Browsing by Subject "Psychosis"
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Item Open Access Arithmetic and temporal transformations of working memory activation in subjects prone to psychosis(Bilkent University, 2018-09) Baş, TimuçinWorking memory (WM) deficit is a well-studied cognitive impairment in psychosis which is stemming from various developmental abnormalities containing neurobiological heterogeneity. Recently, many studies have concluded that the WM impairment is a symptom which manifests itself before the onset of the disorder, but these studies mostly focused on the individuals at clinically high risk. The mild proneness to psychosis which develops during the adolescent period is not well understood and how the working memory is affected due to mild proneness to psychosis has not been elucidated heretofore. In this research, we aimed to examine the association between the mild proneness to psychosis and working memory processing. Thirty-two individuals were split in half as mildly prone to psychosis and not prone to psychosis based on the Structured Interview for Schizotypy (SIS-R). Each participant performed a robust working memory task which consists of computational and temporally varying information loads. The data were collected via a magnetic resonance imaging (MRI) scanner and analysed by applying a general linear model to detect altered working memory activations due to proneness to psychosis. We have observed that the processes requiring manipulation and rapid updating of the information are associated with a large network of prefrontal cortex and superior parietal lobule. The finding of this study suggests that the mild proneness to psychosis has affected the working memory weakly and that the alterations demonstrated in the prefrontal cortex and parietal lobules may be clinically relevant to psychosis.Item Open Access The impact of psychosis genome-wide associated ZNF804A variation on verbal fluency connectivity(Elsevier, 2018) Tecelão, D.; Mendes, A.; Martins, D.; Bramon, E.; Toulopoulou, Timothea; Kravariti, E.; Murray, R.; Prata, D.Schizophrenia (SCZ) and bipolar disorder (BD) have high heritability. Genome-wide association studies (GWAS) have identified ZNF804A as a significant risk gene for both illnesses. A validation of this finding at the brain systems-level is imperative as there is still little understanding of how it heightens risk. Based in part on our recent findings of an effect on widespread decreased white matter microstructural fractional anisotropy (putatively a proxy of its integrity), particularly strong in SCZ, we asked whether the risk allele has a detrimental effect on regional brain activation and functional connectivity during a type of cognitive processing which is, together with its neural correlates, impaired in BD and SCZ: verbal fluency. Functional MRI and genotype data was collected from 80 healthy volunteers, and 54 SCZ and 40 BD patients. A standard multifactorial analysis of variance using statistical parametric mapping and significance correction of FWE p < 0.05 was used. We found the GWAS risk allele A was associated with decreased positive functional coupling between the left precentral gyrus/inferior frontal gyrus (i.e. the most highly recruited area for the task) and: 1) the left inferior frontal gyrus, and 2) the left posterior cingulate gyrus, encompassing the precuneus; both as a main effect across controls and psychosis patients. Such association of the risk allele with reduced functional connectivity (with no area where the opposite main effect was detected), converges with findings in other tasks, our previous finding of its widespread impact on brain white matter microstructure, and with the dysconnectivity hypothesis of SCZ.Item Open Access Integrated assessment of visual perception abnormalities in psychotic disorders and relationship with clinical characteristics(Cambridge University Press, 2019) Türközer, H. B.; Hasoğlu, T.; Chen, Y.; Norris, L. A.; Brown, M.; Delaney-Busch, N.; Kale, E. H.; Pamir, Zahide; Boyacı, Hüseyin; Kuperberg, G.; Lewandowski, K. E.; Topçuoğlu, V.; Öngür, D.Background-The visual system is recognized as an important site of pathology and dysfunction in schizophrenia. In this study, we evaluated different visual perceptual functions in patients with psychotic disorders using a potentially clinically applicable task battery and assessed their relationship with symptom severity in patients, and with schizotypal features in healthy participants. Methods-Five different areas of visual functioning were evaluated in patients with schizophrenia and schizoaffective disorder (n = 28) and healthy control subjects (n = 31) using a battery that included visuospatial working memory (VSWM), velocity discrimination (VD), contour integration, visual context processing, and backward masking tasks. Results-The patient group demonstrated significantly lower performance in VD, contour integration, and VSWM tasks. Performance did not differ between the two groups on the visual context processing task and did not differ across levels of interstimulus intervals in the backward masking task. Performances on VSWM, VD, and contour integration tasks were correlated with negative symptom severity but not with other symptom dimensions in the patient group. VSWM and VD performances were also correlated with negative sychizotypal features in healthy controls. Conclusion-Taken together, these results demonstrate significant abnormalities in multiple visual processing tasks in patients with psychotic disorders, adding to the literature implicating visual abnormalities in these conditions. Furthermore, our results show that visual processing impairments are associated with the negative symptom dimension in patients as well as healthy individuals.Item Open Access Negative social comparisons and psychosis proneness in a healthy adolescent population(Elsevier Masson, 2017) Cotier, F. A.; Toulopoulou, T.There is growing evidence of an association between negative social comparisons (NSC) and both psychosis, and psychosis proneness. The majority of the work thus far, however, has focused largely on one type of NSC, namely, social rank. Whilst social rank is clearly an important factor, an individual's perception of belonging is likely also of importance; particularly, when considering individuals from collectivistic cultures such as China, where greater emphasis is placed on fitting into the group. There is also limited research investigating what factors may contribute towards the relationship between NSC and psychosis proneness, and to what extent this relationship may be due to common familial factors. To address these issues, we examined whether (1) Social rank and perceived belonging predict negative, positive and depressive psychotic experiences in a Chinese, adolescent, twin and sibling population, (2) coping styles moderate the impact of these relationships and (3), there is a familial association between NSC and psychosis proneness. Both social rank and perceived belonging were found to predict the negative and depressive dimensions of psychosis. These relationships were moderated by problem-focused coping styles. Interestingly, the association between perception of belonging, and negative psychotic experiences was familial—and stronger in Monozygotic twins—indicating perhaps shared aetiology due to common genes. Our findings highlight NSC as potential vulnerability markers for negative and depressive psychotic experiences, and suggest potentially different aetiological pathways amongst different NSC and different psychotic experiences. On a clinical level, our findings emphasize the need to consider coping styles when treating at-risk individuals.Item Open Access Schizophrenia polygenic risk score influence on white matter microstructure(Elsevier, 2020) Simões, B.; Vassos, E.; Shergill, S.; McDonald, C.; Toulopoulou, Timothea; Kalidindi, S.; Kane, F.; Murray, R.; Bramon, E.; Ferreira, H.; Prata, D.Schizophrenia (SZ) and bipolar disorder (BD) are highly heritable, share symptomatology, and have a polygenic architecture. The impact of recent polygenic risk scores (PRS) for psychosis, which combine multiple genome-wide associated risk variations, should be assessed on heritable brain phenotypes also previously associated with the illnesses, for a better understanding of the pathways to disease. We have recently reported on the current SZ PRS's ability to predict 1st episode of psychosis case-control status and general cognition. Herein, we test its penetrance on white matter microstructure, which is known to be impaired in SZ, in BD and their relatives, using 141 participants (including SZ, BP, relatives of SZ or BP patients, and healthy volunteers), and two white matter integrity indexes: fractional anisotropy (FA) and mean diffusivity (MD). No significant correlation between the SZ PRS and FA or MD was found, thus it remains unclear whether white matter changes are primarily associated with SZ genetic risk profiles.