Temporal discounting across three psychiatric disorders: Anorexia nervosa, obsessive compulsive disorder, and social anxiety disorder

Waiting for it: Anorexia Risk, Future Orientation, and Intertemporal Discounting

Anorexia Nervosa is a severe eating disorder characterized by food restriction in service of a future goal: thinness and weight loss. Prior work suggests abnormal intertemporal decision-making in anorexia, with more farsighted decisions observed in patients with acute anorexia. Prospective future thinking in daily life, or temporal orientation, promotes more farsighted delay discounting. However, whether temporal orientation is altered in anorexia, and underlies reduced delay discounting in this population, remains unclear. Further, because changes in delay discounting could reflect cognitive effects of an acute clinical state, it is important to determine whether reduced delay discounting is observed in subclinical, at-risk samples. We measured delay discounting behavior and temporal orientation in a large sample of never-diagnosed individuals at risk of anorexia nervosa. We found that farsighted delay discounting was associated with elevated risk for anorexia nervosa. Anorexia nervosa risk was also associated with increased future-oriented cognition. Future-oriented cognition mediated the difference in delay-discounting behavior between high and low-risk groups. These results were unrelated to subjective time perception and were independent of mood and anxiety symptomatology. These findings establish future-oriented cognition as a cognitive mechanism underlying altered intertemporal decision-making in individuals at risk of developing anorexia nervosa.

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.

Avoidant/restrictive food intake disorder differs from anorexia nervosa in delay discounting

BACKGROUND

Avoidant/restrictive food intake disorder (ARFID) and anorexia nervosa (AN) are the two primary restrictive eating disorders; however, they are driven by differing motives for inadequate dietary intake. Despite overlap in restrictive eating behaviors and subsequent malnutrition, it remains unknown if ARFID and AN also share commonalities in their cognitive profiles, with cognitive alterations being a key identifier of AN. Discounting the present value of future outcomes with increasing delay to their expected receipt represents a core cognitive process guiding human decision-making. A hallmark cognitive characteristic of individuals with AN (vs. healthy controls [HC]) is reduced discounting of future outcomes, resulting in reduced impulsivity and higher likelihood of favoring delayed gratification. Whether individuals with ARFID display a similar reduction in delay discounting as those with AN (vs. an opposing bias towards increased delay discounting or no bias) is important in informing transdiagnostic versus disorder-specific cognitive characteristics and optimizing future intervention strategies.

METHOD

To address this research question, 104 participants (ARFID: n = 57, AN: n = 28, HC: n = 19) completed a computerized Delay Discounting Task. Groups were compared by their delay discounting parameter (ln)k.

RESULTS

Individuals with ARFID displayed a larger delay discounting parameter than those with AN, indicating steeper delay discounting (M ± SD = -6.10 ± 2.00 vs. -7.26 ± 1.73, p = 0.026 [age-adjusted], Hedges' g = 0.59), with no difference from HC (p = 0.514, Hedges' g = -0.35).

CONCLUSION

Our findings provide a first indication of distinct cognitive profiles among the two primary restrictive eating disorders. The present results, together with future research spanning additional cognitive domains and including larger and more diverse samples of individuals with ARFID (vs. AN), will contribute to identifying maintenance mechanisms that are unique to each disorder as well as contribute to the optimization and tailoring of treatment strategies across the spectrum of restrictive eating disorders.

Effects of reproductive experience on cost-benefit decision making in female rats

Many individuals undergo mating and/or other aspects of reproductive experience at some point in their lives, and pregnancy and childbirth in particular are associated with alterations in the prevalence of several psychiatric disorders. Research in rodents shows that maternal experience affects spatial learning and other aspects of hippocampal function. In contrast, there has been little work in animal models concerning how reproductive experience affects cost-benefit decision making, despite the relevance of this aspect of cognition for psychiatric disorders. To begin to address this issue, reproductively experienced (RE) and reproductively naïve (RN) female Long-Evans rats were tested across multiple tasks that assess different forms of cost-benefit decision making. In a risky decision-making task, in which rats chose between a small, safe food reward and a large food reward accompanied by variable probabilities of punishment, RE females chose the large risky reward significantly more frequently than RN females (greater risk taking). In an intertemporal choice task, in which rats chose between a small, immediate food reward and a large food reward delivered after a variable delay period, RE females chose the large reward less frequently than RN females. Together, these results show distinct effects of reproductive experience on different forms of cost-benefit decision making in female rats, and highlight reproductive status as a variable that could influence aspects of cognition relevant for 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.

Contextualizing the Neural Vulnerabilities Model of Obesity

In recent years, investigators have focused on neural vulnerability factors that increase the risk of unhealthy weight gain, which has provided a useful organizing structure for obesity neuroscience research. However, this framework, and much of the research it has informed, has given limited attention to contextual factors that may interact with key vulnerabilities to impact eating behaviors and weight gain. To fill this gap, we propose a Contextualized Neural Vulnerabilities Model of Obesity, extending the existing theory to more intentionally incorporate contextual factors that are hypothesized to interact with neural vulnerabilities in shaping eating behaviors and weight trajectories. We begin by providing an overview of the Neural Vulnerabilities Model of Obesity, and briefly review supporting evidence. Next, we suggest opportunities to add contextual considerations to the model, including incorporating environmental and developmental context, emphasizing how contextual factors may interact with neural vulnerabilities to impact eating and weight. We then synthesize earlier models and new extensions to describe a Contextualized Neural Vulnerabilities Model of Obesity with three interacting components-food reward sensitivity, top-down regulation, and environmental factors-all within a developmental framework that highlights adolescence as a key period. Finally, we propose critical research questions arising from the framework, as well as opportunities to inform novel interventions.

Evaluation of delay discounting as a transdiagnostic research domain criteria indicator in 1388 general community adults

BACKGROUND

The Research Domain Criteria (RDoC) approach proposes a novel psychiatric nosology using transdiagnostic dimensional mechanistic constructs. One candidate RDoC indicator is delay discounting (DD), a behavioral economic measure of impulsivity, based predominantly on studies examining DD and individual conditions. The current study sought to evaluate the transdiagnostic significance of DD in relation to several psychiatric conditions concurrently.

METHODS

Participants were 1388 community adults (18-65) who completed an in-person assessment, including measures of DD, substance use, depression, anxiety, posttraumatic stress disorder, and attention-deficit hyperactivity disorder (ADHD). Relations between DD and psychopathology were examined with three strategies: first, examining differences by individual condition using clinical cut-offs; second, examining DD in relation to latent psychopathology variables via principal components analysis (PCA); and third, examining DD and all psychopathology simultaneously via structural equation modeling (SEM).

