Cumhur Tas

Oxidative stress in schizophrenia: a case-control study on the effects on social cognition and neurocognition.

BackgroundSchizophrenia is a debilitating mental disorder that presents impairments in neurocognition and social cognition. Several studies have suggested that the etiology of schizophrenia can be partly explained by oxidative stress. However, our knowledge about the implications of oxidative stress on illness-related cognitive deficits is still far from being clear. The aim of this work was to study the role of oxidative stress molecules on social cognition and neurocognition in patients with schizophrenia.MethodsWe assessed the peripheral levels of several molecules associated with oxidative stress, namely nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), homocysteine, superoxide dismutase (SOD) and neurotrophin 4/5 (NT4/5), in forty-one patients with schizophrenia and forty-three healthy participants. A battery of tests to measure neurocognition and social cognition was also administered to the schizophrenia group.ResultsWe found that the schizophrenia group presented substantially higher levels of oxidative stress than the control group, as revealed by elevated quantities of the pro-oxidants NO and MDA, and decreased levels of the antioxidants GSH, SOD and NT4/5. Interestingly, the levels of NT4/5, which have been shown to have antioxidant effects, correlated with executive functioning, as measured by two distinct tests (WCST and TMT). However, social cognition and symptom severity were not found to be associated with oxidative stress.ConclusionsWe propose a protective role of NT4/5 against oxidative stress, which appears to have a potentially beneficial impact on neurocognition in schizophrenia.

Oxytocin influences avoidant reactions to social threat in adults with borderline personality disorder.

Borderline personality disorder (BPD) is characterized by interpersonal dysfunction, emotional instability, impulsivity, and risk‐taking behavior. Recent research has focused on the role of oxytocin in BPD, with mixed results as regards the processing of social stimuli.

Empathy moderates the effect of repetitive transcranial magnetic stimulation of the right dorsolateral prefrontal cortex on costly punishment.

Humans incur considerable costs to punish unfairness directed towards themselves or others. Recent studies using repetitive transcranial magnetic stimulation (rTMS) suggest that the right dorsolateral prefrontal cortex (DLPFC) is causally involved in such strategic decisions. Presently, two partly divergent hypotheses are discussed, suggesting either that the right DLPFC is necessary to control selfish motives by implementing culturally transmitted social norms, or is involved in suppressing emotion-driven prepotent responses to perceived unfairness. Accordingly, we studied the role of the DLPFC in costly (i.e. third party) punishment by applying rTMS to the left and right DLPFC before playing a Dictator Game with the option to punish observed unfair behavior (DG-P). In addition, sham stimulation took place. Individual differences in empathy were assessed with the German version of the Interpersonal Reactivity Index. Costly punishment increased (non-significantly) upon disruption of the right – but not the left – DLPFC as compared to sham stimulation. However, empathy emerged as a highly significant moderator variable of the effect of rTMS over the right, but not left, DLPFC, suggesting that the right DLPFC is involved in controlling prepotent emotional responses to observed unfairness, depending on individual differences in empathy.

A closer look at the relationship between the subdomains of social functioning, social cognition and symptomatology in clinically stable patients with schizophrenia

Impairments in social functioning commonly seen in schizophrenia are thought to be mediated by deficits in the domains of social cognition. Some previous research has explored how social cognitive skills and psychotic symptoms are associated with social functioning, however these associations are still under debate. The main aim of this study was to investigate the relationship between different domains of social cognition and psychotic symptomatology, and also to look at the relationships with individual subdomains of social functioning within a clinically stable schizophrenia population. 45 outpatients were recruited and symptoms were assessed with the PANSS, and measures of emotion processing, affective and cognitive theory of mind (ToM), mental state reasoning attributional biases, and social functioning were taken. A correlational analysis was performed with the data. Following this, a regression analysis was used to reveal which domains of social cognition best predicted psychotic symptoms. In this stable group of patients, our results support the suggestion of a likely distinction between affective and cognitive components of ToM. The study also demonstrated that ToM and mental state reasoning were the best predictors of psychotic symptoms. Here we reveal that cognitive ToM had the most widespread relationship with social functioning, across multiple subdomains, while only some specific subdomains of social functioning correlated with other domains of social cognition and symptomatology. Further to this, positive symptoms were associated with much fewer subdomains of social functioning than negative and general symptoms. These findings imply that different aspects of social functioning may be served by different domains of social cognition and symptomatology.

