Investigating potential associations between neurocognition/social cognition and oxidative stress in schizophrenia

The relationship between the gut microbiota and oxidative stress in the cognitive function of schizophrenia: A pilot study in China

Cognitive impairment is a core symptom of schizophrenia. The gut microbiota (GM) and oxidative stress may play important roles in the pathophysiological mechanisms of cognitive impairment. This study aimed to explore the relationship between GM and oxidative stress in the cognitive function of schizophrenia. GM obtained by 16S RNA sequencing and serum superoxide dismutase (SOD) levels from schizophrenia patients (N = 68) and healthy controls (HCs, N = 72) were analyzed. All psychiatric symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). Cognitive function was assessed using the MATRICS Consensus Cognitive Battery (MCCB). Correlation analysis was used to explore the relationship between GM, SOD, and cognitive function. Machine learning models were used to identify potential biomarkers. Compared to HCs, the relative abundances of Collinsella, undefined Ruminococcus, Lactobacillus, Eubacterium, Mogibacterium, Desulfovibrio, Bulleidia, Succinivibrio, Corynebacterium, and Atopobium were higher in patients with schizophrenia, but Faecalibacterium, Anaerostipes, Turicibacter, and Ruminococcus were lower. In patients with schizophrenia, the positive factor, general factor, and total score of MCCB positively correlated with Lactobacillus, Collinsella, and Lactobacillus, respectively; SOD negatively correlated with Eubacterium, Collinsella, Lactobacillus, Corynebacterium, Bulleidia, Mogibacterium, and Succinivibrio, but positively correlated with Faecalibacterium, Ruminococcus, and MCCB verbal learning index scores; Faecalibacterium and Turicibacter were positively correlated with MCCB visual learning index scores and speed of processing index scores, respectively. Our findings revealed a correlation between SOD and GM and confirmed that cognitive dysfunction in patients with schizophrenia involves abnormal SOD levels and GM changes.

Mechanisms of Ferritinophagy and Ferroptosis in Diseases

The discovery of the role of autophagy, particularly the selective form like ferritinophagy, in promoting cells to undergo ferroptosis has inspired us to investigate functional connections between diseases and cell death. Ferroptosis is a novel model of procedural cell death characterized by the accumulation of iron-dependent reactive oxygen species (ROS), mitochondrial dysfunction, and neuroinflammatory response. Based on ferroptosis, the study of ferritinophagy is particularly important. In recent years, extensive research has elucidated the role of ferroptosis and ferritinophagy in neurological diseases and anemia, suggesting their potential as therapeutic targets. Besides, the global emergence and rapid transmission of COVID-19, which is caused by SARS-CoV-2, represents a considerable risk to public health worldwide. The potential involvement of ferroptosis in the pathophysiology of brain injury associated with COVID-19 is still unclear. This review summarizes the pathophysiological changes of ferroptosis and ferritinophagy in neurological diseases, anemia, and COVID-19, and hypothesizes that ferritinophagy may be a potential mechanism of ferroptosis. Advancements in these fields will enhance our comprehension of methods to prevent and address neurological disorders, anemia, and COVID-19.

Effects of Ziprasidone or Haloperidol on Theory of Mind in Patients With Schizophrenia: A 16-week Pilot Trial

OBJECTIVES

Schizophrenia is associated with impairment in theory of mind (ToM), which is defined as the ability to make judgments about mental states and is related to medial prefrontal cortical activity. Ziprasidone, but not haloperidol, is known to have a protective effect in the medial prefrontal cortex. Thus, we hypothesized that these 2 drugs would have different efficacy in improving ToM task performance in patients with schizophrenia.

METHODS

Patients with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnosis of schizophrenia matched for sex, duration of illness, and education were randomized to receive ziprasidone (n=30) or haloperidol (n=30). All patients were assessed using the Positive and Negative Syndrome Scale and the Personal and Social Functioning Scale. ToM was assessed using a first-order false belief task, a second-order false belief task, the faux-pas task, and the Reading the Mind in the Eyes Task, in order of developmental complexity and difficulty. The primary outcome was change in ToM performance from baseline to 16 weeks of treatment.

RESULTS

For the first-order false belief task, there were no significant differences between the groups (P>0.05). For the second-order false belief task, the interaction effect was significant (P<0.05), and the simple effect of time showed a significant difference only in the ziprasidone group (P<0.001). For the faux-pas task, the interaction effect was not significant (P>0.05). For the Reading the Mind in the Eyes Task, the interaction effect was significant (P<0.05), and the simple effect of time showed a significant difference only in the ziprasidone group (P<0.001). The Positive and Negative Syndrome Scale results were similar between the groups. The ziprasidone group performed better than the haloperidol group on the Personal and Social Functioning Scale. There were no major safety concerns or adverse events.

