Goal representations and motivational drive in schizophrenia: the role of prefrontal-striatal interactions

Towards zebrafish models to unravel translational insights of obsessive-compulsive disorder: A neurobehavioral perspective

Obsessive-compulsive disorder (OCD) is a chronic and debilitating illness that has been considered a polygenic and multifactorial disorder, challenging effective therapeutic interventions. Although invaluable advances have been obtained from human and rodent studies, several molecular and mechanistic aspects of OCD etiology are still obscure. Thus, the use of non-traditional animal models may foster innovative approaches in this field, aiming to elucidate the underlying mechanisms of disease from an evolutionary perspective. The zebrafish (Danio rerio) has been increasingly considered a powerful organism in translational neuroscience research, especially due to the intrinsic features of the species. Here, we outline target mechanisms of OCD for translational research, and discuss how zebrafish-based models can contribute to explore neurobehavioral aspects resembling those found in OCD. We also identify possible advantages and limitations of potential zebrafish-based models, as well as highlight future directions in both etiological and therapeutic research. Lastly, we reinforce the use of zebrafish as a promising tool to unravel the biological basis of OCD, as well as novel pharmacological therapies in the field.

Reward motivation adaptation in people with negative schizotypal features: development of a novel behavioural paradigm and identifying its neural correlates using resting-state functional connectivity analysis

Reward motivation in individuals with high levels of negative schizotypal traits (NS) has been found to be lower than that in their counterparts. But it is unclear that whether their reward motivation adaptively changes with external effort-reward ratio, and what resting-state functional connectivity (rsFC) is associated with this change. Thirty-five individuals with high levels of NS and 44 individuals with low levels of NS were recruited. A 3T resting-state functional brain scan and a novel reward motivation adaptation behavioural task were administrated in all participants. The behavioural task was manipulated with three conditions (effort > reward condition vs. effort < reward condition vs. effort = reward condition). Under each condition were rated 'wanting' and 'liking' for rewards. The seed-based voxel-wise rsFC analysis was conducted to explore the rsFCs associated with the 'wanting' and 'liking' ratings in individuals with high levels of NS. 'Wanting' and 'liking' ratings of individuals with high levels of NS significantly declined in the effort > reward condition but did not rebound as high as their counterparts in the effort < reward condition. The rsFCs in NS group associated with these ratings were altered. The altered rsFCs in NS group involved regions in the prefrontal lobe, dopaminergic brain regions (ventral tegmental area, substantia nigra), hippocampus, thalamus and cerebellum. Individuals with high levels of NS manifested their reward motivation adaptation impairment as a failure of adjustment adaptively during effort-reward imbalance condition and altered rsFCs in prefrontal, dopaminergic and other brain regions.

Psychosis spectrum symptoms among individuals with schizophrenia-associated copy number variants and evidence of cerebellar correlates of symptom severity

The 3q29 deletion (3q29Del) is a copy number variant (CNV) with one of the highest effect sizes for psychosis-risk (>40-fold). Systematic research offers avenues for elucidating mechanism; however, compared to CNVs like 22q11.2Del, 3q29Del remains understudied. Emerging findings indicate that posterior fossa abnormalities are common among carriers, but their clinical relevance is unclear. We report the first in-depth evaluation of psychotic symptoms in participants with 3q29Del (N=23), using the Structured Interview for Psychosis-Risk Syndromes, and compare this profile to 22q11.2Del (N=31) and healthy controls (N=279). We also explore correlations between psychotic symptoms and posterior fossa abnormalities. Cumulatively, 48% of the 3q29Del sample exhibited a psychotic disorder or attenuated positive symptoms, with a subset meeting criteria for clinical high-risk. 3q29Del had more severe ratings than controls on all domains and only exhibited less severe ratings than 22q11.2Del in negative symptoms; ratings demonstrated select sex differences but no domain-wise correlations with IQ. An inverse relationship was identified between positive symptoms and cerebellar cortex volume in 3q29Del, documenting the first clinically-relevant neuroanatomical connection in this syndrome. Our findings characterize the profile of psychotic symptoms in the largest 3q29Del sample reported to date, contrast with another high-impact CNV, and highlight cerebellar involvement in psychosis-risk.

Modulating the default mode network: Antidepressant efficacy of transcutaneous electrical cranial-auricular acupoints stimulation targeting the insula

BACKGROUND

Transcutaneous electrical cranial-auricular acupoint stimulation (TECAS) is a novel non-invasive therapy for major depressive disorder (MDD) that stimulates acupoints innervated by the trigeminal and auricular vagus nerves. However, there are few neuroimaging studies involving the TECAS for the treatment of MDD. Therefore, this study aimed to investigate the treatment response and neurological effects of TECAS using resting-state functional magnetic resonance imaging (rs-fMRI).

METHOD

A total of 34 patients with mild-to-moderate MDD and 34 demographically matched healthy controls (HCs) were recruited. After an eight-week treatment the primary outcome was clinical response, defined as a baseline-to-endpoint ≥ 50 % reduction in the 17-item Hamilton Depression Rating Scale (HAMD-17). The low-frequency fluctuations (ALFF) method were used to investigate the brain abnormalities of MDD patients and HCs, and altered brain networks were analyzed between pre- and post-treatment using seed-based functional connectivity (FC) analysis.

RESULTS

We found no significant differences in terms of gender, age, and years of education between the two groups. After treatment, the response rate was 58.82 %. Compared to HCs, MDD patients showed lower ALFF values in the left insula(t = -4.298,P < 0.005), the insula-based FC revealed in the right middle frontal gyrus (MFG)/ right superior frontal gyrus, orbital part (ORBsupmed) (t = -5.29,P < 0.005) and the right anterior cingulate gyrus (ACC)were decreased (t = -6.08,P < 0.005). Furthermore, Compared to pre-treatment, abnormal FC values in the ACC /orbital superior frontal gyrus (SFG) (t = 3.42,P < 0.005) and left superior frontal gyrus (SFG)/ supplement motor area (SMA) were enhanced (t = 3.34,P < 0.005).

CONCLUSION

TECAS exhibits antidepressant efficacy, particularly influencing the insula-based functional connections within the Default Mode Network (DMN) related to emotion processing in individuals with MDD.

Enhanced Punishment Responses in Patients With Schizophrenia: An Event-Related Potential Study

It is well known that abnormal reward processing is a characteristic feature of various psychopathologies including schizophrenia. Reduced reward anticipation has been suggested as a core symptom of schizophrenia. The Monetary Incentive Delay Task (MID) is frequently used to detect reward anticipation. The present study aims to evaluate the amplitude and latency of event-related potential (ERP) P300 in patients with schizophrenia (SCH) compared to healthy controls during the MID task. Twenty patients with SCH and 21 demographically matched healthy controls (HC) were included in the study. ERP P300 amplitude and latency values were compared between groups using an MID task in which reward and loss cues were presented. Relations between P300 and clinical facets were investigated in the patient group. SCH group had enhanced mean P300 amplitudes and delayed peak latency in the punishment condition compared with HC. These higher responses were also associated with negative symptoms. SCH group showed altered reward processing as being more sensitive to loss of reward conditions as firstly evidenced by electrophysiological methods, possibly due to abnormality in various systems including social withdrawal, social defeat, and behavioral inhibition system.

Strength-based cognitive-behavioural therapy and peer-to-peer support in the recovery process for people with schizophrenia: A randomised control trial

BACKGROUND AND AIMS

Dysfunctional cognition and negative symptoms in schizophrenia are associated with persistently low social functioning and quality of life (QoL). Recovery interventions report only a modest effect in improving social functioning and QoL. This study examined the therapeutic effects and pathways of interventions using strength-based cognitive-behavioural therapy (SBCBT) and peer-to-peer support (PSP) approaches.

METHODS

A randomised control trial compared SBCBT, PSP and TAU (treatment-as-usual) by recruiting 127 individuals with schizophrenia spectrum disorders and low social functioning.

RESULTS

The three-group comparison found SBCBT produced improved social functioning and social support at post-intervention and 6-month follow-up while PSP reported improved social QoL and defeatist beliefs, but none remained at 6-month follow-up. Unsurprising, no improvement was found in any areas for TAU, both at post-test and 6-month follow-up. Regarding mechanisms of change, improvements in hope and personal recovery consistently and significantly accounted for improvements in social functioning and many aspects of QoL of participants, thus indicating the important contribution of hope and personal recovery in strength-based interventions for people with schizophrenia.

CONCLUSION

This rigorously designed study provides the first few solid empirical evidence on the effectiveness of SBCBT and PSP in recovery from schizophrenia and provides initial evidence of the linkage between dysfunctional cognition, hope and recovery in schizophrenia.

