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

Increased Sensitivity to Effort and Perception of Effort in People with Schizophrenia

OBJECTIVE

Motivational deficits in schizophrenia are proposed to be attributable in part to abnormal effort-cost computations, calculations weighing the costs vs. the benefits of actions. Several reports have shown that people with schizophrenia display a reduced willingness to exert effort for monetary rewards when compared to controls. The primary goal of the current study was to further characterize reduced willingness to exert effort in schizophrenia by determining whether reduced willingness reflects (1) reduced sensitivity to reward, (2) increased sensitivity to effort, or (3) a combination of both.

DESIGN

We assessed effort-cost decision-making in 30 controls and 30 people with schizophrenia, using 2 separate experimental tasks. Critically, one paradigm allowed for independent estimation of effects of reward and effort sensitivity on choice behavior. The other task isolated effort sensitivity by measuring effort in the absence of reward. Clinical interviews and self-report questionnaires were administered to people with schizophrenia to determine negative symptom severity.

RESULTS

Across both tasks, we found evidence for reduced willingness to exert effort in people with schizophrenia compared to controls. Further, in both paradigms reduced willingness to exert effort was driven by increased sensitivity to effort in people with schizophrenia compared to controls. In contrast, measures of reward sensitivity did not significantly differ between groups. Surprisingly, we did not find correlations between task variables and measures of negative symptom severity.

CONCLUSIONS AND RELEVANCE

These findings further specify prior work by identifying a specific contributory role for increased effort sensitivity in effort-cost decision-making deficits in schizophrenia.

Niacin skin flushing response in patients with schizophrenia: Associations with the efficacy of modified electroconvulsive therapy and clinical symptoms

OBJECTIVE

Schizophrenia (SZ) is a group of chronic neurodevelopmental disorders, and antipsychotic medication is the main clinical treatment. However, approximately one-third of patients demonstrate inadequate response to these medications, which is termed treatment-resistant schizophrenia (TRS). The primary objective of this study was to explore the clinical characteristics of patients with TRS, including positive, negative, general psychotic symptoms and niacin skin flushing response (NSFR), which is considered an auxiliary diagnostic biomarker for SZ, and the improvement of these characteristics after modified electroconvulsive therapy (MECT).

METHODS

This study included 32 patients with TRS, who received MECT combined with antipsychotic medication (SZ-MECT group), and 30 patients with non-treatment-resistant SZ (N-TRS), who received antipsychotic medication alone (SZ-N group). We assessed disease severity with the Positive and Negative Syndrome Scale (PANSS) and NSFR at baseline and at weeks 2, 4, and 6 in all patients.

RESULTS

At baseline, the SZ-MECT group had greater PANSS scores (P < 0.0001) and a more blunted NSFR (P = 0.020) than the SZ-N group did, and the PANSS-TOTAL scores were negatively correlated with the NSFR scores (r = -0.361, P = 0.0039). At week 6 after treatment, the SZ-MECT group presented significantly improved PANSS scores (P < 0.0001) and NSFR blunting (P = 0.010) that were comparable with those in the SZ-N group.

CONCLUSION

Compared with patients with N-TRS, patients with TRS presented more severe clinical symptoms and a more blunted NSFR, which significantly improved after MECT treatment. The NSFR may have good clinical application potential as an auxiliary assessment of severity and MECT efficacy in patients with schizophrenia.

A computational approach to understanding effort-based decision-making in depression

Objective

Motivational dysfunction is a core feature of depression, and can have debilitating effects on everyday function. However, it is unclear which disrupted cognitive processes underlie impaired motivation, and whether impairments persist following remission. Decision-making concerning exerting effort to obtain rewards offers a promising framework for understanding motivation, especially when examined with computational tools which can offer precise quantification of latent processes.

Methods

Effort-based decision-making was assessed using the Apple Gathering Task, in which participants decide whether to exert effort via a grip-force device to obtain varying levels of reward; effort levels were individually calibrated and varied parametrically. We present a comprehensive computational analysis of decision-making, initially validating our model in healthy volunteers (N=67), before applying it in a case-control study including current (N=41) and remitted (N=46) unmedicated depressed individuals, and healthy volunteers with (N=36) and without (N=57) a family history of depression.

