Reward/Punishment reversal learning in older suicide attempters

Influences of sleep, cortisol reactivity, and risk/reward-based decision-making on suicide

BACKGROUND AND OBJECTIVES

Poor sleep quality is a known contributor to suicidal thoughts and behaviors. This study examines whether sleep quality modulates the effect of an individual's stress response and risk/reward-based decision making on suicide risk.

METHODS

Participants were 160 adults at a residential substance use treatment facility with lifetime exposure to trauma who completed a clinician-administered measure of suicide risk, the Iowa Gambling Task (IGT), and a self-report measure of sleep. Cortisol reactivity (i.e., changes in cortisol before and after a personalized trauma script) was used to measure stress response. We used quantile regression to examine the effects of sleep, cortisol, and risk/reward decision-making on suicide risk.

RESULTS

We found poor sleep quality to be increasingly salient in individuals at greater risk for suicide than those at lower risk for suicide. Furthermore, individuals with moderate to moderate-high levels of suicide risk seem to have greater cortisol reactivity. In the low-moderate quantile, we found suicide risk to be associated with both high stress reactivity and low-risk, high-reward decision-making, as well as low stress reactivity and high-risk/low-reward decision-making.

LIMITATIONS

These findings should be interpreted considering several methodological constraints, such as the use of a pre-determined sample and instruments not tailored for our hypotheses, the MINI 'Suicide' Module's limited differentiation between suicidal ideation and behavior, and variably timed cortisol sampling.

CONCLUSIONS

Despite these limitations, the findings from this study support the use of evidence-based interventions focused on improving sleep quality and managing emotional reactivity to decrease suicide risk.

Reviewing explore/exploit decision-making as a transdiagnostic target for psychosis, depression, and anxiety

In many everyday decisions, individuals choose between trialling something novel or something they know well. Deciding when to try a new option or stick with an option that is already known to you, known as the "explore/exploit" dilemma, is an important feature of cognition that characterises a range of decision-making contexts encountered by humans. Recent evidence has suggested preferences in explore/exploit biases are associated with psychopathology, although this has typically been examined within individual disorders. The current review examined whether explore/exploit decision-making represents a promising transdiagnostic target for psychosis, depression, and anxiety. A systematic search of academic databases was conducted, yielding a total of 29 studies. Studies examining psychosis were mostly consistent in showing that individuals with psychosis explored more compared with individuals without psychosis. The literature on anxiety and depression was more heterogenous; some studies found that anxiety and depression were associated with more exploration, whereas other studies demonstrated reduced exploration in anxiety and depression. However, examining a subset of studies that employed case-control methods, there was some evidence that both anxiety and depression also were associated with increased exploration. Due to the heterogeneity across the literature, we suggest that there is insufficient evidence to conclude whether explore/exploit decision-making is a transdiagnostic target for psychosis, depression, and anxiety. However, alongside our advisory groups of lived experience advisors, we suggest that this context of decision-making is a promising candidate that merits further investigation using well-powered, longitudinal designs. Such work also should examine whether biases in explore/exploit choices are amenable to intervention.

Exploration-Exploitation and Suicidal Behavior in Borderline Personality Disorder and Depression

Importance

Clinical theory and behavioral studies suggest that people experiencing suicidal crisis are often unable to find constructive solutions or incorporate useful information into their decisions, resulting in premature convergence on suicide and neglect of better alternatives. However, prior studies of suicidal behavior have not formally examined how individuals resolve the tradeoffs between exploiting familiar options and exploring potentially superior alternatives.

Objective

To investigate exploration and exploitation in suicidal behavior from the formal perspective of reinforcement learning.

Design, Setting, and Participants

Two case-control behavioral studies of exploration-exploitation of a large 1-dimensional continuous space and a 21-day prospective ambulatory study of suicidal ideation were conducted between April 2016 and March 2022. Participants were recruited from inpatient psychiatric units, outpatient clinics, and the community in Pittsburgh, Pennsylvania, and underwent laboratory and ambulatory assessments. Adults diagnosed with borderline personality disorder (BPD) and midlife and late-life major depressive disorder (MDD) were included, with each sample including demographically equated groups with a history of high-lethality suicide attempts, low-lethality suicide attempts, individuals with BPD or MDD but no suicide attempts, and control individuals without psychiatric disorders. The MDD sample also included a subgroup with serious suicidal ideation.

Main Outcomes and Measures

Behavioral (model-free and model-derived) indices of exploration and exploitation, suicide attempt lethality (Beck Lethality Scale), and prospectively assessed suicidal ideation.

Results

The BPD group included 171 adults (mean [SD] age, 30.55 [9.13] years; 135 [79%] female). The MDD group included 143 adults (mean [SD] age, 62.03 [6.82] years; 81 [57%] female). Across the BPD (χ23 = 50.68; P < .001) and MDD (χ24 = 36.34; P < .001) samples, individuals with high-lethality suicide attempts discovered fewer options than other groups as they were unable to shift away from unrewarded options. In contrast, those with low-lethality attempts were prone to excessive behavioral shifts after rewarded and unrewarded actions. No differences were seen in strategic early exploration or in exploitation. Among 84 participants with BPD in the ambulatory study, 56 reported suicidal ideation. Underexploration also predicted incident suicidal ideation (χ21 = 30.16; P < .001), validating the case-control results prospectively. The findings were robust to confounds, including medication exposure, affective state, and behavioral heterogeneity.

Conclusions and Relevance

The findings suggest that narrow exploration and inability to abandon inferior options are associated with serious suicidal behavior and chronic suicidal thoughts. By contrast, individuals in this study who engaged in low-lethality suicidal behavior displayed a low threshold for taking potentially disadvantageous actions.

Computational analysis of value learning and value-driven detection of neutral faces by young and older adults

The rapid detection of neutral faces with emotional value plays an important role in social relationships for both young and older adults. Recent psychological studies have indicated that young adults show efficient value learning for neutral faces and the detection of "value-associated faces," while older adults show slightly different patterns of value learning and value-based detection of neutral faces. However, the mechanisms underlying these processes remain unknown. To investigate this, we applied hierarchical reinforcement learning and diffusion models to a value learning task and value-driven detection task that involved neutral faces; the tasks were completed by young and older adults. The results for the learning task suggested that the sensitivity of learning feedback might decrease with age. In the detection task, the younger adults accumulated information more efficiently than the older adults, and the perceptual time leading to motion onset was shorter in the younger adults. In younger adults only, the reward sensitivity during associative learning might enhance the accumulation of information during a visual search for neutral faces in a rewarded task. These results provide insight into the processing linked to efficient detection of faces associated with emotional values, and the age-related changes therein.

Prospective associations between cognitive flexibility and eating disorder symptoms in anorexia nervosa and bulimia nervosa

This study investigated concurrent and prospective associations between measures of reversal learning and attentional set-shifting and eating disorder symptoms at baseline, 3 months, and 6 months among individuals with anorexia nervosa restricting subtype (AN-R, n = 26), AN binge eating/purging subtype (AN-BP, n = 22), bulimia nervosa (BN, n = 35), and healthy controls (n = 27), and explored whether these associations differed by diagnosis. At baseline, participants completed diagnostic interviews, height/weight measurements, and measures of set-shifting (the Intradimensional/Extradimensional shift task) and reversal learning (a probabilistic reversal learning task). At 3- and 6-month follow-up, participants with eating disorders completed assessments of weight and eating disorder symptoms. A one-way analysis of variance found no evidence that baseline reversal learning and attentional set-shifting differed across diagnostic groups. Multilevel modeling analyses indicated that perseverative errors (an index of reversal learning) predicted an increase in purging over time for individuals with AN-BP and BN. Set-shifting errors differentially predicted frequency of loss of control eating for individuals with AN-BP and BN; however, set-shifting was not related to loss of control eating when examined separately in AN-BP and BN. These findings suggest that disentangling facets of cognitive flexibility may help understand change in eating disorder symptoms.