RESULTS

Individual analyses revealed elevations in DD were present in participants screening positive for multiple substance use disorders (tobacco, cannabis, and drug use disorder), ADHD, major depressive disorder (MDD), and an anxiety disorder (ps < 0.05-0.001). The PCA produced two latent components (substance involvement v. the other mental health indicators) and DD was significantly associated with both (ps < 0.001). In the SEM, unique significant positive associations were observed between the DD latent variable and tobacco, cannabis, and MDD (ps < 0.05-0.001).

CONCLUSIONS

These results provide some support for DD as a transdiagnostic indicator, but also suggest that studies of individual syndromes may include confounding via comorbidities. Further systematic investigation of DD as an RDoC indicator is warranted.

Sooner is Better: Longitudinal Relations Between Delay Discounting, and Depression and Anxiety Symptoms among Vietnamese Adolescents

Delay discounting refers to the decline in the present value of an outcome as a function of the delay to its receipt. Research on delay discounting initially focused on substance abuse, generally finding that greater delay discounting is associated with increased risk for and severity of substance abuse. More recently, delay discounting has been linked theoretically and empirically to affective psychopathology, potentially suggesting novel intervention targets for mental health problems such as depression and anxiety. Longitudinal research consequently is critical to determine direction of causality and rule out possible third variable explanations. Only a small number of longitudinal studies have been conducted in this area, however. Furthermore, socio-economic and socio-cultural factors may influence delay discounting and its effects, but thus far the literature is relatively limited in this regard. The present study focused on adolescence, a key time-period for development of delay discounting and emotional problems. Longitudinal relations between delay discounting, and depression and anxiety symptoms were assessed among 414 adolescents in Vietnam, a lower-middle-income Southeast Asian nation with significant cultural divergence from Western countries. In contrast to most cross-sectional studies that have found positive or non-significant correlations, in the present study delay discounting at Time 1 had a negative beta with anxiety and depression symptoms at Time 1, with preference for immediate but smaller rewards (higher discounting) at Time 1 associated with lower anxiety and depression symptoms at Time 2. These results suggest that under certain circumstances, steeper delay discounting may be adaptive and supportive of emotional mental health.

Imagining emotional events benefits future-oriented decisions

How does imagining future events-whether positive or negative-influence our choices in the present? Prior work has shown the simulation of hypothetical future events, dubbed episodic future thinking, can alter the propensity to engage in delay discounting (the tendency to devalue future rewards) and does so in a valence-specific manner. Some research shows that positive episodic future thinking reduces delay discounting, whereas negative future thinking augments it. However, more recent research indicates that both positive and negative episodic future thinking reduce delay discounting, suggesting an effect of episodic future thinking that is independent of valence. In this study, we sought to replicate and extend these latter findings. Here, participants (N = 604; N = 572 after exclusions) completed an online study. In the baseline task, participants completed a delay discounting task. In the experimental task, they engaged in episodic future thinking before completing a second delay discounting task. Participants were randomly assigned to engage in either positive, neutral, or negative episodic future thinking. In accordance with Bulley et al., we found that episodic future thinking, regardless of valence, reduced delay discounting. Although episodic future thinking shifted decision-making in all conditions, the effect was stronger when participants engaged in positive episodic future thinking, even after accounting for personal relevance and vividness of imagined events. These findings suggest that episodic future thinking may promote future-oriented choices by contextualising the future, and this effect is further strengthened when the future is tied to positive emotion.

Selenium deficiency is associated with disease severity, disrupted reward processing, and increased suicide risk in patients with Anorexia Nervosa

BACKGROUND & AIMS

Patients with Anorexia Nervosa (AN) present many nutritional deficiencies (macro- and often also micro-nutrients), possibly explained by their inadequate food intake. Previous studies reported that selenium (Se) deficiency is common in the general population. As Se can be easily added as a supplement, the goal of this study was to evaluate the clinical impact of Se deficiency in patients with AN.

METHODS

This cross-sectional study concerned 153 patients with AN (92.9% women) followed at the Eating Disorder Unit of Lapeyronie Academic Hospital, Montpellier, France. Patients underwent an extensive neuropsychological assessment, and completed validated questionnaires. Blood samples were collected for Se quantification. Results were compared with the t-test, Mann-Whitney U, and Chi square tests, and univariate linear and multivariate logistic regression models.

RESULTS

Se plasma levels were below the cut-off of 80 µg/L in 53.6% (N = 82) of patients. AN onset was earlier in patients with Se deficiency, (p = .005), whereas disease duration was comparable between groups (p = .77). General eating disorder symptomatology in the past 28 days (Eating Disorder Examination Questionnaire) was more severe in patients with Se deficiency (p = .010). The suicide risk (MINI International Neuropsychiatric Evaluation) tended to be higher (p = .037), and suicide attempt history was more frequent (28.39% vs 9.85%, p = .004) in patients with low Se levels. Se plasma concentration was negatively correlated with the performance in the temporal delayed discounting task (p = .006).

CONCLUSIONS

Our findings suggest that in patients with AN, Se plasma concentration might be implicated in disease severity and suicide risk. The finding that Se deficiency in patients with AN was associated only with reward-related processes, but not with other psychological functions suggests the selective involvement of dopamine-related pathways. Our results suggest that it might be useful to monitor the plasma micronutrient profile in patients with AN. Future studies should determine whether Se supplementation in AN might improve clinical outcomes.

Neural, physiological, and psychological markers of appetitive conditioning in anorexia nervosa: a study protocol

BACKGROUND

Anorexia nervosa (AN) is a chronic and disabling psychiatric condition characterized by low hedonic drive towards food, and is thought to be inclusive of altered dimensions of reward processing. Whether there exists a fundamental aberrancy in the capacity to acquire and maintain de novo hedonic associations-a critical component of hedonic responding-has never been studied in AN.

METHODS

This multi-modal study will employ a 2-day Pavlovian appetitive conditioning paradigm to interrogate the (1) acquisition, (2) extinction, (3) spontaneous recovery and (4) reinstatement of appetitive learning in adolescents and young adults with AN. Participants will be 30 currently ill, underweight individuals with AN; 30 weight-restored individuals with AN; and 30 age-matched healthy controls, all aged 12-22 years. All subjects will undergo clinical assessment, followed by the 2-day appetitive conditioning task during which fMRI, pupillometry, heart rate deceleration, and subjective ratings will be acquired.

DISCUSSION

This study will be the first to interrogate appetitive conditioning in AN-a disorder characterized by altered hedonic responding to food. Results will help establish objective biomarkers of appetitive conditioning in AN and lay the groundwork for developing novel lines of treatment for AN and other psychiatric disorders involving diminished ability to experience pleasure and reward.

TRIAL REGISTRATION

Pending.

INTENDED REGISTRY

Clinicaltrials.gov.