Evidence for shallow cognitive maps in schizophrenia

Individuals with schizophrenia can have marked deficits in goal-directed decision making. Prominent theories differ in whether schizophrenia (SZ) affects the ability to exert cognitive control, or the motivation to exert control. An alternative explanation is that schizophrenia negatively impacts the formation of cognitive maps, the internal representations of the way the world is structured, necessary for the formation of effective action plans. That is, deficits in decision-making could also arise when goal-directed control and motivation are intact, but used to plan over ill-formed maps. Here, we test the hypothesis that individuals with SZ are impaired in the construction of cognitive maps. We combine a behavioral representational similarity analysis technique with a sequential decision-making task. This enables us to examine how relationships between choice options change when individuals with SZ and healthy age-matched controls build a cognitive map of the task structure. Our results indicate that SZ affects how people represent the structure of the task, focusing more on simpler visual features and less on abstract, higher-order, planning-relevant features. At the same time, we find that SZ were able to display similar performance on this task compared to controls, emphasizing the need for a distinction between cognitive map formation and changes in goal-directed control in understanding cognitive deficits in schizophrenia.

Dampened motivation in schizophrenia: evidence from a novel effort-based decision-making task in social scenarios

Apathy represents a significant manifestation of negative symptoms within individuals diagnosed with schizophrenia (SCZ) and exerts a profound impact on their social relationships. However, the specific implications of this motivational deficit in social scenarios have yet to be fully elucidated. The present study aimed to examine effort-based decision-making in social scenarios and its relation to apathy symptoms in SCZ patients. We initially recruited a group of 50 healthy participants (16 males) to assess the validity of the paradigm. Subsequently, we recruited 45 individuals diagnosed with SCZ (24 males) and 49 demographically-matched healthy controls (HC, 25 males) for the main study. The Mock Job Interview Task was developed to measure effort-based decision-making in social scenarios. The proportion of hard-task choice and a range of subjective ratings were obtained to examine potential between-group differences. SCZ patients were less likely than HC to choose the hard task with strict interviewers, and this group difference was significant when the hard-task reward value was medium and high. More severe apathy symptoms were significantly correlated with an overall reduced likelihood of making a hard-task choice. When dividing the jobs into two categories based on the levels of social engagement needed, SCZ patients were less willing to expend effort to pursue a potential offer for jobs requiring higher social engagement. Our findings indicated impaired effort-based decision-making in SCZ can be generalized from the monetary/nonsocial to a more ecologically social dimension. Our findings affirm the critical role of aberrant effort allocation on negative symptoms, and may facilitate the development of targeted clinical interventions.

Social cognition and social motivation in schizophrenia and bipolar disorder: are impairments linked to the disorder or to being socially isolated?

BACKGROUND

People with schizophrenia on average are more socially isolated, lonelier, have more social cognitive impairment, and are less socially motivated than healthy individuals. People with bipolar disorder also have social isolation, though typically less than that seen in schizophrenia. We aimed to disentangle whether the social cognitive and social motivation impairments observed in schizophrenia are a specific feature of the clinical condition v. social isolation generally.

METHODS

We compared four groups (clinically stable patients with schizophrenia or bipolar disorder, individuals drawn from the community with self-described social isolation, and a socially connected community control group) on loneliness, social cognition, and approach and avoidance social motivation.

RESULTS

Individuals with schizophrenia (n = 72) showed intermediate levels of social isolation, loneliness, and social approach motivation between the isolated (n = 96) and connected control (n = 55) groups. However, they showed significant deficits in social cognition compared to both community groups. Individuals with bipolar disorder (n = 48) were intermediate between isolated and control groups for loneliness and social approach. They did not show deficits on social cognition tasks. Both clinical groups had higher social avoidance than both community groups.

CONCLUSIONS

The results suggest that social cognitive deficits in schizophrenia, and high social avoidance motivation in both schizophrenia and bipolar disorder, are distinct features of the clinical conditions and not byproducts of social isolation. In contrast, differences between clinical and control groups on levels of loneliness and social approach motivation were congruent with the groups' degree of social isolation.

Reduced Reward Processing in Schizophrenia: A Comprehensive EEG Event-Related Oscillation Study

It is well known that abnormal reward processing is a characteristic feature of various psychopathologies including schizophrenia (SZ). Reduced reward anticipation has been suggested as a core symptom of SZ. The present study aims to evaluate the event-related oscillations (EROs) delta, theta, alpha, beta, and gamma in patients with SZ during the Monetary Incentive Delay (MID) task, which elicits the neural activity of reward processing. Twenty-one patients with SZ and twenty-two demographically matched healthy controls were included in the study. EROs were compared between groups and correlation analyses were conducted to determine a possible relationship between clinical scores and ERO values. Compared with healthy controls, the SZ group had reduced (1) delta and theta amplitudes in the reward condition (2) total beta and non-incentive cue-related beta amplitudes, and (3) incentive cue-related frontal gamma amplitudes. These reductions can be interpreted as impaired dopaminergic neurotransmission and disrupted cognitive functioning in the reward processing of SZ. In contrast, SZ patients showed higher incentive cue-related theta and occipital gamma amplitudes compared to controls. These increments may reflect negative symptoms in SZ. Moreover, theta amplitudes showed a negative correlation with Calgary Depression Scale for Schizophrenia scores and a positive correlation with attentional impulsivity. This is the first study showing the impairments of SZ patients in EROs from delta to gamma frequency bands compared with healthy controls during reward anticipation. Being the first comprehensive study, our results can be interpreted as providing evidence for disrupted brain dynamics in the reward processing of SZ studied by EROs. It may become possible to help patients' wellness by improving our understanding of reward processing in schizophrenia and developing innovative rehabilitation treatments based on these findings.

The validity of a therapeutic invigoration task in avolitional schizophrenia outpatients

BACKGROUND AND OBJECTIVES

Avolition is associated with much morbidity and functional impairment in schizophrenia patients. Vigor may be taken as, in part, the inverse of avolition, but it has not been investigated as a therapeutic pursuit before. To this end, a therapeutic invigoration task was developed drawing on cognitive-behavioral and guided imagery therapies. This study investigated the validity and reliability of a therapeutic invigoration task in avolitional residual phase schizophrenia outpatients.

METHODS

In a proof-of-concept quasi-experimental one-group sequentially repeated pretest/posttest study design, patients (n = 76) participated in a structured invigoration task that was repeated after 1 month (n = 70).

RESULTS

Patients' vigor during the preceding 7 days measured on the Vigor Assessment Scale increased highly significantly in anticipation of the subsequent 7 days on both occasions with respectively very large (Cohen's δ with Hedges' correction [δ] = 1.46) and large (δ = 1.04) effect sizes. The anticipated vigor after the first occasion was partially consummated during the subsequent month in that vigor during the 7 days preceding the second occasion was lower than participants had anticipated but still significantly higher than at baseline (p < 0.001; δ = 0.70). Repeating the task a month later, together with homework, had a cumulative effect as indicated by a very large effect size (δ = 1.61).

CONCLUSION

Results suggest that the invigoration task did what it was supposed do, and did so consistently, in patients with avolitional residual schizophrenia. These results warrant a subsequent randomized controlled trial to establish the efficacy of the invigoration task.

Reinforcement learning profiles and negative symptoms across chronic and clinical high-risk phases of psychotic illness

Negative symptoms are prominent in individuals with schizophrenia (SZ) and youth at clinical high-risk for psychosis (CHR). In SZ, negative symptoms are linked to reinforcement learning (RL) dysfunction; however, previous research suggests implicit RL remains intact. It is unknown whether implicit RL is preserved in the CHR phase where negative symptom mechanisms are unclear, knowledge of which may assist in developing early identification and prevention methods. Participants from two studies completed an implicit RL task: Study 1 included 53 SZ individuals and 54 healthy controls (HC); Study 2 included 26 CHR youth and 23 HCs. Bias trajectories reflecting implicit RL were compared between groups and correlations with negative symptoms were examined. Cluster analysis investigated RL profiles across the combined samples. Implicit RL was comparable between HC and their corresponding SZ and CHR groups. However, cluster analysis was able to parse performance heterogeneity across diagnostic boundaries into two distinct RL profiles: a Positive/Early Learning cluster (65% of participants) with positive bias scores increasing from the first to second task block, and a Negative/Late Learning cluster (35% of participants) with negative bias scores increasing from the second to third block. Clusters did not differ in the proportion of CHR vs. SZ cases; however, the Negative/Late Learning cluster had more severe negative symptoms. Although implicit RL is intact in CHR similar to SZ, distinct implicit RL phenotypic profiles with elevated negative symptoms were identified trans-phasically, suggesting distinct reward-processing mechanisms can contribute to negative symptoms independent of phases of illness.

