The relationship between negative symptom subdomains and cognition

Efficacy of Cortical-Hippocampal Target Intermittent Theta Burst Stimulation (iTBS) on Associative Memory of Schizophrenia: A Double-Blind, Randomized Sham-Controlled Trial

Objective

The objective of our study was to evaluate whether intermittent theta burst stimulation(iTBS) applied to the regions with the strongest cortico-hippocampal connectivity within the lateral parietal cortical (LPC) or dorsolateral prefrontal cortical (DLPFC) areas in individuals with schizophrenia could enhance associative memory.

Methods

We randomized 96 participants with schizophrenia to receive either active iTBS applied to the right DLPFC, left LPC or sham iTBS for 20 days. Clinical and cognitive assessments were performed at baseline and at the end of treatment. The primary outcome was change in associative memory. The secondary outcome was change in other cognitive functions and psychiatric symptoms.

Results

In comparison to the sham group, iTBS targeting the right DLPFC or left LPC in schizophrenia did not yield significant improvements in auditory-auditory associative memory (F=1.27, p=0.294), auditory-visual associative memory (F=0.49, p=0.617), or visual-visual associative memory (F=1.094, p=0.347). Furthermore, after adjusting for variables such as education, disease duration, and negative symptoms, no significant changes were observed in any of these three memory domains.

Conclusion

Although our study suggests that iTBS applied to the cortical-hippocampal did not lead to a significant change in associative memory. However, further investigation combining hippocampal-targeted iTBS with functional magnetic resonance imaging (fMRI) is warranted to elucidate the regulatory effects of iTBS on hippocampal function.

Trial Registration

clinicaltrials.gov NCT03608462.

Dysfunction of the NMDA Receptor in the Pathophysiology of Schizophrenia and/or the Pathomechanisms of Treatment-Resistant Schizophrenia

For several decades, the dopamine hypothesis contributed to the discovery of numerous typical and atypical antipsychotics and was the sole hypothesis for the pathophysiology of schizophrenia. However, neither typical nor atypical antipsychotics, other than clozapine, have been effective in addressing negative symptoms and cognitive impairments, which are indices for the prognostic and disability outcomes of schizophrenia. Following the development of atypical antipsychotics, the therapeutic targets for antipsychotics expanded beyond the blockade of dopamine D2 and serotonin 5-HT2A receptors to explore the partial agonism of the D2 receptor and the modulation of new targets, such as D3, 5-HT1A, 5-HT7, and metabotropic glutamate receptors. Despite these efforts, to date, psychiatry has not successfully developed antipsychotics with antipsychotic properties proven to be superior to those of clozapine. The glutamate hypothesis, another hypothesis regarding the pathophysiology/pathomechanism of schizophrenia, was proposed based on clinical findings that N-methyl-D-aspartate glutamate receptor (NMDAR) antagonists, such as phencyclidine and ketamine, induce schizophrenia-like psychotic episodes. Large-scale genome-wide association studies (GWASs) revealed that approximately 30% of the risk genes for schizophrenia (the total number was over one hundred) encode proteins associated with glutamatergic transmission. These findings supported the validation of the glutamate hypothesis, which was inspired by the clinical findings regarding NMDAR antagonists. Additionally, these clinical and genetic findings suggest that schizophrenia is possibly a syndrome with complicated pathomechanisms that are affected by multiple biological and genetic vulnerabilities. The glutamate hypothesis has been the most extensively investigated pathophysiology/pathomechanism hypothesis, other than the dopamine hypothesis. Studies have revealed the possibility that functional abnormalities of the NMDAR play important roles in the pathophysiology/pathomechanism of schizophrenia. However, no antipsychotics derived from the glutamatergic hypothesis have yet been approved for the treatment of schizophrenia or treatment-resistant schizophrenia. Considering the increasing evidence supporting the potential pro-cognitive effects of glutamatergic agents and the lack of sufficient medications to treat the cognitive impairments associated with schizophrenia, these previous setbacks cannot preclude research into potential novel glutamate modulators. Given this background, to emphasize the importance of the dysfunction of the NMDAR in the pathomechanism and/or pathophysiology of schizophrenia, this review introduces the increasing findings on the functional abnormalities in glutamatergic transmission associated with the NMDAR.

Association of empathy with clinical symptoms and cognitive function in chronic schizophrenia patients with and without suicide attempts

Cognitive impairment is recognized as a risk factor for suicide in schizophrenia (SZ) patients. Despite empathy being an important aspect of social cognition, the association between suicidal behavior and empathy has received little attention. We aimed to compare empathy and neurocognition in SZ patients with and without suicide attempts (SAs), and to explore the relationship between empathy, neurocognition, and clinical symptoms in SZ patients with and without SAs. Data on SAs and socio-demographic characteristics were collected from 628 chronic SZ patients. The patients' symptomatology was measured by the Positive and Negative Syndrome Scale (PANSS). Empathy and neurocognition were assessed with the Interpersonal Reactivity Index (IRI) and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively. Patients with SAs performed better on all IRI domains (except for Perspective Taking) and total scores. Regression results showed that negative symptoms, positive symptoms, and duration of illness were independently associated with IRI total score in patients without SAs (adjusted R2 = 0.048). In patients without SAs, negative symptoms, general psychopathology, education, age, and sex were independently associated with RBANS total score (adjusted R2 = 0.265), while in patients with SAs, education, PANSS total score, and age at onset were independently associated with RBANS total score (adjusted R2 = 0.456). Our results show that SZ patients with SAs may have better empathic performance than patients without SAs. In chronic SZ patients, negative and positive symptoms may have different effects on cognition in the SAs and non-SAs groups.

Association between angiotensin-converting enzyme gene insertion/deletion polymorphism and cognition impairment in patients with schizophrenia

RATIONALE

Several lines of evidence indicate that an insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene (ACE) gene may be involved in the pathogenesis of schizophrenia and cognitive impairment. However, the relationship between ACE I/D polymorphism and cognitive impairment in patients with schizophrenia remains unclear.

OBJECTIVES

The aim of this study was to examine whether ACE gene I/D polymorphism contributed to cognitive impairment in Chinese patients with schizophrenia, and whether the association between clinical symptoms and cognitive impairment depended on different ACE genotypes.

METHODS

The ACE I/D polymorphism was genotyped in 928 schizophrenia patients and 325 healthy controls using a case-control design. The severity of psychopathological symptoms was assessed using the Positive and Negative Syndrome Scale (PANSS). Cognitive functioning was assessed by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS).

RESULTS

There were significant differences in genotype and allele frequencies of the ACE I/D polymorphism between patients and healthy controls (both P < 0.01). After controlling for demographic characteristics, patients who are homozygous carriers of D and I performed worse on the RBANS attention index than heterozygous carriers (P = 0.009). In addition, attention index score was negatively correlated with PANSS negative symptom score in patients of all genotypes (all P < 0.05), and positively correlated with positive symptom score only in the I/I genotype (P = 0.005).

