Cognitive dysfunction in first-episode schizophrenia and its correlation with negative symptoms and insight

Prevalence, correlates and explanatory models of cognitive deficits in patients with schizophrenia-A cross sectional study

Background

Schizophrenia may cause significant impairment in social and economic aspects of a patient's life. Current evidence suggests that cognitive deficits may affect the functioning of a person with schizophrenia more than positive or negative symptoms. There is a lack of literature on explanatory models of cognitive deficits in schizophrenia that can influence help-seeking behavior.

Objectives

This study aimed to estimate the prevalence of cognitive deficits and assess their relationship with socio-demographic and clinical characteristics among patients with schizophrenia. We also planned to explore the explanatory models of cognitive deficits in these patients.

Methods

Consecutive outpatients with schizophrenia who met eligibility criteria were recruited after obtaining informed consent. The Addenbrooke's Cognitive Examination Tamil version (ACE III) and Observable Social Cognition - A Rating Scale (OSCARS) and Positive and Negative Symptom Scale (PANSS) were used to assess cognitive functioning and symptom profile, respectively. Beliefs about illness were recorded using the modified Short Explanatory Model Interview (SEMI). Socio-demographic and treatment-related details were collected with a structured proforma. Statistical analysis was done using SPSS for Windows (version 16.0.1).

Results

One hundred and forty patients participated in the study. The prevalence of cognitive deficits was 75.7% using ACE-III scores, 19.3% on OSCARS, and 40% based on subjective reports. Though the majority (81.4%) of patients reported a medical explanatory model for cognitive impairment, a significant number of them (70.7%) also held non-medical models simultaneously.

Conclusion

Cognitive deficits are prevalent in the majority of patients with schizophrenia. Poor test performance on cognitive testing was observed in those with a significant family history. Multiple contradictory explanatory models for the causation of cognitive deficits were reported.

Forebrain E-I balance controlled in cognition through coordinated inhibition and inhibitory transcriptome mechanism

Introduction

Forebrain neural networks are vital for cognitive functioning, and their excitatory-inhibitory (E-I) balance is governed by neural homeostasis. However, the homeostatic control strategies and transcriptomic mechanisms that maintain forebrain E-I balance and optimal cognition remain unclear.

Methods

We used patch-clamp and RNA sequencing to investigate the patterns of neural network homeostasis with suppressing forebrain excitatory neural activity and spatial training.

Results

We found that inhibitory transmission and receptor transcription were reduced in tamoxifen-inducible Kir2.1 conditional knock-in mice. In contrast, spatial training increased inhibitory synaptic connections and the transcription of inhibitory receptors.

Discussion

Our study provides significant evidence that inhibitory systems play a critical role in the homeostatic control of the E-I balance in the forebrain during cognitive training and E-I rebalance, and we have provided insights into multiple gene candidates for cognition-related homeostasis in the forebrain.

The Role of Two Factors of Negative Symptoms and Cognition on Social Functioning in Male Patients with Schizophrenia: A Mediator Model

OBJECTIVE

This study aims to compare the cognitive function and social functioning in male patients with deficit syndrome (DS) and non-DS, and to explore whether cognitive function serves as a mediator in the relationship between the two factors of negative symptoms (motivation and pleasure (MAP) and expressivity (EXP) deficits, and social functioning in schizophrenia patients.

METHODS

One hundred and fifty-six male patients with schizophrenia and 109 age- and education-matched normal controls were enrolled in the current study. The Chinese version of a Schedule for Deficit Syndrome (SDS) was used for DS and non-DS categorization. The Brief Psychiatric Rating Scale (BPRS) and the Brief Negative Symptoms Scale (BNSS) were used to assess psychotic and negative symptoms in patients. The Social-Adaptive Functioning Evaluation (SAFE) was adopted to evaluate patients' social functioning, and a battery of classical neurocognitive tests was used to assess cognition, including sustained vigilance/attention, cognitive flexibility, ideation fluency, and visuospatial memory.

RESULTS

We found that male patients with DS performed worse in all four cognitive domains and social functioning compared to non-DS patients. Both total negative symptoms and its two factors were significantly associated with all four domains of cognition and social functioning in male patients. Interestingly, our results indicate that only cognitive flexibility mediates the relationship between negative symptoms and social functioning in schizophrenia patients, but there were no differences between EXP and MAP negative factors in this model.