GABAB receptors in prelimbic cortex and basolateral amygdala differentially influence intertemporal decision making and decline with age

The ability to decide adaptively between immediate vs. delayed gratification (intertemporal choice) is critical for well-being and is associated with a range of factors that influence quality of life. In contrast to young adults, many older adults show enhanced preference for delayed gratification; however, the neural mechanisms underlying this age difference in intertemporal choice are largely un-studied. Changes in signaling through GABA_B receptors (GABA_BRs) mediate several age-associated differences in cognitive processes linked to intertemporal choice. The current study used a rat model to determine how GABA_BRs in two brain regions known to regulate intertemporal choice (prelimbic cortex; PrL and basolateral amygdala; BLA) contribute to age differences in this form of decision making in male rats. As in humans, aged rats showed enhanced preference for large, delayed over small, immediate rewards during performance in an intertemporal choice task in operant test chambers. Activation of PrL GABA_BRs via microinfusion of the agonist baclofen increased choice of large, delayed rewards in young adult rats but did not influence choice in aged rats. Conversely, infusion of baclofen into the BLA strongly reduced choice of large, delayed rewards in both young adult and aged rats. Aged rats further showed a significant reduction in expression of GABA_BR1 subunit isoforms in the prefrontal cortex, a discovery that is consonant with the null effect of intra-PrL baclofen on intertemporal choice in aged rats. In contrast, expression of GABA_BR subunits was generally conserved with age in the BLA. Jointly, these findings elucidate a role for GABA_BRs in intertemporal choice and identify fundamental features of brain maturation and aging that mediate an improved ability to delay gratification.

Cognitive and Experienced Flexibility in Patients With Anorexia Nervosa and Obsessive Compulsive Disorder

OBJECTIVE

Anorexia nervosa (AN) and obsessive-compulsive disorder (OCD) share a neuropsychological profile characterized by cognitive inflexibility as evident in set-shifting problems, and by strong detail focus. Clinically, both patient groups display a strong rigidity which may be explained by these neurocognitive difficulties. Cognitive inflexibility may hinder treatment uptake and help explain suboptimal treatment outcomes in both AN and OCD. This is the first study to compare clinical AN and OCD groups andto examine similarities and differences in cognitive flexibility. Specifically, this study aims to investigate neuropsychological outcomes and self-reported difficulties in both clinical groups and a control group, and explore associations between the different flexibility outcomes and illness.

METHOD

Two hundred participants (61 AN, 72 OCD and 67 HC) performed neuropsychological tasks on set-shifting abilities (Trail Making Task, Stroop color-word interference, Intradimensional-Extradimensional shift task), detail focus (Group Embedded Figures Test) and self-reported set-shifting abilities and attention to detail (DFlex).

RESULTS

Similarities between patient groups were found in terms of reduced set-shifting ability on the Trail Making Task and detail focus. Moreover, both patient groups self-reported more set-shifting problems but a less strong detail focus than HC, which in turn were not related to neuropsychological task outcomes in either of the groups. In both patient groups longer illness duration was associated to longer reaction times in the switching tasks and for both groups symptom severity was associated to higher experienced inflexibility and attention to detail.

CONCLUSION

Cognitive inflexibility processes are largely similar in patients with AN and OCD. Both patient groups report inflexibility, yet this is unrelated to neuropsychological outcomes. Illness duration seems to contribute to poorer set-shifting and higher illness severity is linked to more experienced inflexibility. Findings highlight the need for entangling different domains of cognitive flexibility and detail focus and examining self-report measures for a cohesive understanding of clinically relevant flexibility weaknesses in AN and OCD.

Anhedonia in Anxiety Disorders

Humans, like other animals, are fundamentally motivated to pursue rewarding outcomes and avoid aversive ones. Anxiety disorders are conceptualized, defined, and treated based on heightened sensitivity to perceived aversive outcomes, including imminent threats as well as those that are uncertain yet could occur in the future. Avoidance is the central strategy used to mitigate anticipated aversive outcomes - often at the cost of sacrificing potential rewards and hindering people from obtaining desired outcomes. It is for these reasons that people are often motivated to seek treatment. In this chapter, we consider whether and how anhedonia - the loss of interest in pursuing and/or reduced responsiveness to rewarding outcomes - may serve as a barrier to recovering from clinically impairing anxiety. Increasingly recognized as a prominent symptom in many individuals with elevated anxiety, anhedonia is not explicitly considered within prevailing theoretical models or treatment approaches of anxiety. Our goal, therefore, is to review what is known about anhedonia within the anxiety disorders and then integrate this knowledge into a functional perspective to consider how anhedonia could maintain anxiety and limit treatment response. Our overarching thesis is that anhedonia disrupts the key processes that are central to supporting anxiety recovery. We end this chapter by considering how explicitly targeting anhedonia in treatment can optimize outcomes for anxiety disorders.

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.

Executive function in obesity and anorexia nervosa: Opposite ends of a spectrum of disordered feeding behaviour?

Higher-order executive functions such as decision-making, cognitive flexibility and behavioural control are critical to adaptive success in all aspects of life, including the maintenance of a healthy body weight by regulating food intake. Performance on tasks designed to assess these aspects of cognition is impaired in individuals with obesity and anorexia nervosa (AN); conditions at either end of a spectrum of body weight disturbance. While the conceptualisation of obesity and AN as mirror images of each other makes some sense from a metabolic point of view, whether or not these conditions also reflect opposing states of executive function is less clear. Here, we review evidence from neurocognitive and neuroimaging studies to compare the direction and extent of executive dysfunction in subjects with obesity and AN and how these are underpinned by changes in structure and function of subregions of the prefrontal cortex (PFC). Both conditions of extreme body weight disturbance are associated with impaired decision-making and cognitive inflexibility, however, impulsive behaviour presents in opposing directions; obesity being associated with reduced behavioural control and AN being associated with elevated control over behaviour with respect to food and feeding. Accordingly, the subregions of the PFC that guide inhibitory control and valuation of action outcomes (dorsolateral prefrontal cortex and orbitofrontal cortex) show opposite patterns of activation in subjects with obesity compared to those with AN, whereas the subregions implicated in cognitive and behavioural flexibility (ventromedial prefrontal cortex and anterior cingulate cortex) show alterations in the same direction in both conditions but with differential extent of dysfunction. We synthesise these findings in the context of the utility of animal models of obesity and AN to interrogate the detail of the neurobiological contributions to cognition in patient populations and the utility of such detail to inform future treatment strategies that specifically target executive dysfunction.

Adaptive function and correlates of anxiety during a pandemic

BACKGROUND AND OBJECTIVES

Most studies to date have focused on the negative aspects of anxiety. Anxiety, however, is an evolved emotional response that can provide protection in the face of risk. Pandemics are characterized by increased mortality risk coupled with future uncertainties, which both cause heightened anxiety. Here, we examine the factors associated with anxiety levels and risk avoidance behaviours during the first wave of the COVID-19 pandemic. We asked how individual time perspectives (future-oriented consideration and attention to present moment experience) affect anxiety in uncertain times, and whether anxiety reduces mortality risk by promoting risk avoidance behaviour.