Results

Four fundamental computational mechanisms that drive patterns of effort-based decisions, which replicated across samples, were identified: overall bias to accept effort challenges; reward sensitivity; and linear and quadratic effort sensitivity. Traditional model-agnostic analyses showed that both depressed groups showed lower willingness to exert effort. In contrast with previous findings, computational analysis revealed that this difference was primarily driven by lower effort acceptance bias, but not altered effort or reward sensitivity.

Conclusions

This work provides insight into the computational mechanisms underlying motivational dysfunction in depression. Lower willingness to exert effort could represent a trait-like factor contributing to symptoms, and might represent a fruitful target for treatment and prevention.

Decision cost hypersensitivity underlies Huntington's disease apathy

The neuropsychiatric syndrome of apathy is now recognized to be a common and disabling condition in Huntington's disease. However, the mechanisms underlying it are poorly understood. One way to investigate apathy is to use a theoretical framework of normal motivated behaviour, to determine where breakdown has occurred in people with this behavioural disruption. A fundamental computation underlying motivated, goal-directed behaviour across species is weighing up the costs and rewards associated with actions. Here, we asked whether people with apathy are more sensitive to costs of actions (physical effort and time delay), less sensitive to rewarding outcomes, or both. Based on the unique anatomical substrates associated with Huntington's disease pathology, we hypothesized that a general hypersensitivity to costs would underpin Huntington's disease apathy. Genetically confirmed carriers of the expanded Huntingtin gene (premanifest to mild motor manifest disease, n = 53) were compared to healthy controls (n = 38). Participants performed a physical effort-based decision-making task (Apple Gathering Task) and a delay discounting task (Money Choice Questionnaire). Choice data was analysed using linear regression and drift diffusion models that also accounted for the time taken to make decisions. Apathetic people with Huntington's disease accepted fewer offers overall on the Apple Gathering Task, specifically driven by increased sensitivity to physical effort costs, and not explained by motor severity, mood, cognition or medication. Drift diffusion modelling provided further evidence of effort hypersensitivity, with apathy associated with a faster drift rate towards rejecting offers as a function of varying effort. Increased delay sensitivity was also associated with apathy, both when analysing raw choice and drift rate, where there was moderate evidence of Huntington's disease apathy drifting faster towards the immediately available (low-cost) option. Furthermore, the effort and delay sensitivity parameters from these tasks were positively correlated. The results demonstrate a clear mechanism for apathy in Huntington's disease, cost hypersensitivity, which manifests in both the effort and time costs associated with actions towards rewarding goals. This suggests that Huntington's disease pathology may cause a domain-general disruption of cost processing, which is distinct from apathy occurrence in other brain disorders and may require different therapeutic approaches.

The implementation and effectiveness of Integrated Psychological Therapy (IPT) in chronic middle-aged inpatients with schizophrenia

Introduction

Cognitive rehabilitation is essential for schizophrenia treatment since it improves function. Moreover, the relationship between cognitive rehabilitation and functioning is significantly affected by negative symptoms and social cognition. Integrated Psychological Therapy (IPT) is a promising approach that integrates interventions in neurocognition, social cognition, and functional level. This study examines IPT's efficacy in chronic middle-aged inpatients.

Methods

A randomized controlled study involved 44 individuals with schizophrenia. Twenty-one IPT participants received 50 biweekly sessions and medication, while twenty-three control participants received treatment as usual/supportive therapy and pharmacotherapy. Pre- and post-intervention and six- and twelve-month follow-ups were arranged to assess neurocognition, social perception, psychopathology, and functioning using the Matrics Consensus Cognitive Battery, Social Perception Scale, Positive and Negative Syndrome Scale, and Global Assessment of Functioning.

Results

Speed of processing, attention/vigilance, overall composite, and neurocognitive composite scores improved significantly in the IPT group. Social Perception Scale performance improved in all areas after the intervention and persisted for 6 months. Positive, negative, and total psychopathology symptoms decreased significantly post-intervention and at the 12-month follow-up, whereas participants' functioning improved significantly.