Leveraging Decision Science to Characterize Depression

This brief review examines the potential to use decision science to objectively characterize depression. We provide a brief overview of the existing literature examining different domains of decision-making in depression. Because this overview highlights the specific role of reinforcement learning as an important decision process affected in the disorder, we then introduce reinforcement learning modeling and explain how this approach has identified specific reinforcement learning deficits in depression. We conclude with ideas for future research at the intersection of decision science and depression, emphasizing the potential for decision science to help uncover underlying mechanisms and targets for the treatment of depression.

Association of executive function with suicidality based on resting-state functional connectivity in young adults with subthreshold depression

Subthreshold depression (StD) is associated an increased risk of developing major depressive disorder (MDD) and suicidality. Suicidality could be linked to distress intolerance and use of context-dependent strategies. We identified neural correlates of executive functioning among the hubs in the resting-state functional connectome (rs-FCN) and examined associations with recent suicidality in StD and MDD. In total, 79 young adults [27 StD, 30 MDD, and 23 healthy controls (HC)] were scanned using magnetic resonance imaging. Neurocognitive measures of the mean latency to correct five moves in the One Touch Stockings of Cambridge (OTSMLC5), spatial working memory between errors (SWMBE), rapid visual information processing A' (RVPA'), and the stop signal reaction time in the stop signal test (SSTSSRT) were obtained. Global graph metrics were calculated to measure the network integration, segregation, and their balance in the rs-FCN. Regional graph metrics reflecting the number of neighbors (degree centrality; DC), participation in the shortcuts (betweenness centrality; BC), and accessibility to intersections (eigenvector centrality; EC) in the rs-FCN defined group-level hubs for StD, HC, and MDD, separately. Global network metrics were comparable among the groups (all P > 0.05). Among the group-level hubs, regional graph metrics of left dorsal anterior insula (dAI), right dorsomedial prefrontal cortex (dmPFC), right rostral temporal thalamus, right precuneus, and left postcentral/middle temporal/anterior subgenual cingulate cortices were different among the groups. Further, significant associations with neurocognitive measures were found in the right dmPFC with SWMBE, and left dAI with SSTSSRT and RVPA'. Shorter OTSMLC5 was related to the lower centralities of right thalamus and suffer of recent 1-year suicidal ideation (all Ps < 0.05 in ≥ 2 centralities out of DC, BC, and EC). Collectively, salience and thalamic networks underlie spatial strategy and planning, response inhibition, and suicidality in StD and MDD. Anti-suicidal therapies targeting executive function and modulation of salience-thalamic network in StD and MDD are required.

Longitudinal associations between executive function impairments and suicide risk in patients with major depressive disorder: A 1-year follow-up study

Impaired executive function (EF) is a key feature of patients with major depressive disorder (MDD) that several studies have linked to suicidal ideation and suicide attempts. This is the first longitudinal study to examine the association between impaired EF and suicide risk in adult patients with MDD. Longitudinal prospective study with 3 assessment points: baseline, 6 and 12 months. The Columbia-Suicide Severity Rating Scale (C-SSRS) was used to assess suicidality. The Cambridge Neuropsychological Test Automated Battery (CANTAB) was used to assess EF. The association between EF impairments and suicidality was analyzed using mixed-effects models. Out of 167 eligible outpatients, 104 were included in the study. Of these, 72 were re-evaluated at 6 months and 60 at 12 months, obtaining 225 complete observations of the EF. Impaired decision-making and risk-taking behavior were associated with suicidal ideation. Difficulty in impulse control was related to suicidal ideation and to greater severity of suicidal ideation. Impaired spatial planning and working memory was linked to suicide attempts. Our results add to previous literature that the association between EF impairments and suicidality is maintained over the long term, supporting it as a longitudinal risk factor and a possible neurocognitive marker of suicide in patients with MDD.

Dissociated deficits of anticipated and experienced regret in at-risk suicidal individuals

Backgrounds

Decision-making deficits have been reported as trans-diagnostic characteristics of vulnerability to suicidal behaviors, independent of co-existing psychiatric disorders. Individuals with suicidal behaviors often regret their decision to attempt suicide and may have impairments in future-oriented processing. However, it is not clear how people with suicidal dispositions use future-oriented cognition and past experience of regret to guide decision-making. Here, we examined the processes of regret anticipation and experience in subclinical youth with and without suicidal ideation during value-based decision-making.

Methods

In total, 80 young adults with suicidal ideation and 79 healthy controls completed a computational counterfactual thinking task and self-reported measures of suicidal behaviors, depression, anxiety, impulsivity, rumination, hopelessness, and childhood maltreatment.

Results

Individuals with suicidal ideation showed a reduced ability to anticipate regret compared to healthy controls. Specifically, suicidal ideators’ experience of regret/relief was significantly different from that of healthy controls upon obtained outcomes, while their disappointment/pleasure experience was not significantly different from healthy controls.

Conclusion

These findings suggest that young adults with suicidal ideation have difficulty predicting the consequences or the future value of their behavior. Individuals with suicidal ideation showed impairments in value comparison and flat affect to retrospective rewards, whereas individuals with high suicidality showed blunted affect to immediate rewards. Identifying the counterfactual decision-making characteristics of at-risk suicidal individuals may help to elucidate measurable markers of suicidal vulnerability and identify future intervention targets.

Depressive symptoms and persistent negative self-referent thinking among adolescents: A learning account

Learning theories of depression propose that negative thinking is acquired through subsequent rewarding experiences and is often resistant to change even when it becomes associated with punishment. We examined whether this persistency of negative thinking is related to current and future levels of depressive symptoms among adolescents. Persistency of negative self-referent thinking was assessed by means of a decision-making task, namely the emotional reversal learning task. This task offers participants the choice between thinking about negative and positive self-related aspects. Their choice for negative self-referent thinking is initially rewarded but is later punished. Therefore, participants were expected to efficiently switch between negative and positive self-referent thinking, and to internally update their reward expectancy for these thinking options. Results showed that persistency of negative self-referent thinking was related to concurrent levels of depressive symptoms, replicating earlier findings in adults. However, persistency of negative thinking was unrelated to future levels of depressive symptoms. These findings suggest that adolescents with depressive symptoms tend to hold on to the belief that negative self-referent thinking has beneficial consequences, even when it is no longer being rewarded. This tendency should be seen as a concurrent feature of depression, as the predictive value is still in question.

Reinforcement-based responsiveness, depression, and anhedonia: A multi-method investigation of intergenerational risk

Offspring of depressed parents are at an increased risk for depression. Reward- and punishment-based systems might be mechanisms linking maternal outcomes to offspring depression and anhedonia. The current study was designed to investigate the intergenerational relations between maternal markers of reward and punishment responsiveness and their offspring's depression and anhedonia in a community sample of 40 mother (mean age = 44.5; SD = 6.82) and adolescent (mean age = 14.73; SD = 1.25; 52.5% female) dyads. Maternal markers of reward and punishment responsiveness were captured using self-report, behavioral, and neurophysiological methods, and self-reported depression and anhedonia symptoms were used as outcomes among the adolescent offspring. Maternal self-reported reward responsiveness and punishment learning rates were differentially associated with depression across male and female offspring. Regarding anhedonia, maternal punishment learning rate was positively related to adolescent anhedonia regardless of offspring biological sex. Maternal reward learning rate was also positively associated with anhedonia among male offspring. In general, low concurrence across self-report, behavioral, and neurophysiological markers of reward and punishment responsiveness was found. The results from the current study suggest that learning-rates on reinforcement-based behavioral tasks may be important objective markers to consider when evaluating intergenerational risk.

