Neural correlates of mental state decoding and mental state reasoning in schizophrenia.

Theory of mind skills are disrupted in schizophrenia. However, various theory of mind tasks measure different neurocognitive domains. This multimodal neuroimaging study aimed to investigate the neuroanatomical correlates of mental state decoding and reasoning components of theory of mind in schizophrenia and healthy controls (HCs) using T1-weighted and diffusion-weighted (DTI) magnetic resonance imaging (MRI). Sixty-two patients with schizophrenia and 34 HCs were included. The Reading the Mind in the Eyes (RMET) and Hinting tests were used to evaluate mental state decoding and reasoning, respectively. Correlations between social cognition and cortical parameters (thickness, volume, surface area), or DTI scalars (fractional anisotropy, axial diffusivity, radial diffusivity) were cluster-based corrected for multiple comparisons. In schizophrenia, RMET scores showed positive correlations in 3 clusters, including left insula thickness, right superior-temporal thickness, left superior-temporal-sulcus volume, and DTI analysis revealed that fractional anisotropy showed positive correlations in 3 clusters, including right inferior-fronto-occipital fasciculus, left forceps-major, left inferior-fronto-occipital fasciculus. In schizophrenia, Hinting test scores showed positive correlations in 3 clusters in T1-weighted MRI, including left superior-temporal-sulcus volume, left superior-temporal-sulcus surface area, left pars-orbitalis volume. In conclusion, this study provided evidence for the involvement of particular cortical regions and white matter tracts in mental state decoding and reasoning.

Investigating traumatic memory integration in people with and without post-traumatic stress disorder using the event-cueing paradigm.

Poor integration and landmark views make opposing claims regarding the relationship between post-traumatic stress symptoms and trauma memory integration. This study tested these approaches using an event cluster paradigm. In total, 126 participants (Nptsd = 61; Nnon-ptsd = 65) remembered memories from the same story as trauma, positive and neutral memories and reported whether each memory was directly retrieved or generated. Moreover, the retrieval time (RT) was recorded. Finally, the participants completed the Centrality of Event Scale (CES) and Post-traumatic Stress Disorder Symptom Scale-Self Report (PSS-SR). The results demonstrated that participants with post-traumatic stress disorder (PTSD) recalled their clusters of memories more slowly and less directly than those without PTSD. However, the CES predicted PTSD severity more strongly than RT and retrieval strategy. These results suggest that traumatic memories are more disorganised but perceived as more central in PTSD.

Abnormal Structural Network Communication Reflects Cognitive Deficits in Schizophrenia.

Schizophrenia has long been thought to be a disconnection syndrome and several previous studies have reported widespread abnormalities in white matter tracts in individuals with schizophrenia. Furthermore, reductions in structural connectivity may also impair communication between anatomically unconnected pairs of brain regions, potentially impacting global signal traffic in the brain. Therefore, we used different communication models to examine direct and indirect structural connections (polysynaptic) communication in large-scale brain networks in schizophrenia. Diffusion-weighted magnetic resonance imaging scans were acquired from 62 patients diagnosed with schizophrenia and 35 controls. In this study, we used five network communication models including, shortest paths, navigation, diffusion, search information and communicability to examine polysynaptic communication in large-scale brain networks in schizophrenia. We showed less efficient communication between spatially widespread brain regions particulary encompassing cortico-subcortical basal ganglia network in schizophrenia group relative to controls. Then, we also examined whether reduced communication efficiency was related to clinical symptoms in schizophrenia group. Among different measures of communication efficiency, only navigation efficiency was associated with global cognitive impairment across multiple cognitive domains including verbal learning, processing speed, executive functions and working memory, in individuals with schizophrenia. We did not find any association between communication efficiency measures and positive or negative symptoms within the schizophrenia group. Our findings are important for improving our mechanistic understanding of neurobiological process underlying cognitive symptoms in schizophrenia.

Negative symptoms are associated with modularity and thalamic connectivity in schizophrenia.