Conclusions

Middle-aged chronic inpatients with schizophrenia may benefit from IPT in neurocognition, social perception, psychopathology, and functioning. This field of study may provide insight into schizophrenia treatment, hence further research is encouraged.

Mechanisms and correlates of incentivized response inhibition in schizophrenia and bipolar disorder

When healthy individuals are incentivized on response inhibition tasks (e.g., Stroop), they recruit additional cognitive resources, enabling them to make faster, more accurate responses. Schizophrenia (SZ) and bipolar disorder (BP) are associated with poor response inhibition, but it is unknown whether SZ and BP show incentive-related improvements to the same degree as healthy controls (HC). To investigate this question, reaction time data from an incentivized Stroop-style task were analyzed from 37 SZ, 26 B P, and 33 H C. We examined: 1) group differences in mean reaction time, 2) group differences in response caution and in rate of processing task-relevant information derived from a computational approach (drift diffusion modeling), and 3) clinical and cognitive correlates of drift diffusion parameters in SZ and BP groups. When incentives were introduced, both HC and BP showed significantly faster response speed, but SZ did not show the same pattern of improvement as a function of incentives. Computational analyses indicated that groups did not significantly differ in response caution, but that both SZ and BP had a slower information processing rate compared to HC. In SZ, slow information processing rate was related to poor cognition; positive and negative symptoms were associated with impairments in information processing rate, but in opposite directions (i.e., increased information processing rate was associated with positive symptom severity; decreased information processing rate was associated with negative symptom severity). Our findings suggest impaired information processing rate may contribute to poor response inhibition in both SZ and BP, whereas response caution is intact in both disorders. However, SZ is distinguished from BP by a failure to enter an overall motivated state and decrease response speed when incentivized.

Factors Affecting Negative Symptoms in Schizophrenia and Their Relationship with Anxiety and Depression

Objective

Negative symptoms significantly impair daily functioning and worsen clinical outcomes. Meanwhile, these symptoms are closely linked to anxiety and depression, further complicating prognosis. The mechanisms underlying these relationships remain unclear. This study aims to identify the factors influencing negative symptoms in schizophrenia and examine their relationship with anxiety and depression to guide more effective interventions and improve patient outcomes.

Methods

This study recruited 300 inpatients with schizophrenia from October 2022 to May 2023. Sociodemographic data and clinical characteristics were collected via a self-designed questionnaire. Negative symptoms, depression, and anxiety were assessed using the SANS, HAMD, and HAMA scales, respectively.

Results

Multiple regression analysis indicated that familial support (β = -1.285, P = 0.005), friend support (β = -0.797, P = 0.032), sleep quality (β = 2.307, P < 0.001), anxiety (β = 0.264, P = 0.004), and depression (β = 0.324, P = 0.007) were the main factors influencing negative symptoms. After adjusting for the duration of psychiatric disorder and type of antipsychotic medication as covariates, the above factors remained primary contributors to negative symptoms.

Conclusion

Enhancing familial support, friend support, and addressing emotional health and sleep disturbances are strategies that may alleviate negative symptoms in patients with schizophrenia.

Should we consider microbiota-based interventions as a novel therapeutic strategy for schizophrenia? A systematic review and meta-analysis