Self-injurious thoughts and behaviors and alterations in positive valence systems: A systematic review of the literature

Self-injurious thoughts and behaviors (SITBs), which include suicidal ideation (SI), suicide attempts (SA), and nonsuicidal self-injury (NSSI), are prevalent and associated with impairments in functioning and elevated risk of suicide deaths. Preventing suicide is a complex problem, with numerous systems likely contributing to the onset and maintenance of SITBs, and there is a critical need to identify more precise predictors of risk. Positive valence systems (PVS) are an understudied domain with promise for improving understanding of risk processes underlying SITBs. In this systematic review, we evaluate the evidence for the potential role of altered PVS function in SI, SA, and/or NSSI, including alterations in reward responsiveness, learning, and valuation assessed through behavioral, physiological and circuit measures. Results provide preliminary support for associations between distinct aspects of PVS function and alterations in SITBs. Specifically, SI appears to be characterized by low reward responsiveness, whereas little research has examined reward responsiveness in SA, and NSSI has been characterized by hyper-responsiveness to rewards. Alterations in reward learning and valuation are commonly examined in SA, with some evidence that they may be more strongly associated with attempts than SI or NSSI. At the same time, the literature is limited in that some constructs are commonly examined in one form of SITBs but not others. Further, research is predominantly cross-sectional and focused on adults, raising questions about the role of PVS function in developmental pathways to SITBs. We conclude by integrating the research to date and highlighting promising directions for future research.

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.

A Systematic Review of Behavior-Outcome Psychological Assessments as Correlates of Suicidality

AIM

Identifying correlates of suicidality is an important goal for suicide researchers because these correlates may predict suicidal behaviors. Psychological tasks that assess sensitivity to the outcomes of actions (i.e., consequence-based learning) have been commonly used by researchers seeking to identify correlates of suicidality. This is likely due to the straightforward integration of the tasks within most theoretical frameworks for understanding suicidality. Contextual factors have been shown to have a substantial effect on responding in behavior-outcome tasks. However, the direct relevance of these factors as determinants of behavior in suicide research is not clear. Thus, the purpose of this review was to assess the role of context in tasks involving behavior-outcome relations in suicide research.

METHODS

Four databases were searched using terms from general learning theory. Articles that featured evaluation of tasks with hypothetical or real outcomes to differentiate suicidality were included.

RESULTS

Eighty-two studies met inclusion criteria. Across studies there were 27 different tasks. Most instances of tasks across studies involved rewards (76.9%), while others emphasized punishment (15.7%), social (5.6%), or virtual suicide (1.8%) outcomes. Differentiation of suicidality was detected by 43.4%, 64.7%, 83.3%, and 50% of tasks featuring reward, punishment, social contexts, and virtual suicide respectively. All but five studies were retrospective.

CONCLUSION

Tasks that more closely mimic contexts and outcomes related to suicide appear to produce more pronounced differentiation of people with suicidality from people without suicidality. The lack of prospective designs is an important limitation of the literature.HIGHLIGHTSTasks that involve punishment or social outcomes better discriminate suicidality.Reward-based tasks are overused in suicide research.The conditioning hypothesis of suicidality is closely aligned with the literature.Only 5 of 82 studies incorporated prospective measures.

Suicidality in the geriatric population

Suicide in older adults is a major global concern in both public and mental health. With an ageing population on the rise, a surge in suicidal deaths is predicted in the coming years. The objectives of this paper are to review the risk factors, protective factors, assessment rating scales and current prevention strategies in the geriatric population. The identification of modifiable risk factors and strengthening of protective factors as well as staging according to suicidal ideation, behaviors and/or attempt(s) are necessary to devise appropriate personalized interventions in vulnerable older adults. A history or current psychiatric illness particularly depression, physical illnesses, previous suicide attempt, substance abuse, loneliness, marital status, financial stress, a family history of psychiatric illnesses or suicide in 1st degree relatives and low social support most commonly increase suicidal susceptibility in older adults. Conversely, factors that increase resilience in older adults include a good physical health and cognitive function, religiousness, good quality of life and life satisfaction, ability to perform activities of daily living, marital status, having friends and social connectedness. While the risk factors associated with suicide in the geriatric population are complex and multidimensional in nature, the current preventive strategies have provided no substantial decline in suicidal risk. Therefore, a combination of strategies applied via a multilevel prevention program at a primary, mental healthcare, societal and community level could mitigate suicidal risk. Further research and better preventive measures are warranted to diminish suicidal risk in older adults.

Reinforcement Learning in Patients With Mood and Anxiety Disorders vs Control Individuals: A Systematic Review and Meta-analysis

IMPORTANCE

Computational psychiatry studies have investigated how reinforcement learning may be different in individuals with mood and anxiety disorders compared with control individuals, but results are inconsistent.

OBJECTIVE

To assess whether there are consistent differences in reinforcement-learning parameters between patients with depression or anxiety and control individuals.

DATA SOURCES

Web of Knowledge, PubMed, Embase, and Google Scholar searches were performed between November 15, 2019, and December 6, 2019, and repeated on December 3, 2020, and February 23, 2021, with keywords (reinforcement learning) AND (computational OR model) AND (depression OR anxiety OR mood).

STUDY SELECTION

Studies were included if they fit reinforcement-learning models to human choice data from a cognitive task with rewards or punishments, had a case-control design including participants with mood and/or anxiety disorders and healthy control individuals, and included sufficient information about all parameters in the models.

DATA EXTRACTION AND SYNTHESIS

Articles were assessed for inclusion according to MOOSE guidelines. Participant-level parameters were extracted from included articles, and a conventional meta-analysis was performed using a random-effects model. Subsequently, these parameters were used to simulate choice performance for each participant on benchmarking tasks in a simulation meta-analysis. Models were fitted, parameters were extracted using bayesian model averaging, and differences between patients and control individuals were examined. Overall effect sizes across analytic strategies were inspected.

MAIN OUTCOMES AND MEASURES

The primary outcomes were estimated reinforcement-learning parameters (learning rate, inverse temperature, reward learning rate, and punishment learning rate).

RESULTS

A total of 27 articles were included (3085 participants, 1242 of whom had depression and/or anxiety). In the conventional meta-analysis, patients showed lower inverse temperature than control individuals (standardized mean difference [SMD], -0.215; 95% CI, -0.354 to -0.077), although no parameters were common across all studies, limiting the ability to infer differences. In the simulation meta-analysis, patients showed greater punishment learning rates (SMD, 0.107; 95% CI, 0.107 to 0.108) and slightly lower reward learning rates (SMD, -0.021; 95% CI, -0.022 to -0.020) relative to control individuals. The simulation meta-analysis showed no meaningful difference in inverse temperature between patients and control individuals (SMD, 0.003; 95% CI, 0.002 to 0.004).

CONCLUSIONS AND RELEVANCE

The simulation meta-analytic approach introduced in this article for inferring meta-group differences from heterogeneous computational psychiatry studies indicated elevated punishment learning rates in patients compared with control individuals. This difference may promote and uphold negative affective bias symptoms and hence constitute a potential mechanistic treatment target for mood and anxiety disorders.

A Computational Model of Hopelessness and Active-Escape Bias in Suicidality

Currently, psychiatric practice lacks reliable predictive tools and a sufficiently detailed mechanistic understanding of suicidal thoughts and behaviors (STB) to provide timely and personalized interventions. Developing computational models of STB that integrate across behavioral, cognitive and neural levels of analysis could help better understand STB vulnerabilities and guide personalized interventions. To that end, we present a computational model based on the active inference framework. With this model, we show that several STB risk markers - hopelessness, Pavlovian bias and active-escape bias - are interrelated via the drive to maximize one's model evidence. We propose four ways in which these effects can arise: (1) increased learning from aversive outcomes, (2) reduced belief decay in response to unexpected outcomes, (3) increased stress sensitivity and (4) reduced sense of stressor controllability. These proposals stem from considering the neurocircuits implicated in STB: how the locus coeruleus - norepinephrine (LC-NE) system together with the amygdala (Amy), the dorsal prefrontal cortex (dPFC) and the anterior cingulate cortex (ACC) mediate learning in response to acute stress and volatility as well as how the dorsal raphe nucleus - serotonin (DRN-5-HT) system together with the ventromedial prefrontal cortex (vmPFC) mediate stress reactivity based on perceived stressor controllability. We validate the model by simulating performance in an Avoid/Escape Go/No-Go task replicating recent behavioral findings. This serves as a proof of concept and provides a computational hypothesis space that can be tested empirically and be used to distinguish planful versus impulsive STB subtypes. We discuss the relevance of the proposed model for treatment response prediction, including pharmacotherapy and psychotherapy, as well as sex differences as it relates to stress reactivity and suicide risk.