CONCLUSIONS

These findings suggest that ACE I/D gene variants play a role in susceptibility to schizophrenia, specific cognitive impairment and the association between clinical symptoms and cognitive impairment in schizophrenia patients.

Negative symptoms and neurocognition in drug-naïve schizophrenia: moderating role of plasma neutrophil gelatinase-associated lipocalin (NGAL) and interferon-gamma (INF-γ)

Previous studies reported that peripheral inflammation was associated with cognitive performance and brain structure in schizophrenia. However, the moderating effect of inflammation has not been extensively studied. This study investigated whether inflammation markers moderated the association between negative symptoms and neurocognition in schizophrenia. This cross-sectional study included 137 drug-naïve schizophrenia patients (DNS) and 67 healthy controls (HC). We performed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) for cognitive assessment and the Positive and Negative Syndrome Scale (PANSS) for psychiatric symptoms. Plasma concentrations of interferon-gamma (IFN-γ), neutrophil gelatinase-associated lipocalin (NGAL), and nuclear factor kappa B (NF-κB) were measured. The MCCB neurocognition score, social cognition score, and total score; the plasma concentrations of NGAL, IFN-γ, and NF-κB were significantly decreased in DNS than in HC (all P's < 0.001). PANSS negative subscale (PNS), PANSS reduced expressive subdomain (RES) negatively correlated with neurocognition score (P = 0.007; P = 0.011, respectively). Plasma concentrations of IFN-γ and NGAL positively correlated with neurocognition score (P = 0.043; P = 0.008, relatively). The interactions of PNS × NGAL; PNS × IFN-γ; RES × IFN-γ accounted for significant neurocognition variance (P = 0.025; P = 0.029, P = 0.007, respectively). Simple slope analysis showed that all the above moderating effects only occurred in patients with near normal IFN-γ and NGAL levels. Plasma concentrations of IFN-γ and NGAL moderated the relationship between negative symptoms (especially RES) and neurocognition in schizophrenia. Treatment targeting inflammation may contribute to neurocognition improvement in schizophrenia.

Repetitive transcranial magnetic stimulation can improve negative symptoms and/or neurocognitive impairments in the first psychosis episode: A randomized controlled trial

OBJECTIVE

Negative symptoms and neurocognitive impairments in psychosis correlate with their severity. Currently, there is no satisfactory treatment. We aimed to evaluate and compare the effects of repetitive transcranial magnetic stimulation(rTMS) on negative symptoms and neurocognitive impairments in patients in first-episode of psychosis(FEP) in a randomized controlled trial(RCT).

METHOD

This is a single-site RCT of 85 patients with FEP. Patients were randomized to receive a 4-week course of active(n = 45) or sham rTMS(n = 40). Factor analysis was applied to a cross-sectional dataset of 744 FEP patients who completed negative symptom evaluation and neurocognitive battery tests. Two independent dimensions were generated and used for the K-means cluster analysis to produce sub-clusters. rTMS of 1-Hz was delivered to the right orbitofrontal(OFC) cortex.

RESULTS

Two distinct dimensional factors of neurocognitive functions(factor-1) and negative symptoms(factor-2), and three clusters with distinctive features were generated. Significant improvements in factor-1 and factor-2 were observed after 4-weeks of rTMS treatment in both the active and sham rTMS groups. The repeated-measures analysis of variance revealed a significant effect of time×group(F = 5.594, p = 0.021, η2 = 0.073) on factor-2, but no effect of time×group on factor-1. Only improvements in negative symptoms were significantly different between the active and sham rTMS groups(p = 0.028). Patients in cluster-3 characterized by extensive negative symptoms, showed greater improvement in the active rTMS group than in the sham rTMS group.

CONCLUSIONS

The 1-Hz right OFC cortex rTMS is more effective in reducing negative symptoms than neurocognitive impairments. It is especially effective in patients with dominantly negative symptoms in FEP.

Gender differences in cognitive improvements after two months of atypical antipsychotic treatment in first episode schizophrenia

Aims

This study aims to explore the gender differences in cognitive improvements after two months of atypical antipsychotic treatment in first episode schizophrenia (FES).

Methods

82 patients with FES, including 50 male patients and 32 female patients, were enrolled in the present study. Positive and Negative Syndrome Scale (PANSS) and MATRICS Consensus Cognitive Battery (MCCB) were respectively conducted to evaluate the clinical symptoms and cognitive function of patients with FES at baseline and after treatment. Repeated measure ANOVA was performed to compare gender differences in cognitive domains scores between baseline and 2-month follow-up. Stepwise liner regression model was performed to explore the effect factors of cognitive improvements in patients.

Results

There was no significant difference in age of onset, education years, PANSS scores, duration of untreated psychosis and Olanzapine equivalent doses between male and female patients (all p > 0.05). In the comparisons of cognition function, male patients exhibited better performance in social cognition compared with female patients at baseline (t = 3.20, p < 0.05). After treatment, improvements of attention/vigilance and working memory were both found in male patients and female patients (attention/vigilance, F = 11.867, p < 0.05; working memory, F = 18.265, p < 0.05). In addition, improvement of speed of information processing was only found in female patients (F = 11.65, p < 0.01). Significant interaction between time and gender was found in speed information of processing (F = 4.140, p = 0.045). Stepwise liner regression model revealed that improvements of negative symptoms promote improvements of cognitive function in female patients (all p < 0.05).

Conclusions

Our findings revealed gender differences of cognitive improvements in patients with FES after 2-month treatment. It provides new evidence for gender differences in cognitive symptoms of schizophrenia, and also provides preliminary clues for further individualized cognitive intervention strategies.

Insomnia in Chinese patients with chronic schizophrenia: prevalence, clinical correlates and relationship with cognitive impairment

PURPOSE

Insomnia is a major public health concern that often occurs in patients with schizophrenia, complicating the treatment and prognosis of patients. This study aimed to investigate the prevalence of insomnia and its relationship with cognitive function in Chinese patients with chronic schizophrenia.

METHODS

We recruited patients with schizophrenia and collected their clinical and demographic data. Insomnia data were collected through a self-reported questionnaire consisting of three questions. The positive and negative syndrome scale (PANSS) was used to measure psychopathological symptoms, while the repeatable battery for the assessment of neuropsychological status (RBANS) was used to measure cognitive performance.