Schizophrenia is a chronic psychiatric disorder characterized by a variety of symptoms broadly categorized into positive, negative, and cognitive domains. Its etiology is multifactorial, involving a complex interplay of genetic, neurobiological, and environmental factors, and its neurobiology is associated with abnormalities in different neurotransmitter systems. Due to this multifactorial etiology and neurobiology, leading to a wide heterogeneity of symptoms and clinical presentations, current antipsychotic treatments face challenges, underscoring the need for novel therapeutic approaches. Recent studies have revealed differences in the gut microbiome of individuals with schizophrenia compared to healthy controls, establishing an intricate link between this disorder and gastrointestinal health, and suggesting that microbiota-targeted interventions could help alleviate clinical symptoms. Therefore, this meta-analysis investigates whether gut microbiota manipulation can ameliorate psychotic outcomes in patients with schizophrenia receiving pharmacological treatment. Nine studies (n = 417 participants) were selected from 81 records, comprising seven randomized controlled trials and two open-label studies, all with a low risk of bias, included in this systematic review and meta-analysis. The overall combined effect size indicated significant symptom improvement following microbiota treatment (Hedges' g = 0.48, 95% CI = 0.09 to 0.88, p = 0.004, I2 = 62.35%). However, according to Hedges' g criteria, the effect size was small (approaching moderate), and study heterogeneity was moderate based on I2 criteria. This review also discusses clinical and preclinical studies to elucidate the neural, immune, and metabolic pathways by which microbiota manipulation, particularly with Lactobacillus and Bifidobacterium genera, may exert beneficial effects on schizophrenia symptoms via the gut-brain axis. Finally, we address the main confounding factors identified in our systematic review, highlight key limitations, and offer recommendations to guide future high-quality trials with larger participant cohorts to explore microbiome-based therapies as a primary or adjunctive treatment for schizophrenia.

Depressive symptoms are linked to age-specific neuroanatomical and cognitive variations

Depression is a heterogeneous disorder, both in terms of patient symptomatology and in patient sociodemographic factors. Here, we examine the contribution of age to this heterogeneity, by characterizing the associations of depressive symptoms with cognitive performance and brain structure across the lifespan. We analyzed data from the Cambridge Centre for Aging Neuroscience (Cam-CAN) cohort (N = 2591, age 18-99). A subset of this cohort (N = 647) underwent structural MRI. Depressive symptoms were measured using the Hospital Anxiety and Depression Scale. Cognitive assessments were performed using The Addenbrooke's Cognitive Examination Revised. Generalized linear models were employed to examine the relationship between depressive symptoms and cognitive performance. Statistical parametric mapping explored age-dependent associations between depressive symptoms and grey matter volume. Cognitive performance was associated with a significant age by depression by cognitive domain interaction, indicating that older individuals with more depressive symptoms had a lower cognitive performance, particularly in the fluency domain. Structural MRI revealed preferential depression-related reduction in grey matter volume in the left and right hippocampi in older adults. By contrast, in younger adults, depressive symptoms were more strongly associated with grey matter volume reduction in the left superior frontal gyrus and left middle frontal gyrus. Collectively, these findings indicate that the associations of depression with cognitive performance and brain structure are age-dependent, suggesting that the pathophysiological mechanisms underlying depression may differ between young and older adults. Recognizing these differences will support the development of better diagnostic tools and therapeutic interventions for depression across the lifespan.

Intermittent theta burst stimulation for negative symptoms in schizophrenia patients with mild cognitive impairment: a randomized controlled trail

Background

This study aims to evaluate the intervention effect of intermittent Theta burst stimulation (iTBS) on bilateral dorsomedial prefrontal cortex (DMPFC) for negative symptoms in schizophrenia using functional near-infrared spectroscopy (fNIRS) to confirm the therapeutic significance of DMPFC in treating negative symptoms and provide new evidence for schizophrenia treatment and research.

Method

Thirty-nine schizophrenia patients with negative symptoms and mild cognitive impairment were randomly divided into a treatment group (n=20) and a control group (n=19). The treatment group received iTBS in bilateral DMPFC. The control group received the sham treatment. Negative symptoms, cognitive function, emotional state, and social function were assessed at pre-treatment, post-treatment, 4-, 8-, and 12-week follow-ups. Brain activation in regions of interest (ROIs) was evaluated through verbal fluency tasks. Changes in scale scores were analyzed by repeated measures ANOVA.

Result

After 20 sessions of iTBS, the Scale for the Assessment of Negative Symptoms (SANS) total and sub-scale scores significantly improved in the treatment group, with statistically significant differences. SANS scores differed significantly between pre- and post-treatment in both groups, with post-treatment scores markedly lower than pre-treatment and better efficacy in the treatment group. However, there was no significant difference in cognitive function, emotional state, and social function. ROIs did not differ significantly between groups before intervention. After treatment, prefrontal cortex activation was significantly higher in the treatment group than in controls, with a statistically significant difference. Regarding functional connectivity, the small-world properties Sigma and Gamma were enhanced.