CONCLUSIONS

The findings of this study suggest that ziprasidone could improve ToM and might be superior to haloperidol for improving complex ToM as well as personal and social functioning in patients with schizophrenia.

TRIAL REGISTRATION CHINESE CLINICAL TRIAL REGISTER

ChiCTR2200060542.

Schizophrenia and Glutathione: A Challenging Story

Schizophrenia (SZ) is a devastating mental illness with a complex and heterogeneous clinical state. Several conditions like symptoms, stage and severity of the disease are only some of the variables that have to be considered to define the disorder and its phenotypes. SZ pathophysiology is still unclear, and the diagnosis is currently relegated to the analysis of clinical symptoms; therefore, the search for biomarkers with diagnostic relevance is a major challenge in the field, especially in the era of personalized medicine. Though the mechanisms implicated in SZ are not fully understood, some processes are beginning to be elucidated. Oxidative stress, and in particular glutathione (GSH) dysregulation, has been demonstrated to play a crucial role in SZ pathophysiology. In fact, glutathione is a leading actor of oxidative-stress-mediated damage in SZ and appears to reflect the heterogeneity of the disease. The literature reports differing results regarding the levels of glutathione in SZ patients. However, each GSH state may be a sign of specific symptoms or groups of symptoms, candidating glutathione as a biomarker useful for discriminating SZ phenotypes. Here, we summarize the literature about the levels of glutathione in SZ and analyze the role of this molecule and its potential use as a biomarker.

The relationship between cognitive clusters and telomere length in bipolar-schizophrenia spectrum disorders

BACKGROUND

Schizophrenia and bipolar disorder are complex mental illnesses that are associated with cognitive deficits. There is considerable cognitive heterogeneity that exists within both disorders. Studies that cluster schizophrenia and bipolar patients into subgroups based on their cognitive profile increasingly demonstrate that, relative to healthy controls, there is a severely compromised subgroup and a relatively intact subgroup. There is emerging evidence that telomere shortening, a marker of cellular senescence, may be associated with cognitive impairments. The aim of this study was to explore the relationship between cognitive subgroups in bipolar-schizophrenia spectrum disorders and telomere length against a healthy control sample.

METHODS

Participants included a transdiagnostic group diagnosed with bipolar, schizophrenia or schizoaffective disorder (n = 73) and healthy controls (n = 113). Cognitive clusters within the transdiagnostic patient group, were determined using K-means cluster analysis based on current cognitive functioning (MATRICS Consensus Cognitive Battery scores). Telomere length was determined using quantitative PCRs genomic DNA extracted from whole blood. Emergent clusters were then compared to the healthy control group on telomere length.

RESULTS

Two clusters emerged within the patient group that were deemed to reflect a relatively intact cognitive group and a cognitively impaired subgroup. Telomere length was significantly shorter in the severely impaired cognitive subgroup compared to the healthy control group.

CONCLUSIONS

This study replicates previous findings of transdiagnostic cognitive subgroups and associates shorter telomere length with the severely impaired cognitive subgroup. These findings support emerging literature associating cognitive impairments in psychiatric disorders to accelerated cellular aging as indexed by telomere length.

Connecting Neurobiological Features with Interregional Dysconnectivity in Social-Cognitive Impairments of Schizophrenia

Schizophrenia (SZ) is a devastating psychiatric disorder affecting about 1% of the world's population. Social-cognitive impairments in SZ prevent positive social interactions and lead to progressive social withdrawal. The neurobiological underpinnings of social-cognitive symptoms remain poorly understood, which hinders the development of novel treatments. At the whole-brain level, an abnormal activation of social brain regions and interregional dysconnectivity within social-cognitive brain networks have been identified as major contributors to these symptoms. At the cellular and subcellular levels, an interplay between oxidative stress, neuroinflammation and N-methyl-D-aspartate receptor hypofunction is thought to underly SZ pathology. However, it is not clear how these molecular processes are linked with interregional dysconnectivity in the genesis of social-cognitive symptoms. Here, we aim to bridge the gap between macroscale (connectivity analyses) and microscale (molecular and cellular mechanistic) knowledge by proposing impaired myelination and the disinhibition of local microcircuits as possible causative biological pathways leading to dysconnectivity and abnormal activity of the social brain. Furthermore, we recommend electroencephalography as a promising translational technique that can foster pre-clinical drug development and discuss attractive drug targets for the treatment of social-cognitive symptoms in SZ.