RESULTS

Of 957 Chinese patients with chronic schizophrenia 20.2% reported having insomnia (193/957). Male patients (107/630, 17.0%) had a lower rate of insomnia than female patients (86/327, 26.3%) (x2 = 11.60, p = 0.001). Patients with insomnia exhibited significantly higher PANSS total score and positive symptom, negative symptom, and general psychopathology scores, but significantly lower RBANS total score, language, attention and delayed memory scores compared to patients without insomnia (all p < 0.05). Logistic regression analysis showed that female sex, high PANSS total score and the use of diazepam were independently associated with insomnia (all p < 0.05).

CONCLUSIONS

Insomnia is relatively common in Chinese patients with chronic schizophrenia. Some demographic data and clinical symptoms are associated with insomnia. Patients with schizophrenia and insomnia perform poorly on cognition tests suggesting that insomnia and cognitive function are closely related in patients with schizophrenia.

Association between Empathy and Clinical Symptoms among Overweight and Non-Overweight Chinese Chronic Schizophrenia Patients

Patients with schizophrenia are afflicted by severe clinical symptoms and serious cognitive dysfunction. The aim of this study is to investigate the potential relationships between clinical symptoms and empathy and their variations between overweight and non-overweight schizophrenia patients. To address this problem, a group of 776 inpatients diagnosed with chronic schizophrenia (504 overweight patients and 272 non-overweight patients) was recruited. The Positive and Negative Syndrome Scale (PANSS) and its five-factor model were employed to assess clinical symptoms, while empathy levels were measured using the Interpersonal Reactivity Index (IRI). The overweight patients had lower education levels but higher positive symptoms than the non-overweight patients (all p < 0.05). In addition, the overweight patients performed significantly better with respect to empathy (FDR-corrected p < 0.05). Additional multiple regression analyses indicated significant associations between the total score of the IRI and PANSS negative symptoms, gender, and family history of psychiatric disorders among the overweight group; among non-overweight patients, there was a significant correlation between suicide and the total score of the IRI. This study provides evidence suggesting that chronic schizophrenia patients who are overweight may have distinct clinical characteristics, particularly with respect to their empathy, compared with non-overweight patients. Moreover, different variables are associated with empathy in different groups.

The blind men and the elephant: The case for a transdiagnostic approach to initiation

Difficulty initiating voluntary action is an under-recognized and often invisible impairment in various psychiatric, neurodevelopmental, and neurological conditions. Understanding the commonalities of volition impairments across diagnoses is limited by a lack of consistent terminology, arbitrary distinctions between conditions, the habit of looking only to the prevailing definitions and theories to explain observed traits, and the covert nature of initiation. The siloed approach to research in this area evokes the parable of the blind men and the elephant, where understanding the whole picture is impeded by a limited view. There has been little effort to consider how differing terms overlap or to use objective methods to differentiate phenomena along meaningful lines. We propose a triad of interacting elements, all of which are needed for successful initiation of voluntary action: (i) executive function, (ii) volition, and (iii) movement. Failure to initiate a response may be due to impairments in any of these, which often co-occur. This paper calls for the following considerations to improve research in this area: (i) put aside preconceptions about conditions and their mechanisms to adopt a flexible transdiagnostic approach; (ii) consider executive function, movement, and volition as possible dimensional variations with related underlying mechanisms; (iii) carefully differentiate components of complex functions; (iv) look to first-hand reports for covert and previously unrecognized traits. These approaches have the potential to elucidate the cognitive and biological mechanisms underpinning voluntary action and create a foundation to develop more appropriate and informed interventions.

The trajectory of two negative symptom dimensions in first-episode psychosis and the role of cannabis use: A 10-year follow-up study

OBJECTIVE

To investigate the trajectories of diminished expression and apathy over 10 years. Further, to explore the effects of baseline- and persistent cannabis use on the development of diminished expression and apathy during follow-up, while controlling other potential sources and predictors of secondary negative symptoms.

METHODS

351 participants with a first episode of non-affective psychosis were examined at baseline and invited to follow-up at one year and 10 years. The trajectories of diminished expression and apathy were investigated using linear mixed models. Subsequently, cannabis use and other potential predictors and sources of secondary negative symptoms were added to the model to investigate the respective impact on their trajectories.

RESULTS

The severity of both diminished expression and apathy decreased during the follow-up period after the first episode of psychosis, with the most improvement observed from baseline to 1-year follow-up. Cannabis use at baseline was associated with a long-lasting higher symptom load for diminished expression, but not apathy. Introducing persistent cannabis use to the model further strengthened the association with diminished expression.

CONCLUSION

Both cannabis use at baseline and persistent cannabis use after a first episode of psychosis were associated with more severe symptoms of diminished expression. Our results imply a causal relationship between cannabis use and diminished expression and suggest that measures to reduce cannabis use both before and after psychosis onset may reduce expressive negative symptoms.

Longitudinal changes of cognitive function and its relationship with subdomains of negative symptoms in patients with adult-onset first-episode schizophrenia: A 4-year follow up study

BACKGROUNDS

This study explores the longitudinal changes and trajectories of cognitive functions in patients with adult-onset first-episode schizophrenia (FES) over four years and their relationships with the baseline subdomains of negative symptoms.

METHODS

A total of 177 patients of age 25-55 with FES were recruited. Baseline demographics, clinical, social and cognitive functions were assessed. Diminished expression and diminished motivation of negative symptoms were assessed with Scale for the Assessment of Negative Symptoms (SANS). Patients had yearly follow-up of cognitive function assessments over four years. Latent class growth analysis (LCGA) and mixed linear regression model were used to explore the longitudinal changes of cognitive functions and the effect of baseline negative symptoms on the longitudinal cognitive function changes. Relationships of baseline negative symptoms subdomains and cognitive functions were also explored.

RESULTS

Two trajectories of cognitive functions were identified. Longitudinal improvements were found in most cognitive functions apart from the logical memory. One trajectory of patients had significant deterioration of logical memory while the other group had significant improvement. Baseline diminished expression was associated with baseline and longitudinal changes of processing speed and verbal fluency while diminished motivation was associated with baseline and longitudinal changes of processing speed.

CONCLUSIONS

Adult-onset FES patients had a homogeneous longitudinal improvement in most cognitive functions but not for logical memory suggesting the unique nature of verbal memory. The distinct relationship between baseline subdomains of negative symptoms with baseline and longitudinal cognitive functions suggesting the presence of differential overlapping etiology between negative symptom subdomains and cognitive functions.