Conclusion

iTBS on bilateral DMPFC can effectively alleviate negative symptoms and enhance prefrontal cortex activation and the small-world properties in patients of schizophrenia.

Striatal Functional Hypoconnectivity in Patients With Schizophrenia Suffering From Negative Symptoms, Longitudinal Findings

BACKGROUND

Negative symptoms in schizophrenia (SZ), such as apathy and diminished expression, have limited treatments and significantly impact daily life. Our study focuses on the functional division of the striatum: limbic-motivation and reward, associative-cognition, and sensorimotor-sensory and motor processing, aiming to identify potential biomarkers for negative symptoms.

STUDY DESIGN

This longitudinal, 2-center resting-state-fMRI (rsfMRI) study examines striatal seeds-to-whole-brain functional connectivity. We examined connectivity aberrations in patients with schizophrenia (PwSZ), focusing on stable group differences across 2-time points using intra-class-correlation and associated these with negative symptoms and measures of cognition. Additionally, in PwSZ, we used negative symptoms to predict striatal connectivity aberrations at the baseline and used the striatal aberration to predict symptoms 9 months later.

STUDY RESULTS

A total of 143 participants (77 PwSZ, 66 controls) from 2 centers (Berlin/Geneva) participated. We found sensorimotor-striatum and associative-striatum hypoconnectivity. We identified 4 stable hypoconnectivity findings over 3 months, revealing striatal-fronto-parietal-cerebellar hypoconnectivity in PwSZ. From those findings, we found hypoconnectivity in the bilateral associative striatum with the bilateral paracingulate-gyrus and the anterior cingulate cortex in PwSZ. Additionally, hypoconnectivity between the associative striatum and the superior frontal gyrus was associated with lower cognition scores in PwSZ, and weaker sensorimotor striatum connectivity with the superior parietal lobule correlated negatively with diminished expression and could predict symptom severity 9 months later.

CONCLUSIONS

Importantly, patterns of weaker sensorimotor striatum and superior parietal lobule connectivity fulfilled the biomarker criteria: clinical significance, reflecting underlying pathophysiology, and stability across time and centers.

Apathy and effort-based decision-making in Alzheimer's disease and subjective cognitive impairment

INTRODUCTION

Apathy is a significant feature in Alzheimer's disease (AD) and subjective cognitive impairment (SCI), though its mechanisms are not well established.

METHODS

An effort-based decision-making (EBDM) framework was applied to investigate apathy in 30 AD patients, 41 SCI participants, and 55 healthy controls (HC). Data were analyzed using a drift-diffusion model (DDM) to uncover latent psychological processes.

RESULTS

SCI participants reported higher apathy than AD patients and HC. However, informant reports of apathy in AD patients were higher than self-reports and indicated significant apathy compared to HC. Both the AD and SCI groups showed reduced sensitivity to effort changes, linked to executive dysfunction in AD and apathy in SCI. Increased resting functional cortical connectivity with the nucleus accumbens (NA) was associated with higher apathy in SCI.

DISCUSSION

These results highlight a similar disruption of EBDM in AD and SCI, differentially related to executive functioning in AD and apathy in SCI.

Highlights

This is the first study investigating apathy using an effort-based decision-making (EBDM) framework in Alzheimer's disease (AD) and subjective cognitive impairment (SCI).Self-reports underestimate apathy in AD patients when compared to informant reports and healthy controls (HC). SCI participants, in whom self and informant reports were more concordant, also showed higher degrees of apathy.Both AD and SCI groups showed reduced sensitivity to effort.Reduced sensitivity to effort correlates with executive dysfunction in AD and apathy, but not depression, in SCI.Increased nucleus accumbens (ventral striatum) connectivity with the frontoparietal network was associated with higher apathy scores in SCI.The results thus suggest that while AD and SCI can have similar deficits in EBDM, these deficits correlate with distinct clinical manifestations: executive dysfunction in AD and apathy in SCI.