METHODOLOGY

We conducted an online survey in the UK (N = 1088) and Turkey (N = 3935) and measured participants' generalized and pandemic-related anxiety levels, future-oriented consideration, mindfulness, intolerance of uncertainty, risk perception and risk avoidance behaviours.

RESULTS

We found that people less tolerant of uncertainties had higher levels of pandemic anxiety. Those with higher pandemic anxiety exhibited risk avoidance behaviours more frequently. Mindfulness and increased financial satisfaction reduced pandemic anxiety. People in Turkey reported higher levels of generalized and pandemic anxiety and greater engagement in risk avoidance behaviours than people in the UK.

CONCLUSIONS AND IMPLICATIONS

Our study shows an elevated anxiety response can help mitigate infection risk during pandemics and emphasizes the importance of the underlying situation in understanding whether an anxiety response is adaptive or pathological. Maintaining a healthy level of anxiety can promote engagement in protective behaviours. Therapies addressing anxiety can focus on increasing tolerance to future uncertainties.

LAY SUMMARY

Anxiety is an emotional response triggered in the anticipation of a possible threat. We found that intolerance of uncertainty strongly predicted anxiety and that people with elevated anxiety levels engaged in protective behaviours more frequently during the COVID-19 pandemic, suggesting that anxiety can help mitigate mortality risk.

The sooner the better: clinical and neural correlates of impulsive choice in Tourette disorder

Reward sensitivity has been suggested as one of the central pathophysiological mechanisms in Tourette disorder. However, the subjective valuation of a reward by introduction of delay has received little attention in Tourette disorder, even though it has been suggested as a trans-diagnostic feature of numerous neuropsychiatric disorders. We aimed to assess delay discounting in Tourette disorder and to identify its brain functional correlates. We evaluated delayed discounting and its brain functional correlates in a large group of 54 Tourette disorder patients and 31 healthy controls using a data-driven approach. We identified a subgroup of 29 patients with steeper reward discounting, characterised by a higher burden of impulse-control disorders and a higher level of general impulsivity compared to patients with normal behavioural performance or to controls. Reward discounting was underpinned by resting-state activity of a network comprising the orbito-frontal, cingulate, pre-supplementary motor area, temporal and insular cortices, as well as ventral striatum and hippocampus. Within this network, (i) lower connectivity of pre-supplementary motor area with ventral striatum predicted a higher impulsivity and a steeper reward discounting and (ii) a greater connectivity of pre-supplementary motor area with anterior insular cortex predicted steeper reward discounting and more severe tics. Overall, our results highlight the heterogeneity of the delayed reward processing in Tourette disorder, with steeper reward discounting being a marker of burden in impulsivity and impulse control disorders, and the pre-supplementary motor area being a hub region for the delay discounting, impulsivity and tic severity.

An informatics approach to examine decision-making impairments in the daily life of individuals with depression

Mental health informatics studies methods that collect, model, and interpret a wide variety of data to generate useful information with theoretical or clinical relevance to improve mental health and mental health care. This article presents a mental health informatics approach that is based on the decision-making theory of depression, whereby daily life data from a natural sequential decision-making task are collected and modeled using a reinforcement learning method. The model parameters are then estimated to uncover specific aspects of decision-making impairment in individuals with depression. Empirical results from a pilot study conducted to examine decision-making impairments in the daily lives of university students with depression are presented to illustrate this approach. Future research can apply and expand on this approach to investigate a variety of daily life situations and psychiatric conditions and to facilitate new informatics applications. Using this approach in mental health research may generate useful information with both theoretical and clinical relevance and high ecological validity.

A review of effort-based decision-making in eating and weight disorders

Effort-based decision-making provides a framework to understand the mental computations estimating the amount of work ("effort") required to obtain a reward. The aim of the current review is to systematically synthesize the available literature on effort-based decision-making across the spectrum of eating and weight disorders. More specifically, the current review summarises the literature examining whether 1) individuals with eating disorders and overweight/obesity are willing to expend more effort for rewards compared to healthy controls, 2) if particular components of effort-based decision-making (i.e. risk, discounting) relate to specific binge eating conditions, and 3) how individual differences in effort and reward -processing measures relate to eating pathology and treatment measures. A total of 96 studies were included in our review, following PRISMA guidelines. The review suggests that individuals with binge eating behaviours 1) are more likely to expend greater effort for food rewards, but not monetary rewards, 2) demonstrate greater decision-making impairments under risk and uncertainty, 3) prefer sooner rather than delayed rewards for both food and money, and 4) demonstrate increased implicit 'wanting' for high fat sweet foods. Finally, individual differences in effort and reward -processing measures relating to eating pathology and treatment measures are also discussed.

Identification of biomarkers that predict response to subthalamic nucleus deep brain stimulation in resistant obsessive-compulsive disorder: protocol for an open-label follow-up study

INTRODUCTION

Deep brain stimulation (DBS) of bilateral anteromedial subthalamic nucleus (amSTN) has been found to be helpful in a subset of patients with severe, chronic and treatment-refractory obsessive-compulsive disorder (OCD). Biomarkers may aid in patient selection and optimisation of this invasive treatment. In this trial, we intend to evaluate neurocognitive function related to STN and related biosignatures as potential biomarkers for STN DBS in OCD.

METHODS AND ANALYSIS

Twenty-four subjects with treatment-refractory OCD will undergo open-label STN DBS. Structural/functional imaging, electrophysiological recording and neurocognitive assessment would be performed at baseline. The subjects would undergo a structured clinical assessment for 12 months postsurgery. A group of 24 healthy volunteers and 24 subjects with treatment-refractory OCD who receive treatment as usual would be recruited for comparison of biomarkers and treatment response, respectively. Baseline biomarkers would be evaluated as predictors of clinical response. Neuroadaptive changes would be studied through a reassessment of neurocognitive functioning, imaging and electrophysiological activity post DBS.

ETHICS AND DISSEMINATION

The protocol has been approved by the National Institute of Mental Health and Neurosciences Ethics Committee. The study findings will be disseminated through peer-reviewed scientific journals and scientific meetings.

