Temporal discounting in major depressive disorder

The impact of pandemic threats on intertemporal choices in Chinese and Americans

Intertemporal decisions are crucial to survival, especially when humans are exposed to ecological threats. However, it remains unclear whether and how pandemic threats impact intertemporal choices across cultures. We conducted two studies in two cultural contexts (N = 1180). Study 1a found that Chinese who perceived more pandemic threats showed higher temporal discounting rates (i.e., preferred immediate smaller over delayed larger rewards), and this relationship was mediated by negative emotions. Study 1b, using threat priming, revealed that Chinese participants primed with a high-threat condition (depicting a pandemic threat) showed higher temporal discounting rates compared to those primed with a low-threat condition (describing the flu). Differently, Study 2a revealed that perceived pandemic threat levels of Americans did not directly predict temporal discounting rates. Using similar threat priming, Study 2b further confirmed that Americans in the high-threat priming condition showed no significant differences in temporal discounting rates compared to those in the low-threat priming condition. The current research deepens the understanding of the cultural difference in the impact of pandemic threats on intertemporal decision-making and further informs the development of interventions that promote individual future-oriented thinking in the face of pandemics.

Functioning in patients with major depressive disorder in remission: A systematic review and meta-analysis

BACKGROUND

Major depressive disorder (MDD) is one of the leading causes of burden of disease globally. We aimed to investigate whether global functioning is impaired in patients with MDD in full or partial remission compared to healthy control individuals (HC).

METHODS

We conducted a systematic review and meta-analysis according to the PRISMA guideline. We searched the databases PubMed, EMBASE and PsycINFO from January 1st 1980 to February 1st 2023. We included studies of adults with a diagnosis/former diagnosis of MDD with assessment of global functioning performed during a state of full or partial remission. The methodological quality was assessed using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. Standardised mean differences (SMD) using random-effects models were calculated as the summary measure. We further performed meta-analyses of the mean raw score in patients with MDD for individual functioning scales.

RESULTS

Forty-two studies, comprising 17,999 patients with MDD and 35,550 HC, were included, 14 of which included both patients with MDD in full or partial remission and HC. Global functioning was lower in patients with MDD in full or partial remission compared with HC (SMD -2.00, 95 % CI: -0.9 to -3.03, 15 comparisons, I2: 99.8 %).

LIMITATIONS

Important information about the study participants and setting was not reported for most studies, or the reporting was unclear.

CONCLUSION

Patients with MDD have lower levels of functioning compared with HC also when in full or partial remission. Assessment of functioning should be an essential component of managing patients with MDD, also during remission.

A multinational analysis of how emotions relate to economic decisions regarding time or risk

Emotions have been theorized to be important drivers of economic choices, such as intertemporal or risky decisions. Our systematic review and meta-analysis of the previous literature (378 results and 50,972 participants) indicates that the empirical basis for these claims is mixed and the cross-cultural generalizability of these claims has yet to be systematically tested. We analysed a dataset with representative samples from 74 countries (n = 77,242), providing a multinational test of theoretical claims that individuals' ongoing emotional states predict their economic preferences regarding time or risk. Overall, more positive self-reported emotions generally predicted a willingness to wait for delayed rewards or to take favourable risks, in line with some existing theories. Contrary to the assumption of a universal relationship between emotions and decision-making, we show that these relationships vary substantially and systematically across countries. Emotions were stronger predictors of economic decisions in more economically developed and individualistic countries.

Effects of a 5-HT4 receptor antagonist in the caudate nucleus on the performance of macaques in a delayed reward task

Temporal discounting, in which the recipient of a reward perceives the value of that reward to decrease with delay in its receipt, is associated with impulsivity and psychiatric disorders such as depression. Here, we investigate the role of the serotonin 5-HT4 receptor (5-HT4R) in modulating temporal discounting in the macaque dorsal caudate nucleus (dCDh), the neurons of which have been shown to represent temporally discounted value. We first mapped the 5-HT4R distribution in macaque brains using positron emission tomography (PET) imaging and confirmed dense expression of 5-HT4R in the dCDh. We then examined the effects of a specific 5-HT4R antagonist infused into the dCDh. Blockade of 5-HT4R significantly increased error rates in a goal-directed delayed reward task, indicating an increase in the rate of temporal discounting. This increase was specific to the 5-HT4R blockade because saline controls showed no such effect. The results demonstrate that 5-HT4Rs in the dCDh are involved in reward-evaluation processes, particularly in the context of delay discounting, and suggest that serotonergic transmission via 5-HT4R may be a key component in the neural mechanisms underlying impulsive decisions, potentially contributing to depressive symptoms.

Decision-making under stress: A psychological and neurobiological integrative model

Understanding the impact of stress on cognitive processes, particularly decision-making, is crucial as it underpins behaviors essential for survival. However, research in this domain has yielded disparate results, with inconsistencies evident across stress-induction paradigms and drug administration protocols designed to investigate specific stress pathways or neuromodulators. Building upon empirical studies, this research identifies a multifaceted matrix of variables contributing to the divergent findings. This matrix encompasses factors such as the temporal proximity between stressors and decision tasks, the nature of stressors and decision contexts, individual characteristics including psychobiological profiles and affective states at the time of decision-making and even cultural influences. In response to these complexities, we propose a comprehensive model that integrates these relevant factors and their intricate interplay to elucidate the mechanisms governing decision-making during stressful events. By synthesizing these insights, our model not only refines existing paradigms but also provides a framework for future study designs, offering avenues for theoretical advancements and translational developments in the field of stress's impact on cognitive functions. This research contributes to a deeper understanding of the nuanced relationship between stress and decision-making, ultimately advancing our knowledge of cognitive processes under challenging conditions.

Delay discounting is associated with addiction and mental health measures while controlling for health behaviors and health barriers in a large US sample

Background

Excessive discounting of future rewards [delay discounting (DD)] may be a transdiagnostic process and treatment target underlying behavioral health outcomes, including trauma, depression, anxiety, and problematic substance use. However, multiple health behaviors and barriers are also related to these outcomes, including social media usage, adverse childhood experiences (ACEs), sleep quality, healthcare access, housing status, and exercise. To extend research examining DD as transdiagnostic process, we recruited a large, heterogenous sample to examine the association between DD, problematic substance use, and mental health outcomes while controlling for certain health behaviors and health barriers.