Two and five-factor models of negative symptoms in schizophrenia are differentially associated with trait affect, defeatist performance beliefs, and psychosocial functioning

Recent factor analytic evidence supports both two-factor (motivation and pleasure, MAP; diminished expression, EXP) and five-factor (anhedonia, asociality, avolition, blunted affect, alogia) conceptualizations of negative symptoms. However, it is unclear whether these two conceptualizations of the latent structure of negative symptoms have differential associations with external correlates. The current study evaluated external correlates of the two- and five-factor structures by examining associations with variables known to have critical relations with negative symptoms: trait affect, defeatist performance beliefs, neurocognition, and community-based psychosocial functioning. Participants included a total of 245 outpatients diagnosed with schizophrenia who were rated on the Brief Negative Symptom Scale and completed a battery of additional measures during periods of clinical stability. These additional measures included the Positive and Negative Affect Schedule, Defeatist Performance Beliefs scale, MATRICS Consensus Cognitive Battery, and Level of Function Scale. Pearson correlations indicated differential patterns of associations between the BNSS scores and the external correlates. Support for the two-factor model was indicated by a stronger association of MAP with positive affect and psychosocial functioning, compared to EXP with neurocognition. Significance tests examining a differential magnitude of associations showed that the two-dimension negative symptom structure masked unique correlational relationships among the five negative symptom domains with neurocognition and social/vocational community functioning and captured unique patterns of correlation with trait affect. Support for the five-factor model was shown by a stronger association between Blunted Affect with Attention/Vigilance, and stronger associations between Avolition, Anhedonia, and Asociality with psychosocial functioning. Results offer support for both the two-dimension and five-domain model of negative symptoms as well as a hierarchical two-dimensions-five-domains model of negative symptoms. Findings may have implications for diagnostic criteria and descriptions of the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5), as well as possible treatment targets of negative symptoms.

Revisiting reward impairments in schizophrenia spectrum disorders: a systematic review and meta-analysis for neuroimaging findings

BACKGROUND

Abnormal reward functioning is central to anhedonia and amotivation symptoms of schizophrenia (SCZ). Reward processing encompasses a series of psychological components. This systematic review and meta-analysis examined the brain dysfunction related to reward processing of individuals with SCZ spectrum disorders and risks, covering multiple reward components.

METHODS

After a systematic literature search, 37 neuroimaging studies were identified and divided into four groups based on their target psychology components (i.e. reward anticipation, reward consumption, reward learning, effort computation). Whole-brain Seed-based d Mapping (SDM) meta-analyses were conducted for all included studies and each component.

RESULTS

The meta-analysis for all reward-related studies revealed reduced functional activation across the SCZ spectrum in the striatum, orbital frontal cortex, cingulate cortex, and cerebellar areas. Meanwhile, distinct abnormal patterns were found for reward anticipation (decreased activation of the cingulate cortex and striatum), reward consumption (decreased activation of cerebellum IV/V areas, insula and inferior frontal gyri), and reward learning processing (decreased activation of the striatum, thalamus, cerebellar Crus I, cingulate cortex, orbitofrontal cortex, and parietal and occipital areas). Lastly, our qualitative review suggested that decreased activation of the ventral striatum and anterior cingulate cortex was also involved in effort computation.

CONCLUSIONS

These results provide deep insights on the component-based neuro-psychopathological mechanisms for anhedonia and amotivation symptoms of the SCZ spectrum.

Negative symptoms and cognitive impairment are associated with distinct motivational deficits in treatment resistant schizophrenia

BACKGROUND

Motivational deficits are a central feature of the negative syndrome in schizophrenia. They have consistently been associated with reduced willingness to expend physical effort in return for monetary rewards on effort based decision making (EBDM) paradigms. Nevertheless, the mechanisms underlying such altered performance are not well characterised, and it remains unclear if they are driven purely by negative symptoms, or also in part by cognitive impairment, antipsychotic treatment or even positive symptoms. Here we investigated the impact of all these factors using a paradigm that has not previously been used to measure EBDM in schizophrenia.

METHODS

Forty treatment resistant schizophrenia (TRS) patients on clozapine and matched controls (N = 80) completed a well validated EBDM task which offers monetary rewards in return for physical effort. Choice and reaction time data was analysed using logistic regressions, as well as Bayesian hierarchical drift diffusion modelling (HDDM). Behavioural parameters were compared between groups and their association with negative symptoms, cognitive function and serum clozapine levels were assessed.

RESULTS

Overall, TRS patients accepted significantly less offers than controls during effort-based decision making, suggesting they were less motivated. They demonstrated reduced sensitivity to increasing rewards, but surprisingly were also less averse to increasing effort. Despite a positive correlation between negative symptoms and cognitive function in TRS, reward sensitivity was associated only with cognitive performance. In contrast, reduced effort aversion correlated with negative symptom severity. Clozapine levels and positive symptoms were not associated with either behavioural parameter.

CONCLUSION

Motivational deficits in TRS are characterised by both diminished reward sensitivity and reduced effort aversion during EBDM. Cognitive dysfunction and negative symptom severity account for distinct aspects of these behavioural changes, despite positive associations between themselves. Overall, these findings demonstrate that negative symptoms and cognitive impairment have significant independent contributions to EBDM in TRS, thereby opening the possibility of individualised treatment targeting these mechanisms to improve motivation.

Altered brain functional networks in schizophrenia with persistent negative symptoms: an activation likelihood estimation meta-analysis

Objective

To investigate brain structural and functional characteristics of three brain functional networks including default mode network (DMN), central executive network (CEN), and salience network (SN) in persistent negative symptoms (PNS) patients.

Methods

We performed an activation likelihood estimation (ALE) meta-analysis of functional connectivity (FC) studies and voxel-based morphometry (VBM) studies to detect specific structural and functional alterations of brain networks between PNS patients and healthy controls.

Results

Seventeen VBM studies and twenty FC studies were included. In the DMN, PNS patients showed decreased gray matter in the bilateral medial frontal gyrus and left anterior cingulate gyrus and a significant reduction of FC in the right precuneus. Also, PNS patients had a decrease of gray matter in the left inferior parietal lobules and medial frontal gyrus, and a significant reduction of FC in the bilateral superior frontal gyrus in the CEN. In comparison with healthy controls, PNS patients exhibited reduced gray matter in the bilateral insula, anterior cingulate gyrus, left precentral gyrus and right claustrum and lower FC in these brain areas in the SN, including the left insula, claustrum, inferior frontal gyrus and extra-nuclear.

Conclusion

This meta-analysis reveals brain structural and functional imaging alterations in the three networks and the interaction among these networks in PNS patients, which provides neuroscientific evidence for more personalized treatment.Systematic Review RegistrationThe PROSPERO (https://www.crd.york.ac.uk/PROSPERO/, registration number: CRD42022335962).

Modeling Effort-Based Decision Making: Individual Differences in Schizophrenia and Major Depressive Disorder

BACKGROUND

A critical facet of motivation is effort-based decision making, which refers to the mental processes involved in deciding whether a potential reward is worth the effort. To advance understanding of how individuals with schizophrenia and major depressive disorder utilize cost-benefit information to guide choice behavior, this study aimed to characterize individual differences in the computations associated with effort-based decision making.

METHODS

One hundred forty-five participants (51 with schizophrenia, 43 with depression, and 51 healthy control participants) completed the Effort Expenditure for Rewards Task, with mixed effects modeling conducted to estimate the predictors of decision making. These model-derived, subject-specific coefficients were then clustered using k-means to test for the presence of discrete transdiagnostic subgroups with different profiles of reward, probability, and cost information utilization during effort-based decision making.

RESULTS

An optimal 2-cluster solution was identified, with no significant differences in the distribution of diagnostic groups between clusters. Cluster 1 (n = 76) was characterized by overall lower information utilization during decision making than cluster 2 (n = 61). Participants in this low information utilization cluster were also significantly older and more cognitively impaired, and their utilization of reward, probability, and cost was significantly correlated with clinical amotivation, depressive symptoms, and cognitive functioning.

CONCLUSIONS

Our findings revealed meaningful individual differences among participants with schizophrenia, depression, and healthy control participants in their utilization of cost-benefit information in the context of effortful decision making. These findings may provide insight into different processes associated with aberrant choice behavior and may potentially guide the identification of more individualized treatment targets for effort-based motivation deficits across disorders.

The relationships between amotivation, employee engagement, introjected regulation, and intrinsic motivation: A double-layered moderated-mediation model

The objective of this research is to examine the amotivation-turnover intention relationship through self-determination theory (SDT). A double-layered moderated-mediation model was developed to investigate the influence of three components: affective, continuance, and normative commitment on turnover intention. The data collected from 771 faculty members from higher educational institutions (HEI) in southern India were analyzed to test the hypothesized relationships. After testing the psychometric properties of the survey instrument through LISREL software of structural equation modeling, Hayes's PROCESS was used to test the structural model. The results indicate that (i) amotivation was negatively related to normative commitment, (ii) normative commitment was negatively related to turnover intentions, and (iii) normative commitment mediated the relationship between amotivation and turnover intentions. The findings also suggest that affective commitment (first moderator) and continuance commitment (second moderator) interact with amotivation to influence normative commitment. Further, the three-way interaction between normative commitment, intrinsic motivation, and introjected regulation to decrease turnover intention was significant. The double-layered moderated-mediation model is a novel concept that contributes to the literature on commitment and motivation. The theoretical and practical implications are discussed.