Negative symptoms, including avolition, anhedonia, asociality, blunted affect and alogia are associated with poor long-term outcome and functioning. However, treatment options for negative symptoms are limited and neurobiological mechanisms underlying negative symptoms in schizophrenia are still poorly understood. Diffusion-weighted magnetic resonance imaging scans were acquired from 64 patients diagnosed with schizophrenia and 35 controls. Global and regional network properties and rich club organization were investigated using graph analytical methods. We found that the schizophrenia group had higher modularity, clustering coefficient and characteristic path length, and lower rich connections compared to controls, suggesting highly connected nodes within modules but less integrated with nodes in other modules in schizophrenia. We also found a lower nodal degree in the left thalamus and left putamen in schizophrenia relative to the control group. Importantly, higher modularity was associated with greater negative symptoms but not with cognitive deficits in patients diagnosed with schizophrenia suggesting an alteration in modularity might be specific to overall negative symptoms. The nodal degree of the left thalamus was associated with both negative and cognitive symptoms. Our findings are important for improving our understanding of abnormal white-matter network topology underlying negative symptoms in schizophrenia.

Event centrality, transitional impact and symptoms of posttraumatic stress in a clinical sample.

Background and Objectives: There is growing research indicating that event centrality strongly predicts posttraumatic stress disorder (PTSD). However, there is not much research on what makes a traumatic event central to one's life story. One reason a traumatic memory becomes a reference point for one's life story is that it brings about significant changes in one's life. This study investigated the relationships between transitional impact of an event, event centrality, and PTSD symptoms. Specifically, it tested whether higher negative changes were associated with higher levels of event centrality and PTSD symptoms. It also investigated whether event centrality mediated the relationship between transitional impact and PTSD severity.Methods: 101 individuals diagnosed with PTSD completed the Transitional Impact Scale (TIS), Centrality of Event Scale, and Impact of Event Scale-Revised regarding their traumatic experiences. Furthermore, they responded to the Posttraumatic Stress Disorder Symptom Scale-Self Report (PSS-SR), Traumatic Events Checklist (TELC), and Beck Anxiety Inventory (BAI).Results and Conclusions: Results indicate that (a) the TIS had valid and reliable psychometric properties in a PTSD sample, (b) most of the traumatic events received high negative psychological and material change scores, and (c) event centrality mediated the relationship between transitional impact and PTSD severity.

The Relationship between 10 Years Risk of Cardiovascular Disease and Schizophrenia Symptoms: Preliminary Results.

OBJECTIVE: Previous research shows that patients with schizophrenia have increased cardiovascular disease risk than general population. Increased cardiovascular risk in schizophrenia patients have been associated with many reasons such as antipsychotic drugs, genetic predisposition, andlifestyle. In this study, we aimed to investigate the relationship between the risk of heart disease and schizophrenia symptomatology. METHODS: The 10-year cardiovascular risk was assessed by the Framingham Risk Score (FRS) in 103 patients with schizophrenia and in 39 healthy controls. Sociodemographic characteristics, age at schizophrenia onset, duration of illness, number of hospitalizations, the course of the disease and antipsychotic medications were recorded. Patients' symptoms were evaluated via The Scale for the Assessment of Negative Symptoms (SANS), The Scale for the Assessment of Positive Symptoms (SAPS), and Calgary Depression Scale for Schizophrenia (CDSS). RESULTS: Ten-year cardiovascular risk was 5.16% inpatients with schizophrenia, and 3.02% in control group (p=0.030). No significant correlation was found between FRS scores, SANS, SAPS, and CDSS scores. However, FRS scores were significantly correlated with age, number of hospitalizations and duration of disease (r=0.300, 0.261, 0.252, respectively). Moreover FRS scores were higher (p=0.008) and high-density lipoprotein (HDL) levels were lower (p=0.048) in patients using multiple antipsychotics. CONCLUSION: Our findings suggest a relationship between the risk of cardiovascular disease and the duration and overall severity of schizophrenia and also highlights the role of antipsychotics in this relationship.