Impact of Cognitive Impairments on Health-Related Quality of Life in Schizophrenia

The impact of cognitive impairments on the health-related quality of life (HRQoL) in individuals with schizophrenia is unclear. The aim of this study was to examine the association between cognitive impairments and HRQoL in individuals with schizophrenia. A total of 609 individuals with schizophrenia were assessed on the Positive and Negative Syndrome Scale (PANSS) and a neurocognitive battery which comprised of the Wechsler Abbreviated Scale of Intelligence matrix reasoning, the Benton Judgment of Line Orientation Test, Continuous Performance Tests-Identical Pairs, and the Brief Assessment of Cognition in Schizophrenia. A cognitive factor g was derived from the neurocognitive battery. EuroQol five-dimensional (EQ-5D-5L) utility scores were derived from PANSS scores via a previously validated algorithm and used as a measure of HRQoL. Hierarchical multiple regression was conducted to examine the association between cognitive factor g and the EQ-5D-5L. Cognitive factor g (β = 0.189, t = 4.956, p < 0.001) was found to be significantly associated with EQ-5D-5L scores. Age (β = -0.258, t = -6.776, p < 0.001), sex (β = 0.081, t = 2.117, p = 0.035), and being employed (β = 0.091, t = 2.317, p = 0.021) were also significant predictors of EQ-5D-5L. Our results add to the extant literature on the burden cognitive impairments exact in individuals with schizophrenia. More research is needed to develop effective interventions for cognitive impairments in schizophrenia.

Association of empathy with clinical symptoms and cognitive function in Chinese chronic schizophrenia patients with and without deficit syndrome

BACKGROUND

Patients with deficit syndrome (DS) are known to experience cognitive impairment. However, there is no consistent conclusion on the impairment of neurocognitive features in DS patients, and no studies have examined their empathy. The purpose of this study was to compare neurocognition and empathy in patients with DS and non-DS schizophrenia.

METHODS

Totally, 665 patients with chronic schizophrenia were enrolled. DS patients were identified by the Proxy Scale for Deficit Syndrome (PDS). Neurocognition and social cognition were assessed by Repeatable Battery for the measurement of Neuropsychological Status (RBANS) and the Interpersonal Reactivity Index (IRI), respectively. In addition, psychopathological symptom severity was assessed by the Positive and Negative Syndrome Scale (PANSS).

RESULTS

Participants included 150 patients with DS and 140 patients with non-DS. DS patients performed significantly worse on the all RBANS domain (except for visuospatial) and total scores as well as IRI scores. Regression analysis showed that PANSS general psychopathology and education were associated with RBANS total score in the DS group (adjusted R² = 0.29), while education and PANSS negative symptoms were correlated with RBANS total score in non-DS patients (adjusted R² = 0.33). In the non-DS group, suicide attempts and PANSS negative symptom score were independently associated with IRI total score (adjusted R² = 0.06), whereas in the DS group, no variable was associated with IRI total score.

CONCLUSIONS

Our findings suggest that patients with DS may have poor neurocognitive and empathy performance. In chronic schizophrenia patients, negative symptoms may play a different role in cognition between DS and non-DS groups.

Identifying psychiatric manifestations in schizophrenia and depression from audio-visual behavioural indicators through a machine-learning approach

Schizophrenia (SCZ) and depression (MDD) are two chronic mental disorders that seriously affect the quality of life of millions of people worldwide. We aim to develop machine-learning methods with objective linguistic, speech, facial, and motor behavioral cues to reliably predict the severity of psychopathology or cognitive function, and distinguish diagnosis groups. We collected and analyzed the speech, facial expressions, and body movement recordings of 228 participants (103 SCZ, 50 MDD, and 75 healthy controls) from two separate studies. We created an ensemble machine-learning pipeline and achieved a balanced accuracy of 75.3% for classifying the total score of negative symptoms, 75.6% for the composite score of cognitive deficits, and 73.6% for the total score of general psychiatric symptoms in the mixed sample containing all three diagnostic groups. The proposed system is also able to differentiate between MDD and SCZ with a balanced accuracy of 84.7% and differentiate patients with SCZ or MDD from healthy controls with a balanced accuracy of 82.3%. These results suggest that machine-learning models leveraging audio-visual characteristics can help diagnose, assess, and monitor patients with schizophrenia and depression.

Associations between symptom and neurocognitive dimensions in clinical high risk for psychosis

Introduction

Clinical high risk for psychosis (CHR) is associated with mild cognitive impairments. Symptoms are clustered into positive, negative and disorganization symptoms. The association between specific symptom dimensions and cognitive functions remains unclear. The aim of this study was to investigate the associations between cognitive functions and positive, negative, and disorganization symptoms.

Method

53 CHR subjects fulfilling criteria for attenuated psychotic syndrome in the Structural Interview for Prodromal Syndromes (SIPS) were assessed for cognitive function. Five cognitive domain z-scores were defined by contrasting with observed scores of a group of healthy controls (n = 40). Principal Components Analyses were performed to construct general cognitive composite scores; one using all subtests and one using the cognitive domains. Associations between cognitive functions and symptoms are presented as Spearman's rank correlations and partial Spearman's rank correlations adjusted for age and gender.

Results

Positive symptoms were negatively associated with executive functions and verbal memory, and disorganization symptoms with poorer verbal fluency. Negative symptoms were associated with better executive functioning. There were no significant associations between the general cognitive composites and any of the symptom domains, except for a trend for positive symptoms.

Conclusion

In line with previous research, data indicated associations between positive symptoms and poorer executive functioning. Negative symptoms may not be related to executive functions in CHR the same way as in psychosis. Our results could indicate that attenuated positive symptoms are more related to cognitive deficits in CHR than positive symptoms in schizophrenia and FEP.

Negative symptom dimensions and social functioning in Chinese patients with schizophrenia

OBJECTIVE

Negative symptoms can seriously affect social functioning in patients with schizophrenia. However, the role of various components of negative symptoms in social functioning remains unclear. This study aimed to explore the associations among three different dimensions of negative symptoms (i.e., communication, emotion, and motivation) and social functioning to identify potential therapeutic targets.

METHODS

This cross-sectional study enrolled 202 Chinese participants with schizophrenia. Negative symptoms were evaluated using the Negative Symptom Assessment (NSA). Social functioning was represented by the Personal and Social Performance Scale (PSP) total score and employment status. Correlation analysis was conducted to clarify the relationship between negative symptoms and the PSP total score. Regression analysis was performed to explore the determinants of the PSP total score and employment status, considering negative symptoms and possible confounders, such as demographic features, positive symptoms, cognitive symptoms, depressive symptoms, and extrapyramidal side effects.

RESULTS

The PSP total score was correlated with all three dimensions of negative symptoms (i.e., emotion, motivation, and communication; rs = -0.509, -0.662, and -0.657, respectively). Motivation, instead of emotion or communication, predicted both low PSP total scores and unemployment.

CONCLUSION

Social functioning in patients with schizophrenia was significantly related to motivation. Further studies should focus on motivation and consider it as a therapeutic target to improve patients' social functioning.