Temporal discounting when outcomes are experienced in the moment: Validation of a novel paradigm and comparison with a classic hypothetical intertemporal choice task

When faced with intertemporal choices, people typically devalue rewards available in the future compared to rewards more immediately available, a phenomenon known as temporal discounting. Decisions involving intertemporal choices arise daily, with critical impact on health and financial wellbeing. Although many such decisions are "experiential" in that they involve delays and rewards that are experienced in real-time and can inform subsequent choices, most studies have focused on intertemporal choices with hypothetical outcomes (or outcomes delivered after all decisions are made). The present study focused on experiential intertemporal choices. First, a novel intertemporal choice task was developed and validated, using delays experienced in real time and artistic photographs as consumable perceptual rewards. Second, performance on the experiential task was compared to performance on a classic intertemporal choice task with hypothetical outcomes. Involvement of distinct processes across tasks was probed by examining differential relations to state and trait anxiety. A two-parameter logistic function framework was proposed to fit indifference point data. This approach accounts for individual variability not only in the delay at which an individual switches from choosing the delayed to more immediate option, but also in the slope of that switch. Fit results indicated that the experiential task elicited temporal discounting, with effective trade-off between delay and perceptual reward. Comparison with the hypothetical intertemporal choice task suggested distinct mechanisms: first, temporal discounting across the two tasks was not correlated; and second, state and trait anxiety both were associated with choice behavior in the experiential task, albeit in distinct ways, whereas neither was significantly associated with choice behavior in the hypothetical task. The engagement of different processes in the experiential compared to hypothetical task may align with neural evidence for the recruitment of the hippocampus in animal but not in classic human intertemporal choice studies.

Deficient Goal-Directed Control in a Population Characterized by Extreme Goal Pursuit

Research in computational psychiatry has sought to understand the basis of compulsive behavior by relating it to basic psychological and neural mechanisms: specifically, goal-directed versus habitual control. These psychological categories have been further identified with formal computational algorithms, model-based and model-free learning, which helps to provide quantitative tools to distinguish them. Computational psychiatry may be particularly useful for examining phenomena in individuals with anorexia nervosa (AN), whose self-starvation appears both excessively goal directed and habitual. However, these laboratory-based studies have not aimed to examine complex behavior, as seen outside the laboratory, in contexts that extend beyond monetary rewards. We therefore assessed (1) whether behavior in AN was characterized by enhanced or diminished model-based behavior, (2) the domain specificity of any abnormalities by comparing learning in a food-specific (i.e., illness-relevant) context as well as in a monetary context, and (3) whether impairments were secondary to starvation by comparing learning before and after initial treatment. Across all conditions, individuals with AN, relative to healthy controls, showed an impairment in model-based, but not model-free, learning, suggesting a general and persistent contribution of habitual over goal-directed control, across domains and time points. Thus, eating behavior in individuals with AN that appears very goal-directed may be under more habitual than goal-directed control, and this is not remediated by achieving weight restoration.

Study protocol of comprehensive risk evaluation for anorexia nervosa in twins (CREAT): a study of discordant monozygotic twins with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a severe disorder, for which genetic evidence suggests psychiatric as well as metabolic origins. AN has high somatic and psychiatric comorbidities, broad impact on quality of life, and elevated mortality. Risk factor studies of AN have focused on differences between acutely ill and recovered individuals. Such comparisons often yield ambiguous conclusions, as alterations could reflect different effects depending on the comparison. Whereas differences found in acutely ill patients could reflect state effects that are due to acute starvation or acute disease-specific factors, they could also reflect underlying traits. Observations in recovered individuals could reflect either an underlying trait or a "scar" due to lasting effects of sustained undernutrition and illness. The co-twin control design (i.e., monozygotic [MZ] twins who are discordant for AN and MZ concordant control twin pairs) affords at least partial disambiguation of these effects.

METHODS

Comprehensive Risk Evaluation for Anorexia nervosa in Twins (CREAT) will be the largest and most comprehensive investigation of twins who are discordant for AN to date. CREAT utilizes a co-twin control design that includes endocrinological, neurocognitive, neuroimaging, genomic, and multi-omic approaches coupled with an experimental component that explores the impact of an overnight fast on most measured parameters.

DISCUSSION

The multimodal longitudinal twin assessment of the CREAT study will help to disambiguate state, trait, and "scar" effects, and thereby enable a deeper understanding of the contribution of genetics, epigenetics, cognitive functions, brain structure and function, metabolism, endocrinology, microbiology, and immunology to the etiology and maintenance of AN.

Heterogeneity in Fear Processing across and within Anxiety, Eating, and Compulsive Disorders

BACKGROUND

To assess within and across diagnosis variability we examined fear processing in healthy controls (HC) and three diagnostic groups that share symptoms of pathological anxiety: obsessive compulsive disorder (OCD); social anxiety disorder (SAD), and anorexia nervosa (AN).

METHODS

Unmedicated adults (N=166) participated in a paradigm assessing associative fear acquisition, extinction, extinction recall, and fear renewal. Data were analyzed from two perspectives: comparison of each disorder to HC and exploratory latent class analysis (LCA) of the combined data.

RESULTS

The diagnosis-based analyses indicated significantly increased fear renewal in OCD and trends toward decreased extinction recall in OCD and increased renewal in SAD. The LCA indicated four Response Types, none of which were congruent with the diagnostic categories. Most participants had a normative response (50%) or a moderate extinction recall deficit (30%). The two remaining groups (8% each) had more extreme responses: one showed complete failure of extinction recall; the other persistent arousal in expectation of, but prior to, actual conditioning (threat sensitivity).

LIMITATIONS

Due to small sample size (N=20) results for AN are regarded as preliminary.

CONCLUSIONS

Our diagnosis-based findings are consistent with previous data suggesting an association between pathological anxiety and difficulties maintaining fear extinction. The LCA reveal substantial within-diagnosis heterogeneity in fear processing and support inclusion of empirically driven approaches as a complement to standard analyses. This heterogeneity may also have implications for treatment, particularly cognitive behavioral therapy, which relies on strengthening extinction recall and requires patients to tolerate anxious expectation in order to engage with feared situations.

Metabolic state and value-based decision-making in acute and recovered female patients with anorexia nervosa

BACKGROUND

Patients with anorexia nervosa forgo eating despite emaciation and severe health consequences. Such dysfunctional decision-making might be explained by an excessive level of self-control, alterations in homeostatic and hedonic regulation, or an interplay between these processes. We aimed to understand value-based decision-making in anorexia nervosa and its association with the gut hormone ghrelin. Besides its homeostatic function, ghrelin has been implicated in the hedonic regulation of appetite and reward via the modulation of phasic dopamine signalling.

METHODS

In a cross-sectional design, we studied acutely underweight (n = 94) and recovered (n = 37) patients with anorexia nervosa of the restrictive subtype, as well as healthy control participants (n = 119). We assessed plasma concentrations of desacyl ghrelin and parameters of delay discounting, probability discounting for gains and losses, and loss aversion.

RESULTS

Recovered patients displayed higher risk aversion for gains, but we observed no group differences for the remaining decision-making parameters. Desacyl ghrelin was higher in acutely underweight and recovered participants with anorexia nervosa relative to healthy controls. Moreover, we found a significant group × desacyl ghrelin interaction in delay discounting, indicating that in contrast to healthy controls, acutely underweight patients with anorexia nervosa who had high desacyl ghrelin concentrations preferably chose the delayed reward option.