When Games Influence Words: Gaming Addiction among College Students Increases Verbal Aggression through Risk-Biased Drifting in Decision-Making

Increased aggression due to gaming addiction is a widespread and highly publicized problem. The underlying processes by which verbal aggression, a more harmful and persistent subcategory of aggression, is affected by gaming addiction may differ from other types of aggression. In this study, data came from 252 randomly recruited current university students (50.79% male, mean age 19.60 years, SD: 1.44 years, range 17 to 29 years). Participants reported gaming addiction and different types of aggression through questionnaires. In addition, two important explanatory processes, inhibitory control, and risk preference, were measured through behavioral experiments. A Bayesian hierarchical drift-diffusion model was employed to interpret the data from the risk preference task. In contrast to previous work, the study found that inhibitory control did not significantly correlate with either gaming addiction or any form of aggression However, the drift rate, a measure of decision-making inclination under risk, partially mediates the relationship between gaming addiction and verbal aggression (but not other forms of aggression). The findings illuminate risk preference under adverse conditions as a key predictor of verbal aggression, offering avenues for early intervention and suggesting game design modifications to mitigate verbal aggression by adjusting reward mechanisms.

Negative symptoms in treatment-resistant schizophrenia and its relationship with functioning

BACKGROUND

Recent operational criteria for treatment-resistant schizophrenia (TRS) recognized positive and negative symptoms. TRS patients may have heterogeneity in negative symptoms, but empirical data were lacking. We aimed to characterize TRS patients based on negative symptoms using cluster analysis, and to examine between-cluster differences in social functioning.

METHODS

We administered the Clinical Assessment Interview of Negative symptoms (CAINS), Brief Negative Symptom Scale (BNSS), the Positive and Negative Syndrome Scale (PANSS) and the Social and Occupational Functional Assessment (SOFAS to 126 TRS outpatients. All patients also completed the Temporal Experience of Pleasure Scale (TEPS), the Emotion Expressivity Scale (EES), and the Social Functional Scale (SFS). A two-stage hierarchical cluster analysis was performed with the CAINS, TEPS and EES as clustering variables. We validated the clusters using ANOVAs to compare group differences in the BNSS, PANSS, SOFAS and SFS.

RESULTS

Clustering indices supported a 3-cluster solution. Clusters 1 (n = 46) and 3 (n = 16) exhibited higher CAINS scores than Cluster 2 (n = 64), and were negative-symptom TRS subtypes. Cluster 1 reported lower TEPS than Cluster 3; but Cluster 3 reported lower EES than Cluster 1. Upon validation, Clusters 1 and 3 exhibited higher BNSS scores than Cluster 2, but only Cluster 1 exhibited lower SOFAS and higher PANSS general symptoms than Cluster 2. Both Clusters 1 and 3 had higher self-report functioning than Cluster 2.

CONCLUSION

We provided evidence for heterogeneity of negative symptoms in TRS. Negative symptoms can characterize TRS patients and predict functional outcome.

Effort-cost decision-making associated with negative symptoms in schizophrenia and bipolar disorder

Motivational deficits and reduced goal-directed behavior for external rewards have long been considered an important features of negative symptoms in patients with schizophrenia (SCZ). Negative symptoms have also a high prevalence in bipolar disorder (BP). We used a transdiagnostic approach in order to examine association between negative symptoms and effort allocation for monetary rewards. 41 patients with SCZ and 34 patients with BP were enrolled in the study along with 41 healthy controls (HC). Effort-Expenditure for Rewards Task (EEfRT) was used to measure subjects' effort allocation for monetary rewards. Generalized estimating equation models were used to analyze EEfRT choice behavior. Negative symptoms were assessed using the Brief Negative Symptom Scale (BNSS). SCZ and BP groups expended lower effort to obtain a monetary rewards compared to HC. Severity of negative symptoms was negatively correlated with EEfRT performance in both diagnostic groups. Each diagnostic group showed lower effort allocation for monetary rewards compared to HC suggesting reduced motivation for monetary rewards. In addition, our results suggest that abnormal effort-based decision-making might be a transdiagnostic factor underlying negative symptoms.