Regional cerebral blood flow at rest in schizophrenia and major depressive disorder: A functional neuroimaging meta-analysis

Severe mental disorders (SMDs) such as schizophrenia (SCZ), major depressive disorder (MDD) and bipolar disorder (BD) are associated with altered brain function. Neuroimaging studies have illustrated spontaneous activity alterations across SMDs, but no meta-analysis has directly compared resting-state regional cerebral blood flow (rCBF) with one another. We conducted a meta-analysis of PET, SPECT and ASL neuroimaging studies to identify specific alterations of rCBF at rest in SMDs. Included are 20 studies in MDD, and 18 studies in SCZ. Due to the insufficient number of studies in BD, this disorder was left out of the analyses. Compared to controls, the SCZ group displayed reduced rCBF in the triangular part of the left inferior frontal gyrus and in the medial orbital part of the bilateral superior frontal gyrus. After correction, only a small cluster in the right inferior frontal gyrus exhibited reduced rCBF in MDD, compared to controls. Differences were found in these brain regions between SCZ and MDD. SCZ displayed reduced rCBF at rest in regions associated with default-mode, reward processing and language processing. MDD was associated with reduced rCBF in a cluster involved in response inhibition. Our meta-analysis highlights differences in the resting-state rCBF alterations between SCZ and MDD.

Evidence for functional improvement in reward anticipation in recent onset schizophrenia after one year of coordinated specialty care

BACKGROUND

Motivational impairment associated with deficits in processing the anticipation of future reward is hypothesized to be a cardinal feature of schizophrenia spectrum disorders (SZ). Evidence from short-term follow-up (6-week post-treatment) studies suggests that these deficits may improve or be reversed with treatment, although longer-term outcomes are unknown. Here we examined the one-year trajectory of functional activation in brain circuitry associated with reward anticipation in people with recent onset SZ who participated in coordinated specialty care (CSC) treatment, hypothesizing normalization of brain response mirroring previous short-term findings in first-episode individuals.

METHOD

Blood oxygen level-dependent (BOLD) response in the dorsal anterior cingulate cortex, anterior insula, and ventral striatum (VS) associated with reward anticipation during the Incentivized Control Engagement Task (ICE-T) was analyzed in a baseline sample of 49 healthy controls (HCs) and 52 demographically matched people with SZ, with follow-up data available for 35 HCs and 17 people with SZ.

RESULTS

In agreement with our hypothesis, significant time × diagnosis interactions were observed across all regions, in which reward anticipation-associated BOLD response increased in SZ to above baseline HC levels at follow-up. Increased VS activation was associated with decreased reality distortion symptoms over the follow-up period. Baseline reward anticipation-associated BOLD response in the right anterior insula was associated with improvement in reality distortion symptoms.

CONCLUSIONS

These findings suggest that functional deficits in reward anticipation may be reversed after one year of CSC in recent onset participants with SZ, and that this improvement is associated with reduced positive symptoms in the illness.

Social Motivation in Schizophrenia: What's Effort Got to Do With It?

BACKGROUND AND HYPOTHESIS

Social motivation, defined as the fundamental human desire to seek out, engage in, and maintain interpersonal bonds, has become a growing area of research in schizophrenia. The major focus has been on understanding the impact of social reward-related processes. An obvious but rarely acknowledged fact is that social interactions, much like other goal-directed acts, require the exertion of effort. In this Review Article, we argue that social motivation in schizophrenia can be conceptualized through the lens of an established framework: effort-based decision-making (EBDM).

STUDY DESIGN

We conducted a literature review on social reward processing in schizophrenia, then extended these findings by applying concepts and insights from the literature on EBDM to the study of social motivation.

STUDY RESULTS

Within the EBDM framework, decisions about whether or not to pursue social interactions are bound by cost/benefit calculations. That is, people do not pursue social behaviors when the estimated "cost" of the required effort outweighs the anticipated "benefit" or reward. We propose that people with schizophrenia are less likely to engage in social interaction compared with healthy samples because they: (1) underestimate the benefits of relationships (based on expectations of reward/punishment), (2) overestimate the effort costs associated with social interaction, and/or (3) fail to integrate cost-benefit information in an optimal manner.

CONCLUSIONS

EBDM is an especially promising framework of social motivation that goes beyond the current focus on social reward processing to include a focus on effort.

Towards an integrative hope-dysfunctional beliefs perspective to personal recovery in schizophrenia: a path analysis

BACKGROUND

Evidence shows that negative symptoms of schizophrenia and underlying dysfunctional cognition are related to persistently low functioning and quality of life. However, despite the abundance of existing recovery programs for people with schizophrenia, few have examined whether and how the widely-adopted hope-motivation recovery pathway and the deficit-oriented cognitive pathway might converge to influence functioning and quality of life.

METHODS

A cross-sectional, quantative survey recruited a convenient sample of adult outpatients with DSM-5 schizophrenia spectrum disorders and low social functioning (n = 124). Self-reported measurements included personal recovery (30-item Mental Health Recovery Measure), social functioning (8-item Social Functioning Questionnaire), hope (12-item Hope Scale), quality of life (28-item World Health Organization Quality of Life Scale-Abbreviated Version-Hong Kong), defeatist beliefs (15-item extracted from Dysfunctional Attitude Scale), and asocial beliefs (15-item extracted from Revised Social Anhedonia Scale). Correlation analysis and structural equation modelling was applied to investigate how the two pathways intertwined to predict social functioning and quality of life.

RESULTS

Asocial beliefs and hope separately mediated two partial mediation pathways from defeatist beliefs to recovery outcomes (social functioning and personal recovery). Meanwhile, defeatist beliefs, social functioning, and personal recovery further predicted quality of life.

CONCLUSIONS

This is one of the very few studies that provides empirical evidence of a deficit-strength linkage in the recovery from schizophrenia. Remediation of dysfunctional beliefs and the injection of hope and successful experiences should be undertaken concurrently in recovery as they are associated with differential effects on enhancing social functioning and personal recovery, which then converge and contribute to a better quality of life.

The organization of frontostriatal brain wiring in non-affective early psychosis compared with healthy subjects using a novel diffusion imaging fiber cluster analysis

BACKGROUND

Alterations in brain connectivity may underlie neuropsychiatric conditions such as schizophrenia. We here assessed the degree of convergence of frontostriatal fiber projections in 56 young adult healthy controls (HCs) and 108 matched Early Psychosis-Non-Affective patients (EP-NAs) using our novel fiber cluster analysis of whole brain diffusion magnetic resonance imaging tractography.

METHODS

Using whole brain tractography and our fiber clustering methodology on harmonized diffusion magnetic resonance imaging data from the Human Connectome Project for Early Psychosis we identified 17 white matter fiber clusters that connect frontal cortex (FCtx) and caudate (Cd) per hemisphere in each group. To quantify the degree of convergence and, hence, topographical relationship of these fiber clusters, we measured the inter-cluster mean distances between the endpoints of the fiber clusters at the level of the FCtx and of the Cd, respectively.

RESULTS

We found (1) in both groups, bilaterally, a non-linear relationship, yielding convex curves, between FCtx and Cd distances for FCtx-Cd connecting fiber clusters, driven by a cluster projecting from inferior frontal gyrus; however, in the right hemisphere, the convex curve was more flattened in EP-NAs; (2) that cluster pairs in the right (p = 0.03), but not left (p = 0.13), hemisphere were significantly more convergent in HCs vs EP-NAs; (3) in both groups, bilaterally, similar clusters projected significantly convergently to the Cd; and, (4) a significant group by fiber cluster pair interaction for 2 right hemisphere fiber clusters (numbers 5, 11; p = .00023; p = .00023) originating in selective PFC subregions.

CONCLUSIONS

In both groups, we found the FCtx-Cd wiring pattern deviated from a strictly topographic relationship and that similar clusters projected significantly more convergently to the Cd. Interestingly, we also found a significantly more convergent pattern of connectivity in HCs in the right hemisphere and that 2 clusters from PFC subregions in the right hemisphere significantly differed in their pattern of connectivity between groups.

Mice lacking Ptprd exhibit deficits in goal-directed behavior and female-specific impairments in sensorimotor gating

Protein Tyrosine Phosphatase receptor type D (PTPRD) is a member of the protein tyrosine phosphatase family that mediates cell adhesion and synaptic specification. Genetic studies have linked Ptprd to several neuropsychiatric phenotypes, including Restless Leg Syndrome (RLS), opioid abuse disorder, and antipsychotic-induced weight gain. Genome-wide association studies (GWAS) of either pediatric obsessive-compulsive traits, or Obsessive-Compulsive Disorder (OCD), have identified loci near PTPRD as genome-wide significant, or strongly suggestive for this trait. We assessed Ptprd wild-type (WT), heterozygous (HT), and knockout (KO) mice for behavioral dimensions that are altered in OCD, including anxiety and exploration (open field test, dig test), perseverative behavior (splash-induced grooming, spatial d), sensorimotor gating (prepulse inhibition), and home cage goal-directed behavior (nest building). No effect of genotype was observed in any measure of the open field test, dig test, or splash test. However, Ptprd KO mice of both sexes showed impairments in nest building behavior. Finally, female, but not male, Ptprd KO mice showed deficits in prepulse inhibition, an operational measure of sensorimotor gating that is reduced in female, but not male, OCD patients. Our results indicate that constitutive lack of Ptprd may contribute to the development of certain domains that are altered OCD, including goal-directed behavior, and reduced sensorimotor gating specifically in females.