LIMITATIONS

We probed decision-making using monetary rewards, but patients with anorexia nervosa may react differently to disorder-relevant stimuli. Furthermore, in contrast to acyl ghrelin, the functions of desacyl ghrelin are unclear. Therefore, the interpretation of the results is preliminary.

CONCLUSION

The propensity for risk aversion as found in recovered patients with anorexia nervosa could help them successfully complete therapy, or it could reflect sequelae of the disorder. Conversely, ghrelin findings might be related to a mechanism contributing to disease maintenance; that is, in acutely underweight anorexia nervosa, a hungry state may facilitate the ability to forgo an immediate reward to achieve a (dysfunctional) long-term goal.

Moving towards specificity: A systematic review of cue features associated with reward and punishment in anorexia nervosa

Models of anorexia nervosa (AN) posit that symptoms are maintained through deficient reward and enhanced punishment processing. However, theoretical and empirical inconsistencies highlight the need for a more nuanced conceptualization of this literature. Our goal was to comprehensively review the research on reward and punishment responding in AN from a cue-specific lens to determine which stimuli evoke or discourage reward and punishment responses in this population, and, ultimately, what properties these rewarding and punishing cues might share. A systematic review interrogating reward and punishment responses to specific cues yielded articles (n = 92) that examined responses to disorder relevant (e.g., food) and irrelevant (e.g., money) stimuli across self-report, behavioral, and biological indices. Overall, in most studies individuals with AN exhibited aversive responses to cues signaling higher body weights, social contexts, and monetary losses, and appetitive responses to cues for weight loss behaviors and thinness. Findings were more mixed on responses to palatable food and monetary gains. Results highlight that reward and punishment responding in AN are context specific and may be affected by varied stimulus qualities (e.g., predictability, controllability, delay, effort). Increasing specificity in future research on reward and punishment mechanisms in AN will better inform development of precisely-targeted interventions.

Intact value-based decision-making during intertemporal choice in women with remitted anorexia nervosa? An fMRI study

BACKGROUND

Extreme restrictive food choice in anorexia nervosa is thought to reflect excessive self-control and/or abnormal reward sensitivity. Studies using intertemporal choice paradigms have suggested an increased capacity to delay reward in anorexia nervosa, and this may explain an unusual ability to resist immediate temptation and override hunger in the long-term pursuit of thinness. It remains unclear, however, whether altered delay discounting in anorexia nervosa constitutes a state effect of acute illness or a trait marker observable after recovery.

METHODS

We repeated the analysis from our previous fMRI investigation of intertemporal choice in acutely underweight patients with anorexia nervosa in a sample of weight-recovered women with anorexia nervosa (n = 36) and age-matched healthy controls (n = 36) who participated in the same study protocol. Follow-up analyses explored functional connectivity separately in both the weight-recovered/healthy controls sample and the acute/healthy controls sample.

RESULTS

In contrast to our previous findings in acutely underweight patients with anorexia nervosa, we found no differences between weight-recovered patients with anorexia nervosa and healthy controls at either behavioural or neural levels. New analysis of data from the acute/healthy controls sample sample revealed increased coupling between dorsal anterior cingulate cortex and posterior brain regions as a function of decision difficulty, supporting the hypothesis of altered neural efficiency in the underweight state.

LIMITATIONS

This was a cross-sectional study, and the results may be task-specific.

CONCLUSION

Although our results underlined previous demonstrations of divergent temporal reward discounting in acutely underweight patients with anorexia nervosa, we found no evidence of alteration in patients with weight-recovered anorexia nervosa. Together, these findings suggest that impaired valuebased decision-making may not constitute a defining trait variable or “scar” of the disorder.

Toward identifying reproducible brain signatures of obsessive-compulsive profiles: rationale and methods for a new global initiative

BACKGROUND

Obsessive-compulsive disorder (OCD) has a lifetime prevalence of 2-3% and is a leading cause of global disability. Brain circuit abnormalities in individuals with OCD have been identified, but important knowledge gaps remain. The goal of the new global initiative described in this paper is to identify robust and reproducible brain signatures of measurable behaviors and clinical symptoms that are common in individuals with OCD. A global approach was chosen to accelerate discovery, to increase rigor and transparency, and to ensure generalizability of results.

METHODS

We will study 250 medication-free adults with OCD, 100 unaffected adult siblings of individuals with OCD, and 250 healthy control subjects at five expert research sites across five countries (Brazil, India, Netherlands, South Africa, and the U.S.). All participants will receive clinical evaluation, neurocognitive assessment, and magnetic resonance imaging (MRI). The imaging will examine multiple brain circuits hypothesized to underlie OCD behaviors, focusing on morphometry (T1-weighted MRI), structural connectivity (Diffusion Tensor Imaging), and functional connectivity (resting-state fMRI). In addition to analyzing each imaging modality separately, we will also use multi-modal fusion with machine learning statistical methods in an attempt to derive imaging signatures that distinguish individuals with OCD from unaffected siblings and healthy controls (Aim #1). Then we will examine how these imaging signatures link to behavioral performance on neurocognitive tasks that probe these same circuits as well as to clinical profiles (Aim #2). Finally, we will explore how specific environmental features (childhood trauma, socioeconomic status, and religiosity) moderate these brain-behavior associations.

DISCUSSION

Using harmonized methods for data collection and analysis, we will conduct the largest neurocognitive and multimodal-imaging study in medication-free subjects with OCD to date. By recruiting a large, ethno-culturally diverse sample, we will test whether there are robust biosignatures of core OCD features that transcend countries and cultures. If so, future studies can use these brain signatures to reveal trans-diagnostic disease dimensions, chart when these signatures arise during development, and identify treatments that target these circuit abnormalities directly. The long-term goal of this research is to change not only how we conceptualize OCD but also how we diagnose and treat it.

Delay Discounting as a Transdiagnostic Process in Psychiatric Disorders: A Meta-analysis

IMPORTANCE

Delay discounting is a behavioral economic index of impulsive preferences for smaller-immediate or larger-delayed rewards that is argued to be a transdiagnostic process across health conditions. Studies suggest some psychiatric disorders are associated with differences in discounting compared with controls, but null findings have also been reported.

OBJECTIVE

To conduct a meta-analysis of the published literature on delay discounting in people with psychiatric disorders.

DATA SOURCES

PubMed, MEDLINE, PsycInfo, Embase, and Web of Science databases were searched through December 10, 2018. The psychiatric keywords used were based on DSM-IV or DSM-5 diagnostic categories. Collected data were analyzed from December 10, 2018, through June 1, 2019.

STUDY SELECTION

Following a preregistered Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol, 2 independent raters reviewed titles, abstracts, and full-text articles. English-language articles comparing monetary delay discounting between participants with psychiatric disorders and controls were included.