CONCLUSION

Our findings suggest that DS patients may represent a unique clinical subgroup of schizophrenia, and the integrated interventions targeting both negative symptoms and cognition, especially cognitive flexibility, may optimally improve functional outcomes in schizophrenia patients.

Impaired insight in schizophrenia: impact on patient-reported and physician-reported outcome measures in a randomized controlled trial

BACKGROUND

Impaired insight poses a challenge in the treatment of patients with schizophrenia because of its potential to jeopardize therapeutic engagement and medication adherence. This study explored how insight impairment, graded from none to extreme, is related to patient-reported mental health status, depression, and neurocognition in schizophrenia.

METHODS

In a post hoc analysis of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study (NCT00014001), insight was measured using the Positive and Negative Syndrome Scale (PANSS) Item G12 (lack of insight). Additional assessments for this analysis included the 12-Item Short-Form Health Survey (SF-12) Mental Component Summary (MCS), physician- and patient-reported Clinical Global Impression-Severity (CGI-S), MATRICS Consensus Cognitive Battery, and Calgary Depression Scale for Schizophrenia. Relationships between patient-reported outcomes and PANSS total and Item G12 ratings were evaluated.

RESULTS

Among 1431 CATIE study participants in this analysis, increasingly impaired insight at baseline was significantly associated with better patient-reported quality of life (QoL), lower baseline depression, and greater divergence between physician- and patient-reported illness severity. Patients with more severely impaired insight reported milder illness compared with physician reports, particularly those with moderate-severe to extreme impairment (PANSS Item G12 rating ≥ 5), approximately 10% (138/1431) of CATIE participants. For the 90% of patients with PANSS Item G12 ratings < 5, patient-reported QoL decreased with increasing symptoms. SF-12 MCS scores were linearly related to baseline PANSS total score only in patients with PANSS total score < 90 (moderately ill or better), and better symptom scores were associated with higher QoL. No significant relationship between insight and neurocognition was observed.

CONCLUSIONS

In the small subgroup (10%) of CATIE study patients with schizophrenia and PANSS Item G12 ratings ≥5, moderate-severe-severe/extreme insight impairment was associated with significantly more positive perception of QoL and illness severity by the patient versus the treating physician. This was not observed in the remaining 90% of patients with normal to moderately impaired insight, suggesting that poor insight as a threat to the validity of self-report is uncommon.

Associations of the serum kynurenine pathway metabolites with P50 auditory gating in non-smoking patients with first-episode schizophrenia

OBJECTIVE

Our study aimed to investigate the associations between the serum level of kynurenine pathway (KP) metabolites and P50 auditory gating in non-smoking patients with first-episode schizophrenia (FES).

MATERIALS AND METHODS

In this study, 82 non-smoking patients with FES and 73 healthy controls (HC). P50 auditory gating was measured using a fully functional digital 64-channel EEG system, and the components included S1 amplitude, S2 amplitude, gating ratio (S2/S1), and amplitude difference (S1-S2). Serum levels of kynurenine and kynurenine acid were assessed using a combination of liquid chromatography with tandem mass spectrometry. Psychopathology was assessed by the Positive and Negative Syndrome Scale (PANSS).

RESULTS

The serum kynurenine (251.46 ± 65.93 ng/ml vs. 320.65 ± 65.89 ng/ml, t = -6.38, p < 0.001), and kynurenine acid levels (5.19 ± 2.22 ng/ml vs. 13.26 ± 4.23 ng/ml, t = -14.73, p < 0.001), S1 amplitude [2.88 (1.79, 3.78) μV vs. 3.08 (2.46, 4.56) μV, Z = -2.17, p = 0.030] and S1-S2 [1.60 (0.63, 2.49) μV vs. 1.92 (1.12, 2.93) μV, Z = -2.23, p = 0.026] in patients with FES were significantly lower than those in HC. The serum kynurenine and kynurenine acid levels were negatively associated with S1-S2 (r = -0.32, p = 0.004 and r = -0.42, p < 0.001; respectively) and positively correlated with S2/S1 ratio (r = 0.34, p = 0.002 and r = 0.35, p = 0.002; respectively) in patients.

CONCLUSION

Our findings suggested that neuroactive metabolites of the KP might play an important role in sensory gating deficit in first episode patients with schizophrenia. Furthermore, metabolites of the KP may be a new target for the treatment of cognitive impairments in schizophrenia.