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  • Yayın
    Analyzing language ability in first-episode psychosis and their unaffected siblings: a diffusion tensor imaging tract-based spatial statistics analysis study
    (Elsevier Ltd, 2024-11) Çabuk, Tuğçe; Şahin Çevik, Didenur; Çakmak, Işık Batuhan; Yılmaz Kafalı, Helin; Şenol, Bedirhan; Avcı, Hanife; Karlı Oğuz, Kader; Toulopoulou, Timothea
    Schizophrenia (SZ) is a highly heritable mental disorder, and language dysfunctions play a crucial role in diagnosing it. Although language-related symptoms such as disorganized speech were predicted by the polygenic risk for SZ which emphasized the common genetic liability for the disease, few studies investigated possible white matter integrity abnormalities in the language-related tracts in those at familial high-risk for SZ. Also, their results are not consistent. In this current study, we examined possible aberrations in language-related white matter tracts in patients with first-episode psychosis (FEP, N = 20), their siblings (SIB, N = 20), and healthy controls (CON, N = 20) by applying whole-brain Tract-Based Spatial Statistics and region-of-interest analyses. We also assessed language ability by Thought and Language Index (TLI) using Thematic Apperception Test (TAT) pictures and verbal fluency to see whether the scores of these language tests would predict the differences in these tracts. We found significant alterations in language-related tracts such as inferior longitudinal fasciculus (ILF) and uncinate fasciculus (UF) among three groups and between SIB and CON. We also proved partly their relationship with the language test as indicated by the significant correlation detected between TLI Impoverished thought/language sub-scale and ILF. We could not find any difference between FEP and CON. These results showed that the abnormalities, especially in the ILF and UF, could be important pathophysiological vulnerability indexes of schizophrenia. Further studies are required to understand better the role of language as a possible endophenotype in schizophrenia with larger samples.
  • Yayın
    Formal thought disorder and familial risk in first-episode psychosis: A study of cortical thickness and neuroimaging-transcriptomic association analysis
    (Elsevier Ireland Ltd, 2026-01-16) Çabuk, Tuğçe; Zhang, Yuanchao; Palaniyappan, Lena; Şahin Çevik, Didenur; Avcı, Hanife; Çakmak, Işık Batuhan; Yılmaz Kafalı, Helin; Şenol, Bedirhan; Karlı Oğuz, Kader; Toulopoulou, Timothea
    Formal thought disorder (FTD), a prominent feature of schizophrenia, encompasses disruptions in thought, language, and communication. This study examines cortical thickness (CT) alterations in first-episode psychosis (FEP) patients (N = 24), their siblings (SIB) (N = 21), and healthy controls (CON) (N = 21) to explore potential neural correlates of FTD. Using structural MRI, we analyzed whole-brain CT and its relationship with positive and negative FTD measured by Thought and Language Index. Out-of-sample spatial correlations of gene expression with regional CT were also performed using a transcriptomic dataset. FEP had significant CT reductions in right middle frontal gyrus (MFG) compared with SIB and CON and in superior frontal gyrus (SFG) compared to CON; but SIB did not differ from CON. GLM analyses demonstrated that negative FTD exerted a significant main effect on CT in the MFG and SFG. By contrast, positive FTD showed no significant associations with CT. Neuroimaging-transcriptomic association analysis identified key biological pathways linked to cortical morphology. These findings emphasize the specific association between negative FTD and CT alterations in frontal brain regions, confirming prior reports. Future research should examine larger cohorts and investigate additional FTD subtypes to further elucidate neural correlates and potential familial risks of schizophrenia.