DATA EXTRACTION AND SYNTHESIS

Hedges g effect sizes were computed and random-effects models were used for all analyses. Heterogeneity statistics, one-study-removed analyses, and publication bias indices were also examined.

MAIN OUTCOMES AND MEASURES

Categorical comparisons of delay discounting between a psychiatric group and a control group.

RESULTS

The sample included 57 effect sizes from 43 studies across 8 diagnostic categories. Significantly steeper discounting for individuals with a psychiatric disorder compared with controls was observed for major depressive disorder (Hedges g = 0.37; P = .002; k = 7), schizophrenia (Hedges g = 0.46; P = .004; k = 12), borderline personality disorder (Hedges g = 0.60; P < .001; k = 8), bipolar disorder (Hedges g = 0.68; P < .001; k = 4), bulimia nervosa (Hedges g = 0.41; P = .001; k = 4), and binge-eating disorder (Hedges g = 0.34; P = .001; k = 7). In contrast, anorexia nervosa exhibited statistically significantly shallower discounting (Hedges g = -0.30; P < .001; k = 10). Modest evidence of publication bias was indicated by a statistically significant Egger test for schizophrenia and at the aggregate level across studies.

CONCLUSIONS AND RELEVANCE

Results of this study appear to provide empirical support for delay discounting as a transdiagnostic process across most of the psychiatric disorders examined; the literature search also revealed limited studies in some disorders, notably posttraumatic stress disorder, which is a priority area for research.

Reduced Plasma Orexin-A Concentrations are Associated with Cognitive Deficits in Anorexia Nervosa

Orexins/hypocretins are neuropeptides implicated in numerous processes, including food intake and cognition. The role of these peptides in the psychopathology of anorexia nervosa (AN) remains poorly understood. The aim of the current study was to evaluate the associations between plasma orexin-A (OXA) concentrations and neuropsychological functioning in adult women with AN, and a matched control group. Fasting plasma OXA concentrations were taken in 51 females with AN and in 51 matched healthy controls. Set-shifting was assessed using the Wisconsin Card Sorting Test (WCST), whereas decision making was measured using the Iowa Gambling Task (IGT). The AN group exhibited lower plasma OXA levels than the HC group. Lower mean scores were obtained on the IGT in AN patients. WCST perseverative errors were significantly higher in the AN group compared to HC. In both the AN and HC group, OXA levels were negatively correlated with WCST non-perseverative errors. Reduced plasma OXA concentrations were found to be associated with set-shifting impairments in AN. Taking into consideration the function of orexins in promoting arousal and cognitive flexibility, future studies should explore whether orexin partly underpins the cognitive impairments found in AN.

Time is overestimated in obesity: A cohort study

Food addiction and high impulsivity are common traits in obesity. In accordance with the evidence that time is overestimated in patients with a history of impulsivity and/or drug addiction, we tested the hypothesis that duration is overestimated in obesity. A total of 92 obese participants and 182 healthy controls completed a timing task of visual stimuli. In line with our prediction, obese participants overestimated the duration of the displayed visual stimuli than controls. Our result has potential clinical implications in the field of obesity, as it suggests a potential contribution of this cognitive dysfunction in the emergence and maintenance of obesity-related behaviour.

Cognitive Neuroscience of Eating Disorders

Anorexia nervosa and bulimia nervosa are characterized by severely restricted intake, binge eating, and compensatory behaviors like self-induced vomiting. The neurobiological underpinnings of these maladaptive behaviors are poorly understood, but the application of cognitive neuroscience and neuroimaging to eating disorders has begun to elucidate their pathophysiology. Specifically, this review focuses on 3 areas that suggest paths forward: reward, cognitive and behavioral control, and decision making. Understanding the brain-based mechanisms that promote and maintain these often chronic symptoms could guide the development of new and more effective treatments.

Computational psychiatry of impulsivity and risk: how risk and time preferences interact in health and disease

Choice impulsivity is an important subcomponent of the broader construct of impulsivity and is a key feature of many psychiatric disorders. Choice impulsivity is typically quantified as temporal discounting, a well-documented phenomenon in which a reward's subjective value diminishes as the delay to its delivery is increased. However, an individual's proclivity to-or more commonly aversion to- risk can influence nearly all of the standard experimental tools available for measuring temporal discounting. Despite this interaction, risk preference is a behaviourally and neurobiologically distinct construct that relates to the economic notion of utility or subjective value. In this opinion piece, we discuss the mathematical relationship between risk preferences and time preferences, their neural implementation, and propose ways that research in psychiatry could, and perhaps should, aim to account for this relationship experimentally to better understand choice impulsivity and its clinical implications. This article is part of the theme issue 'Risk taking and impulsive behaviour: fundamental discoveries, theoretical perspectives and clinical implications'.

Can delay discounting deliver on the promise of RDoC?

The National Institute of Mental Health launched the Research Domain Criteria (RDoC) initiative to better understand dimensions of behavior and identify targets for treatment. Examining dimensions across psychiatric illnesses has proven challenging, as reliable behavioral paradigms that are known to engage specific neural circuits and translate across diagnostic populations are scarce. Delay discounting paradigms seem to be an exception: they are useful for understanding links between neural systems and behavior in healthy individuals, with potential for assessing how these mechanisms go awry in psychiatric illnesses. This article reviews relevant literature on delay discounting (or the rate at which the value of a reward decreases as the delay to receipt increases) in humans, including methods for examining it, its putative neural mechanisms, and its application in psychiatric research. There exist rigorous and reproducible paradigms to evaluate delay discounting, standard methods for calculating discount rate, and known neural systems probed by these paradigms. Abnormalities in discounting have been associated with psychopathology ranging from addiction (with steep discount rates indicating relative preference for immediate rewards) to anorexia nervosa (with shallow discount rates indicating preference for future rewards). The latest research suggests that delay discounting can be manipulated in the laboratory. Extensively studied in cognitive neuroscience, delay discounting assesses a dimension of behavior that is important for decision-making and is linked to neural substrates and to psychopathology. The question now is whether manipulating delay discounting can yield clinically significant changes in behavior that promote health. If so, then delay discounting could deliver on the RDoC promise.

Social anxiety in the eating disorders: a systematic review and meta-analysis

Social anxiety disorder is one of the most common comorbid conditions in eating disorders (EDs). The aim of the current review and meta-analysis is to provide a qualitative summary of what is known about social anxiety (SA) in EDs, as well as to compare levels of SA in those with EDs and healthy controls. Electronic databases were systematically searched for studies using self-report measures of SA in ED populations. In total, 38 studies were identified, 12 of which were included in the meta-analyses. For both anorexia nervosa (AN) and bulimia nervosa, there were significant differences between ED groups and HCs, with medium to large effect sizes. Findings from the qualitative review indicate that levels of SA are similar across the ED diagnoses, and SA improves with treatment in AN. In addition, high levels of SA are associated with more severe ED psychopathology, but not body mass index. These findings add to the wider literature on socio-emotional functioning in EDs, and may have implications for treatment strategies.