Potential therapeutic avenues to tackle social cognition problems in schizophrenia

Therapeutic strategies for improving social cognition in patients with schizophrenia have shown much promise in improving social functioning, as well as remediating core psychotic symptoms. However, the efficacy of previous interventions has often been limited by the ambiguity and inconsistency of the categorized subdomains of social cognition, including theory of mind, emotion processing, social perception and attributional bias. Recent research in social and cognitive neuroscience has revealed many new issues that could contribute to the development of more integrated approaches for improving social functioning. The application of such neuroscientific work to a therapeutic and diagnostic context is likely to encourage more effective transference of learned skills to real-world social functioning. This article seeks to provide a comprehensive review of previous social cognitive interventions for schizophrenia, highlight some crucial limitations of these and present the relevance of recent advances in neuroscientific research in possible future treatment strategies. It is emphasized that a more integrated and naturalistic approach for improving social functioning with greater sensitivity for neuroscientific findings related to the psychopathology of schizophrenia is warranted.

EEG power, cordance and coherence differences between unipolar and bipolar depression

INTRODUCTION Understanding the biological underpinnings of unipolar (UD) and bipolar depression (BD) is vital for avoiding inappropriate treatment through the misdiagnosis of bipolar patients in their first depressive episode. One plausible way to distinguish between UD and BD is to compare EEG brain dynamics to identify potential neurophysiological biomarkers. Here we aimed to test group differences in EEG power, cordance and coherence values between UD and BD. METHODS Twenty-five bipolar and 56 unipolar depression patients were recruited. Sociodemographic and clinical variables were collected in addition to resting state EEG. Data was analyzed with multivariate and repeated analyses of variance where parametric assumptions were met. RESULTS Accordingly, we did not find any differences in the EEG absolute power and frontal asymmetry indexes between UD and BD. Regarding cordance, significant group differences were observed in the right theta cordance values (p=0.031). Regarding coherence, BD patients (as compared to UD) exhibited greater central-temporal theta (p=0.003), and parietal-temporal alpha (p=0.007) and theta (p=0.001) coherence. Lastly, less alpha coherence in BD was present at right frontal-central (p=0.007) and central inter-hemispheric (p=0.019) regions. CONCLUSIONS Our results demonstrate that EEG cordance and coherence values have potential to discriminate between UD and BD. The loss of temporal synchronization in the frontal interhemispheric and right sided frontolimbic neuronal networks may be a unique feature that distinguishes between BD and UD.

Neuroanatomical correlates of genetic risk for bipolar disorder: A voxel-based morphometry study in bipolar type I patients and healthy first degree relatives.

BACKGROUND Bipolar disorder (BD) is a highly heritable mental illness which is associated with neuroanatomical abnormalities. Investigating healthy individuals at high genetic risk for bipolar disorder may help to identify neuroanatomical markers of risk and resilience without the confounding effects of burden of illness or medication. METHODS Structural magnetic resonance imaging scans were acquired from 30 euthymic patients with BD-I (BP), 28 healthy first degree relatives of BD-I patients (HR), and 30 healthy controls (HC). Data was analyzed using DARTEL for voxel based morphometry in SPM8. RESULTS Whole-brain analysis revealed a significant main effect of group in the gray matter volume in bilateral inferior frontal gyrus, left parahippocampal gyrus, left lingual gyrus and cerebellum, posterior cingulate gyrus, and supramarginal gyrus (alphasim corrected (≤0.05 FWE)). Post-hoc t-tests showed that inferior frontal gyrus volumes were bilaterally larger both in BP and HR than in HC. BP and HR also had smaller cerebellar volume compared with HC. In addition, BP had smaller left lingual gyrus volume, whereas HR had larger left parahippocampal and supramarginal gyrus volume compared with HC. LIMITATIONS This study was cross-sectional and the sample size was not large. All bipolar patients were on medication, therefore we were not able to exclude medication effects in bipolar group in this study. CONCLUSIONS Our findings suggest that increased inferior frontal gyrus and decreased cerebellar volumes might be associated with genetic predisposition for bipolar disorder. Longitudinal studies are needed to better understand the predictive and prognostic value of structural changes in these regions.

