Browsing by Subject "Network connectivity"
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Item Open Access Effects of genetic liability to psychosis proneness and psychosis proneness on functional connectivity of the salience network(2022-12) Aydoğan, İlaydaThe effect of psychosis proneness, a psychometrically defined index of subclinical psychosis, has limited research on its effect on brain connectivity in healthy populations. In addition, functional connectivity research in psychosis proneness mainly focuses on brain networks such as the default-mode network (DMN) and the central executive network (CEN) but not on the salience network (SN). On a similar note, research on genetic susceptibility to psychosis in healthy populations and the combinatory analysis between brain connectivity and genetic liability have not been explored thoroughly. This thesis assessed the relationship between psychosis proneness and genetic liability to psychosis to functional connectivity of the salience network. Seventy-two pairs of twins, siblings, and triplets were included in the analysis for genetic liability and functional connectivity. Participants’ psychosis proneness was assessed via the Community Assessment of Psychic Experience (CAPE-42) questionnaire, and genetic liability scores (PRS-SCZ) were calculated through PLINK and PRSIce-2 software. Global patterns of connectivity, seed-based connectivity, and network topology of the salience network were examined. The findings have revealed that the connectivity levels within the salience network differed in individuals with high psychosis proneness com- pared to individuals with low psychosis proneness. Further analysis has shown that PRS-SCZ did not show a significant difference between high and low psy- chosis proneness groups. The results show that connectivity levels in the salience network differ in individuals with psychometrically defined psychosis proneness. These results were not explained by differences in genetic loading among the participants.Item Open Access Effects of recreational cannabis use and subclinical psychosis risk on brain white matter integrity and structural connectivity in adolescence(2022-06) Atmaca, Hande EzgiThe impact of cannabis use on the psychosis risk in the healthy population has been less examined in the literature. Furthermore, previous diffusion tensor imag-ing and structural connectivity studies investigating the effects of cannabis use and psychosis risk offer contradictory results. To address these gaps and inconsistencies in the literature, the author examined whether recreational use of cannabis increases the risk of subclinical psychosis. The author further ex-amined the relationship between recreational cannabis use, subclinical psychosis, and white matter microstructure or structural network connectivity. Twenty-five adolescent cannabis users and 25 demographically matched controls participated in the study. The Cannabis Experience Questionnaire (CEQ) was used to assess cannabis consumption. Subclinical psychosis was evaluated with the Community Assessment of Psychic Experience (CAPE-42) questionnaire. While ROI-based Tract Based Spatial Statistics (TBSS) was used to examine white matter integrity in specified region of interests, Structural Connectivity Analysis was performed to examine brain structural topology. White matter integrity was assessed by four diffusion tensor derived measures: fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity, while structural network topology was examined by several graph-theory metrics: global efficiency, local efficiency and clustering coefficient. In order to eliminate possible confounding effects of alcohol and to-bacco use, weekly alcohol and daily tobacco consumption were also considered. The findings revealed that cannabis users scored higher on subclinical psychosis compared to non-users. ROI-based TBSS analysis indicated that cannabis use and subclinical psychosis do not affect white matter integrity in corpus collosum and superior longitudinal fasciculus. Similarly, the network connectivity parame-ters were not affected by the recreational cannabis use and psychosis risk. These results might indicate that recreational cannabis use increases the psychosis risk in adolescence, but that recreational cannabis use and subclinical psychosis risk together do not affect white matter microstructure and topology.