Method

In a cross-sectional online survey of 3992 US residents, we administered validated measures of PTSD, depression, anxiety, and problematic alcohol, stimulant, and opioid use. Using linear or ordinal logistic models, scores for each outcome were regressed onto DD while controlling for demographics, health behaviors, and health barriers.

Results

Including only DD and demographics, DD was associated with each outcome at low effect sizes (ƒ2 = .013, OR range = 1.08-1.16). Except for opioid ASSIST scores, these relationships held when controlling for social media usage, sleep, housing status, healthcare access, ACEs, physical exercise, and demographic variables (ƒ2 = .002, OR range = 1.03-1.12), increasing confidence that DD concurrently and directly relates to four of these five clinical outcomes.

Discussion

These findings support the conceptualization of DD as a transdiagnostic process underlying certain psychopathologies and suggest targeting DD in co-occurring substance use disorder and/or mental health treatments may result in clinically significant outcomes.

Optogenetic activation of dorsal raphe serotonin neurons induces brain-wide activation

Serotonin is a neuromodulator that affects multiple behavioral and cognitive functions. Nonetheless, how serotonin causes such a variety of effects via brain-wide projections and various receptors remains unclear. Here we measured brain-wide responses to optogenetic stimulation of serotonin neurons in the dorsal raphe nucleus (DRN) of the male mouse brain using functional MRI with an 11.7 T scanner and a cryoprobe. Transient activation of DRN serotonin neurons caused brain-wide activation, including the medial prefrontal cortex, the striatum, and the ventral tegmental area. The same stimulation under anesthesia with isoflurane decreased brain-wide activation, including the hippocampal complex. These brain-wide response patterns can be explained by DRN serotonergic projection topography and serotonin receptor expression profiles, with enhanced weights on 5-HT1 receptors. Together, these results provide insight into the DR serotonergic system, which is consistent with recent discoveries of its functions in adaptive behaviors.

Psychometric properties of the Chinese version of the Quick Delay Questionnaire (C-QDQ) and ecological characteristics of reward-delay impulsivity of adults with ADHD

BACKGROUND

The Quick Delay Questionnaire (QDQ) is a short questionnaire designed to assess delay-related difficulties in adults. This study aimed to examine the reliability and validity of the Chinese version of the QDQ (C-QDQ) in Chinese adults, and explore the ecological characteristics of delay-related impulsivity in Chinese adults with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Data was collected from 302 adults, including ADHD (n = 209) and healthy controls (HCs) (n = 93). All participants completed the C-QDQ. The convergent validity, internal consistency, retest reliability and confirmatory factor analysis (CFA) of the C-QDQ were analyzed. The correlations between C-QDQ and two laboratory measures of delay-related difficulties and Barratt Impulsiveness Scale-11 (BIS-11), the comparison of C-QDQ scores between ADHD subgroups and HCs were also analyzed.

RESULTS

The Cronbach's α of C-QDQ was between 0.83 and 0.89. The intraclass correlation coefficient of C-QDQ was between 0.80 and 0.83. The results of CFA of C-QDQ favoured the original two-factor model (delay aversion and delay discounting). Significant positive associations were found between C-QDQ scores and BIS-11 total score and performance on the laboratory measure of delay-related difficulties. Participants with ADHD had higher C-QDQ scores than HCs, and female ADHD reported higher scores on delay discounting subscale than male. ADHD-combined type (ADHD-C) reported higher scores on delay aversion subscale than ADHD-inattention type (ADHD-I).

CONCLUSION

The C-QDQ is a valid and reliable tool to measure delay-related responses that appears to have clinical utility. It can present the delay-related impulsivity of patients with ADHD. Compared to HCs, the level of reward-delay impulsivity was higher in ADHD.

Depression is associated with reduced outcome sensitivity in a dual valence, magnitude learning task

BACKGROUND

Learning from rewarded and punished choices is perturbed in depressed patients, suggesting that abnormal reinforcement learning may be a cognitive mechanism of the illness. However, previous studies have disagreed about whether this behavior is produced by alterations in the rate of learning or sensitivity to experienced outcomes. This previous work has generally assessed learning in response to binary outcomes of one valence, rather than to both rewarding and punishing continuous outcomes.

METHODS

A novel drifting reward and punishment magnitude reinforcement-learning task was administered to patients with current (n = 40) and remitted depression (n = 39), and healthy volunteers (n = 40) to capture potential differences in learning behavior. Standard questionnaires were administered to measure self-reported depressive symptom severity, trait and state anxiety and level of anhedonic symptoms.

RESULTS

Our findings demonstrate that patients with current depression adjust their learning behaviors to a lesser degree in response to trial-by-trial variations in reward and loss magnitudes than the other groups. Computational modeling revealed that this behavioral signature of current depressive state is better accounted for by reduced reward and punishment sensitivity (all p < 0.031), rather than a change in learning rate (p = 0.708). However, between-group differences were not related to self-reported symptom severity or comorbid anxiety disorders in the current depression group.

CONCLUSION

These findings suggest that current depression is associated with reduced outcome sensitivity rather than altered learning rate. Previous findings reported in this domain mainly from binary learning tasks seem to generalize to learning from continuous outcomes.

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.

Theta burst stimulation add on to dialectical behavioral therapy in borderline-personality-disorder: methods and design of a randomized, single-blind, placebo-controlled pilot trial

Specialized psychotherapeutic treatments like dialectical behavioral therapy (DBT) are recommended as first treatment for borderline personality disorder (BPD). In recent years, studies have emerged that focus on repetitive transcranial magnetic stimulation (rTMS) in BPD. Both have independently demonstrated efficacy in the treatment of BPD. Intermitted theta burst stimulation (iTBS), a modified design of rTMS, is thought to increase the excitability of neurons and could be a supplement to psychotherapy in addition to being a standalone treatment. However, no studies to date have investigated the combination of DBT and rTMS/iTBS. This study protocol describes the methods and design of a randomized, single-blinded, sham-controlled clinical pilot study in which BPD patients will be randomly assigned to either iTBS or sham during four consecutive weeks (20 sessions in total) in addition to standardized DBT treatment. The stimulation will focus on the unilateral stimulation of the left dorsolateral prefrontal cortex (DLPFC), which plays an important role in the control of impulsivity and risk-taking. Primary outcome is the difference in borderline symptomatology, while secondary target criteria are depressive symptoms, general functional level, impulsivity and self-compassion. Statistical analysis of therapy response will be conducted by Mixed Model Repeated Measurement using a 2 × 2-factorial between-subjects design with the between-subject factor stimulation (TMS vs. Sham) and the within-subject factor time (T0 vs. T1). Furthermore, structural magnetic resonance imaging (MRI) will be conducted and analyzed. The study will provide evidence and insight on whether iTBS has an enhancing effect as add-on to DBT in BPD.Trial registration: drks.de (DRKS00020413) registered 13/01/2020.