Relationship of subjective quality of life with symptomatology, neurocognition and psychosocial functioning in first-episode psychosis: a structural equation modelling approach

Subjective quality of life (SQoL) represents an important outcome of psychotic disorders. However, determinants of SQoL and their complex inter-relationships in the early course of illness remain to be clarified. Association between neurocognitive impairment and SQoL in first-episode psychosis (FEP) is understudied. This study employed structural equation modeling (SEM) to examine relationships among SQoL, depressive, positive and negative symptoms, neurocognition, and psychosocial functioning in FEP patients. Three hundred and forty-seven patients aged 25-55 years presenting with FEP to early intervention program in Hong Kong were recruited. Assessment encompassing symptom profiles, psychosocial functioning and a battery of neurocognitive tests were conducted. SF-12 mental component summary scores were computed as the primary measure of SQoL. Our correlation analyses revealed differential relationships between negative symptom subdomains and SQoL, with amotivation, but not diminished expression, being related to SQoL. Final SEM model yielded a good model fit (comparative fix index = 0.94; root mean square error of approximation = 0.05; standardized root mean square residuals = 0.07) and demonstrated that depression, positive symptoms and psychosocial functioning were directly associated with SQoL, with depression showing the strongest effect. Amotivation, neurocognition and positive symptoms had an indirect effect on SQoL via the mediation of psychosocial functioning. This study affirms depression as a critical determinant of subjective mental wellbeing, and underscores an intermediary role of psychosocial functioning in linking amotivation, neurocognitive impairment and positive symptoms to SQoL in FEP patients. Depression and functional impairment thus constitute as crucial therapeutic targets for improvement of SQoL in the early illness stage.

Association of negative symptoms with cognitive impairment in Chinese Han patients with chronic schizophrenia

OBJECTIVE

Cognitive impairment is an essential feature of schizophrenia; however, the relationship between clinical psychiatric symptoms with cognitive impairment is still unclear. Therefore, we aimed to assess cognitive deficits and the relationship between clinical symptoms and cognitive function in patients with chronic schizophrenia, which provide a reference guide for psychiatrists.

METHODS

We compared the cognitive function in 312 schizophrenia inpatients and 397 healthy controls by using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). The positive and negative symptom scale (PANSS) was used to assess the clinical symptoms of the patients.

RESULTS

Analysis of covariance showed that the RBANS total and four index scores (all p < 0.001) were significantly lower in patients than healthy controls. After Bonferroni correction, Pearson correlation analysis showed that there was a significant negative association between PANSS negative symptom subscale and RBANS total score and all 5 domain scores (all p < 0.01). Further regression analysis showed that negative symptoms, age, age of onset, and antipsychotic dose were important independent predictors of cognitive deficits.

CONCLUSIONS

Our findings suggest that patients with chronic schizophrenia exhibit cognitive deficits compared with healthy people. Negative symptoms and some clinical variables are associated with cognitive impairment in patients with schizophrenia.KEYPOINTSThis study indicates that patients with chronic schizophrenia have extensive cognitive impairment shown on RBANS except for the visuospatial/constructional domain.Cognitive impairment in patients is associated with age, negative symptoms, age of onset, and antipsychotic dose.There is a significant negative association between cognitive deficits and negative symptoms in patients with chronic schizophrenia.The results of this study need to be confirmed in future studies with longitudinal designs with a large and sex-balanced sample in first-episode drug naïve patients with schizophrenia.

Association between empathy and clinical symptoms in chronic schizophrenia: A large sample study based on Chinese Han population

BACKGROUND

In patients with schizophrenia, clinical symptoms and cognitive impairment are its core features, both of which have a significant impact on the prognosis and functional outcome. Empathy, as an important social cognition, has been found to be associated with the clinical symptoms in schizophrenia, but the conclusions on this issue are inconsistent. Therefore, this study will continue to explore it through a large sample of inpatients with chronic schizophrenia in the Chinese Han population.

METHODS

We obtained the sociodemographic characteristics of 987 inpatients, measured their clinical symptoms using the Positive and Negative Syndrome Scale (PANSS), and assessed their self-reported empathy using the Interpersonal Reactivity Index (IRI). The factor score for negative symptoms (FSNS) of PANSS was additionally calculated.

RESULTS

Correlation and linear regression analysis showed that patients' PANSS scores were widely correlated with their IRI scores. In particular, the negative symptoms of patients were significantly correlated to IRI total score (r = -0.131, p < .001) and subscales such as Perspective Taking (PT) (r = -0.233, p < .001). FSNS had close relationships with empathy as well. There are also many significant associations between other dimensions, such as general psychopathology and Perspective Taking (PT) or Fantasy (FS) (all p < .05).

CONCLUSIONS

Our results indicated that clinical symptoms, especially negative symptoms, were closely related to their current empathy in patients with schizophrenia, suggesting that the severity of clinical symptoms may be a powerful factor in predicting social cognition such as empathy of schizophrenia.

Cognitive Subtyping in Schizophrenia: A Latent Profile Analysis

Cognitive dysfunction is a core feature of schizophrenia. The subtyping of cognitive performance in schizophrenia may aid the refinement of disease heterogeneity. The literature on cognitive subtyping in schizophrenia, however, is limited by variable methodologies and neuropsychological tasks, lack of validation, and paucity of studies examining longitudinal stability of profiles. It is also unclear if cognitive profiles represent a single linear severity continuum or unique cognitive subtypes. Cognitive performance measured with the Brief Assessment of Cognition in Schizophrenia was analyzed in schizophrenia patients (n = 767). Healthy controls (n = 1012) were included as reference group. Latent profile analysis was performed in a schizophrenia discovery cohort (n = 659) and replicated in an independent cohort (n = 108). Longitudinal stability of cognitive profiles was evaluated with latent transition analysis in a 10-week follow-up cohort. Confirmatory factor analysis (CFA) was carried out to investigate if cognitive profiles represent a unidimensional structure. A 4-profile solution was obtained from the discovery cohort and replicated in an independent cohort. It comprised of a "less-impaired" cognitive subtype, 2 subtypes with "intermediate cognitive impairment" differentiated by executive function performance, and a "globally impaired" cognitive subtype. This solution showed relative stability across time. CFA revealed that cognitive profiles are better explained by distinct meaningful profiles than a severity linear continuum. Associations between profiles and negative symptoms were observed. The subtyping of schizophrenia patients based on cognitive performance and its associations with symptomatology may aid phenotype refinement, mapping of specific biological mechanisms, and tailored clinical treatments.

What is the Best Latent Structure of Negative Symptoms in Schizophrenia? A Systematic Review

Background

Determining the best latent structure of negative symptoms in schizophrenia could benefit assessment tools, neurobiological research, and targeted interventions. However, no review systematically evaluated studies that assessed and validated latent models of negative symptoms.

Objective

To identify and evaluate existing latent structure models in the literature of negative symptoms and to determine the best model.