Alpha Event-Related Desynchronization During Reward Processing in Schizophrenia

BACKGROUND

Alterations in the brain's reward system may underlie motivation and pleasure deficits in schizophrenia (SZ). Neuro-oscillatory desynchronization in the alpha band is thought to direct resource allocation away from the internal state, to prioritize processing salient environmental events, including reward feedback. We hypothesized reduced reward-related alpha event-related desynchronization (ERD) in SZ, consistent with less externally focused processing during reward feedback.

METHODS

Electroencephalography was recorded while participants with SZ (n = 54) and healthy control participants (n = 54) played a simple slot machine task. Total alpha band power (8-14 Hz), a measure of neural oscillation magnitude, was extracted via principal component analysis and compared between groups and reward outcomes. The clinical relevance of hypothesized alpha power alterations was examined by testing associations with negative symptoms within the SZ group and with trait rumination, dimensionally, across groups.

RESULTS

A group × reward outcome interaction (p = .018) was explained by healthy control participants showing significant posterior-occipital alpha power suppression to wins versus losses (p < .001), in contrast to participants with SZ (p > .1). Among participants with SZ, this alpha ERD was unrelated to negative symptoms (p > .1). Across all participants, less alpha ERD to reward outcomes covaried with greater trait rumination for both win (p = .005) and loss (p = .002) outcomes, with no group differences in slope.

CONCLUSIONS

These findings demonstrate alpha ERD alterations in SZ during reward outcome processing. Additionally, higher trait rumination was associated with less alpha ERD during reward feedback, suggesting that individual differences in rumination covary with external attention to reward processing, regardless of reward outcome valence or group membership.

The human cerebellum in reward anticipation and reward outcome processing: An activation likelihood estimation meta-analysis

The cerebellum generates internal prediction models and actively compares anticipated and actual outcomes in order to reach a desired end state. In this process, reward can serve as a reinforcer that shapes internal prediction models, enabling context-appropriate behavior. While the involvement of the cerebellum in reward processing has been established in animals, there is no detailed account of which cerebellar regions are involved in reward anticipation and reward outcome processing in humans. To this end, an activation likelihood estimation meta-analysis of functional neuroimaging studies was performed to investigate cerebellar functional activity patterns associated with reward anticipation and reward outcome processing in healthy adults. Results showed that reward anticipation (k=31) was associated with regional activity in the bilateral anterior lobe, bilateral lobule VI, left Crus I and the posterior vermis, while reward outcome (k=16) was associated with regional activity in the declive and left lobule VI. The findings of this meta-analysis show distinct involvement of the cerebellum in reward anticipation and reward outcome processing as part of a predictive coding routine.

Negative schizotypal traits predict the reduction of reward motivation in effort-reward imbalance

The schizotypy construct is useful for studying the effects of environmental stress on development of subclinical negative symptoms. The relationship among self-report motivation, effort-reward imbalance (ERI), and schizotypal features has seldom been studied. We aimed to examine the possible moderation effect of schizotypal traits on ERI and reward motivation. Eight-hundred-and-forty-three college students were recruited online to complete a set of self-reported measures capturing schizotypal traits, effort-reward imbalance and reward motivation, namely the Schizotypal Personality Questionnaire (SPQ), the Effort-Reward Imbalance-School Version Questionnaire (C-ERI-S) and the Motivation and Pleasure Scale-Self Report (MAP-SR). We conducted multiple linear regression to construct models to investigate the moderating effects of schizotypal traits on the relationship between ERI and reward motivation. Stressful ERI situation predicted the reduction of reward motivation. Negative schizotypal traits showed a significant negative moderating effect on the relationship between ERI and reward motivation, while positive and disorganized schizotypal traits had significant positive moderating effects. Schizotypal traits subtypes differently moderate the relationship between ERI and reward motivation. Only negative schizotypal traits and stressful ERI situation together have negative impact on reward motivation.

The positivity offset theory of anhedonia in schizophrenia: evidence for a deficit in daily life using digital phenotyping

BACKGROUND

Negative symptoms of schizophrenia have recently been proposed to result from a decoupling of (intact) hedonic experience and (diminished) approach behavior. The current study challenged this view by exploring the hypothesis that negative symptoms are driven by a specific type of emotional experience abnormality, a reduction in the positivity offset (i.e. the tendency to experience greater levels of positive relative to negative emotion in low-arousal contexts), which limits the production of approach behaviors in neutral environments.

METHODS

Participants included outpatients with SZ (n = 44) and healthy controls (CN: n = 48) who completed one week of active (ecological momentary assessment surveys of emotional experience and symptoms) and passive (geolocation, accelerometry) digital phenotyping. Mathematical modeling approaches from Cacioppo's Evaluative Space Model were used to quantify the positivity offset in daily life. Negative symptoms were assessed via standard clinical ratings, as well as active (EMA surveys) and passive (geolocation, accelerometry) digital phenotyping measures.

RESULTS

Results indicated that the positivity offset was reduced in SZ and associated with more severe anhedonia and avolition measured via clinical interviews and active and passive digital phenotyping.

CONCLUSIONS

These findings suggest that current conceptual models of negative symptoms, which assume hedonic normality, may need to be revised to account for reductions in the positivity offset and its connection to diminished motivated behavior. Findings identify key real-world contexts where negative symptoms could be targeted using psychosocial treatments.

Reduced willingness to expend effort for rewards is associated with risk for conversion and negative symptom severity in youth at clinical high-risk for psychosis

BACKGROUND

Schizophrenia (SZ) is typically preceded by a prodromal (i.e. pre-illness) period characterized by attenuated positive symptoms and declining functional outcome. Negative symptoms are prominent among individuals at clinical high-risk (CHR) for psychosis (i.e. those with prodromal syndromes) and predictive of conversion to illness. Mechanisms underlying negative symptoms are unclear in the CHR population.

METHODS

The current study evaluated whether CHR participants demonstrated deficits in the willingness to expend effort for rewards and whether these impairments are associated with negative symptoms and greater risk for conversion. Participants included 44 CHR participants and 32 healthy controls (CN) who completed the Effort Expenditure for Reward Task (EEfRT).

RESULTS

Compared to CN, CHR participants displayed reduced likelihood of exerting high effort for high probability and magnitude rewards. Among CHR participants, reduced effort expenditure was associated with greater negative symptom severity and greater probability of conversion to a psychotic disorder on a cross-sectional risk calculator.

CONCLUSIONS

Findings suggest that effort-cost computation is a marker of illness liability and a transphasic mechanism underlying negative symptoms in the SZ spectrum.

Resting-State Brain Activity Dysfunctions in Schizophrenia and Their Associations with Negative Symptom Domains: An fMRI Study

The aim of the present study was to examine the neurobiological correlates of the two negative symptom domains of schizophrenia, the Motivational Deficit domain (including avolition, anhedonia, and asociality) and the Expressive Deficit domain (including blunted affect and alogia), focusing on brain areas that are most commonly found to be associated with negative symptoms in previous literature. Resting-state (rs) fMRI data were analyzed in 62 subjects affected by schizophrenia (SZs) and 46 healthy controls (HCs). The SZs, compared to the HCs, showed higher rs brain activity in the right inferior parietal lobule and the right temporoparietal junction, and lower rs brain activity in the right dorsolateral prefrontal cortex, the bilateral anterior dorsal cingulate cortex, and the ventral and dorsal caudate. Furthermore, in the SZs, the rs brain activity in the left orbitofrontal cortex correlated with negative symptoms (r = -0.436, p = 0.006), in particular with the Motivational Deficit domain (r = -0.424, p = 0.002), even after controlling for confounding factors. The left ventral caudate correlated with negative symptoms (r = -0.407, p = 0.003), especially with the Expressive Deficit domain (r = -0.401, p = 0.003); however, these results seemed to be affected by confounding factors. In line with the literature, our results demonstrated that the two negative symptom domains might be underpinned by different neurobiological mechanisms.

Distinct profiles of psychological and neuropsychological functions underlying goal-directed pursuit in schizophrenia

OBJECTIVES

Several components are known to underlie goal-directed pursuit, including executive, motivational and volitional functions. These were explored in schizophrenia spectrum disorders in order to identify subgroups with distinct profiles.

METHODS

Multiple executive, motivational and volitional tests were administered to a sample of outpatients with schizophrenia spectrum diagnoses (n = 59) and controls (n = 63). Research questions included whether distinct profiles exist and whether some functions are impacted disproportionately. These questions were addressed via cluster analysis and profile analysis, respectively.

RESULTS

Some such functions were significantly altered in schizophrenia while others were unaffected. Two distinct profiles emerged, one characterized by energizing deficits, reduced reward sensitivity and few subjective complaints; while another was characterized by markedly increased punishment sensitivity, intact reward sensitivity and substantial subjective reporting of avolitional symptoms and boredom susceptibility.

