Cognitive Dysfunctions Measured with the MCCB in Deficit and Non-Deficit Schizophrenia

The importance of oxidative biomarkers in diagnosis, treatment, and monitoring schizophrenia patients

INTRODUCTION

The etiology of schizophrenia (SCZ), an incredibly complex disorder, remains multifaceted. Literature suggests the involvement of oxidative stress (OS) in the pathophysiology of SCZ.

OBJECTIVES

Determination of selected OS markers and brain-derived neurotrophic factor (BDNF) in patients with chronic SCZ and those in states predisposing to SCZ-first episode psychosis (FP) and ultra-high risk (UHR).

MATERIALS AND METHODS

Determination of OS markers and BDNF levels by spectrophotometric methods and ELISA in 150 individuals (116 patients diagnosed with SCZ or in a predisposed state, divided into four subgroups according to the type of disorder: deficit schizophrenia, non-deficit schizophrenia, FP, UHR). The control group included 34 healthy volunteers.

RESULTS

Lower activities of analyzed antioxidant enzymes and GSH and TAC concentrations were found in all individuals in the study group compared to controls (p < 0.001). BDNF concentration was also lower in all groups compared to controls except in the UHR subgroup (p = 0.01). Correlations were observed between BDNF, R-GSSG, GST, GPx activity, and disease duration (p < 0.02). A small effect of smoking on selected OS markers was also noted (rho<0.06, p < 0.03).

CONCLUSIONS

OS may play an important role in the pathophysiology of SCZ before developing the complete clinical pattern of the disorder. The redox imbalance manifests itself with such severity in individuals with SCZ and in a state predisposing to the development of this psychiatric disease that natural antioxidant systems become insufficient to compensate against it completely. The discussed OS biomarkers may support the SCZ diagnosis and predict its progression.

Fractional amplitude of low-frequency fluctuations in sensory-motor networks and limbic system as a potential predictor of treatment response in patients with schizophrenia

BACKGROUND

Previous investigations have revealed substantial differences in neuroimaging characteristics between healthy controls (HCs) and individuals diagnosed with schizophrenia (SCZ). However, we are not entirely sure how brain activity links to symptoms in schizophrenia, and there is a need for reliable brain imaging markers for treatment prediction.

METHODS

In this longitudinal study, we examined 56 individuals diagnosed with 56 SCZ and 51 HCs. The SCZ patients underwent a three-month course of antipsychotic treatment. We employed resting-state functional magnetic resonance imaging (fMRI) along with fractional Amplitude of Low Frequency Fluctuations (fALFF) and support vector regression (SVR) methods for data acquisition and subsequent analysis.

RESULTS

In this study, we initially noted lower fALFF values in the right postcentral/precentral gyrus and left postcentral gyrus, coupled with higher fALFF values in the left hippocampus and right putamen in SCZ patients compared to the HCs at baseline. However, when comparing fALFF values in brain regions with abnormal baseline fALFF values for SCZ patients who completed the follow-up, no significant differences in fALFF values were observed after 3 months of treatment compared to baseline data. The fALFF values in the right postcentral/precentral gyrus and left postcentral gyrus, and the left postcentral gyrus were useful in predicting treatment effects.

CONCLUSION

Our findings suggest that reduced fALFF values in the sensory-motor networks and increased fALFF values in the limbic system may constitute distinctive neurobiological features in SCZ patients. These findings may serve as potential neuroimaging markers for the prognosis of SCZ patients.

Reliability and validity of a novel mobile-based automatic battery of cognitive tests in healthy young Chinese adults

PURPOSE

To evaluate the reliability and validity of a newly developed computerized Automated Battery of Cognitive Tests in healthy individuals without cognitive impairments or psychiatric disorders.

METHODS

From April 20 to July 1, 2023, 142 healthy individuals in Beijing and Tangshan, China were assessed using the Automated Battery of Cognitive Tests. After a 3-week interval, 36 participants were randomly selected for retesting. The assessment also included administration of the Repeatable Battery for the Assessment of Neuropsychological Status and the Automated Battery of Cognitive Tests to 59 participants.

RESULTS

The Automated Battery of Cognitive Tests consists of 16 subtests. Internal consistency reliability was 0.75. The test-retest reliability for each factor ranged from 0.337 to 0.850 (p < 0.05). The criterion-related validity, as measured by correlation with the total Repeatable Battery for the Assessment of Neuropsychological Status score, was 0.748 (p < 0.001). The cumulative variance contribution rate is 70.109%. The results of the confirmatory factor analysis indicated a good model fit.

CONCLUSIONS

The computerized Automated Battery of Cognitive Tests is a cognitive self-assessment tool with good reliability and validity. It can evaluate multiple aspects of cognitive performance in healthy individuals and is suitable for self-administration through remote access via Internet.