Method

Systematic search of MEDLINE, EMBASE, and Scopus on July 19, 2020, for confirmatory factor analysis models of negative symptoms in patients with schizophrenia. The available evidence was assessed through 2 sets of criteria: (1) study design quality—based on negative symptoms assessment and modeling strategy and (2) psychometric quality and model fit—based on fit indices and factor definition quality.

Results

In total, 22 studies (n = 17 086) from 9 countries were included. Studies differed greatly regarding symptom scales, setting, and sample size (range = 86–6889). Dimensional models included 2–6 factors (median = 4). Twelve studies evaluated competing models and adopted appropriate instruments to assess the latent structure of negative symptoms. The 5-factor and hierarchical models outperformed unitary, 2-factor, and 3-factor models on all direct comparisons, and most of the analyses derived from the Brief Negative Symptom Scale. Considering the quality criteria proposed, 5-factor and hierarchical models achieved excellent fit in just one study.

Conclusions

Our review points out that the 5-factor and hierarchical models represent the best latent structure of negative symptoms, but the immaturity of the relevant current literature may affect the robustness of this conclusion. Future studies should address current limitations regarding psychometric properties and also address biological and clinical validity to refine available models.

Sex differences in association between clinical correlates and cognitive impairment in patients with chronic schizophrenia

Schizophrenia is a heterogeneous disorder with sex differences in clinical manifestations and cognitive function. However, the nature of its sex-specific relationship between clinical manifestations and cognitive impairment remains equivocal. This study aimed to explore the sex differences in the association between cognitive function and clinical features of hospitalized patients with schizophrenia. A total of 251 schizophrenia patients (males/females = 167/84) and 178 healthy controls (males/females = 84/94) were enrolled. Cognitive function was assessed through the Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB). The Positive and Negative Syndrome Scale (PANSS) was used to evaluate psychiatric symptoms in patients. Both male and female patients performed more impaired than their counterparts on all MCCB tests. However, only the scores of category fluency, attention and reasoning/problem solving of female patients were significantly lower than those of male patients. Multivariate regression analyses demonstrated that attention was independently associated with negative symptoms in female patients, and general psychopathology in male patients. Negative symptoms were also independently associated with verbal learning and memory and social cognition only in male patients, while general psychopathology was independently associated with symbol coding only in female patients. Our results suggest that there are noticeable sex differences in clinical features, cognitive impairment and their associations in schizophrenia patients. These sex-specific associations may provide useful information for future studies aimed at predicting and interfering with the outcome of schizophrenia from a sex perspective.

Circuits and functions of the lateral habenula in health and in disease

The past decade has witnessed exponentially growing interest in the lateral habenula (LHb) owing to new discoveries relating to its critical role in regulating negatively motivated behaviour and its implication in major depression. The LHb, sometimes referred to as the brain's 'antireward centre', receives inputs from diverse limbic forebrain and basal ganglia structures, and targets essentially all midbrain neuromodulatory systems, including the noradrenergic, serotonergic and dopaminergic systems. Its unique anatomical position enables the LHb to act as a hub that integrates value-based, sensory and experience-dependent information to regulate various motivational, cognitive and motor processes. Dysfunction of the LHb may contribute to the pathophysiology of several psychiatric disorders, especially major depression. Recently, exciting progress has been made in identifying the molecular and cellular mechanisms in the LHb that underlie negative emotional state in animal models of drug withdrawal and major depression. A future challenge is to translate these advances into effective clinical treatments.

Anterior Cingulate Cortex Glutamate Levels Are Related to Response to Initial Antipsychotic Treatment in Drug-Naive First-Episode Schizophrenia Patients

The glutamatergic system has previously been shown to be involved in the pathophysiology of schizophrenia and the mechanisms of action of antipsychotic treatment. The present study aimed to investigate the relationship between the levels of glutamate (Glu) or Glu/total creatine (Glu/Cr+PCr) in the anterior cingulate cortex (ACC) and psychiatric symptoms as well as the response to antipsychotic treatment. We performed proton magnetic resonance spectroscopy (¹H-MRS) to measure Glu and Glu/Cr+PCr in the ACC of 35 drug-naïve first-episode schizophrenia (FES) patients and 40 well-matched healthy controls (HCs). After scanning, we treated the patients with risperidone for eight weeks. Remission status was based on the Positive and Negative Syndrome Scale (PANSS) scores at week 8. At baseline, there were no significant differences in the levels of Glu or Glu/Cr+PCr in the ACC between drug-naïve FES patients and HCs. Lower baseline levels of Glu/Cr+PCr but not Glu in the ACC were associated with more severe negative symptoms of schizophrenia. Compared to the remission group (RM), the non-remission group (NRM) had lower baseline ACC Glu levels (P < 0.05). Our results suggest that ACC Glu levels may be related to the severity of symptoms in the early stages of schizophrenia and therefore may be a marker with which to evaluate the treatment effect of antipsychotics in schizophrenia patients.

Clinical utility of the Negative Symptom Assessment-16 in individuals with schizophrenia

This study examined the clinical utility of the Negative Symptom Assessment-16 (NSA-16) in schizophrenia. 274 individuals with schizophrenia were assessed on the NSA-16, Positive and Negative Syndrome Scale (PANSS), Clinical Assessment for Negative Symptoms (CAINS), Calgary Depression Scale for Schizophrenia (CDSS), Social and Occupational Functioning Assessment Scale (SOFAS) and the Simpson-Angus Extrapyramidal Side Effects Scale (SAS). Factor analyses were conducted and Cronbach's alpha was computed. Correlations were assessed using Spearman's correlation coefficient. The 5-factor model of the NSA-16 did not give good fit statistics from our sample. Exploratory factor analysis on a randomly selected split-half of the sample followed by confirmatory factor analysis on the remaining sample supported a 4-factor structure with 12 items. The factors were: Restricted speech, Poor quality of speech, Affective blunting and Amotivation. The NSA-16 with the 12 items was termed as the NSA-12. The NSA-12 showed good internal reliability. The NSA-12 total score and global negative symptom rating had strong correlations with CAINS total and PANSS negative factor scores, suggesting good convergent validity. Weak correlations of the NSA-12 total score and global negative symptom rating with PANSS positive, CDSS and SAS scores suggested good divergent validity. The NSA-12 total score and global negative symptom rating were strongly and inversely associated with SOFAS and positively associated with NSA-12 global level of functioning. In conclusion, the NSA-12 is useful to evaluate negative symptoms in clinical and research settings in individuals with schizophrenia. Our study results also support a 4-factor structure of the NSA-12 in outpatients with schizophrenia.