Reward Functioning in General and Specific Psychopathology in Children and Adults

OBJECTIVE

Problems with reward processing have been implicated in multiple psychiatric disorders, but psychiatric comorbidities are common and their specificity to individual psychopathologies is unknown. Here, we evaluate the association between reward functioning and general or specific psychopathologies.

METHOD

1,213 adults and their1,531 children (ages 6-12) completed various measures of the Positive Valence System domain from the Research Domain Criteria (RDoC). Psychopathology was assessed using the Child Behavior Checklist for children and the Adult Self Report for parents.

RESULTS

One general factor identified via principal factors factor analysis explained most variance in psychopathology in both groups. Measures of reward were associated with the general factor and most specific psychopathologies. Certain reward constructs were associated solely with specific psychopathologies but not general psychopathology. However, some prior associations between reward and psychopathology did not hold following removal of comorbidity.

CONCLUSION

Reward dysfunction is significantly associated with both general and specific psychopathologies.

Poke And Delayed Drink Intertemporal Choice Task (POKE-ADDICT): An open-source behavioral apparatus for intertemporal choice testing in rodents

Advancements in neuroscience research present opportunities and challenges, requiring substantial resources and funding. To address this, we describe here "Poke And Delayed Drink Intertemporal Choice Task (POKE-ADDICT)", an open-source, versatile, and cost-effective apparatus for intertemporal choice testing in rodents. This allows quantification of delay discounting (DD), a cross-species phenomenon observed in decision making which provides valuable insights into higher-order cognitive functioning. In DD, the subjective value of a delayed reward is reduced as a function of the delay for its receipt. Using our apparatus, we implemented an effective intertemporal choice paradigm for the quantification of DD based on an adjusting delayed amount (ADA) algorithm using mango juice as a reward. Our paradigm requires limited training, a few 3D-printed parts and inexpensive electrical components, including a Raspberry Pi control unit. Furthermore, it is compatible with several in vivo procedures and the use of nose pokes instead of levers allows for faster task learning. Besides the main application described here, the apparatus can be further extended to implement other behavioral tests and protocols, including standard operant conditioning. In conclusion, we describe a versatile and cost-effective design based on Raspberry Pi that can support research in animal behavior, decision making and, more specifically, delay discounting.

Lesions to different regions of frontal cortex have dissociable effects on voluntary persistence

Deciding how long to keep waiting for uncertain future rewards is a complex problem. Previous research has shown that choosing to stop waiting results from an evaluative process that weighs the subjective value of the awaited reward against the opportunity cost of waiting. In functional neuroimaging data, activity in ventromedial prefrontal cortex (vmPFC) tracks the dynamics of this evaluation, while activation in the dorsomedial prefrontal cortex (dmPFC) and anterior insula (AI) ramps up before a decision to quit is made. Here, we provide causal evidence of the necessity of these brain regions for successful performance in a willingness-to-wait task. 28 participants with frontal lobe lesions were tested on their ability to adaptively calibrate how long they waited for monetary rewards. We grouped the participants based on the location of their lesions, which were primarily in ventromedial, dorsomedial, or lateral parts of their prefrontal cortex (vmPFC, dmPFC, and lPFC, respectively), or in the anterior insula. We compared the performance of each subset of lesion participants to behavior in a control group without lesions (n=18). Finally, we fit a newly developed computational model to the data to glean a more mechanistic understanding of how lesions affect the cognitive processes underlying choice. We found that participants with lesions to the vmPFC waited less overall, while participants with lesions to the dmPFC and anterior insula were specifically impaired at calibrating their level of persistence to the environment. These behavioral effects were accounted for by systematic differences in parameter estimates from a computational model of task performance: while the vmPFC group showed reduced initial willingness to wait, lesions to the dmPFC/anterior insula were associated with slower learning from negative feedback. These findings corroborate the notion that failures of persistence can be driven by sophisticated cost-benefit analyses rather than lapses in self-control. They also support the functional specialization of different parts of the prefrontal cortex in service of voluntary persistence.

Short-active gestational photoperiod reduces effortful choice behavior in mice, partial normalization by d-amphetamine

RATIONALE

Seasonal birth patterns consistently implicate winter gestation as a risk factor for several psychiatric conditions. We recently demonstrated that short-active (SA; 19:5 light:dark)-i.e., "winter-like"-photoperiod exposure across gestation and early life (E0-P28) induces psychiatrically relevant behavioral abnormalities in adult mice, including reduced immobility in the forced swim test (FST) and effortful amotivation. It is unknown, however, whether these effects were driven primarily by prenatal or postnatal mechanisms, and whether perinatal SA photoperiod would similarly reduce effort expenditure in a task relevant to everyday decision-making.

OBJECTIVES AND METHODS

We first tested male and female mice exposed to either gestational (E0-P0) or postnatal (E0-P28) SA photoperiod in the FST to determine whether the previously observed alteration was driven primarily by prenatal versus postnatal photoperiod. We then assessed whether SA gestational photoperiod reduces effortful choice behavior in the cross-species effort-based decision-making task (EBDMT) and whether any such deficit could be remediated by d-amphetamine (0.1 and 0.3 mg/kg, i.p.).

RESULTS

Mice exposed to prenatal, but not postnatal, SA photoperiod exhibited reduced FST immobility relative to controls and also demonstrated condition-dependently reduced preference for high-effort/high-reward versus low-effort/low-reward contingencies in the EBDMT. This effortful choice deficit was normalized by 0.1 mg/kg amphetamine.

CONCLUSIONS

These data: (1) suggest a greater contribution of gestational versus postnatal light conditions to the behavioral effects of perinatal SA photoperiod; and (2) implicate altered dopamine signaling in the behavioral phenotype of the SA-born mouse and possibly in the etiology of winter gestation-associated cases of psychiatric disease.

A new paradigm for addictions

AIM

To suggest a new paradigm for addictions.

METHODS

Consideration of relevant research findings and thought experiments.

