Relation between EEG source functional connectivity and the negative symptom severity in schizophrenia: a preliminary report from a multicentre study

IntroductionNeural dysconnectivity is hypothesized to be a key element in pathophysiology of schizophrenia. However, the relation of disordered connectivity with the different clinical characteristics of the syndrome is not fully elucidated.ObjectivesThe current research investigated the relations between resting-state EEG Source Functional Connectivity (EEG-SFC) and the two main clusters of negative symptoms derived from the Brief Negative Symptom Scale, the Expressive Deficit (ED) and the Avolition (AV), in subjects with schizophrenia (SCZ) enrolled to the multicentre study of the Italian Network for Research on Psychoses.MethodsOut of 97 chronic, stabilized SCZ included, we selected subjects according the lower and the upper quartile of the ED and AV value distribution: 25 were in upper and 24 in the lower quartile of ED (respectively, HIGH-ED and LOW-ED); 27 were in upper and 24 in the lower quartile of AV (respectively, HIGH-AV and LOW-AV). Fifty-five healthy controls (HC) were included, comparable to SCZ for gender, age and educational level. EEG-SFC analysis was based on the lagged phase synchronization (LPS) computed by eLORETA from 5 minutes resting-state EEG recordings in eyes closed condition. LPS indices were determined for each spectrum band and between all 28 regions of interest (ROI) pairs. Group differences were significant for corrected P-value &lt; 0.05.ResultsSCZ had higher theta band LPS than HC. Respect to LOW-ED, HIGH-ED showed significant increased alpha LPS in fronto-cingulate, para-hippocampal and insular inter-hemispheric ROI pairs. No significant difference emerged between HIGH-AV and LOW-AV.ConclusionsSubgrouping SCZ according to negative symptom severity reveals heterogeneous patterns of resting-state LPS connectivity.Disclosure of interestThe authors have not supplied their declaration of competing interest.</jats:sec

Interplay Among Psychopathologic Variables, Personal Resources, Context-Related Factors, and Real-life Functioning in Individuals With Schizophrenia: A Network Analysis

Enhanced understanding of factors associated with symptomatic and functional recovery is instrumental to designing personalized treatment plans for people with schizophrenia. To date, this is the first study using network analysis to investigate the associations among cognitive, psychopathologic, and psychosocial variables in a large sample of community-dwelling individuals with schizophrenia

The Brief Negative Symptom Scale (BNSS): Independent validation in a large sample of Italian patients with schizophrenia

BACKGROUND: The Brief Negative Symptom Scale (BNSS) was developed to address the main limitations of the existing scales for the assessment of negative symptoms of schizophrenia. The initial validation of the scale by the group involved in its development demonstrated good convergent and discriminant validity, and a factor structure confirming the two domains of negative symptoms (reduced emotional/verbal expression and anhedonia/asociality/avolition). However, only relatively small samples of patients with schizophrenia were investigated. Further independent validation in large clinical samples might be instrumental to the broad diffusion of the scale in clinical research. METHODS: The present study aimed to examine the BNSS inter-rater reliability, convergent/discriminant validity and factor structure in a large Italian sample of outpatients with schizophrenia. RESULTS: Our results confirmed the excellent inter-rater reliability of the BNSS (the intraclass correlation coefficient ranged from 0.81 to 0.98 for individual items and was 0.98 for the total score). The convergent validity measures had r values from 0.62 to 0.77, while the divergent validity measures had r values from 0.20 to 0.28 in the main sample (n=912) and in a subsample without clinically significant levels of depression and extrapyramidal symptoms (n=496). The BNSS factor structure was supported in both groups. CONCLUSIONS: The study confirms that the BNSS is a promising measure for quantifying negative symptoms of schizophrenia in large multicenter clinical studies

Social cognition in people with schizophrenia: A cluster-analytic approach

Background The study aimed to subtype patients with schizophrenia on the basis of social cognition (SC), and to identify cut-offs that best discriminate among subtypes in 809 out-patients recruited in the context of the Italian Network for Research on Psychoses. Method A two-step cluster analysis of The Awareness of Social Inference Test (TASIT), the Facial Emotion Identification Test and Mayer-Salovey-Caruso Emotional Intelligence Test scores was performed. Classification and regression tree analysis was used to identify the cut-offs of variables that best discriminated among clusters. Results We identified three clusters, characterized by unimpaired (42%), impaired (50.4%) and very impaired (7.5%) SC. Three theory-of-mind domains were more important for the cluster definition as compared with emotion perception and emotional intelligence. Patients more able to understand simple sarcasm (14 for TASIT-SS) were very likely to belong to the unimpaired SC cluster. Compared with patients in the impaired SC cluster, those in the very impaired SC cluster performed significantly worse in lie scenes (TASIT-LI &lt;10), but not in simple sarcasm. Moreover, functioning, neurocognition, disorganization and SC had a linear relationship across the three clusters, while positive symptoms were significantly lower in patients with unimpaired SC as compared with patients with impaired and very impaired SC. On the other hand, negative symptoms were highest in patients with impaired levels of SC. Conclusions If replicated, the identification of such subtypes in clinical practice may help in tailoring rehabilitation efforts to the person's strengths to gain more benefit to the person