Executive dysfunctions differentially predict amotivation in first-episode schizophrenia-spectrum disorder: a prospective 1-year follow-up study

Amotivation is a major determinant of functional outcome in schizophrenia but it is understudied in the early course of illness. There is a paucity of longitudinal research investigating predictors of amotivation. In this study, we aimed to examine baseline cognitive and clinical predictors of amotivation at 6 and 12 months of follow-up in patients aged 18-55 years presenting with first-episode DSM-IV schizophrenia-spectrum disorder (FES). Of 145 patients recruited at intake, 116 and 113 completed assessments at 6- and 12-month follow-up, respectively. Amotivation was measured by avolition-apathy and anhedonia-asociality subscale scores of the Scale of the Assessment of Negative Symptoms. Cognitive assessment was administered at baseline. As executive dysfunction has been more consistently found to be associated with negative symptoms and amotivation in prior literature, we adopted fractionated approach to subdivide executive function into distinct components encompassing switching and flexibility, response initiation, response inhibition, planning and strategy allocation, sustained attention and working memory. Our results showed that baseline amotivation (p = 0.01) and switching and flexibility (p = 0.01) were found to independently predict amotivation at 6 months follow-up. Baseline amotivation (p < 0.01) and switching and flexibility (albeit with trend-wise significance, p = 0.06) were also retained in final multivariate regression model for 12-month amotivation prediction. No other executive components or cognitive domains predicted amotivation at follow-up. Findings of our study thus indicate amotivation at initial presentation as a critical determinant of subsequent motivational deficits over 1 year of treatment for FES patients. Cognitive flexibility might be specifically related to the development of amotivation in the early stage of illness.

Objective and subjective cognitive functioning in relation to psychopathology among women with early psychosis

BACKGROUND

Subjective cognitive impairment (SCI) among early psychosis is under-recognized and under-studied. However, SCI is as important as objective impairment to be understood, since it assesses cognitive difficulties in real-life situations from a personal perspective and is therefore an essence of individualized medicine. This study aims to explore the associations between the objective and subjective measures of cognitive impairments and to identify factors contributing to SCI among people with early psychosis.

METHODS

Participants were 60 females (mean age 24.57 ± 8.28) who had a diagnosis of psychotic-spectrum disorder within 5 years. They completed a battery of neuropsychological tests assessing a range of cognitive functions including verbal learning, memory, attention, and executive functions. The Subjective Cognitive Impairment Scale (SCIS) was used to assess their perceived cognitive decline. Psychotic symptoms and depression were also assessed.

RESULTS

SCIS was not correlated with any of the objective cognitive tests results. It was positively correlated with depression and positive symptoms. A hierarchical multiple regression model revealed that positive symptoms and depression together explained 31.9% of the total variance in SCIS and only depression significantly predicted SCI. Performances on the memory tests were correlated with, and predicted by negative symptoms.

CONCLUSIONS

There was no correlation between SCI and objective cognitive performances in patients with early psychosis. Treatments should not only focus on symptomatic remission and performance of cognitive tests, but also place emphasis on improving moods and subjective cognitive functions of individuals with early psychosis.

Validation of the Brief Negative Symptom Scale and its association with functioning

INTRODUCTION

The Brief Negative Symptom Scale (BNSS) includes five domains of negative symptoms suggested by the NIMH Consensus Development Conference (anhedonia, asociality, avolition, blunted affect, and alogia), which could be clustered into two factors - Motivation-Pleasure (MAP) and Emotional Expressivity (EE). Our study aims to examine the psychometric properties of BNSS, and its association with functioning.

METHODS

274 individuals with schizophrenia were assessed on the BNSS, Positive and Negative Syndrome Scale (PANSS), Scale for the Assessment of Negative Symptoms (SANS), Global Assessment of Functioning Scale (GAF), Calgary Depression Scale for Schizophrenia (CDSS), and Simpson-Angus Extrapyramidal Side Effects Scale (SAS). Internal consistency was examined using Cronbach's alpha. Concurrent, discriminant, and construct validity were examined. Factor structure of BNSS was explored using confirmatory factor analyses. Association between GAF and BNSS was examined with GAF as the dependent variable and BNSS Total, MAP and EE, and BNSS five domains as independent variables in three multiple regression models after controlling for covariates.

RESULTS

BNSS showed good internal consistency (Cronbach's alpha = 0.880) and validity. The five-factor model fit the data better than the two-factor model; a second-order model was superior to both models. More severe symptoms on BNSS Total (B = -0.438, p < .001), MAP (B = -0.876, p < .001), Avolition (B = -2.503, p < .001) and Asociality (B = -0.950, p = .001) were associated with lower GAF.

CONCLUSION

Our results lend support to the use of BNSS in clinical practice and in future research into negative symptoms. Composite scores could be computed using either the five-factor or second-order models. Negative symptoms, particularly MAP, avolition and asociality, were associated with functioning.

Glutamate hypothesis in schizophrenia

Schizophrenia is a chronic and severe psychiatric disorder that has profound impact on an individual's life and on society. Thus, developing more effective therapeutic interventions is essential. Over the past quarter-century, an abundance of evidence from pharmacologic challenges, post-mortem studies, brain imaging, and genetic studies supports the role of glutamatergic dysregulation in the pathophysiology of schizophrenia, and the results of recent randomized clinical trials based on this evidence have yielded promising results. In this article, we review the evidence that alterations in glutamatergic neurotransmission, especially focusing on the N-methyl-d-aspartate receptor (NMDAR) function, may be a critical causative feature of schizophrenia, how this contributes to pathologic circuit function in the brain, and how these insights are revealing whole new avenues for treatment development that could reduce treatment-resistant symptoms, which account for persistent disability.

Assessing negative symptoms in schizophrenia: Validity of the clinical assessment interview for negative symptoms in Singapore

This study aimed to examine the validity of the Clinical Assessment Interview for Negative Symptoms (CAINS) in Singapore. 274 participants with schizophrenia were assessed on the CAINS, Scale for the Assessment of Negative Symptoms (SANS), Positive and Negative Syndrome Scale (PANSS), Calgary Depression Scale for Schizophrenia (CDSS), Social and Occupational Functioning Assessment Scale (SOFAS) and the Simpson-Angus Extrapyramidal Side Effects Scale (SES). Factor analyses were conducted and Cronbach's coefficient alpha was calculated. Spearman's correlation coefficient was used to assess correlations. The 2-factor model of the CAINS failed to fit our data. Exploratory factor analysis of a randomly selected split-half of the sample yielded four factors: motivation-pleasure (MAP) social, MAP vocational, MAP recreational and expression (EXP), accounting for 73.94% of the total variance. Confirmatory factor analysis on the remaining sample supported this factor structure. Cronbach's alpha for the CAINS was 0.770. Significant correlations were observed between the CAINS total and the SANS total and PANSS negative subscale scores. Good divergent validity was shown by insignificant correlations with PANSS positive subscale score and CDSS total score. The MAP social and recreational factor scores had moderate correlations with the SANS anhedonia-asociality subscale scores, whereas the MAP vocational factor had the highest correlation with the avolition-apathy subscale of the SANS. EXP factor score correlated strongly with the SANS affective flattening and alogia subscales scores. In conclusion, the CAINS has good psychometric properties and can be used by clinicians to assess negative symptoms in individuals with schizophrenia in the local population.

