on individual differences in response patterns. One hundred and fifty healthy female participants completed the DD task twice, before and after undergoing an acute laboratory stress induction procedure. Saliva samples and self-report mood and affect measures were collected at four time points throughout the session. Fifty-nine matched healthy control participants completed only the DD task twice, with no stress in between. Results indicate that the acute stress procedure elicited the expected effects of increased cortisol release and increased negative mood and affect, at the group level. With respect to DD, stress indeed increased CI at the group level, yet participants differed in the magnitude and direction of this effect. Interestingly, regression analysis revealed quadratic relations between stress-induced changes in CI and cortisol release. Indeed, dividing the sample into three sub-groups based on the impact of stress on CI revealed that, compared to participants that exhibited no substantial change in their CI following stress, participants that exhibited either stress-induced increase or decrease in their CI also exhibited more stress-induced cortisol release, as well as more negative affect. Taken together, these findings suggest that elevated physiological and psychological responses to stress are associated with either increased or decreased choice impulsivity, thus depicting quadratic relations between stress and impulsivity.

An empirical taxonomy of reward response patterns in a transdiagnostic eating disorder sample

Reward response patterns may contribute to risk and maintenance of eating disorders (EDs), and there may be clinically meaningful heterogeneity in behavioral responses to different actual and anticipated rewards across ED diagnoses. We used an empirical approach to classify individuals with EDs based on self-reported tendencies for responding to reward-related stimuli. Latent profile analysis was conducted in a transdiagnostic ED sample (N = 104) using Temperament and Character Inventory (Cloninger et al., 1993) subscales to categorize participants on reward responses of behavioral activation towards immediate, hedonic rewards (Novelty Seeking subscale), persistence towards long-term rewards (Persistence subscale), and maintenance by social rewards (Reward Dependence subscale) rewards. Two profiles were identified: (1) Behavioral Activation group (elevated Novelty Seeking; n = 62); and (b) Behavioral Persistence group (elevated Persistence; n = 42). Generalized linear models comparing profiles showed that frequency of these reward response profiles did not differ in probable AN, BN, or OSFED groups; however, individuals with probable BED more often demonstrated the Behavioral Activation profile (p = .041). These profiles exhibited comparable ED severity, but different presentations. Across probable ED diagnoses, the Behavioral Activation group reported greater binge eating (p = .006, d = 0.32) and had higher BMIs (p = .001, d = 0.57); the Behavioral Persistence group endorsed greater driven exercise (p = .042, d = 0.33). Categorization by activation to novel, immediate rewards versus persistence towards long-term rewards was associated with different symptoms across diagnoses, potentially supporting the role of specific reward response profiles in ED phenomenology.