A mutant allele of glycoprotein M6-B (Gpm6b) facilitates behavioral flexibility but increases delay discounting

The neuronal membrane glycoprotein M6B (Gpm6b) gene encodes a membrane glycoprotein that belongs to the proteolipid protein family, and is enriched in neurons, oligodendrocytes, and subset of astrocytes in the central nervous system. GPM6B is thought to play a role in neuronal differentiation, myelination, and inactivation of the serotonin transporter via internalization. Recent human genome-wide association studies (GWAS) have implicated membrane glycoproteins (both GPM6B and GPM6A) in the regulation of traits relevant to psychiatric disorders, including neuroticism, depressed affect, and delay discounting. Mouse studies have implicated Gpm6b in sensorimotor gating and regulation of serotonergic signaling. We used CRISPR to create a mutant Glycoprotein M6B (Gpm6b) allele on a C57BL/6J mouse background. Because Gpm6b is located on the X chromosome, we focused on male Gpm6b mutant mice and their wild-type littermates (WT) in two behavioral tests that measured aspects of impulsive or flexible decision-making. We found that Gpm6b deletion caused deficits in a delay discounting task. In contrast, reward sensitivity was enhanced thereby facilitating behavioral flexibility and improving performance in the probabilistic reversal learning task. Taken together these data further delineate the role of Gpm6b in decision making behaviors that are relevant to multiple psychiatric disorders.

Learning from gain and loss: Links to suicide risk

Despite preliminary evidence that people with suicide attempt histories demonstrate deficits in processing feedback, no studies have examined the interrelations of learning from feedback and emotional state on suicide risk. This study examined the influence of suicide risk and negative emotions on learning accuracy and rates among individuals with a range of borderline personality features (N = 145). Participants completed a reinforcement learning task after neutral and negative emotion inductions. Results revealed interactions between suicide risk and emotion condition, with elevated risk linked to greater increases in loss learning rate (training phase models) and gain learning rate (test phase models) post-negative emotion induction. Emotion-dependent fluctuations in learning performance may be markers of decision-making that are associated with greater suicide risk. This line of work has the potential to identify the contexts that confer greater risk for suicidal behaviors.

Search for solutions, learning, simulation, and choice processes in suicidal behavior

Suicide may be viewed as an unfortunate outcome of failures in decision processes. Such failures occur when the demands of a crisis exceed a person's capacity to (i) search for options, (ii) learn and simulate possible futures, and (iii) make advantageous value-based choices. Can individual-level decision deficits and biases drive the progression of the suicidal crisis? Our overview of the evidence on this question is informed by clinical theory and grounded in reinforcement learning and behavioral economics. Cohort and case-control studies provide strong evidence that limited cognitive capacity and particularly impaired cognitive control are associated with suicidal behavior, imposing cognitive constraints on decision-making. We conceptualize suicidal ideation as an element of impoverished consideration sets resulting from a search for solutions under cognitive constraints and mood-congruent Pavlovian influences, a view supported by mostly indirect evidence. More compelling is the evidence of impaired learning in people with a history of suicidal behavior. We speculate that an inability to simulate alternative futures using one's model of the world may undermine alternative solutions in a suicidal crisis. The hypothesis supported by the strongest evidence is that the selection of suicide over alternatives is facilitated by a choice process undermined by randomness. Case-control studies using gambling tasks, armed bandits, and delay discounting support this claim. Future experimental studies will need to uncover real-time dynamics of choice processes in suicidal people. In summary, the decision process framework sheds light on neurocognitive mechanisms that facilitate the progression of the suicidal crisis. This article is categorized under: Economics > Individual Decision-Making Psychology > Emotion and Motivation Psychology > Learning Neuroscience > Behavior.

Anhedonia and Suicide

Suicide is a leading cause of death, and presently, there is no definitive clinical indicator of future suicide behaviors. Anhedonia, a transdiagnostic symptom reflecting diminished ability to experience pleasure, has recently emerged as a risk factor for suicidal thoughts and behaviors (STBs). This overview, therefore, has the following aims. First, prior research relating anhedonia to STBs will be reviewed, with a particular focus on clarifying whether anhedonia is more closely associated with suicidal thoughts versus behaviors. Second, the National Institute of Mental Health's Research Domain Criteria Positive Valence Systems provide a useful heuristic to probe anhedonia across different units of analysis, including clinical symptoms, behaviors, neural mechanisms, and molecular targets. Accordingly, anhedonia-related constructs linked to STBs will be detailed as well as promising next steps for future research. Third, although anhedonia is not directly addressed in leading suicide theories, this review will provide potential inroads to explore anhedonia within diathesis-stress and interpersonal suicide frameworks. Last, novel approaches to treat anhedonia as a means of reducing STBs will be examined.

A qualitative systematic review of neurocognition in suicide ideators and attempters: Implications for cognitive-based psychotherapeutic interventions

BACKGROUND

Growing evidence suggests cognitive deficits may represent neurocognitive markers with predictive utility in identifying those at risk for suicide. Characterizing these deficits may offer the opportunity to develop targeted interventions.

AIM

The aim of this systematic qualitative review is to provide a synthesis of the published data on neurocognition in suicide ideators and attempters in order to clarify which neurocognitive targets may be most relevant to address using cognitive-based psychotherapeutic strategies in patients at risk for suicide.

RESULTS

A total of 63 studies met criteria for inclusion. The most consistent findings were in depressed suicide attempters, where deficits in executive subdomains of inhibition, selective attention and decision-making, as well as in working memory, were identified. In contrast, no clear pattern of neurocognitive deficits emerged from studies in suicide ideators across diagnoses.

CONCLUSIONS

More studies are needed to clarify the role of cognitive deficits in specific subtypes of individuals at risk for suicide. The findings are discussed in the context of promising research on cognitive remediation and other psychological interventions.

Influence Factors for Decision-Making Performance of Suicide Attempters and Suicide Ideators: The Roles of Somatic Markers and Explicit Knowledge

Impaired decision-making has been observed in suicide attempters during the Iowa Gambling Task (IGT). Decision-making performance is influenced by somatic markers and explicit knowledge, but it is still unclear of the influencing role on decision-making performance in suicidal individuals. We aimed to investigate whether there is a decision-making deficit in suicide attempters, suicide ideators, as well as the distinct roles of somatic markers and explicit knowledge wherein. Thirteen suicide attempters, 23 suicide ideators, and 19 healthy controls performed the IGT. Both somatic markers (by the skin conductance responses, SCRs) and explicit knowledge (by the subjective experience rating and a list of questions) were recorded. No significant differences were found among the three groups on IGT performance, explicit knowledge, and anticipatory SCRs. IGT Performance of suicide attempters was positively correlated with explicit knowledge index while behavior performance was positively associated with the SCRs in healthy controls. These results indicate that the suicide attempters seem to apply a compensatory strategy by mostly utilizing explicit knowledge to perform normally as healthy controls in the IGT.

Multimodal Elements of Suicidality Reduction After Transcranial Magnetic Stimulation

OBJECTIVES

Repetitive transcranial magnetic stimulation (TMS) is a promising treatment for suicidality, but it is underlying neural mechanisms remain poorly understood. Our prior findings indicated that frontostriatal functional connectivity correlates with the severity of suicidal thoughts and behaviors. In this secondary analysis of data from an open label trial, we evaluated whether changes in frontostriatal functional connectivity would accompany suicidality reductions following TMS. We also explored the relationship between frontostriatal connectivity change and underlying white matter (WM) organization.