Repetitive Transcranial Magnetic Stimulation for Working Memory Deficits in Schizophrenia: A Systematic Review of Randomized Controlled Trials

Working memory (WM) deficits are a significant component of neurocognitive impairment in individuals with schizophrenia (SCZ). Two previous meta-analyses, conducted on randomized controlled trials (RCTs), examined the effectiveness of repetitive transcranial magnetic stimulation (rTMS) in addressing WM deficits in individuals diagnosed with SCZ. However, the conclusions drawn from these analyses were inconsistent. Additionally, the commonly used random effects (RE) models might underestimate statistical errors, attributing a significant portion of perceived heterogeneity between studies to variations in study quality. Therefore, this review utilized both RE and quality effects (QE) models to assess relevant RCTs comparing TMS with sham intervention in terms of clinical outcomes. A comprehensive literature search was conducted using PubMed and Scopus databases, resulting in the inclusion of 13 studies for data synthesis. Overall, regardless of whether the RE or QE model was used, eligible RCTs suggested that the TMS and sham groups exhibited comparable therapeutic effects after treatment. The current state of research regarding the use of rTMS as a treatment for WM deficits in patients with SCZ remains in its preliminary phase. Furthermore, concerning the mechanism of action, the activation of brain regions focused on the dorsolateral prefrontal cortex and alterations in gamma oscillations may hold significant relevance in the therapeutic application of rTMS for addressing WM impairments. Finally, we believe that the application of closed-loop neuromodulation may contribute to the optimization of rTMS for WM impairment in patients with SCZ.

Cognitive control impairment in ax-continuous performance test in patients with schizophrenia: A pilot EEG study

OBJECTIVES

This study aimed to investigate the mechanism of cognitive control impairment in patients with schizophrenia (SPs) using electroencephalogram (EEG).

METHODS

A total of 17 SPs and 17 healthy controls (HCs) were included in this study. We measured the EEG activity, whereas they performed the AX-continuous performance test which consisted of the preparatory phase and the response phase. The MATRICS Consensus Cognitive Battery (MCCB) was used for cognitive function, and the Positive and Negative Syndrome Scale (PANSS) was used for clinical symptom assessment. A univariate linear regression model was used to explore the relationships among behavioral index, event-related potentials (ERPs), rhythmic oscillation power, and score of MCCB and PANSS.

RESULTS

A significant difference was found in response accuracy and reaction time (RT) during the preparatory phase between patients and HCs (p < .05). During the response phase, the SPs exhibited longer RT than the HCs (p < .05). Analysis of the ERPs revealed that the amplitude of P3a on BX clues was significantly smaller in SPs than in HCs (p < .05). Additionally, the midline frontal theta power of neural oscillation was significantly lower in the SPs than in NCs both during the preparatory and response phases. The accuracies on BX clues (r = .694, p = .002) and d'context (r = .698, p = .002) were positively correlated with MCCB scores.

CONCLUSION

The present study revealed that patients with schizophrenia have deficits both in proactive and reactive cognitive control, with a greater reliance on reactive control during conflict resolution. The neural mechanisms of the cognitive control impairment may involve the inability to engage additional neural resources for proactive control, and a reduction in frontal midline theta power during both proactive and reactive control. The severity of proactive control impairment is positively correlated with an increased tendency to rely on reactive control.

Structural abnormalities in the Fronto-Parietal Network: Linking white matter integrity to sustained attention deficits in Schizophrenia

Schizophrenia is associated with a range of cognitive deficits, among which impairments in sustained attention are particularly significant. Previous research has investigated functional changes in the fronto-parietal network (FPN) related to attentional control in schizophrenia. However, the role of structural connectivity within the FPN in sustained attention deficits remains under-explored. Utilizing diffusion tensor imaging (DTI), this study investigated white matter integrity in 75 participants, comprising 37 individuals with schizophrenia (SZ) and 38 healthy controls (HC). Psychomotor vigilance task (PVT) performance was assessed to gauge sustained attention. The SZ group showed a significant reduction in fractional anisotropy (FA) and streamline counts within white matter tracts connecting frontal and parietal regions, compared to the HC group. Further, significant negative correlations were found between PVT performance and white matter integrity measures within the SZ group, specifically in the left FPN. Our findings indicate that structural abnormalities in the FPN are associated with sustained attention deficits in schizophrenia. These results contribute to our understanding of the neurobiological mechanisms underlying cognitive impairments in schizophrenia and offer potential avenues for targeted therapeutic interventions. Further research is warranted to validate these outcomes and explore their clinical implications.

Correlations between Negative Symptoms and Cognitive Deficits in Individuals at First Psychotic Episode or at High Risk of Psychosis: A Systematic Review

The present review aims to identify correlations between negative symptoms (NS) and deficits in neurocognition and social cognition in subjects with first-episode psychosis (FEP) and at-high-risk populations (HR). A systematic search of the literature published between 1 January 2005 and 31 December 2022 was conducted on PubMed, Scopus, and PsycInfo. Out of the 4599 records identified, a total of 32 studies met our inclusion/exclusion criteria. Data on a total of 3086 FEP and 1732 HR were collected. The available evidence shows that NS correlate with executive functioning and theory of mind deficits in FEP subjects, and with deficits in the processing speed, attention and vigilance, and working memory in HR subjects. Visual learning and memory do not correlate with NS in either FEP or HR subjects. More inconsistent findings were retrieved in relation to other cognitive domains in both samples. The available evidence is limited by sample and methodological heterogeneity across studies and was rated as poor or average quality for the majority of included studies in both FEP and CHR populations. Further research based on shared definitions of first-episode psychosis and at-risk states, as well as on more recent conceptualizations of negative symptoms and cognitive impairment, is highly needed.