RESULTS

Common mental motors leading to addictions are pleasure-seeking and hyperbolic discounting. The important point of the latter is that given two choices of future rewards, commonly one initially prefers the larger one available after a longer waiting time but despite this the smaller and sooner reward will be chosen when it becomes available. These are general biological properties, found at least in human beings, the rat, and the pigeon. If this continues it may create an unconscious habit, difficult to change. Several other risk factors for addictions are known, notably both externalizing and internalizing mental problems. Predisposing factors are likely to interact.

CONCLUSIONS

The above suggests a new paradigm for addictions. Pleasure provides temptations, hyperbolic discounting weakens the will. Habits emerge. Addictions seem to be a group of problems of its own kind, not diseases, because diseases do not bring about pleasure, and are not sought for pleasure.

Neural dynamics underlying self-control in the primate subthalamic nucleus

The subthalamic nucleus (STN) is hypothesized to play a central role in neural processes that regulate self-control. Still uncertain, however, is how that brain structure participates in the dynamically evolving estimation of value that underlies the ability to delay gratification and wait patiently for a gain. To address that gap in knowledge, we studied the spiking activity of neurons in the STN of monkeys during a task in which animals were required to remain motionless for varying periods of time in order to obtain food reward. At the single-neuron and population levels, we found a cost-benefit integration between the desirability of the expected reward and the imposed delay to reward delivery, with STN signals that dynamically combined both attributes of the reward to form a single integrated estimate of value. This neural encoding of subjective value evolved dynamically across the waiting period that intervened after instruction cue. Moreover, this encoding was distributed inhomogeneously along the antero-posterior axis of the STN such that the most dorso-posterior-placed neurons represented the temporal discounted value most strongly. These findings highlight the selective involvement of the dorso-posterior STN in the representation of temporally discounted rewards. The combination of rewards and time delays into an integrated representation is essential for self-control, the promotion of goal pursuit, and the willingness to bear the costs of time delays.

Pharmacological Modulation of Temporal Discounting: A Systematic Review

Temporal discounting is a phenomenon where a reward loses its value as a function of time (e.g., a reward is more valuable immediately than when it delays in time). This is a type of intertemporal decision-making that has an association with impulsivity and self-control. Many pathologies exhibit higher discounting rates, meaning they discount more the values of rewards, such as addictive behaviors, bipolar disorder, attention-deficit/hyperactivity disorders, social anxiety disorders, and major depressive disorder, among others; thus, many studies look for the mechanism and neuromodulators of these decisions. This systematic review aims to investigate the association between pharmacological administration and changes in temporal discounting. A search was conducted in PubMed, Scopus, Web of Science, Science Direct and Cochrane. We used the PICO strategy: healthy humans (P-Participants) that received a pharmacological administration (I-Intervention) and the absence of a pharmacological administration or placebo (C-Comparison) to analyze the relationship between the pharmacological administration and the temporal discounting (O-outcome). Nineteen studies fulfilled the inclusion criteria. The most important findings were the involvement of dopamine modulation in a U-shape for choosing the delayed outcome (metoclopradime, haloperidol, and amisulpride). Furthermore, administration of tolcapone and high doses of d-amphetamine produced a preference for the delayed option. There was a time-dependent hydrocortisone effect in the preference for the immediate reward. Thus, it can be concluded that dopamine is a crucial modulator for temporal discounting, especially the D2 receptor, and cortisol also has an important time-dependent role in this type of decision. One of the limitations of this systematic review is the heterogeneity of the drugs used to assess the effect of temporal discounting.

Overharvesting in human patch foraging reflects rational structure learning and adaptive planning

Patch foraging presents a sequential decision-making problem widely studied across organisms-stay with a current option or leave it in search of a better alternative? Behavioral ecology has identified an optimal strategy for these decisions, but, across species, foragers systematically deviate from it, staying too long with an option or "overharvesting" relative to this optimum. Despite the ubiquity of this behavior, the mechanism underlying it remains unclear and an object of extensive investigation. Here, we address this gap by approaching foraging as both a decision-making and learning problem. Specifically, we propose a model in which foragers 1) rationally infer the structure of their environment and 2) use their uncertainty over the inferred structure representation to adaptively discount future rewards. We find that overharvesting can emerge from this rational statistical inference and uncertainty adaptation process. In a patch-leaving task, we show that human participants adapt their foraging to the richness and dynamics of the environment in ways consistent with our model. These findings suggest that definitions of optimal foraging could be extended by considering how foragers reduce and adapt to uncertainty over representations of their environment.

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.

Investigating associations of delay discounting with brain structure, working memory, and episodic memory

INTRODUCTION

Delay discounting (DD), the preference for smaller and sooner rewards over larger and later ones, is an important behavioural phenomenon for daily functioning of increasing interest within psychopathology. The neurobiological mechanisms behind DD are not well understood and the literature on structural correlates of DD shows inconsistencies.

METHODS

Here we leveraged a large openly available dataset (n = 1196) to investigate associations with memory performance and gray and white matter correlates of DD using linked independent component analysis.

RESULTS

Greater DD was related to smaller anterior temporal gray matter volume. Associations of DD with total cortical volume, subcortical volumes, markers of white matter microscopic organization, working memory, and episodic memory scores were not significant after controlling for education and income.

CONCLUSION

Effects of size comparable to the one we identified would be unlikely to be replicated with sample sizes common in many previous studies in this domain, which may explain the incongruities in the literature. The paucity and small size of the effects detected in our data underscore the importance of using large samples together with methods that accommodate their statistical structure and appropriate control for confounders, as well as the need to devise paradigms with improved task parameter reliability in studies relating brain structure and cognitive abilities with DD.

Revisiting fruit and vegetable determinants: Evidence from Latin America

Introduction

In the past decade, the public health discussion regarding fruit and vegetable (FV) consumption has been dominated by economic and physical accessibility.

Methods

Using an online survey in four Latin American countries, we applied a set of tobit models to compare the determinants of desirable and current consumption of FV levels for satisfied and unsatisfied respondents.

Results

We found that, even when consuming less than five FV portions a day, most of the respondents were satisfied with their current FV consumption level. Satisfied respondents consumed significantly more FV than unsatisfied ones. In general, the desirable and current consumption of FV levels were associated with different sets of determinants, while years of education were relevant in both cases. Finally, in a hypothetical case where unsatisfied respondents would not face any physical or economic access restrictions, unsatisfied respondents would not reach the goal of five FV portions a day.