CONCLUSION

These findings highlight the importance of considering distinct patterns of strengths and deficits in functions governing goal-directed pursuit in schizophrenia that demarcate identifiable subtypes. These distinctions have implications for treatment, assessment and research.

Neutral CB1 Receptor Antagonists as Pharmacotherapies for Substance Use Disorders: Rationale, Evidence, and Challenge

Cannabinoid receptor 1 (CB1R) has been one of the major targets in medication development for treating substance use disorders (SUDs). Early studies indicated that rimonabant, a selective CB1R antagonist with an inverse agonist profile, was highly promising as a therapeutic for SUDs. However, its adverse side effects, such as depression and suicidality, led to its withdrawal from clinical trials worldwide in 2008. Consequently, much research interest shifted to developing neutral CB1R antagonists based on the recognition that rimonabant’s side effects may be related to its inverse agonist profile. In this article, we first review rimonabant’s research background as a potential pharmacotherapy for SUDs. Then, we discuss the possible mechanisms underlying its therapeutic anti-addictive effects versus its adverse effects. Lastly, we discuss the rationale for developing neutral CB1R antagonists as potential treatments for SUDs, the supporting evidence in recent research, and the challenges of this strategy. We conclude that developing neutral CB1R antagonists without inverse agonist profile may represent attractive strategies for the treatment of SUDs.

Pleasant and unpleasant odor identification ability is associated with distinct dimensions of negative symptoms transdiagnostically in psychotic disorders

Negative symptoms are among the greatest sources of functional impairment for individuals with schizophrenia, yet their mechanisms remain poorly understood. Olfactory impairment is associated with negative symptoms. The processing of pleasant olfactory stimuli is subserved by reward-related neural circuitry while unpleasant olfactory processing is subserved by emotion-related neural circuitry, suggesting that these two odor dimensions may offer a window into differential mechanisms of negative symptoms. We examined whether pleasant and unpleasant odor identification bears differential relationships with avolition and inexpressivity dimensions of negative symptoms, whether these relationships are transdiagnostic, and whether pleasant and unpleasant odor processing also relate differently to other domains of functioning in a sample of individuals diagnosed with schizophrenia (N = 54), other psychotic disorders (N = 65), and never-psychotic adults (N = 160). Hierarchical regressions showed that pleasant odor identification was uniquely associated with avolition, while unpleasant odor identification was uniquely associated with inexpressivity. These relationships were largely transdiagnostic across groups. Additionally, pleasant and unpleasant odor identification displayed signs of specificity with other functional and cognitive measures. These results align with past work suggesting dissociable pathomechanisms of negative symptoms and provide a potential avenue for future work using valence-specific olfactory dysfunction as a semi-objective and low-cost marker for understanding and predicting the severity of specific negative symptom profiles.

Low goal-directed behavior in negative symptoms is explained by goal setting - Results of a diary study

BACKGROUND AND OBJECTIVES

Engaging in goal-directed activities is a core difficulty of people with negative symptoms in schizophrenia. A previously developed goal pursuit model of negative symptoms (Schlier et al. 2017) postulates that negative symptom severity correlates with a tendency to set more avoidance- than approach-oriented goals. This shift in goal orientation correlates with low levels of goal expectancy, goal importance, and goal commitment. We explored whether these alterations translate into reduced goal-directed behavior (i.e., reduced goal striving and goal attainment).

METHODS

We conducted a one-week diary-study in a population sample (N=91). Participants were assessed for subclinical negative symptoms at baseline. Next, they set a daily goal and completed an online survey measuring goal orientation, goal characteristics, goal pursuit, and goal attainment once per day for one week.

RESULTS

Multilevel regression analyses and structural equation models showed that negative symptoms correlated with a tendency to set less approach-oriented goals with reduced goal expectancy and goal commitment. Goal orientation, expectancy, and commitment mediated the association between negative symptoms and reduced goal pursuit and attainment.

LIMITATIONS

We used a community sample, thus our results need to be replicated in a clinical sample of people with motivational negative symptoms.

CONCLUSIONS

Our results support the hypothesis that dysfunctional goal pursuit processes explain why negative symptoms lead to reduced goal-directed behavior. Interventions focusing on goal setting and goal expectations could be promising in improving goal-directed behavior in people with negative symptoms.

Δ9-THC reduces reward-related brain activity in healthy adults

RATIONALE

Greater availability of cannabis in the USA has raised concerns about adverse effects of the drug, including possible amotivational states. Lack of motivation may be assessed by examining acute effects of cannabinoids on reward processing.

OBJECTIVES

This study examined single doses of delta-9-tetrahydrocannabinol (∆9-THC; 7.5, 15 mg oral) in healthy adults using a version of the monetary incentive delay (MID) task adapted for electroencephalography (EEG; e-MID) in a within-subjects, double blind design.

METHODS

Two phases of reward processing were examined: anticipation, which occurs with presentation of cues that indicate upcoming reward, punishment, or neutral conditions, and outcome, which occurs with feedback indicating hits or misses. During anticipation, we measured two event-related potential (ERP) components: the P300, which measures attention and motivation, and the LPP, which measures affective processing. During outcome processing, we measured P300 and LPP, as well as the RewP, which measures outcome evaluation.

RESULTS

We found that ∆9-THC modulated outcome processing, but not reward anticipation. Specifically, both doses of ∆9-THC (7.5 and 15 mg) reduced RewP amplitudes after outcome feedback (hits and misses) relative to placebo. ∆9-THC (15 mg) also reduced P300 and LPP amplitudes following hits compared to misses, relative to both placebo and 7.5 mg ∆9-THC.

CONCLUSIONS

These findings suggest that ∆9-THC dampens responses to both reward and loss feedback, which may reflect an "amotivational" state. Future studies are needed to determine generalizability of this effect, such as its pharmacological specificity and its specificity to monetary vs other types of reward.

Impaired Effort Allocation in Patients with Recent-Onset Schizophrenia and Its Relevance to Negative Symptoms Assessments and Persistent Negative Symptoms

(1) Background: Our aims in this study were (i) to compare effort allocation capacity measured between patients with recent-onset schizophrenia (SCZ) and healthy controls (HCs), (ii) within the SCZ, to investigate the association of effort allocation capacity with negative symptoms (NS), and (iii) to compare this association with the type of NS scale used. (2) Methods: Thirty-one patients with SCZ and 30 HCs participated in the study. The NS was examined using an older-generation (Scale for the Assessment of Negative Symptoms, SANS), a newer-generation (Brief Negative Symptoms Scale, BNSS), and a self-rated (Self-evaluation of Negative Symptoms Scale, SNS) negative symptom scale, as well as longitudinally by using persistent NS (PNS) distinction. (3) Results: The SCZ group was less willing to expend effort in high/moderate-probability and -magnitude conditions but more in low-probability and -magnitude conditions. A general reduction in effort allocation capacity was also present. Patients with PNS were less likely to choose hard tasks than non-PNS patients. Clinician-rated scales correlated with 50% probability and moderate-reward-magnitude conditions. Correlations with the SNS were minimal. (4) Conclusions: Our findings suggest that patients with SCZ may show a general reduction in effort allocation capacity and make inefficient choices, although they are not totally reward-insensitive. The effects of NS on effort expenditure can be more pronounced when the rewarding stimulus is vague.

Striatal dopamine dissociates methylphenidate effects on value-based versus surprise-based reversal learning

Psychostimulants such as methylphenidate are widely used for their cognitive enhancing effects, but there is large variability in the direction and extent of these effects. We tested the hypothesis that methylphenidate enhances or impairs reward/punishment-based reversal learning depending on baseline striatal dopamine levels and corticostriatal gating of reward/punishment-related representations in stimulus-specific sensory cortex. Young healthy adults (N = 100) were scanned with functional magnetic resonance imaging during a reward/punishment reversal learning task, after intake of methylphenidate or the selective D_2/3-receptor antagonist sulpiride. Striatal dopamine synthesis capacity was indexed with [¹⁸F]DOPA positron emission tomography. Methylphenidate improved and sulpiride decreased overall accuracy and response speed. Both drugs boosted reward versus punishment learning signals to a greater degree in participants with higher dopamine synthesis capacity. By contrast, striatal and stimulus-specific sensory surprise signals were boosted in participants with lower dopamine synthesis. These results unravel the mechanisms by which methylphenidate gates both attention and reward learning.

The mechanisms underpinning the variability in methylphenidate’s effects on cognition remain unclear. Here, the authors show that such effects reflect changes in striatal dopamine-related output gating of task-relevant cortical signals, and that these changes depend on baseline dopamine synthesis capacity.

