Browsing by Author "Diaz, Camila"

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    Predictors of clozapine discontinuation at 2 years in treatment-resistant schizophrenia
    (ELSEVIER, 2021) Iruretagoyena Bruce Barbara Arantzazu; Castañeda, Carmen Paz; Mena, Cristian; Diaz, Camila; Nachar, Ruben; Ramirez Mahaluf Juan Pablo; González Valderrama, Alfonso; Undurraga, Juan; Maccabe, James H; Crossley, Nicolas A
    Little is known about predictors of clinical response to clozapine treatment in treatment-resistant psychosis. Most published cohorts are small, providing inconsistent results. We aimed to identify baseline clinical predictors of future clinical response
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    Premorbid school performance trajectories in patients with treatment-resistant schizophrenia prescribed clozapine in the public health system in Chile: a case-control study, 2007–2020
    (2025) Conejeros Pavez, Jose Daniel Hernan; Blanco Vasquez, Javiera Alejandra; Diaz, Camila; Mena, Cristian; Undurraga, Juan; Gonzalez-Valderrama, Alfonso; Claro Larrain, Susana; Undurraga, Eduardo A.; Crossley, Nicolas A.
    BackgroundThe premorbid phase of treatment-resistant schizophrenia (TRS) may reveal underlying mechanisms and inform early interventions. According to the neurodevelopmental hypothesis, treatment resistance may be linked to pronounced developmental impairments. We examined school grades and attendance trajectories in children who later developed TRS.MethodsThis case-control study analyzed school grade point average and attendance among all individuals born after 1990 and started on clozapine in Chile’s public health system as a proxy for TRS. Control groups included children later diagnosed with treatment-responsive schizophrenia, bipolar disorder, and unaffected classmates. Linear mixed models accounted for individual and school-level confounders.ResultsWe included 1072 children (9929 observations, 29.3% female) subsequently diagnosed with TRS, 323 (2802 observations, 25.7% female) with schizophrenia, 175 (1784 observations, 53.8% female) bipolar disorder, and 273,260 (533,335 observations, 47% female) unaffected classmates. Children who later developed TRS had worse grades across levels than their classmates (−0.26 SD [−0.2, −0.4]), but not treatment-responsive schizophrenia. All severe mental illness groups showed grade declines in later school levels, with TRS showing steeper linear decline than treatment-responsive schizophrenia (group×age of −0.03; 95%CI −0.04, −0.01) and steeper quadratic decline than bipolar disorder (group×age2 of −0.005; −0.01, −0.001). Attendance declined over time in the two groups developing schizophrenia compared to their classmates. Those developing TRS experienced the sharpest drop (group×age compared to schizophrenia −0.03; −0.05, −0.01 and bipolar disorder −0.027; −0.049, −0.006).ConclusionsTRS may stem from a more aggressive pathological process or pronounced late-maturation abnormality, rather than an early premorbid impairment, suggesting an intervention target.
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    Quantitative Susceptibility Mapping MRI in Deep-Brain Nuclei in First-Episode Psychosis
    (2023) García Saborit, Marisleydis; Jara Vallejos, Alejandro Antonio; Muñoz Camelo, Néstor Andrés; Milovic, Carlos; Tepper, Angeles; Alliende Correa, Luz María; Mena, Carlos; Iruretagoyena Bruce, Bárbara Arantzazu; Ramírez Mahaluf, Juan Pablo; Diaz, Camila; Nachar, Rubén; Castaneda, Carmen Paz; Gonzalez, Alfonso; Undurraga, Juan; Crossley, Nicolás; Tejos Núñez, Cristián Andrés
    Background 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. Methods 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. Results 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. Conclusions 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.
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    Uso de cannabis en jóvenes hospitalizados por un primer episodio de psicosis: un estudio caso-control
    (2020) Castañeda, Carmen Paz; Alliende Correa, Luz María; Iruretagoyena, Bárbara; Nachar, Rubén; Mancilla, Felipe; Diaz, Camila; Gallardo, Carlos; Mena, Cristian; Ramírez Mahaluf, Juan Pablo; Undurraga, Juan; González Valderrama, Alfonso; Crossley, Nicolás
    Background: Cannabis use among young people in Chile has increased significantly in the last years. There is a consistent link between cannabis and psychosis. Aim: To compare cannabis use in patients with a first episode of psychosis and healthy controls. Material and Methods: We included 74 patients aged 20 +/- 3 years (78% males) admitted to hospital with a first episode of psychosis and a group of 60 healthy controls aged 23 +/- 4 years (63% males). Cannabis consumption was assessed, including age of first time use and length of regular use. Results: Patients with psychosis reported a non-significantly higher frequency of life-time cannabis use. Patients had longer periods of regular cannabis use compared with healthy subjects (Odds ratio [OR] 2.4; 95% confidence intervals [CI] 1.14-5.05). Patients also used cannabis for the first time at an earlier age (16 compared with 17 years, p < 0.0). The population attributable fraction for regular cannabis use associated with hospital admissions due to psychosis was 17.7% (95% CI 1.2-45.5%). Conclusions: Cannabis use is related to psychosis in this Chilean group of patients. This relationship is stronger in patients with early exposure to the drug and longer the regular use. One of every five admissions due to psychosis is associated with cannabis consumption. These data should influence cannabis legislation and the public policies currently being discussed in Chile.