Discussion

Assuming that physical and economic access improved, this would automatically increase FV to reach the five-a-day recommendation may be inaccurate in some cases. We also need to take mental access into account. We may ask how to improve the desirable level of FVs and then how to close the gap between the current and desirable FV levels.

Reduced social risk-taking in depression

Evolutionary models of depression posit that depressed mood represents an adaptive response to unacceptably low social status, motivating the inhibition of social risk-taking in favor of submissive behaviors which reduce the likelihood of social exclusion. We tested the hypothesis of reduced social risk taking using a novel adaptation of the Balloon Analogue Risk Task (BART) in participants with major depressive disorder (MDD; n = 27) and never-depressed comparison participants (n = 35). The BART requires participants to pump up virtual balloons. The more the balloon is pumped up, the more money a participant gains on that trial. However, more pumps also increase the risk the balloon will burst such that all money is lost. Prior to performing the BART, participants took part in a team induction in small groups in order to prime social-group membership. Participants then completed two conditions of the BART: an Individual condition where they risked only their own money, and a Social condition, where they risked the money of their social group. The groups did not differ in their performance in the individual condition (Cohen's d = 0.07). However, the MDD group risked fewer pumps in the Social condition than the never-depressed group (d = 0.57). The study supports the notion of an aversion to social risk-taking in depression. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

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.

Facing the pandemic in the dark: Psychopathic personality traits and life history strategies during COVID-19 lockdown period in different areas of China

The current research aims to examine variation in psychopathic personality traits and life history strategies during COVID-19 lockdown period in different areas of China. In Study 1 (N = 564), participants completed explicit measures of psychopathic traits and of life history strategy. To attenuate common method biases, Study 2 (N = 267) employed an alternative measure of psychopathy and an indirect measure of life history strategy, namely, future-discounting. Across two studies, we found consistent and significant evidence that participants from Wuhan, the initial epicenter of the pandemic, evidenced a faster life history strategy and a markedly higher level of psychopathic traits than did participants from Chongqing, which was less affected by the virus. Furthermore, a consistent pattern of correlation between life history strategy and psychopathy was observed across different groups of participants. We also replicated some previously reported studies but found that not all sex effects were consistent with life history in Chinese populations. Taken together, these findings suggest that individuals may show a high degree of variation in life history speed and psychopathic traits in response to unpredictable and adverse environments, which provide support for extended life history plasticity.

The impact of automatic enrolment on the mental health gap in pension participation: Evidence from the UK

A large body of evidence shows that individuals with poor mental health have lower income over the lifespan but a dearth of evidence exists on how poor mental health affects savings behaviour. In this paper, we provide novel evidence of a mental health gap in pension participation in the UK using nationally representative longitudinal data from Understanding Society (UKHLS). Beginning in 2012, the UK government introduced automatic enrolment enabling us to assess the impact of one of the largest pension policy reforms in the world on this mental health gap. We measure mental health using the General Health Questionnaire (GHQ-12) which is a commonly used tool for measuring psychological distress. Prior to automatic enrolment, we find that male private sector employees with poor mental health are 3.7 percentage points less likely to participate in a workplace pension scheme while female private sector employees with poor mental health are 2.9 percentage points less likely to participate after controlling for key observables including age, education, race, marital status, number of children, occupation type, industry type, presence of a physical health condition and cognitive ability. The implementation of automatic enrolment removes the mental health gap in pension participation, equalising the pension participation rates of individuals with and without poor mental health in the private sector.

Intersections between environmental reward availability, loss aversion, and delay discounting as potential risk factors for cigarette smoking and other substance use

Behavioral theory suggests that density of environmental rewarding activities and biases in decision making influence risk for substance use disorder (SUD). To better understand intersections of these potential risk factors, this study examined whether environmental reward predicted smoking status or other drug use and whether such associations were independent of two decision-making biases known to predict SUD risk, namely loss aversion and delay discounting. Individuals that reported current daily cigarette smoking (n = 186; >10 cigarettes/day) and never-smoking (n = 241; <100 cigarettes lifetime) were recruited with standard crowdsourcing methods. Participants answered questions on alcohol and other drug use. Environmental reward was assessed using the Reward Probability Index (RPI), and loss aversion (LA) and delay discounting (DD) using a gamble-acceptance task and monetary choice questionnaire, respectively. Associations of RPI, LA, and DD with cigarette smoking, alcohol use, other drug use, and combinations of co-use were examined with logistic regression controlling for sociodemographic variables (educational attainment, gender, age). Low RPI (odds ratio[OR] = 0.97, p = .006), low LA (OR = 1.22, p < .001), and high DD (OR = 1.12, p = .03), were each independently associated with increased risk for cigarette smoking, as well as other substance use, and use combinations. We saw no evidence that RPI was significantly influencing associations between LA and DD with smoking status or other substance use. Finally, RPI, but not LA or DD, was significantly associated with depressed mood and sleep disturbance. These results provide new evidence on associations of RPI with smoking status and other substance use while further documenting independent associations between LA and DD and those outcomes.

The effect of social exclusion on intertemporal choice in suicide attempters: A preliminary experimental study

BACKGROUND

Suicide-related theories and a growing body of evidence suggest that suicidal patients may have a tendency toward "short-sightedness"-the preference for immediate gratification when making intertemporal choice-and that social exclusion may exacerbate this tendency in suicidal patients. The present study examined the intertemporal choice performance of suicide attempters under conditions of social exclusion in a sample of affective disorder patients.

METHODS

A total of 64 affective disorder patients (22 non-suicidal patients, 24 single-suicide attempters and 18 multiple-suicide attempters) completed an intertemporal choice task in an exclusion or a non-exclusion condition. Social exclusion was manipulated using the Cyberball paradigm.

RESULTS

Non-suicidal patients and single-suicide attempters both exhibited an exaggerated preference for immediate rewards in the exclusion condition compared with the non-exclusion condition; in contrast, the multiple-suicide attempters appeared relatively indifferent to the social exclusion, exhibiting virtually identical preferences for immediate rewards in both the exclusion and non-exclusion conditions. In addition, the multiple-suicide attempters exhibited an exaggerated preference for immediate rewards compared with non-suicidal patients and single-suicide attempters in the non-exclusion condition, while the three groups did not differ in the exclusion condition.