Reduced neural activity when anticipating social versus nonsocial rewards in schizophrenia: Preliminary evidence from an ERP study

Diminished social motivation is a core feature of schizophrenia that might reflect disturbances in social reward processing. It is not known whether these disturbances reflect anticipatory ("wanting") and/or consummatory ("liking") pleasure deficits. The primary aim of this study was to examine social versus nonsocial reward processing during these temporally distinct substages using event-related potential (ERP) components. Twenty-three schizophrenia participants and 20 healthy participants completed an incentive delay task with social (i.e., smiling expressions) and nonsocial (i.e., money) rewards. We measured two anticipatory ERPs (i.e., "wanting") (target anticipation: Contingent Negative Variation [CNV]; feedback anticipation: Stimulus Preceding Negativity [SPN]) and one consummatory ERP (i.e., "liking") (feedback receipt: P300). As a secondary aim, we examined correlations between the ERPs and interview-rated motivational negative symptoms and social functioning. Schizophrenia participants showed overall less target anticipation (blunted CNV) across all trials (social and nonsocial) than healthy participants. Importantly, schizophrenia participants exhibited less anticipation of social rewards relative to nonsocial rewards (SPN), whereas healthy participants showed similar anticipation for both reward types. Both groups showed similar responses to social and nonsocial reward receipt (P300). Furthermore, social reward anticipation during the incentive delay task was associated with more social approach behaviors in the real-world. Together, these findings provide preliminary evidence for intact social reward "liking" and impaired "wanting" in schizophrenia.

Assessment of Noninvasive Brain Stimulation Interventions for Negative Symptoms of Schizophrenia: A Systematic Review and Network Meta-analysis

IMPORTANCE

Negative symptoms have a detrimental impact on functional outcomes and quality of life in people with schizophrenia, and few therapeutic options are considered effective for this symptomatic dimension. Studies have suggested that noninvasive brain stimulation (NIBS) interventions may be effective in treating negative symptoms. However, the comparative efficacy of different NIBS protocols for relieving negative symptoms remains unclear.

OBJECTIVE

To compare the efficacy and acceptability of different NIBS interventions for treating negative symptoms.

DATA SOURCES

The ClinicalKey, Cochrane CENTRAL, Embase, ProQuest, PubMed, ScienceDirect, ClinicalTrials.gov, and Web of Science electronic databases were systematically searched from inception through December 7, 2021.

STUDY SELECTION

A frequentist model network meta-analysis was conducted to assess the pooled findings of trials that evaluated the efficacy of repetitive transcranial magnetic stimulation (rTMS), theta-burst stimulation, transcranial random noise stimulation, transcutaneous vagus nerve stimulation, and transcranial direct current stimulation on negative symptoms in schizophrenia. Randomized clinical trials (RCTs) examining NIBS interventions for participants with schizophrenia were included.

DATA EXTRACTION AND SYNTHESIS

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline was followed. Data were independently extracted by multiple observers. The pair-wise meta-analytic procedures were conducted using a random-effects model.

MAIN OUTCOMES AND MEASURES

The coprimary outcomes were changes in the severity of negative symptoms and acceptability (ie, dropout rates owing to any reason). Secondary outcomes were changes in positive and depressive symptoms.

RESULTS

Forty-eight RCTs involving 2211 participants (mean [range] age, 38.7 [24.0-57.0] years; mean [range] proportion of female patients, 30.6% [0%-70.0%]) were included. Compared with sham control interventions, excitatory NIBS strategies (standardized mean difference [SMD]: high-definition transcranial random noise stimulation, -2.19 [95% CI, -3.36 to -1.02]; intermittent theta-burst stimulation, -1.32 [95% CI, -1.88 to -0.76]; anodal transcranial direct current stimulation, -1.28 [95% CI, -2.55 to -0.02]; high-frequency rTMS, -0.43 [95% CI, -0.68 to -0.18]; extreme high-frequency rTMS, -0.45 [95% CI, -0.79 to -0.12]) over the left dorsolateral prefrontal cortex with or without other inhibitory stimulation protocols in the contralateral regions of the brain were associated with significantly larger reductions in negative symptoms. Acceptability did not significantly differ between the groups.

CONCLUSIONS AND RELEVANCE

In this network meta-analysis, excitatory NIBS protocols over the left dorsolateral prefrontal cortex were associated with significantly large improvements in the severity of negative symptoms. Because relatively few studies were available for inclusion, additional well-designed, large-scale RCTs are warranted.

Updated perspectives on the clinical significance of negative symptoms in patients with schizophrenia

INTRODUCTION

Negative symptoms in schizophrenia are associated with poor response to available treatments, poor quality of life, and functional outcome. Therefore, they represent a substantial burden for people with schizophrenia, their families, and health-care systems.

AREAS COVERED

In this manuscript, we will provide an update on the conceptualization, assessment, and treatment of this complex psychopathological dimension of schizophrenia.

EXPERT OPINION

Despite the progress in the conceptualization of negative symptoms and in the development of state-of-the-art assessment instruments made in the last decades, these symptoms are still poorly recognized, and not always assessed in line with current conceptualization. Every effort should be made to disseminate the current knowledge on negative symptoms, on their assessment instruments and available treatments whose efficacy is supported by research evidence. Longitudinal studies should be promoted to evaluate the natural course of negative symptoms, improve our ability to identify the different sources of secondary negative symptoms, provide effective interventions, and target primary and persistent negative symptoms with innovative treatment strategies. Further research is needed to identify pathophysiological mechanisms of primary negative symptoms and foster the development of new treatments.

The instrumental role of operant paradigms in translational psychiatric research: Insights from a maternal immune activation model of schizophrenia risk

Rigorous behavioral analysis is essential to the translation of research conducted using animal models of neuropsychiatric disease. Here we discuss the use of operant paradigms within our lab as a powerful approach for exploring the biobehavioral bases of disease in the maternal immune activation rat model of schizophrenia. We have investigated a range of disease features in schizophrenia including abnormal perception of time, cognition, learning, motivation, and internal state (psychosis), providing complex insights into brain and behavior. Beyond simple phenotyping, implementing sophisticated operant procedures has been effective in delineating aspects of pathological behavior, identifying interacting pathologies, and isolating contributing mechanisms of disease. We provide comment on the strengths of operant techniques to support high-quality behavioral investigations in fundamental neuropsychiatric research.

Determinants of Recreational Outcomes in Schizophrenia: An Exploratory Study Focusing on Gender Differences

While recreation is impactful for recovery in schizophrenia, no study has examined the effects of schizophrenic symptoms on recreational outcomes. This study examined the determinants of recreational outcomes based on gender. We investigated the relationship between recreational outcomes, positive and negative symptoms, cognitive function, and factors such as negative self-evaluation and evaluation by others. Motivation had a significant impact on both men and women. However, participation in recreational activities was impacted by negative self-assessment for men and evaluations from others for women. The importance of matching strategies based on gender when using recreation therapeutically was emphasized.

Validity and Reliability of the Staden Schizophrenia Anxiety Rating Scale

In schizophrenia, none of the standard anxiety measures exhibit strong psychometric properties, and all performed poorly against quality assessment criteria. Developed for the schizophrenia population, this study examined the validity and reliability of the Staden Schizophrenia Anxiety Rating Scale (S-SARS) that measures both specified and undifferentiated anxiety. Among 353 schizophrenia patients, strong correlations with anxiety parameters supported the S-SARS's convergent validity. Criterion-related validity testing yielded accuracy, sensitivity, and specificity rates of around 95%. Its discriminant validity was observed for measures of depression, psychosis, akathisia, fatigue, vigour, procrastination, behavioural inhibition and activation, and personal growth and initiative. Structural validity was found in a single-factor unidimensional model with a 0.953 factor score. Excellent results were found for internal consistency (Cronbach's alpha = 0.931; Spearman-Brown coefficient = 0.937; Guttman split-half coefficient = 0.928) and inter-rater reliability (Krippendorff's alpha = 0.852). It incurred no more than a small error of measurement whereby the observed scores were within 1.54 to 3.58 of a true score on a zero to 50 scale. These strong psychometric properties suggest that the S-SARS is a valid and reliable instrument for measuring specified and undifferentiated anxiety in schizophrenia, providing the means for the accurate measurement of anxiolytic treatment effects.

Psychological Dimensions Relevant to Motivation and Pleasure in Schizophrenia

Motivation and pleasure deficits are common in schizophrenia, strongly linked with poorer functioning, and may reflect underlying alterations in brain functions governing reward processing and goal pursuit. While there is extensive research examining cognitive and reward mechanisms related to these deficits in schizophrenia, less attention has been paid to psychological characteristics that contribute to resilience against, or risk for, motivation and pleasure impairment. For example, psychological tendencies involving positive future expectancies (e.g., optimism) and effective affect management (e.g., reappraisal, mindfulness) are associated with aspects of reward anticipation and evaluation that optimally guide goal-directed behavior. Conversely, maladaptive thinking patterns (e.g., defeatist performance beliefs, asocial beliefs) and tendencies that amplify negative cognitions (e.g., rumination), may divert cognitive resources away from goal pursuit or reduce willingness to exert effort. Additionally, aspects of sociality, including the propensity to experience social connection as positive reinforcement may be particularly relevant for pursuing social goals. In the current review, we discuss the roles of several psychological characteristics with respect to motivation and pleasure in schizophrenia. We argue that individual variation in these psychological dimensions is relevant to the study of motivation and reward processing in schizophrenia, including interactions between these psychological dimensions and more well-characterized cognitive and reward processing contributors to motivation. We close by emphasizing the value of considering a broad set of modulating factors when studying motivation and pleasure functions in schizophrenia.