The impact of hazes on schizophrenia admissions and the synergistic effect with the combined atmospheric oxidation capacity in Hefei, China

OBJECTIVES

Currently, most epidemiological studies on haze focus on respiratory diseases, cardiovascular diseases, etc. However, the relationship between haze and mental health has not been adequately explored. The purpose of this study was to investigate the influence of hazes on schizophrenia admissions and to further explore the potential interaction effect with the combined atmospheric oxidative indices (O_x and O_x^wt).

METHODS

We collected 5328 cases during the cold season from 2013 to 2015 in Hefei, China. By integrating the Poisson Generalized Linear Models with the Distributed Lag Non-linear Models, the association between haze and schizophrenia admissions was evaluated. The interaction between hazes and two combined oxidation indexes was tested by stratifying hazes and O_x, and O_x^wt.

RESULTS

Haze was found to be significantly linked to an increased risk of hospitalization for schizophrenia, and a 9-day lag effect on schizophrenia (lag 3-lag 11), with the largest effect on lag 6 (RR = 1.080, 95% confidence interval (CI): 1.046-1.116). Males, females, and <40 y (people under 40 years old) were sensitive to hazes. Furthermore, in the stratified analysis, we found synergies between two combined oxidation indexes and hazes. The interaction relative risk (IRR) and relative excess risk due to interaction (RERI) between O_x and hazes were 1.170 (95% CI: 1.071-1.277) and 0.149 (95% CI: 0.045-0.253), respectively. For O_x^wt, the IRR and RERI were 1.179 (95% CI: 1.087-1.281) and 0.159 (95% CI: 0.056-0.263), respectively. It is noteworthy that this synergistic effect was significant in males and <40 y when examining the various subgroups in the interaction analysis.

CONCLUSIONS

Our findings suggest that exposure to haze significantly increases the risk of hospitalization for schizophrenia. More significant public health benefits can be obtained by prioritizing haze periods with high combined atmospheric oxidation capacity.

Oxidative Stress and Emergence of Psychosis

Treatment and prevention strategies for schizophrenia require knowledge about the mechanisms involved in the psychotic transition. Increasing evidence suggests a redox imbalance in schizophrenia patients. This narrative review presents an overview of the scientific literature regarding blood oxidative stress markers’ evolution in the early stages of psychosis and chronic patients. Studies investigating peripheral levels of oxidative stress in schizophrenia patients, first episode of psychosis or UHR individuals were considered. A total of 76 peer-reviewed articles published from 1991 to 2022 on PubMed and EMBASE were included. Schizophrenia patients present with increased levels of oxidative damage to lipids in the blood, and decreased levels of non-enzymatic antioxidants. Genetic studies provide evidence for altered antioxidant functions in patients. Antioxidant blood levels are decreased before psychosis onset and blood levels of oxidative stress correlate with symptoms severity in patients. Finally, adjunct treatment of antipsychotics with the antioxidant N-acetyl cysteine appears to be effective in schizophrenia patients. Further studies are required to assess its efficacy as a prevention strategy. Redox imbalance might contribute to the pathophysiology of emerging psychosis and could serve as a therapeutic target for preventive or adjunctive therapies, as well as biomarkers of disease progression.

Neuroinflammation and oxidative stress in schizophrenia: are these opportunities for repurposing?

Purpose: To summarize the main findings on the subject of neuroinflammation and oxidative stress in patients with Schizophrenia (SCZ).Methods: A narrative review of all the relevant papers known to the authors was conducted.Results: SCZ is a chronic, debilitating, neuropsychiatric disorder associated with an immense and adverse impact on both the patient and the caregiver, and impairs the overall quality of life. The current modality of treatment involves the use of antipsychotics to balance the disturbances in the neurotransmitters in the dopaminergic and serotonin pathways in the brain, which have a role to play in SCZ. Contemporary management of SCZ focuses mainly on symptomatic control due to the lack of effective curative treatments.Despite the optimum use of antipsychotics, there is a considerable proportion of the patient population who are poor responders. This has necessitated the exploration of new etiopathologies in order to evolve new modalities of treatment. This narrative review, conducted over a period of 3 months, throws light on the large-scale evidence pointing toward neuroinflammation and oxidative stress as key etiopathological markers that merit further consideration in SCZ, and may even be the basis for devising novel pharmacotherapies for SCZ.Conclusions: This review discusses the various plausible hypotheses, viz., cytokine hypothesis of peripheral inflammation, acute-phase reactants in SCZ, microglial hypothesis of central inflammation, neurogenesis in relation to neuroinflammation, and oxidative stress in SCZ. It also highlights the many opportunities available for repurposing already marketed drugs with anti-inflammatory and antioxidant properties with a view to devising more effective and comprehensive therapies to manage SCZ.