CONCLUSIONS

Affective disorder patients with a single or no suicide attempts are more short-sighted after being excluded, while those with multiple suicide attempts appeared consistent short-sightedness in both exclusion and non-exclusion conditions. The study provides preliminary evidence of the role of disadvantageous intertemporal choice in the suicidal process. Future research replicate and extend these findings could have implications for suicide prevention and intervention.

Hippocampal neurogenesis promotes effortful responding but does not regulate effort-based choice

A fundamental trait of depression is low motivation. Hippocampal neurogenesis has been associated with motivational deficits but detailed evidence on how it regulates human-relevant behavioral traits is still missing. We used the hGFAP-TK rat model to deplete actively dividing neural stem cells in the rat hippocampus. Use of the effort-discounting operant task allowed us to identify specific and detailed deficits in motivation behavior. In this task, rats are given a choice between small and large food rewards, where 2-20 lever presses are required to obtain the large reward (four sugar pellets) versus one press to receive the smaller reward (two sugar pellets). We found that depleting adult neurogenesis did not affect effort-based choice or general motivation to complete the task. However, lack of adult neurogenesis reduced the pressing rate and thus increased time to complete the required presses to obtain a reward. In summary, the present study finds that adult hippocampal neurogenesis specifically reduces response vigor to obtain rewards and thus deepens our understanding in how neurogenesis shapes depression.

Decision value signals in the ventromedial prefrontal cortex and motivational and hedonic symptoms across mood and psychotic disorders

Deficits in motivation and pleasure are common across many psychiatric disorders, and manifest as symptoms of amotivation and anhedonia, which are prominent features of both mood and psychotic disorders. Here we provide evidence for an association between neural value signals and symptoms of amotivation and anhedonia across adults with major depression, bipolar disorder, schizophrenia, or no psychiatric diagnosis. We found that value signals in the ventromedial prefrontal cortex (vmPFC) during intertemporal decision-making were dampened in individuals with greater motivational and hedonic deficits, after accounting for primary diagnosis. This relationship remained significant while controlling for diagnosis-specific symptoms of mood and psychosis, such as depression as well as positive and negative symptoms. Our results demonstrate that dysfunction in the vmPFC during value-based decision-making is specifically linked to motivational and hedonic impairments. These findings provide a quantitative neural target for the potential development of novel treatments for amotivation and anhedonia.

Expectations of immediate and delayed reward differentially affect cognitive task performance

The current study used a modified Monetary Incentive Delay task to examine the neural mechanisms underlying anticipating and receiving an immediate or delayed reward and examined the influence of pursuing these rewards on cognitive task performance. A pre-cue indicating the potential of gaining a monetary reward (immediate-, delayed-, vs. no-reward) was followed by a target stimulus requiring a fast and accurate response. Then, response-contingent feedback was presented indicating whether or not the participant would receive the corresponding reward. Linear mixed-effect models revealed the fastest behavioural responses and the strongest neural activity, as reflected in event-related-potentials and event-related-spectral-perturbation responses, for immediate reward, followed by delayed reward, with the slowest behavioural responses and the weakest neural activities observed in the no-reward condition. Expectations related to the cue-P3 component and the cue-delta activities predicted behavioural performance, especially in the immediate reward condition. Moreover, exploratory analyses revealed that depression moderated the relationship between target-locked neural activity and behavioural performance in the delayed reward condition, with lower neural activity being related to worse behavioural performance amongst participants scoring high on depression. These results indicate that differential value representations formed through delay discounting directly affect neural responses in reward processing and directly influence the effort invested in the current task, which is reflected by behavioural responses and is in agreement with the expected value of control theory.

What Can Reinforcement Learning Models of Dopamine and Serotonin Tell Us about the Action of Antidepressants?

Although evidence suggests that antidepressants are effective at treating depression, the mechanisms behind antidepressant action remain unclear, especially at the cognitive/computational level. In recent years, reinforcement learning (RL) models have increasingly been used to characterise the roles of neurotransmitters and to probe the computations that might be altered in psychiatric disorders like depression. Hence, RL models might present an opportunity for us to better understand the computational mechanisms underlying antidepressant effects. Moreover, RL models may also help us shed light on how these computations may be implemented in the brain (e.g., in midbrain, striatal, and prefrontal regions) and how these neural mechanisms may be altered in depression and remediated by antidepressant treatments. In this paper, we evaluate the ability of RL models to help us understand the processes underlying antidepressant action. To do this, we review the preclinical literature on the roles of dopamine and serotonin in RL, draw links between these findings and clinical work investigating computations altered in depression, and appraise the evidence linking modification of RL processes to antidepressant function. Overall, while there is no shortage of promising ideas about the computational mechanisms underlying antidepressant effects, there is insufficient evidence directly implicating these mechanisms in the response of depressed patients to antidepressant treatment. Consequently, future studies should investigate these mechanisms in samples of depressed patients and assess whether modifications in RL processes mediate the clinical effect of antidepressant treatments.

Childhood adversity and impaired reward processing: A meta-analysis

BACKGROUND

Childhood adversity (CA) is associated with increased risk of psychopathology, and reward processing (RP) may be one of the underlying mechanisms. However, evidence on impaired RP in childhood adversity is theoretically and methodologically heterogeneous.

OBJECTIVE

To provide a quantitative overview of studies on the relation between childhood adversity and RP assessed at the behavioral and subjective levels, and identify differences between studies that influence the effect size.

PARTICIPANTS AND SETTING

Twenty-seven studies (overall N = 6801) were included.

METHODS

Peer-reviewed publications describing empirical studies on the relation between CA and behavioral and self-report measures of RP in humans were identified through systematic searches in six bibliographic databases. Effect sizes (r) were pooled using random-effects models. The potential moderator role of RP dimension, type of RP assessment, type of childhood adversity assessment, and age were examined.

RESULTS

Results indicated a small, but consistent association between CA and impaired RP (r = 0.12; 95% CI: 0.07, 0.16), with medium heterogeneity (I² = 62.43). The effect size was significantly larger (i.e., medium-sized) in studies that focused on reward learning rather than reward valuation and reward responsiveness; used cognitive tasks rather than self-report assessments of RP; and relied on official records rather than subjective reports of CA. There was evidence of publication bias, but overall effect size remained significant after imputation.

CONCLUSIONS

These results suggest that multidimensional RP impairments (e.g., deficits in reward learning, biased reward valuation) are a consistent marker of CA, and may represent mechanisms underlying the increased risk of psychopathology.

