Browsing by Subject "Endophenotype"

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    Language ability in schizophrenia patients and genetic high-risk individuals: neuropsychological and computational investigation
    (2024-05) Çabuk, Tuğçe
    The study aimed to define language-related phenotypes in schizophrenia and analyze language in schizophrenia patients (SZ) and their unaffected siblings (SIB) as a possible endophenotype. For experiment 1, language was evaluated with the Thought and Language Disorder Scale (TALD), Thought and Language Index (TLI), phonemic and semantic verbal fluency, Boston Naming Test, and Scale for Scoring the Inclusion and the Quality of the Parts of the Story. Language skills of SIB were higher than those of SZ, but lower than those of healthy controls (HC). The best predictor of SZ and SIB was TLI score in the main regression model compared to HC. For experiment 2, I utilized Natural Language Processing (NLP) to explore whether there are altered linguistic features in Turkish-speaking SZ and whether these possible features as phenotypes are language-dependent or -independent. Analyses was conducted in two parts. Firstly, mean sentence length (MSL), total completed words (TCW), moving average type-token ratio (MATTR), and first- person singular pronoun usage (FPSP) were calculated. Secondly, I used parts-of- speech tagging (POS) and Word2Vec. I found that SZ had lower MSL and MATTR but higher use of FPSP. Results were correlated with the TALD. POS demonstrated that SZ used fewer coordinating conjunctions. Word2Vec detected that SZ had higher semantic similarity than HC and K-Means could differentiate between SZ and HC into two distinct groups with high accuracy, 86.84%. My findings suggest that semantics as subparts of language could be a possible endophenotype in schizophrenia. Thus, their assessment may improve the early diagnosis of the illness. Also, it showed that altered linguistic features in SZ are mostly language- independent.
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    Working memory in unaffected relatives of patients with schizophrenia: a meta-analysis of functional magnetic resonance imaging studies
    (Oxford University Press, 2016) Zhang, R.; Picchioni, M.; Allen, P.; Toulopoulou, T.
    Working memory deficits, a core cognitive feature of schizophrenia may arise from dysfunction in the frontal and parietal cortices. Numerous studies have also found abnormal neural activation during working memory tasks in patients' unaffected relatives. The aim of this study was to systematically identify and anatomically localize the evidence for those activation differences across all eligible studies. Fifteen functional magnetic resonance imaging (fMRI) manuscripts, containing 16 samples of 289 unaffected relatives of patients with schizophrenia, and 358 healthy controls were identified that met our inclusion criteria: (1) used a working memory task; and (2) reported standard space coordinates. Activation likelihood estimation (ALE) identified convergence across studies. Compared to healthy controls, patients' unaffected relatives showed decreases in neural activation in the right middle frontal gyrus (BA9), as well as right inferior frontal gyrus (BA44). Increased activation was seen in relatives in the right frontopolar (BA10), left inferior parietal lobe (BA40), and thalamus bilaterally. These results suggest that the familial risk of schizophrenia is expressed in changes in neural activation in the unaffected relatives in the cortical-subcortical working memory network that includes, but is not restricted to the middle prefrontal cortex.