New Treatment Perspectives in Adolescents With Anorexia Nervosa: The Efficacy of Non-invasive Brain-Directed Treatment

Poor treatment outcomes are available for anorexia nervosa (AN) and treatment innovations are urgently needed. Recently, non-invasive neuromodulation tools have suggested to have potential for reducing an symptomatology targeting brain alterations. The objective of the study was to verify whether left anodal/right cathodal prefrontal cortex transcranial direct current stimulation (tDCS), may aid in altering/resetting inter-hemispheric balance in patients with AN, re-establishing control over eating behaviors. Twenty-three adolescents with an underwent a treatment as usual (AU), including nutritional, pharmacological, and psychoeducational treatment, plus 18 sessions of tDCS (TDCS+AU = n11; mean age = 13.9, SD = 1.8 years) or a family based therapy (FBT+AU = n12, mean age = 15.1, SD = 1.5 years). Psychopathological scales and the body mass index (BMI) were assessed before and after treatment. After 6 weeks of treatment, the BMI values increased only in the tDCS group, even at 1-month follow-up. Independently of the treatment, all participants improved in several psychopathological measures, included AN psychopathology and mood and anxiety symptoms. Our results demonstrated for the first time a specific effect of the left anodal/right cathodal tDCS treatment protocol on stable weight gain and a superiority compared to an active control treatment for adolescents with AN. Results were interpreted as a possible direct/indirect effect of tDCS in into some pathophysiological mechanisms of AN, involving the mesocortical dopaminergic pathways and the promotion of food intake. This pilot study opens new perspectives in the treatment of an in adolescence, supporting the targeted and beneficial effects of a brain-based treatment.

Risk preferences impose a hidden distortion on measures of choice impulsivity

Measuring temporal discounting through the use of intertemporal choice tasks is now the gold standard method for quantifying human choice impulsivity (impatience) in neuroscience, psychology, behavioral economics, public health and computational psychiatry. A recent area of growing interest is individual differences in discounting levels, as these may predispose to (or protect from) mental health disorders, addictive behaviors, and other diseases. At the same time, more and more studies have been dedicated to the quantification of individual attitudes towards risk, which have been measured in many clinical and non-clinical populations using closely related techniques. Economists have pointed to interactions between measurements of time preferences and risk preferences that may distort estimations of the discount rate. However, although becoming standard practice in economics, discount rates and risk preferences are rarely measured simultaneously in the same subjects in other fields, and the magnitude of the imposed distortion is unknown in the assessment of individual differences. Here, we show that standard models of temporal discounting —such as a hyperbolic discounting model widely present in the literature which fails to account for risk attitudes in the estimation of discount rates— result in a large and systematic pattern of bias in estimated discounting parameters. This can lead to the spurious attribution of differences in impulsivity between individuals when in fact differences in risk attitudes account for observed behavioral differences. We advance a model which, when applied to standard choice tasks typically used in psychology and neuroscience, provides both a better fit to the data and successfully de-correlates risk and impulsivity parameters. This results in measures that are more accurate and thus of greater utility to the many fields interested in individual differences in impulsivity.

Delay Discounting of Reward and Impulsivity in Eating Disorders: From Anorexia Nervosa to Binge Eating Disorder

Evidence points to eating disorder patients displaying altered rates of delay discounting (one's degree of preference for immediate rewards over larger delayed rewards). Anorexia nervosa (AN) patients are believed to have an increased capacity to delay reward, which reflects their ability to override the drive to eat. Contrarily, binge eating disorder (BED) patients are associated with a reduced predisposition to delay gratification. Here, we investigated monetary delay discounting and impulsivity in 80 adult women with EDs (56 AN and 24 BED), diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria, and 80 healthy controls. AN-restrictive (AN-R) subtype patients showed less steep discounting rates than BED and AN-bingeing/purging subtype patients. Compared with healthy controls and AN-R patients, BED and AN-bingeing/purging patients presented higher delay discounting and positive and negative urgency levels. Our findings suggest that restriction in AN-R patients is associated with disproportionate self-control, whereas bingeing behaviours could be more driven by emotional states and impulsivity traits. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

The Perception of Time Is Underestimated in Adolescents With Anorexia Nervosa

Research has revealed reduced temporal discounting (i.e., increased capacity to delay reward) and altered interoceptive awareness in anorexia nervosa (AN). In line with the research linking temporal underestimation with a reduced tendency to devalue a reward and reduced interoceptive awareness, we tested the hypothesis that time duration might be underestimated in AN. Our findings revealed that patients with AN displayed lower timing accuracy in the form of timing underestimation compared with controls. These results were not predicted by clinical, demographic factors, attention, and working memory performance of the participants. The evidence of a temporal underestimation bias in AN might be clinically relevant to explain their abnormal motivation in pursuing a long-term restrictive diet, in line with the evidence that increasing the subjective temporal proximity of remote future goals can boost motivation and the actual behavior to reach them.

Anhedonia in Trauma-Exposed Individuals: Functional Connectivity and Decision-Making Correlates

BACKGROUND

Reward processing deficits have been increasingly associated with trauma exposure and are a core feature of posttraumatic stress disorder (PTSD). While altered resting-state functional connectivity (rsFC) of ventral striatal regions, including the nucleus accumbens (NAcc), has been associated with anhedonia in some stress-related disorders, relationships between NAcc rsFC and anhedonia have not previously been investigated in trauma-exposed individuals. Additionally, relationships between anhedonia and reward-related decision making remain unexplored in relation to trauma exposure. We hypothesized that elevated anhedonia would be associated with altered rsFC between NAcc and default mode network regions and with increased delay discounting.

METHODS

The sample included 51 participants exposed to a DSM-IV PTSD Criterion A event related to community trauma. Participants completed the Clinician Administered PTSD Scale, the Snaith-Hamilton Pleasure Scale, the Beck Depression Inventory, a computerized delay discounting paradigm, and resting-state functional magnetic resonance imaging. rsFC data were analyzed in SPM12 and CONN.

RESULTS

Higher levels of anhedonia were associated with increased rsFC between seed regions of bilateral NAcc and areas of right dorsomedial prefrontal cortex. This relationship remained significant after accounting for Clinician Administered PTSD Scale total scores, Beck Depression Inventory total scores, or diagnostic group in the regression. Additionally, anhedonia was associated with elevated (increased) delay discounting.

CONCLUSIONS

Greater anhedonia was related to higher positive connectivity between NAcc and right dorsomedial prefrontal cortex and to increased delay discounting, i.e., greater preference for smaller immediate versus larger delayed rewards. These findings contribute to a growing body of literature emphasizing the importance of anhedonia in trauma-exposed individuals.