MATERIALS AND METHODS

We conducted seed-based functional connectivity analysis on participants (N = 25) with comorbid post-traumatic stress disorder and depression who received eight weeks of 5 Hz TMS to left dorsolateral prefrontal cortex. We measured clinical symptoms with the Inventory of Depressive Symptomatology-Self Report (IDS-SR) and the PTSD Checklist for DSM-5 (PCL-5). We derived suicidality from IDS-SR item 18. Magnetic resonance imaging data were collected before TMS, and at treatment end point. These data were entered into analyses of covariance, evaluating the effect of suicidality change across treatment on striatal and thalamic functional connectivity. Changes in other PTSD and depression symptoms were included as covariates and results were corrected for multiple comparisons. Diffusion connectometry in a participant subsample (N = 17) explored the relationship between frontal WM integrity at treatment baseline and subsequent functional connectivity changes correlated with differences in suicidality.

RESULTS

Suicidal ideation decreased in 65% of participants. Reductions in suicidality and functional connectivity between the dorsal striatum and frontopolar cortex were correlated (p-False Discover Rate-corrected < 0.001), after covariance for clinical symptom change. All other results were nonsignificant. Our connectometry results indicated that the integrity of frontostriatal WM may circumscribe functional connectivity response to TMS for suicide.

CONCLUSIONS

Targeted reduction of fronto-striatal connectivity with TMS may be a promising treatment for suicidality. Future research can build on this multimodal approach to advance individualized stimulation approaches in high-risk patients.

Executive dysfunction and risk of suicide in older adults: a population-based prospective cohort study

OBJECTIVE

It is uncertain what factors increases the risk of suicide in older adults without depression, and it is unknown whether executive dysfunction (ED) is one of those factors. We aimed to examine the effect of ED on the risk of suicide in non-demented older adults without depression.

METHODS

In an ongoing population-based prospective cohort of Korean older adults, we identified suicide using the National Mortality Database and suicidal ideation or attempt (SIA) based on the Korean version of the Mini International Neuropsychiatric Interview. We defined ED as performing below -1.5 SD of age-adjusted, gender-adjusted and education-adjusted norms in any of following tests: Frontal Assessment Battery, Trail Making Test A, Digit Span Test or Verbal Fluency Test.

RESULTS

The mean age of the 4791 participants at baseline was 69.7 (SD 6.4) years, and 57.1% of them were women (mean follow-up duration=4.9 years). ED at baseline increased the risk of suicide by about seven times (HR 7.20, 95% CI 1.84 to 28.12, p=0.005) but did not change the risk of SIA. However, cognitive impairment without ED did not change the risks of suicide and SIA. In participants with ED, being aged 75 years or above, living alone, and having a low socioeconomic status were associated with the risk of suicide.

CONCLUSION

ED is a strong risk factor of late life suicide independent from depression, particularly in very old adults living in disadvantaged environments.

To Be or Not to Be Flexible: Selective impairments as a means to differentiate between depression and PTSD symptoms

During the course of their lives, most individuals experience at least one potentially traumatic event. For some individuals this experience may result in them developing depression and/or post-traumatic stress disorder (PTSD) symptoms. The aim of the present study was to test the interactive effect of traumatic exposure and impaired cognitive flexibility on the tendency to develop either depression or PTSD symptoms. Eighty-two college students (M age = 25.32, SD age = 4.09) were assessed for exposure to traumatic events, depressive and PTSD symptoms. In addition, they completed a performance-based learning paradigm to evaluate the unique patterns of cognitive flexibility, defined as reduced and enhanced updating of prior knowledge in the face of new information. We predicted and found that for individuals with reduced updating, greater exposure to trauma was associated with elevated depressive symptoms. Contrary to our prediction, for individuals with enhanced updating, greater exposure was associated with elevated PTSD symptoms. While cognitive flexibility is traditionally associated with adaptive outcomes, our results illuminate the important role of a delicate updating balance to adaptively cope with aversive life events. The findings highlight the possible different roles of cognitive flexibility in the development of psychopathology and may serve as a first step toward developing tailored prevention and treatment methods.

Temporal dynamics alterations of spontaneous neuronal activity in anterior cingulate cortex predict suicidal risk in bipolar II patients

Bipolar disorder type II (BD-II) is linked to an increased suicidal risk. Since a prior suicide attempt (SA) is the single most important risk factor for sequent suicide, the elucidation of involved neural substrates is critical for its prevention. Therefore, we examined the spontaneous brain activity and its temporal variabilities in suicide attempters with bipolar II during a major depressive episode. In this cross-sectional study, 101 patients with BD-II, including 44 suicidal attempters and 57 non-attempters, and 60 non-psychiatric controls underwent a resting-state functional magnetic resonance imaging (fMRI). Participants were assessed with Hamilton Rating Scale for Depression (HAMD) and Nurses^, Global Assessment of Suicide Risk (NGASR). The dynamics of low-frequency fluctuation (dALFF) was measured using sliding-window analysis and its correlation with suicidal risk was conducted using Pearson correlation. Compared to non-attempters, suicidal attempters showed an increase in brain activity and temporal dynamics in the anterior cingulate cortex (ACC). In addition, the temporal variabilities of ACC activity positively correlated with suicidal risk (R = 0.45, p = 0.004), while static ACC activity failed to (R = 0.08, p > 0.05). Our findings showed that an aberrant static ALFF and temporal variability could affect suicidal behavior in BD-II patients. However, temporal variability of neuronal activity was more sensitive than static amplitude in reflecting diathesis for suicide in BD-II. Dynamics of brain activity could be considered in developing neuromarkers for suicide prevention.

Social reinforcement learning as a predictor of real-life experiences in individuals with high and low depressive symptomatology

BACKGROUND

Several studies have reported diminished learning from non-social outcomes in depressed individuals. However, it is not clear how depression impacts learning from social feedback. Notably, mood disorders are commonly associated with deficits in social functioning, which raises the possibility that potential impairments in social learning may negatively affect real-life social experiences in depressed subjects.

METHODS

Ninety-two participants with high (HD; N = 40) and low (LD; N = 52) depression scores were recruited. Subjects performed a learning task, during which they received monetary outcomes or social feedback which they were told came from other people. Additionally, participants answered questions about their everyday social experiences. Computational models were fit to the data and model parameters were related to social experience measures.

RESULTS

HD subjects reported a reduced quality and quantity of social experiences compared to LD controls, including an increase in the amount of time spent in negative social situations. Moreover, HD participants showed lower learning rates than LD subjects in the social condition of the task. Interestingly, across all participants, reduced social learning rates predicted higher amounts of time spent in negative social situations, even when depression scores were controlled for.

CONCLUSION

These findings indicate that deficits in social learning may affect the quality of everyday social experiences. Specifically, the impaired ability to use social feedback to appropriately update future actions, which was observed in HD subjects, may lead to suboptimal interpersonal behavior in real life. This, in turn, may evoke negative feedback from others, thus bringing about more unpleasant social encounters.

Impulsivity and compulsivity in anorexia and bulimia nervosa: A systematic review

This study aimed to systematically appraise cross-sectional research that compared the cognitive performance of individuals in the acute phase of BN and/or AN to HCs on measures of impulsivity and compulsivity. The results of the systematic review showed support for the trans-diagnostic approach to eating disorders. There was no strong evidence to support the characterisation of AN as high in compulsivity (and low in impulsivity), nor to support the characterisation of BN as high in impulsivity (and low in compulsivity). There appeared to be mixed findings for both impulsivity and compulsivity across AN and BN. Results were highly variable due to the heterogeneous tasks used, and lack of replication across studies. There was no consensus amongst the included studies on the most appropriate task and/or outcome measures that should be used to study the constructs of impulsivity and compulsivity.

