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Author: search.filters.author.Luz María AlliendeSubject: search.filters.subject.case control study

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    Quantitative Susceptibility Mapping MRI in Deep-Brain Nuclei in First-Episode Psychosis
    (2023)
    Marisleydis García Saborit
    ;
    Alejandro Jara
    ;
    Néstor Muñoz
    ;
    Carlos Milovic
    ;
    Angeles Tepper
    <jats:title>Abstract</jats:title> <jats:sec> <jats:title>Background</jats:title> <jats:p>Psychosis is related to neurochemical changes in deep-brain nuclei, particularly suggesting dopamine dysfunctions. We used an magnetic resonance imaging-based technique called quantitative susceptibility mapping (QSM) to study these regions in psychosis. QSM quantifies magnetic susceptibility in the brain, which is associated with iron concentrations. Since iron is a cofactor in dopamine pathways and co-localizes with inhibitory neurons, differences in QSM could reflect changes in these processes.</jats:p> </jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>We scanned 83 patients with first-episode psychosis and 64 healthy subjects. We reassessed 22 patients and 21 control subjects after 3 months. Mean susceptibility was measured in 6 deep-brain nuclei. Using linear mixed models, we analyzed the effect of case-control differences, region, age, gender, volume, framewise displacement (FD), treatment duration, dose, laterality, session, and psychotic symptoms on QSM.</jats:p> </jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Patients showed a significant susceptibility reduction in the putamen and globus pallidus externa (GPe). Patients also showed a significant R2* reduction in GPe. Age, gender, FD, session, group, and region are significant predictor variables for QSM. Dose, treatment duration, and volume were not predictor variables of QSM.</jats:p> </jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Reduction in QSM and R2* suggests a decreased iron concentration in the GPe of patients. Susceptibility reduction in putamen cannot be associated with iron changes. Since changes observed in putamen and GPe were not associated with symptoms, dose, and treatment duration, we hypothesize that susceptibility may be a trait marker rather than a state marker, but this must be verified with long-term studies.</jats:p> </jats:sec>
    Scopus© Citations 1  1
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    Abnormal nodal and global network organization in resting state functional MRI from subjects with the 22q11 deletion syndrome
    (2021)
    Teuntje A. D. Pelgrim
    ;
    Matthijs G. Bossong
    ;
    Analía Cuiza
    ;
    Luz María Alliende
    ;
    Carlos Mena
    <jats:title>Abstract</jats:title><jats:p>The 22q11 deletion syndrome is a genetic disorder associated with a high risk of developing psychosis, and is therefore considered a neurodevelopmental model for studying the pathogenesis of schizophrenia. Studies have shown that localized abnormal functional brain connectivity is present in 22q11 deletion syndrome like in schizophrenia. However, it is less clear whether these abnormal cortical interactions lead to global or regional network disorganization as seen in schizophrenia. We analyzed from a graph-theory perspective fMRI data from 40 22q11 deletion syndrome patients and 67 healthy controls, and reconstructed functional networks from 105 brain regions. Between-group differences were examined by evaluating edge-wise strength and graph theoretical metrics of local (weighted degree, nodal efficiency, nodal local efficiency) and global topological properties (modularity, local and global efficiency). Connectivity strength was globally reduced in patients, driven by a large network comprising 147 reduced connections. The 22q11 deletion syndrome network presented with abnormal local topological properties, with decreased local efficiency and reductions in weighted degree particularly in hub nodes. We found evidence for abnormal integration but intact segregation of the 22q11 deletion syndrome network. Results suggest that 22q11 deletion syndrome patients present with similar aberrant local network organization as seen in schizophrenia, and this network configuration might represent a vulnerability factor to psychosis.</jats:p>
    Scopus© Citations 2  1
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    Uso de cannabis en jóvenes hospitalizados por un primer episodio de psicosis: un estudio caso-control
    (2020)
    Carmen Paz Castañeda
    ;
    Luz María Alliende
    ;
    Bárbara Iruretagoyena
    ;
    Rubén Nachar
    ;
    Felipe Mancilla
    Scopus© Citations 2  13