Familial aggregation of MATRICS Consensus Cognitive Battery scores in a large sample of outpatients with schizophrenia and their unaffected relatives

Background The increased use of the MATRICS Consensus Cognitive Battery (MCCB) to investigate cognitive dysfunctions in schizophrenia fostered interest in its sensitivity in the context of family studies. As various measures of the same cognitive domains may have different power to distinguish between unaffected relatives of patients and controls, the relative sensitivity of MCCB tests for relative-control differences has to be established. We compared MCCB scores of 852 outpatients with schizophrenia (SCZ) with those of 342 unaffected relatives (REL) and a normative Italian sample of 774 healthy subjects (HCS). We examined familial aggregation of cognitive impairment by investigating within-family prediction of MCCB scores based on probands' scores.Methods Multivariate analysis of variance was used to analyze group differences in adjusted MCCB scores. Weighted least-squares analysis was used to investigate whether probands' MCCB scores predicted REL neurocognitive performance.Results SCZ were significantly impaired on all MCCB domains. REL had intermediate scores between SCZ and HCS, showing a similar pattern of impairment, except for social cognition. Proband's scores significantly predicted REL MCCB scores on all domains except for visual learning.Conclusions In a large sample of stable patients with schizophrenia, living in the community, and in their unaffected relatives, MCCB demonstrated sensitivity to cognitive deficits in both groups. Our findings of significant within-family prediction of MCCB scores might reflect disease-related genetic or environmental factors

Social cognition in people with schizophrenia: A cluster-analytic approach

Background The study aimed to subtype patients with schizophrenia on the basis of social cognition (SC), and to identify cut-offs that best discriminate among subtypes in 809 out-patients recruited in the context of the Italian Network for Research on Psychoses. Method A two-step cluster analysis of The Awareness of Social Inference Test (TASIT), the Facial Emotion Identification Test and Mayer-Salovey-Caruso Emotional Intelligence Test scores was performed. Classification and regression tree analysis was used to identify the cut-offs of variables that best discriminated among clusters. Results We identified three clusters, characterized by unimpaired (42%), impaired (50.4%) and very impaired (7.5%) SC. Three theory-of-mind domains were more important for the cluster definition as compared with emotion perception and emotional intelligence. Patients more able to understand simple sarcasm (14 for TASIT-SS) were very likely to belong to the unimpaired SC cluster. Compared with patients in the impaired SC cluster, those in the very impaired SC cluster performed significantly worse in lie scenes (TASIT-LI <10), but not in simple sarcasm. Moreover, functioning, neurocognition, disorganization and SC had a linear relationship across the three clusters, while positive symptoms were significantly lower in patients with unimpaired SC as compared with patients with impaired and very impaired SC. On the other hand, negative symptoms were highest in patients with impaired levels of SC. Conclusions If replicated, the identification of such subtypes in clinical practice may help in tailoring rehabilitation efforts to the person's strengths to gain more benefit to the person

Electrophysiological aberrations associated with negative symptoms in schizophrenia

Clinical heterogeneity is a confound common to all of schizophrenia research. Deficit schizophrenia has been proposed as a homogeneous disease entity within the schizophrenia syndrome. The use of the Schedule for the Deficit Syndrome (SDS) has allowed the definition of a subgroup dominated by persistent and primary negative symptoms. While a number of studies have appeared over the years examining the electrophysiological correlates of the cluster of negative symptoms in schizophrenia, only a few studies have actually focused on the Deficit Syndrome (DS). In this chapter, electrophysiological investigations utilizing EEG, Evoked Potentials (EPs), polysomnography (PSG), or magnetoencephalography (MEG) to probe ‘‘negative symptoms,’’ or ‘‘Deficit Syndrome’’ are reviewed. While this line of research is evidently in its infancy, two significant trends emerge. First, spectral EEG studies link increased slow wave activity during wakefulness to the prevalence of negative symptoms. Second, sleep studies point to an association between decrease in slow wave sleep and prevalence of negative symptoms. Several studies also indicate a relationship of negative symptoms with reduced alpha activity. A host of other abnormalities including sensory gating and P300 attenuation are less consistently reported. Three studies specifically addressed electrophysiology of the DS. Two of the three studies provided evidence suggesting that the DS may be a separate disease entity and not simply a severe form of schizophrenia