Opposite effects of stress on effortful motivation in high and low anxiety are mediated by CRHR1 in the VTA

Individuals frequently differ in their behavioral and cognitive responses to stress. However, whether motivation is differently affected by acute stress in different individuals remains to be established. By exploiting natural variation in trait anxiety in outbred Wistar rats, we show that acute stress facilitates effort-related motivation in low anxious animals, while dampening effort in high anxious ones. This model allowed us to address the mechanisms underlying acute stress-induced differences in motivated behavior. We show that CRHR1 expression levels in dopamine neurons of the ventral tegmental area (VTA)-a neuronal type implicated in the regulation of motivation-depend on animals' anxiety, and these differences in CRHR1 expression levels explain the divergent effects of stress on both effortful behavior and the functioning of mesolimbic DA neurons. These findings highlight CRHR1 in VTA DA neurons-whose levels vary with individuals' anxiety-as a switching mechanism determining whether acute stress facilitates or dampens motivation.

Social trust and the discounting of gains and losses in prolonged grief

Prolonged grief (PG) is a potentially debilitating consequence of bereavement. Previous studies have associated PG severity with relative deficits in key future-oriented cognitive processes, including the discounting of future rewards. Individual differences in the rate at which one devalues the future have been associated with a range of important economic and health outcomes. To extend understanding of the mechanisms underlying discounting behaviour in PG, this study investigated discounting behaviour using an online paradigm where future consequences were made salient at the time of the decision. Ninety-four bereaved participants made choices to accept or reject offers that involved either an immediate gain and a long-term loss, or an immediate loss and a longer-term gain. Lower levels of social trust and higher PG severity were associated with greater discounting of future losses. Social trust but not PG severity was related to discounting of future gains. Results replicate and extend on previous findings in PG, and suggest potentially modifiable factors to reduce the biases in decision making processes that may contribute to ongoing dysfunction in PG.

A translational perspective on the anti-anhedonic effect of ketamine and its neural underpinnings

Anhedonia, a pronounced reduction in interest or pleasure in any of life's daily activities, is a cardinal symptom of major depression. In this Perspective article, we synthesise the recent evidence from rodent, monkey and human neuroimaging literature to highlight how the habenula, a small evolutionarily conserved subcortical structure located in the midbrain, may orchestrate the behavioural expression of anhedonia across fronto-mesolimbic networks. We then review how this circuitry can be modulated by ketamine, an NMDA receptor antagonist with rapid antidepressant properties. We propose that experimental paradigms founded in reinforcement learning and value-based decision-making can usefully probe this network and thereby help elucidate the mechanisms underlying ketamine's rapid antidepressant action.

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.

Executive Functioning and the Pursuit of Happiness

Executive functioning and happiness are each associated with successful learning and other desirable individual and societal outcomes; however, it is unclear whether a relation exists between them. Executive regulation of happiness pursuits in daily life, operationalized as hedonic (e.g., pursuing pleasure) and eudaimonic (e.g., pursuing personal growth) motives for action, may be a way the constructs relate to each other. In this initial investigation, we aimed to explore whether objectively measured executive functioning skills relate to happiness motives. A sample of 119 college students completed six objective neuropsychological measures of executive functioning and self-reported levels of hedonic and eudaimonic motives for action in daily life. Correlation and regression analyses examined the relations among temporal discounting and two latent executive functioning factors (inhibitory control and working memory) with hedonic and eudaimonic motives, as well as their interaction. Results suggested a possible association between higher levels of eudaimonic motives and preference for higher delayed rewards, as well as poorer working memory. Further analyses suggested that endorsing high levels of eudaimonic and hedonic motives simultaneously (i.e., the "full life") was associated with poorer inhibitory control and working memory performance, whereas endorsing low levels of both simultaneously (i.e., the "empty life") was associated with a preference for more immediate monetary rewards. Findings are discussed in the context of goal conflict and risk assessment among individuals who endorse the "full life". Overall, these findings suggest that complex relations may exist between executive functioning and trait-level happiness pursuits, and have implications for possible interventions aimed at enhancing happiness-related motives and cognitive processes to facilitate learning. Given the exploratory nature of the present study, further investigations are necessary.

Anhedonia as a central factor in depression: Neural mechanisms revealed from preclinical to clinical evidence

Anhedonia is one of the core symptoms of major depressive disorder (MDD), which is often inadequately treated by traditional antidepressants. The modern framework of anhedonia extends the definition from impaired consummatory pleasure or interest in rewards to a broad spectrum of deficits that impact functions such as reward anticipation, approach motivation, effort expenditure, reward valuation, expectation, and reward-cue association learning. Substantial preclinical and clinical research has explored the neural basis of reward deficits in the context of depression, and has implicated mesocorticolimbic reward circuitry comprising the nucleus accumbens, ventral pallidum, ventral tegmental area, amygdala, hippocampus, anterior cingulate, insula, orbitofrontal cortex, and other prefrontal cortex regions. Dopamine modulates several reward facets including anticipation, motivation, effort, and learning. As well, serotonin, norepinephrine, opioids, glutamate, Gamma aminobutyric acid (GABA), and acetylcholine are also involved in anhedonia, and medications targeting these systems may also potentially normalize reward processing in depression. Unfortunately, whereas reward anticipation and reward outcome are extensively explored by both preclinical and clinical studies, translational gaps remain in reward motivation, effort, valuation, and learning, where clinical neuroimaging studies are in the early stages. This review aims to synthesize the neurobiological mechanisms underlying anhedonia in MDD uncovered by preclinical and clinical research. The translational difficulties in studying the neural basis of reward are also discussed.

Single caudate neurons encode temporally discounted value for formulating motivation for action

The term 'temporal discounting' describes both choice preferences and motivation for delayed rewards. Here we show that neuronal activity in the dorsal part of the primate caudate head (dCDh) signals the temporally discounted value needed to compute the motivation for delayed rewards. Macaque monkeys performed an instrumental task, in which visual cues indicated the forthcoming size and delay duration before reward. Single dCDh neurons represented the temporally discounted value without reflecting changes in the animal's physiological state. Bilateral pharmacological or chemogenetic inactivation of dCDh markedly distorted the normal task performance based on the integration of reward size and delay, but did not affect the task performance for different reward sizes without delay. These results suggest that dCDh is involved in encoding the integrated multi-dimensional information critical for motivation.