Central CRF and acute stress differentially modulate probabilistic reversal learning in male and female rats

Acute stress can have variable and sometimes sex-dependent effects on different executive functions, including cognitive flexibility, some of which may be mediated by increased corticotropin releasing factor (CRF). Previous studies on the effects of stress and CRF on cognitive flexibility have used procedures entailing deterministic rewards, yet how they may alter behavior when outcomes are probabilistic is unclear. The present study examined how acute stress and increased CRF activity alters probabilistic reversal learning (PRL) in male and female rats. Rats learned to discriminate between a 'correct' lever rewarded on 80 % of trials, and an "incorrect" lever delivering reward on 20 % of trials, with reward contingencies reversed after 8 consecutive correct choices. Separate groups received either intracerebroventricular infusions of CRF (3 μg) or restraint stress prior to a PRL session. Experiments examined how these manipulations affected learning when given prior to a one-day acquisition test or during performance in well-trained rats. Exogenous CRF, and to a lesser extent acute stress, impaired motivation across sexes, slowing deliberation times and increasing the number of trials omitted, particularly following a switch in reward contingencies. Neither manipulation significantly altered errors or reversal performance. However, increased CRF activity reduced negative feedback sensitivity. Across manipulations, females showed increased omissions and choice latencies, and were less sensitive to feedback than males. These results reveal the complexity with which stress, CRF, sex, and experience interact to alter aspects of motivation and probabilistic reinforcement learning and provide insight into how CRF activity may contribute to symptoms of stress-related disorders.

Differentiating clinically depressed adolescents with and without active suicidality: An examination of neurophysiological and self-report measures of reward responsiveness

BACKGROUND

Suicidality in youth is a major public health problem and objective methods for identifying those at greatest risk are critically needed. Suicidality has been associated with alterations in reward-related decision-making, but the extent to which measures of reward responsiveness (RR) can differentiate youth with and without suicidality in clinical samples remains unclear.

METHODS

We examined reliable and accessible neurophysiological (i.e., reward positivity [RewP] event-related potential) and self-report (Behavioral Activation System subscales) measures of RR in relation to active suicidality in 58 clinically depressed adolescents (14- to 18-year-olds).

RESULTS

Logistic regression analysis indicated that active suicidality in depressed adolescents was associated with heightened RR at both the self-report and neurophysiological levels. A relatively more positive RewP to win and a more negative RewP to loss uniquely predicted active suicidality beyond demographic, clinical, and self-report measures.

CONCLUSIONS

Results support the utility of neurophysiological measures in differentiating clinically depressed adolescents with and without suicidality. Although depression is commonly characterized by reduced RR, depressed adolescents with active suicidality exhibited relatively enhanced neural responses to reward and loss feedback. Results highlight the need for consideration of heterogeneity in RR in depression and research on personalized depression treatment.

Neurocomputational mechanisms of adaptive learning in social exchanges

Prior work on prosocial and self-serving behavior in human economic exchanges has shown that counterparts' high social reputations bias striatal reward signals and elicit cooperation, even when such cooperation is disadvantageous. This phenomenon suggests that the human striatum is modulated by the other's social value, which is insensitive to the individual's own choices to cooperate or defect. We tested an alternative hypothesis that, when people learn from their interactions with others, they encode prediction error updates with respect to their own policy. Under this policy update account striatal signals would reflect positive prediction errors when the individual's choices correctly anticipated not only the counterpart's cooperation but also defection. We examined behavior in three samples using reinforcement learning and model-free analyses and performed an fMRI study of striatal learning signals. In order to uncover the dynamics of goal-directed learning, we introduced reversals in the counterpart's behavior and provided counterfactual (would-be) feedback when the individual chose not to engage with the counterpart. Behavioral data and model-derived prediction error maps (in both whole-brain and a priori striatal region of interest analyses) supported the policy update model. Thus, as people continually adjust their rate of cooperation based on experience, their behavior and striatal learning signals reveal a self-centered instrumental process corresponding to reciprocal altruism.

Effects of Depressive Symptoms, Feelings, and Interoception on Reward-Based Decision-Making: Investigation Using Reinforcement Learning Model

Background: In this study, we examined the relationships between reward-based decision-making in terms of learning rate, memory rate, exploration rate, and depression-related subjective emotional experience, in terms of interoception and feelings, to understand how reward-based decision-making is impaired in depression. Methods: In all, 52 university students were randomly assigned to an experimental group and a control group. To manipulate interoception, the participants in the experimental group were instructed to tune their internal somatic sense to the skin-conductance-response waveform presented on a display. The participants in the control group were only instructed to stay relaxed. Before and after the manipulation, the participants completed a probabilistic reversal-learning task to assess reward-based decision-making using reinforcement learning modeling. Similarly, participants completed a probe-detection task, a heartbeat-detection task, and self-rated scales. Results: The experimental manipulation of interoception was not successful. In the baseline testing, reinforcement learning modeling indicated a marginally-significant correlation between the exploration rate and depressive symptoms. However, the exploration rate was significantly associated with lower interoceptive attention and higher depressive feeling. Conclusions: The findings suggest that situational characteristics may be closely involved in reward exploration and highlight the clinically-meaningful possibility that intervention for affective processes may impact reward-based decision-making in those with depression.

Ventromedial prefrontal value signals and functional connectivity during decision-making in suicidal behavior and impulsivity

Suicide is linked to impaired value-based decision-making and impulsivity, but whether these risk factors share neural underpinnings is unclear. Disrupted ventromedial prefrontal cortex (vmPFC) value signals may underlie this behavioral phenotype. We investigated vmPFC value signals, vmPFC-frontoparietal connectivity, and the impact of impulsivity during decision-making in depressed individuals with and without suicidal behavior. Middle-aged and older adults (n = 116; 35 with a history of suicide attempts, 25 with ideation only, 25 depressed controls with no ideation, and 31 nonpsychiatric controls) completed a decision-making task with drifting reward probabilities during fMRI. Values of choices, estimated by a reinforcement learning model, were regressed against BOLD signal. VmPFC value activation was compared between groups. Moderating effects of impulsivity on vmPFC-frontoparietal connectivity were assessed in nonpsychiatric controls and compared among patient groups. VmPFC value responses in participants with a history of suicide attempts were reduced relative to nonpsychiatric controls (p < 0.05). In nonpsychiatric controls, vmPFC-frontoparietal connectivity was negatively moderated by impulsivity (pFWE corrected < 0.05). This effect was preserved in comparison patient groups but abolished in suicide attempters (p < 0.001). This change in neural connectivity patterns also affected behavior: people with a history of suicide attempts showed a disrupted effect of vmPFC-frontoparietal connectivity, impulsivity, and reinforcement on choice quality (p < 0.001). These effects were specific to vmPFC and not to striatum. In summary, findings from this study largely support disrupted vmPFC value signals in suicidal behavior. In addition, it uncovers an altered pattern of vmPFC-frontoparietal connectivity in impulsive people with suicidal behavior, which may underlie disrupted choice processes in a suicidal crisis.

A further assessment of decision-making in anorexia nervosa

Objective:

Anorexia nervosa (AN) may be associated with impaired decision-making. Cognitive processes underlying this impairment remain unclear, mainly because previous assessments of this complex cognitive function were completed with a single test. Furthermore, clinical features such as mood status may impact this association. We aim to further explore the hypothesis of altered decision-making in AN.

Method:

Sixty-three adult women with AN and 49 female controls completed a clinical assessment and were assessed by three tasks related to decision-making [Iowa Gambling Task (IGT), Balloon Analogue Risk Task (BART), Probabilistic Reversal Learning Task (PRLT)].

Results:

People with AN had poorer performance on the IGT and made less risky choices on the BART, whereas performances were not different on PRLT. Notably, AN patients with a current major depressive disorder showed similar performance to those with no current major depressive disorder.

Conclusion:

These results tend to confirm an impaired decision making-process in people with AN and suggest that various cognitive processes such as inhibition to risk-taking or intolerance of uncertainty may underlie this condition Furthermore, these impairments seem unrelated to the potential co-occurent major depressive disorders.