A transdiagnostic meta-analysis of physical and social Anhedonia in major depressive disorder and schizophrenia spectrum disorders

INTRODUCTION

Anhedonia is a transdiagnostic construct conceptualized as physical or social, however, the extent to which these subtypes differ across psychotic and mood pathology remains poorly understood. We aimed to quantify the severity of physical and social anhedonia across Major Depressive Disorder (MDD) and Schizophrenia Spectrum Disorder (SSDs).

METHODS

We conducted meta-analyses of the Chapman Physical and Social Anhedonia Scales (PAS;SAS). We reviewed data from participants with MDD, and SSDs separately.

RESULTS

Our first meta-analysis (n = 8 studies, 409 participants) with MDD revealed elevated SAS and PAS in MDD compared to controls. Within-group differences were not significant. Depressive symptom severity moderated the between-group effect of PAS. Our second meta-analysis (n = 44 studies, 3352 participants) revealed elevated SAS and PAS in SSDs compared to controls. We detected a moderate difference between the SAS and PAS within the SSD group. Age moderated within-group differences of SAS and PAS.

DISCUSSION

People with SSD or MDD experience elevated SAS and PAS compared to controls. People with SSDs endorse greater challenges experiencing social rewards relative to physical rewards. People with MDD experience social and physical rewards similarly. The moderating role of depressive symptoms in MDD suggests that physical anhedonia is more state-like than social anhedonia.

Negative and depressive symptoms differentially relate to real-world anticipatory and consummatory pleasure in schizophrenia

It has been suggested that schizophrenia is associated with deficits in anticipatory but not consummatory pleasure, though there is mixed support for this hypothesis. As individuals with schizophrenia can experience both negative and depressive symptoms, symptom heterogeneity in this population could contribute to these mixed hedonic findings. Specifically, while some research suggests that negative symptoms of schizophrenia are related to reduced anticipatory but not consummatory pleasure, research on major depressive disorder suggests that depressive symptoms are associated with both decreased anticipatory and consummatory pleasure. Still, it is unclear whether depressive symptoms are associated with experiences of pleasure in schizophrenia as they are in major depressive disorder. Thus, the present study used Ecological Momentary Assessment (four prompts per day over one week) to investigate the unique relationships of negative and depressive symptoms with daily reports of real-world anticipatory and consummatory pleasure in 63 individuals with schizophrenia. Higher negative symptoms related to reduced anticipatory but not consummatory pleasure. On the other hand, higher depressive symptoms related to reductions in both anticipatory and consummatory pleasure. Overall, these results indicate that negative and depressive symptoms are differentially associated with hedonic experience in schizophrenia, and suggest the need to account for the severity of both these symptom types when examining pleasure in this population. Elucidating the nature of these symptom contributions to hedonic impairments could increase causal understanding of these deficits and contribute to the development of more targeted treatments to enhance motivation and pleasure in schizophrenia.

The prediction-error hypothesis of schizophrenia: new data point to circuit-specific changes in dopamine activity

Schizophrenia is a severe psychiatric disorder affecting 21 million people worldwide. People with schizophrenia suffer from symptoms including psychosis and delusions, apathy, anhedonia, and cognitive deficits. Strikingly, schizophrenia is characterised by a learning paradox involving difficulties learning from rewarding events, whilst simultaneously 'overlearning' about irrelevant or neutral information. While dysfunction in dopaminergic signalling has long been linked to the pathophysiology of schizophrenia, a cohesive framework that accounts for this learning paradox remains elusive. Recently, there has been an explosion of new research investigating how dopamine contributes to reinforcement learning, which illustrates that midbrain dopamine contributes in complex ways to reinforcement learning, not previously envisioned. This new data brings new possibilities for how dopamine signalling contributes to the symptomatology of schizophrenia. Building on recent work, we present a new neural framework for how we might envision specific dopamine circuits contributing to this learning paradox in schizophrenia in the context of models of reinforcement learning. Further, we discuss avenues of preclinical research with the use of cutting-edge neuroscience techniques where aspects of this model may be tested. Ultimately, it is hoped that this review will spur to action more research utilising specific reinforcement learning paradigms in preclinical models of schizophrenia, to reconcile seemingly disparate symptomatology and develop more efficient therapeutics.

Confirmation Bias in the Course of Instructed Reinforcement Learning in Schizophrenia-Spectrum Disorders

A large body of research attributes learning deficits in schizophrenia (SZ) to the systems involved in value representation (prefrontal cortex, PFC) and reinforcement learning (basal ganglia, BG) as well as to the compromised connectivity of these regions. In this study, we employed learning tasks hypothesized to probe the function and interaction of the PFC and BG in patients with SZ-spectrum disorders in comparison to healthy control (HC) subjects. In the Instructed Probabilistic Selection task (IPST), participants received false instruction about one of the stimuli used in the course of probabilistic learning which creates confirmation bias, whereby the instructed stimulus is overvalued in comparison to its real experienced value. The IPST was administered to 102 patients with SZ and 120 HC subjects. We have shown that SZ patients and HC subjects were equally influenced by false instruction in reinforcement learning (RL) probabilistic task (IPST) (p-value = 0.441); however, HC subjects had significantly higher learning rates associated with the process of overcoming cognitive bias in comparison to SZ patients (p-value = 0.018). The behavioral results of our study could be hypothesized to provide further evidence for impairments in the SZ-BG circuitry; however, this should be verified by neurofunctional imaging studies.

Two Factors, Five Factors, or Both? External Validation Studies of Negative Symptom Dimensions in Schizophrenia

OBJECTIVES

Negative symptom studies frequently use single composite scores as indicators of symptom severity and as primary endpoints in clinical trials. Factor analytic and external validation studies do not support this practice but rather suggest a multidimensional construct. The current study used structural equation modeling (SEM) to compare competing dimensional models of negative symptoms to determine the number of latent dimensions that best capture variance in biological, psychological, and clinical variables known to have associations with negative symptoms.

METHODS

Three independent studies (total n = 632) compared unidimensional, two-factor, five-factor, and hierarchical conceptualizations of negative symptoms in relation to cognition, psychopathology, and community functioning (Study 1); trait emotional experience and defeatist performance beliefs (Study 2); and glutamate and gamma-aminobutyric acid levels in the anterior cingulate cortex quantified using proton magnetic resonance spectroscopy (Study 3).

RESULTS

SEM favored the five-factor and hierarchical models over the unidimensional and two-factor models regardless of the negative symptom measure or external validator. The five dimensions-anhedonia, asociality, avolition, blunted affect, and alogia-proved vital either as stand-alone domains or as first-order domains influenced by second-order dimensions-motivation and pleasure and emotional expression. The two broader dimensions sometimes masked important associations unique to the five narrower domains. Avolition, anhedonia, and blunted affect showed the most domain-specific associations with external variables across study samples.

CONCLUSIONS

Five domains and a hierarchical model reflect the optimal conceptualization of negative symptoms in relation to external variables. Clinical trials should consider using the two dimensions as primary endpoints and the five domains as secondary endpoints.

Prenatal metal mixture concentrations and reward motivation in children

Reward motivation is a complex umbrella term encompassing the cognitions, emotions, and behaviors involved in the activation, execution, and persistence of goal-directed behavior. Altered reward motivation in children is characteristic of many neurodevelopmental and psychiatric disorders. Previously difficult to operationalize, the Progressive Ratio (PR) task has been widely used to assess reward motivation in animal and human studies, including children. Because the neural circuitry supporting reward motivation starts developing during pregnancy, and is sensitive to disruption by environmental toxicants, including metals, the goal of this study was to examine the association between prenatal concentrations of a mixture of neurotoxic metals and reward motivation in children. We measured reward motivation by administering a PR test to 373 children ages 6-8 years enrolled in the Programming Research in Obesity, Growth, Environment and Social Stressors (PROGRESS) Study in Mexico City. Children were asked to press a response lever for a token reward; one press on the response lever was required to earn the first token and each subsequent token required an additional 10 lever presses. Maternal blood concentrations of lead, manganese, zinc, arsenic, cadmium, and selenium were measured using inductively-coupled plasma mass spectrometry during the 2nd and 3rd trimesters of pregnancy. We performed generalized Weighted Quantile Sum (gWQS) regression analyses to examine associations between the prenatal metal mixture and reward motivation; adjusting for child sex, birthweight and age; and maternal IQ, education, and socioeconomic status. The prenatal metal mixture was significantly associated with higher motivation as indicated by more lever presses (ß = 0.02, p < 0.001) and a shorter time between receiving the reinforcer and the first press (ß = 0.23, p = 0.01), and between subsequent presses (ß = 0.07, p = 0.005). Contributions of different metals to this association differed by trimester and child sex. These findings suggest that children with increased exposure to metal during the 2nd and 3rd trimesters of gestation demonstrate increased reward motivation, which may reflect a tendency to perseverate or hypersensitivity to positive reinforcement.