Residual Effects of Cannabis Use on Effort-Based Decision-Making

OBJECTIVE

Acute Δ9-tetrahydrocannabinol (THC) administration in humans (Lawn etal., 2016) and rats (Silveira, Adams, Morena, Hill, & Winstanley, 2016) has been associated with decreased effort allocation that may explain amotivation during acute cannabis intoxication. To date, however, whether residual effects of cannabis use on effort-based decision-making are present and observable in humans have not yet been determined. The goal of this study was to test whether prolonged cannabis use has residual effects on effort-based decision-making in 24-hr abstinent cannabis using adults.

METHOD

We evaluated performance on the Effort Expenditure for Reward Task (EEfRT) in 41 adult cannabis users (mean age = 24.63 years, 21 males) and 45 nonusers (mean age = 23.90 years, 19 males). A mixed 2x3x3 ANOVA with age as a covariate was performed to examine the effect of group, probability of winning, and reward amount on EEfRT performance. EEfRT performance was operationalized as % of trials for which the hard (vs. easy) condition was chosen. Pearson's correlations were conducted to test the relationship between EEfRT performance and measures of cannabis use, anhedonia and motivation.

RESULTS

We found that cannabis users selected hard trials significantly more than nonusers regardless of win probability or reward level. Frequency of cannabis use was positively correlated with amount of % hard trials chosen. There were no significant correlations between % hard trials chosen, self-reported anhedonia, or motivation.

CONCLUSIONS

These results suggest that unlike acute effects, residual effects of cannabis following 24 hrs of abstinence are associated with greater effort allocation during effort-based decision-making.

Perceptions of Diseases of Despair by Members of Rural and Urban High-Prevalence Communities: A Qualitative Study

IMPORTANCE

Diseases of despair (ie, mortality or morbidity from suicidality, drug abuse, and alcoholism) were first characterized as increasing in rural White working-class populations in midlife with low educational attainment and associated with long-term economic decline. Excess mortality now appears to be associated with working-class citizens across demographic and geographic boundaries, but no known qualitative studies have engaged residents of rural and urban locales with high prevalence of diseases of despair to learn their perspectives.

OBJECTIVE

To explore perceptions about despair-related illness and potential intervention strategies among diverse community members residing in discrete rural and urban hotspots.

DESIGN, SETTING, AND PARTICIPANTS

In this qualitative study, high-prevalence hotspots for diseases of despair were identified from health insurance claims data in Central Pennsylvania. Four focus groups were conducted with 60 community members in organizations and coalitions from 3 census block group hotspot clusters in the health system between September 2019 and January 2020. Focus groups explored awareness and beliefs about causation and potential intervention strategies.

MAIN OUTCOMES AND MEASURES

A descriptive phenomenological approach was applied to thematic analysis, and a preliminary conceptual model was constructed to describe how various factors may be associated with perpetuating despair and with public health.

RESULTS

In total, 60 adult community members participated in 4 focus groups (44 women, 16 men; 40 White non-Hispanic, 17 Black, and 3 Hispanic/Latino members). Three focus groups with 43 members were held in rural areas with high prevalence of diseases of despair, and 1 focus group with 17 members in a high-prevalence urban area. Four themes emerged with respect to awareness and believed causation of despair-related illness, and participants identified common associated factors, including financial distress, lack of critical infrastructure and social services, deteriorating sense of community, and family fragmentation. Intervention strategies focused around 2 themes: (1) building resilience to despair through better community and organizational coordination and peer support at the local level and (2) encouraging broader state investments in social services and infrastructure to mitigate despair-related illness.

CONCLUSIONS AND RELEVANCE

In this qualitative study, rural and urban community members identified common factors associated with diseases of despair, highlighting the association between long-term political and economic decline and public health and a need for both community- and state-level solutions to address despair. Health care systems participating in addressing community health needs may improve processes to screen for despair (eg, social history taking) and codesign primary, secondary, and tertiary interventions aimed at addressing factors associated with distress. Such actions have taken on greater urgency with the COVID-19 pandemic.

Transdiagnostic neuroimaging of reward system phenotypes in ADHD and comorbid disorders

ADHD is a disorder characterized by changes in the reward system and which is highly comorbid with other mental disorders, suggesting common neurobiological pathways. Transdiagnostic neuroimaging findings could help to understand whether a dysregulated reward pathway might be the actual link between ADHD and its comorbidities. We here synthesize ADHD neuroimaging findings on the reward system with findings in obesity, depression, and substance use disorder including their comorbid appearance regarding neuroanatomical features (structural MRI) and activation patterns (resting-state and functional MRI). We focus on findings from monetary-incentive-delay (MID) and delay-discounting (DD) tasks and then review data on striatal connectivity and volumetry. Next, for better understanding of comorbidity in adult ADHD, we discuss these neuroimaging features in ADHD, obesity, depression and substance use disorder and ask whether ADHD heterogeneity and comorbidity are reflected by a common dysregulation in the reward system. Finally, we highlight conceptual issues related to heterogeneous paradigms, different phenotyping, longitudinal prediction and highlight some promising future directions for using striatal reward functioning as a clinical biomarker.

Functional and behavioral effects of de novo mutations in calcium-related genes in patients with bipolar disorder

Bipolar disorder is a common mental illness occurring in approximately 1% of individuals and exhibits lifetime prevalence. Although genetic factors are known to contribute to this disorder, the genetic architecture has not yet been completely clarified. Our initial trio-based exome sequencing study of bipolar disorder showed enrichment of de novo, loss-of-function (LOF) or protein-altering mutations in a combined group with bipolar I and schizoaffective disorders, and the identified de novo mutations were enriched in calcium-related genes. These findings suggested a role for de novo mutations in bipolar disorder. The validity of these statistical associations can be demonstrated if the functional impact of the mutations on cellular function and behavior are identified. In this study, we focused on two de novo LOF mutations in calcium-related genes, EHD1 and MACF1, found in patients with bipolar disorder. We first showed that the EHD1 mutation resulted in a truncated protein with diminished effect on neurite outgrowth and inhibited endocytosis. Next, we used CRISPR/Cas9 to establish two knock-in mouse lines to model the in vivo effects of these mutations. We performed behavioral screening using IntelliCage and long-term wheel running analysis. Ehd1 mutant mice showed higher activity in the light phase. Macf1 mutant mice showed diminished attention and persistence to rewards. These behavioral alterations were similar to the phenotypes in previously proposed animal models of bipolar disorder. These findings endorse the possible role of de novo mutations as a component of the genetic architecture of bipolar disorder which was suggested by the statistical evidence.