Sleep problems and suicide risk in youth: A systematic review, developmental framework, and implications for hospital treatment

OBJECTIVE

Sleep problems are transdiagnostic symptoms that confer significant risk for suicidal thoughts and behaviors (STBs) in adults. However, less is known about the sleep-STB association in adolescence-a developmental period when rates of STBs increase drastically, and sleep problems may be particularly pernicious. This article provides a systematic review of research on the sleep-STB association in youth, an overview of changes in sleep regulation during adolescence that may make sleep problems particularly detrimental for youth, and a discussion of the clinical implications of the sleep-STB association for hospitalized youth.

METHOD

The systematic review included all longitudinal studies in which sleep problems were examined as prospective predictors of STBs in adolescents (aged 10-24 years). The search was conducted on December 1, 2017 using PsychINFO, PubMed, and Web of Science databases.

RESULTS

Ten studies qualified for inclusion in this review. Of these, seven studies found at least one type of sleep problem significantly predicted a STB outcome.

CONCLUSIONS

Although findings are mixed, growing research suggests that sleep problems may be a unique risk factor for STBs in youth. Sleep problems may be particularly important intervention target because they are easily assessed across healthcare settings and are amenable to treatment.

Multiple Facets of Value-Based Decision Making in Major Depressive Disorder

Depression is clinically characterized by obvious changes in decision making that cause distress and impairment. Though several studies suggest impairments in depressed individuals in single tasks, there has been no systematic investigation of decision making in depression across tasks. We compare participants diagnosed with Major Depressive Disorder (MDD) (n = 64) to healthy controls (n = 64) using a comprehensive battery of nine value-based decision-making tasks which yield ten distinct measures. MDD participants performed worse on punishment (d = −0.54) and reward learning tasks (d = 0.38), expressed more pessimistic predictions regarding winning money in the study (d = −0.47) and were less willing to wait in a persistence task (d = −0.39). Performance on learning, expectation, and persistence tasks each loaded on unique dimensions in a factor analysis and punishment learning and future expectations each accounted for unique variance in predicting depressed status. Decision-making performance alone could predict depressed status out-of-sample with 72% accuracy. The findings are limited to MDD patients ranging between moderate to severe depression and the effects of medication could not be accounted for due to the cross sectional nature of the study design. These results confirm hints from single task studies that depression has the strongest effects on reinforcement learning and expectations about the future. Our results highlight the decision processes that are impacted in major depression, and whose further study could lead to a more detailed computational understanding of distinct facets of this heterogeneous disorder.

Resting-state functional connectivity of the anterior cingulate cortex in young adults depressed patients with and without suicidal behavior

Functional alterations in the subregions of the anterior cingulate cortex (ACC) have been observed in patients with major depressive disorder (MDD). Studies have shown that higher depressive symptoms are associated with altered functional connectivity (FC) in different ACC sub-regions. Suicide is highly prevalent in patients with MDD; however, it is unclear whether suicidal behavior is associated with the FC alterations in the subregions of the ACC in these indibiduals. Seventy-six patients with MDD (41 with and 35 without a history of suicidal behavior) underwent functional magnetic resonance imaging (fMRI) and were assessed using the Hamilton Rating Scale for Depression (HAMD), the Scale for Suicide Ideation (SSI), and the Columbia Scale for Rating of Suicide Severity. We investigated the FC between the ACC subregions and other brain regions in young MDD patients with and without a history of suicidal behavior. The FC in the subregions of the ACC-superior frontal gyrus differed significantly between the two groups. Additionally, the anterior sgACC-right caudate FC and the pgACC-left insula FC were found to be abnormal in the suicidal MDD group. Interestingly, the suicidal ideation score positively correlated with decreased FC in the pgACC-superior frontal gyrus in both groups, but it negatively correlated with increased FC in the anterior sgACC-superior frontal gyrus in the non-suicidal MDD group. Our findings indicate that altered connections of subregions in the ACC may be involved in the neurological mechanisms underlying suicide in young adults with MDD.

Modulation of cognitive flexibility by reward and punishment in BALB/cJ and BALB/cByJ mice

Learning from feedback is one of the key mechanisms within cognitive flexibility, which is needed to react swiftly to constantly changing environments. The motivation to change behavior is highly dependent on the expectancy of positive (reward) or negative (punishment) feedback. Individuals with conduct disorder (CD) with high callous unemotional traits show decreased sensitivity to negative feedback and increased reward seeking. Previous studies have modeled traits associated with CD (i.e. heightened aggression and anti-social behavior) in BALB/cJ mice (compared to the BALB/cByJ mouse as controls). Based on these findings, we hypothesized reduced negative feedback-related cognitive flexibility to be present in BALB/cJ mice. The effect of negative feedback and reward sensitivity on cognitive flexibility in BALB/cJ and BALB/cByJ mice was examined in a reversal learning paradigm. BALB/cJ mice were more flexible in the acquisition of new contingencies under rewarding conditions compared to BALB/cByJ mice, while the presence of an aversive punishing stimulus decreased their learning performance. Additionally, BALB/cJ mice needed more correction trials to reach the reversal learning criterion. This was accompanied by a higher rate of perseverance, which could represent impaired error detection. The addition of a second punishment enhanced punishment sensitivity in BALB/cJ mice. In contrast, the performance of the BALB/cByJ mice was not affected by additional negative feedback. Taken together, the BALB/cJ can be considered to be less sensitive to learn from negative feedback and therefore may be a useful model to further characterize molecular and neural underpinnings of callous unemotional traits in CD.

How Behavioral Economics and Nudges Could Help Diminish Irrationality in Suicide-Related Decisions

People regularly make decisions that are not aligned with their own self-interests. These irrational decisions often stem from humans having bounded rationality (e.g., limited computational power), which produces reliable cognitive biases that occur outside of people's awareness and influences the decisions people make. There are many important decisions leading up to a suicide attempt, and it is likely that these same biases exist within suicide-related decisions. This article presents an argument for the likely existence of cognitive biases within suicide-related decision making and how they may influence people to make irrational decisions. In addition, this article provides new evidence for using a behavioral economic intervention-nudges-as a potential way to combat rising suicide rates. We explore how nudges can help increase means safety, disseminate suicide prevention skills/materials, diminish well-known biases (e.g., confirmation bias), and uncover biases that may be occurring when making suicide-related decisions.

Lethality of Previous Suicidal Behavior among Patients Hospitalized for Suicide Risk Predicts Lethality of Future Suicide Attempts

OBJECTIVE

A suicide attempt is an established risk factor for subsequent suicide attempts and suicide. Nonetheless, the prediction of future suicidal behavior is poor. The lethality of previous suicidal behavior may be informative to better understand future suicide risk among patients hospitalized for suicidal thoughts and behavior. The current study examined whether the lethality of patients' index (most recent suicidal episode at hospitalization), first, and worst suicidal episode predicts the lethality of one's most lethal suicide attempt during a 2-year follow-up period.

METHOD

A total of 98 patients hospitalized at an emergency department for high suicide risk (i.e., acute suicidal ideation or a suicide attempt) were included in the study.

RESULTS

Results indicated that the lethality of the index suicidal episode predicted the lethality of the worst suicide attempt during a 2-year follow-up period.

CONCLUSIONS

These findings extend a growing literature examining risk factors that influence the progression toward high lethality suicidal behavior.

Difficulty in updating positive beliefs about negative cognition is associated with increased depressed mood

BACKGROUND AND OBJECTIVES

Depressed people hold positive beliefs about negative cognition (e.g., rumination is useful to find a solution), which may motivate those individuals to engage in sustained negative thinking. However, in reality, rumination often leads to unfavorable outcomes. Thus, such beliefs create a large discrepancy between one's expectations and the actual outcome. Therefore, we hypothesized that this prediction error would be associated with increased depressed mood.

METHODS

We observed how people update their positive beliefs about negative cognition within a volatile environment, in which negative cognition does not always result in a beneficial outcome. Forty-six participants were offered two response options (retrieving a negative or positive personal memory) and subsequently provided either an economic reward or punishment. Retrieving a negative (rather than positive) memory was initially reinforced, although this action-outcome contingency was reversed during the task. In the control condition, positive memory retrieval was initially reinforced, although a contingency reversal was employed to encourage negative memory retrieval.