Amendment of traditional assessment measures for the negative symptoms of schizophrenia

Schizophrenia research based on traditional assessment measures for negative symptoms appears to be, to some extent, unreliable. The limitations of the Positive and Negative Syndrome Scale (PANSS) and the Scale for the Assessment of Negative Symptoms (SANS) have been extensively acknowledged and should be taken into account. The aim of this study is to show how the PANSS and the SANS conflate negative symptoms and cognition and to offer alternatives for the limitations found.

METHODS

A sample of 117 participants with schizophrenia from two independent studies was retrospectively investigated. Linear regression models were computed to explore the effect of negative symptoms and illness duration as predictors of cognitive performance.

RESULTS

For the PANSS, the item "abstract thinking" accounted for the association between negative symptoms and cognition. For the SANS, the "attention" subscale predicted the performance in verbal memory, but illness duration emerged as a stronger predictor than negative symptoms for outcomes of processing speed, verbal and working memory.

CONCLUSION

Utilizing alternative models to the traditional PANSS and SANS formats, and accounting for illness duration, provide more precise evidence on the relationship between negative symptoms and cognition. Since these measures are still extensively utilized, we recommend adopting more rigorous approaches to avoid misleading results.

C-Reactive Protein Correlates with Negative Symptoms in Patients with Schizophrenia

Peripheral and CNS-localized inflammatory processes are hypothesized to contribute to the complex pathophysiology of schizophrenia. Elevated levels of the acute phase reactant C-reactive protein (CRP) have been observed in schizophrenia, yet relatively few studies have investigated the association between this inflammatory biomarker and psychotic symptoms in schizophrenia. This study is a pilot cross-sectional analysis investigating the relation of plasma CRP levels and the positive and negative symptoms of schizophrenia (the primary aim), assessed by the Positive and Negative Syndrome Scale (PANSS). A secondary analysis was also performed evaluating the potential association of CRP with cognitive function using the NIH Toolbox Cognitive Test Battery. After adjusting for age, sex, race, and body mass index, a positive correlation was observed between CRP and PANSS negative symptoms (rho = 0.37, p = 0.05). There was no correlation between plasma CRP and any of the NIH Toolbox measures of cognitive function in the unadjusted or adjusted analyses. Though limited by a relatively small sample size and the unavailability of longitudinal data, the correlation between CRP and psychopathology in this sample of patients supports a role for inflammation in the pathophysiology of schizophrenia.

Disease Severity in Treatment Resistant Schizophrenia Patients Is Mainly Affected by Negative Symptoms, Which Mediate the Effects of Cognitive Dysfunctions and Neurological Soft Signs

This post-hoc study was aimed at assessing whether disease severity was higher in a sample of Treatment Resistant Schizophrenia patients (TRS) compared to schizophrenia patients responsive to antipsychotics (non-TRS). Determinants of disease severity were also investigated in these groups. Eligible patients were screened by standardized diagnostic algorithm to categorize them as TRS or non-TRS. All patients underwent the following assessments: CGI-S; PANSS; DAI; NES; a battery of cognitive tests. Socio-demographic and clinical variables were also recorded. TRS patients exhibited significantly higher disease severity and psychotic symptoms, either as PANSS total score or subscales' scores. A preliminary correlation analysis ruled out clinical and cognitive variables not associated with disease severity in the two groups. Hierarchical linear regression showed that negative symptoms were the clinical variable explaining the highest part of variation in disease severity in TRS, while in non-TRS patients PANSS-General Psychopathology was the variable explaining the highest variation. Mediation analysis showed that negative symptoms mediate the effects of verbal fluency dysfunctions and high-level neurological soft signs (NSS) on TRS' disease severity. These results show that determinants of disease severity sharply differ in TRS and non-TRS patients, and let hypothesize that TRS may stem from cognitive disfunctions and putatively neurodevelopmental aberrations.

The Role of Serine Racemase in the Pathophysiology of Brain Disorders

The N-methyl-d-aspartate receptor (NMDAR) is unique in requiring two agonists to bind simultaneously to open its cation channel: the neurotransmitter, glutamate, and the coagonists, glycine, or d-serine. The Snyder laboratory was the first to clone serine racemase (SR), the enzyme that synthesizes d-serine, and to localize it immunocytochemically. Our laboratory has focused on the role of d-serine in brain disorders. Silencing the expression of SR, a risk gene for schizophrenia (SCZ), in mice (SR-/-), results in a phenotype that closely resembles SCZ including: cortical atrophy, reduced dendritic spine density and complexity, downregulation of parvalbumin-positive cortical GABAergic neurons, and cognitive impairments. This pathology can be reversed by treatment of SR-/- mice with d-serine in adulthood. SR-/- mice also exhibit abnormal response toward abusable substances, such as stimulants. They show reduced behavioral sensitization to d-amphetamine, but fail to extinguish it. Place preference to cocaine is altered, and the hedonic response to it is profoundly impaired as assessed by intracranial self-stimulation. d-cycloserine, a partial agonist at the NMDAR glycine modulatory site, shows therapeutic benefit for treating pathologic anxiety in combination with behavioral therapies. Studies in vitro with cortical culture and in vivo with middle cerebral artery occlusion show that silencing SR provides substantial protection against ischemic neuronal death. Finally, the switch of SR expression from neurons to reactive astrocytes after closed head trauma accounts for the reduced in vivo neuroplasticity, electroencephalogram abnormalities, and cognitive impairments.

Categorizing and assessing negative symptoms

PURPOSE OF REVIEW

To provide a review on studies published in the last year relevant to the categorization and assessment of negative symptoms.

RECENT FINDINGS

Recent research supported the validity of the 'deficit/non-deficit schizophrenia' categorization. Few studies confirmed the validity of the category 'persistent negative symptoms', whereas no recent study explored the validity of the category 'predominant negative symptoms'. The two-factor structure of the negative dimension is supported by studies reporting different correlates for the two subdomains: diminished expression and avolition/apathy. The need to further split avolition/apathy in two distinct components, that is anhedonia and amotivation, is confirmed in recent papers. Additional approaches to the assessment of negative symptoms have been proposed, including the self-assessment of negative symptoms, and the evaluation of negative symptoms in daily life and their assessment by means of computerized analyses.

SUMMARY

Negative symptoms represent an unmet need in the care of schizophrenia, as they are associated to poor response to available treatments and to poor functional outcome. Their accurate categorization and assessment represent a major challenge for research on neurobiological substrates and new treatment strategies.