Social approach and avoidance behaviour for negative emotions is modulated by endogenous oxytocin and paranoia in schizophrenia

Patients with schizophrenia suffer from dysfunctional social behaviour. Social approach and avoidance (AA) has been associated with motor responses, as the affective valence and gaze direction of facial stimuli can bias push and pull motor tendencies. The aim of this study was to investigate the role of endogenous oxytocin in social AA behaviour in schizophrenia. Basal plasma oxytocin levels were collected from 28 patients who were then given a joystick-based Approach-Avoidance Task (AAT). Reaction times were recorded and AAT effect scores calculated for responses to happy and angry faces, which either had direct or averted gaze. Individual differences in basal oxytocin had a significant relationship with AAT responses, and patients with higher levels of oxytocin tended to avoid angry faces more. Furthermore, greater avoidance of angry faces was correlated with more severe psychotic (positive and general) symptoms and greater paranoia. This suggests that the endogenous effects of oxytocin may be specific to the interpretation of negative threatening emotions in schizophrenia patients, and also provides evidence that psychotic symptoms and paranoia can impact on social AA behaviour by heightening threat avoidance.

Hypnotic ingroup-outgroup suggestion influences economic decision-making in an Ultimatum Game.

Studies in economic decision-making have demonstrated that individuals appreciate social values supporting equity and disapprove unfairness when distributing goods between two or more parties. However, this seems to critically depend on psychological mechanisms partly pertaining to the ingroup-outgroup distinction. Little is known as to what extent economic bargaining can be manipulated by means of psychological interventions such has hypnosis. Here we show that a hypnotic ingroup versus outgroup suggestion impacts the tolerance of unfairness in an Ultimatum Game. Specifically, the ingroup suggestion was associated with significantly greater acceptance rates of unfair offers than the outgroup suggestion, whereas hypnosis alone exerted only small effects on unfairness tolerance. These findings indicate that psychological interventions such as hypnotic suggestion can contribute to ingroup favoritism and outgroup rejection.

Alterations in event-related potential responses to empathy for pain in schizophrenia

Lack of empathy is a critical factor impacting on social functioning and quality of life in schizophrenia. There is, however, a paucity of research into the underlying neurophysiological correlates of empathy deficits in this disorder. Accordingly, we sought: (1) to identify whether dysfunctional empathic abilities in schizophrenia are related to alterations in early or late brain processes, and (2) to explore the potential relationship between brain activity and mood, self-reported empathy and symptom severity. Eighteen patients with schizophrenia and 21 healthy matched controls performed an empathy-for-pain paradigm where photographs of hands in neutral or painful situations were shown while we recorded their electroencephalography (EEG), and we examined mood, empathic concern for others and symptom severity. Significant group differences between patients and controls emerged in early (50-150ms after stimulus onset) and late (after 300ms) timeframes. Moreover, brain activity was related with unpleasantness ratings in all participants, with self-reported empathic concern only in controls and with negative mood and personal distress only in patients. Differences in social behavior in schizophrenia may be explained by early as well as late differences, affecting mostly the early frontocentral ERPs, i.e. those suggested to correspond to the emotional sharing component of empathy.