RESULTS

Model-based computational modeling revealed that participants who showed a delay in switching from negative to positive (but not from positive to negative) responses experienced increased levels of depressed mood. This delay in switching was also found to be associated with depressive symptoms and trait rumination.

LIMITATIONS

The non-clinical nature of the sample may limit the clinical implications of the results.

CONCLUSIONS

Difficulty in updating positive beliefs (or outcome predictions) for negative cognition may play an important role in depressive symptomatology.

Value-Based Choice, Contingency Learning, and Suicidal Behavior in Mid- and Late-Life Depression

BACKGROUND

Suicidal behavior is associated with impaired decision making in contexts of uncertainty. Existing studies, however, do not definitively address whether suidice attempers have 1) impairment in learning from experience or 2) impairment in choice based on comparison of estimated option values. Our reinforcement learning model-based behavioral study tested these hypotheses directly in middle-aged and older suicide attempters representative of those who die by suicide.

METHODS

Two samples (sample 1, n = 135; sample 2, n = 125) of suicide attempters with depression (n_attempters = 54 and 39, respectively), suicide ideators, nonsuicidal patients with depression, and healthy control participants completed a probabilistic three-choice decision-making task. A second experiment in sample 2 experimentally dissociated long-term learned value from reward magnitude. Analyses combined computational reinforcement learning and mixed-effects models of decision times and choices.

RESULTS

With regard to learning, suicide attempters (vs. all comparison groups) were less sensitive to one-back reinforcement, as indicated by a reduced effect on both choices and decision times. Learning deficits scaled with attempt lethality and were partially explained by poor cognitive control. With regard to value-based choice, suicide attempters (vs. all comparison groups) displayed abnormally long decision times when choosing between similarly valued options and were less able to distinguish between the best and second-best options. Group differences in value-based choice were robust to controlling for cognitive performance, comorbidities, impulsivity, psychotropic exposure, and possible brain damage from attempts.

CONCLUSIONS

Serious suicidal behavior is associated with impaired reward learning, likely undermining the search for alternative solutions. Attempted suicide is associated with impaired value comparison during the choice process, potentially interfering with the consideration of deterrents and alternatives in a crisis.

Oxytocin improves probabilistic reversal learning but not effortful motivation in Brown Norway rats

Deficits in cognition and motivation are common and debilitating aspects of psychiatric disorders, yet still go largely untreated. The neuropeptide oxytocin (OT) is a potential novel therapeutic for deficits in social cognition and motivation in psychiatric patients. However, the effects of OT on clinically relevant domains of non-social cognition and motivation remain under studied. The present study investigated the effects of acute and chronic (21-day) administration of subcutaneous OT (0.04, 0.2, and 1 mg/kg) in cross-species translatable operant paradigms of reward learning and effortful motivation in male and female Brown Norway (BN) rats (n = 8-10/group). Reward learning was assessed using the probabilistic reversal learning task (PRLT) and effortful motivation was measured using the progressive ratio breakpoint task (PRBT). As predicted, BN rats exhibited baseline deficits in the detection of reversals of reward contingency in the PRLT relative to Long Evans (LE) rats. The two strains performed equally in the PRBT. Thirty minutes after a single OT injection (1 mg/kg), measures of both initial probabilistic learning (trials to first criterion) and subsequent reversal learning (contingency switches) were significantly improved to levels comparable with LE rats. The OT effect on switches persisted in male, but not female, BN rats 30 min, 24 h, and 6 days after long-term OT administration, suggesting the induction of neuroplastic changes. OT did not affect effortful motivation at any time-point. The beneficial effects of OT on reward learning in the absence of increased effortful motivation support the development of OT as a novel therapeutic to improve cognitive functioning.

Reward systems and cognitions in Major Depressive Disorder

A lack of motivation and anhedonia represent frequent and pervasive symptoms in depression, although with poor specificity. Historically described as a response bias, reward-related impairments in depression may account for the important aspects of the cognitive impairments associated with diagnosis of major depressive disorder. Reward processing is a broad psychological construct that can be parsed into 3 distinct components known as "reinforcement learning" (learning), "reward responsiveness" (liking), and "motivation to obtain a reward" (wanting). Depressed patients respond hyposensitively to reward and maladaptively to punishment: this pattern is related to a dysfunction in the frontostriatal systems modulated by the monoamine systems; seems to be observed in medicated and unmedicated patients with depression and in healthy individuals with high levels of anhedonia; and could be observed in patients with a history of depression, even when in full remission. Considered to be cognitive impairments, reward-related-impairments may also constitute part of an underlying neurobiological vulnerability to major depressive disorder (MDD). For example, the reward-related impairment is state dependent and, more or less, correlated with symptom severity in some studies but has also been proposed as being trait like, with endophenotype characteristics, possibly contributing to the persistence of the disease or treatment resistance. The 3 core aspects of reward processing have specific neurobiological correlates that involve the ventral and dorsal striatum, lateral habenula, ventral tegmental area, orbitofrontal cortex, anterior cingulate cortex, and ventromedial and dorsolateral prefrontal cortex. These structures underline the important role of the dopaminergic mesolimbic pathway, but glutamate and serotonin could also have an important role, at least in some aspects of reward-related impairments.

Major Depression Impairs the Use of Reward Values for Decision-Making

Depression is a debilitating condition with a high prevalence. Depressed patients have been shown to be diminished in their ability to integrate their reinforcement history to adjust future behaviour during instrumental reward learning tasks. Here, we tested whether such impairments could also be observed in a Pavlovian conditioning task. We recruited and analysed 32 subjects, 15 with depression and 17 healthy controls, to study behavioural group differences in learning and decision-making. Participants had to estimate the probability of some fractal stimuli to be associated with a binary reward, based on a few passive observations. They then had to make a choice between one of the observed fractals and another target for which the reward probability was explicitly given. Computational modelling was used to succinctly describe participants' behaviour. Patients performed worse than controls at the task. Computational modelling revealed that this was caused by behavioural impairments during both learning and decision phases. Depressed subjects showed lower memory of observed rewards and had an impaired ability to use internal value estimations to guide decision-making in our task.

Nonlinear Change Processes During Psychotherapy Characterize Patients Who Have Made Multiple Suicide Attempts

Research suggests that multiple suicide attempters experience considerable variability in suicide ideation and longer-duration suicidal crises, which suggests the possibility of two states of stability (one low risk and one high risk). To date, however, few studies have examined nonlinear change processes in suicide ideation among patients. In a sample of 76 active duty U.S. Army soldiers receiving brief cognitive behavioral therapy for acute suicide risk, we examined differences in the ebb and flow of suicide ideation among multiple attempters, first-time attempters, and ideators. Results indicated that multiple attempters were characterized by two states of stability corresponding to low and high intensity suicide ideation; these states were separated by a region of instability corresponding to moderate intensity suicide ideation. In contrast, ideators and first-time attempters were characterized by only a single state of stability corresponding to low intensity suicide ideation. Among patients who have made multiple suicide attempts, suicide ideation may function as a bimodal rather than a continuous construct.

The Influence of Emotional State on Learning From Reward and Punishment in Borderline Personality Disorder

Despite preliminary evidence that individuals with borderline personality disorder (BPD) demonstrate deficits in learning from corrective feedback, no studies have examined the influence of emotional state on these learning deficits in BPD. This laboratory study examined the influence of negative emotions on learning among participants with BPD (n = 17), compared with clinical (past-year mood/anxiety disorder; n = 20) and healthy (n = 23) controls. Participants completed a reinforcement learning task before and after a negative emotion induction. The learning task involved presenting pairs of stimuli with probabilistic feedback in the training phase, and subsequently assessing accuracy for choosing previously rewarded stimuli or avoiding previously punished stimuli. ANOVAs and ANCOVAs revealed no significant between-group differences in overall learning accuracy. However, there was an effect of group in the ANCOVA for postemotion induction high-conflict punishment learning accuracy, with the BPD group showing greater decrements in learning accuracy than controls following the negative emotion induction.