Browsing by Author "Mena, Cristian"

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    Gender, age and geographical representation over the past 50 years of schizophrenia research
    (2022) Alliende, Luz MarÍa; Czepielewski, Leticia S.; Aceituno Farías, David; Paz Castaneda, Carmen; Díaz, Camila; Iruretagoyena Bruce, Bárbara Arantzazu; Mena, Carlos; Mena, Cristian; Ramírez Mahaluf, Juan Pablo; Tepper, Ángeles; Vásquez, Javiera; Fonseca, Lais; Machado, Viviane; Hernández, Camilo E.; Vargas Upegui, Cristian; Gómez Cruz, Gladys; Kobayashi Romero, Luis F.; Moncada Habib, Tomas; Evans Lacko, Sara; Bressan, Rodrigo; Gama, Clarissa S.; López Jaramillo, Carlos; de la Fuente Sandoval, Camilo; González Valderrama, Alfonso; Undurraga, Juan; Gadelha, Ary; Crossley Karmelic, Nicolás Andrés; ANDES Network
    Previous studies have suggested that subjects participating in schizophrenia research are not representative of the demographics of the global population of people with schizophrenia, particularly in terms of gender and geographical location. We here explored if this has evolved throughout the decades, examining changes in geographical location, gender and age of participants in studies of schizophrenia published in the last 50 years. We examined this using a meta-analytical approach on an existing database including over 3,000 studies collated for another project. We found that the proportion of studies and participants from low-and-middle income countries has significantly increased over time, with considerable input from studies from China. However, it is still low when compared to the global population they represent. Women have been historically underrepresented in studies, and still are in high-income countries. However, a significantly higher proportion of female participants have been included in studies over time. The age of participants included has not changed significantly over time. Overall, there have been improvements in the geographical and gender representation of people with schizophrenia. However, there is still a long way to go so research can be representative of the global population of people with schizophrenia, particularly in geographical terms.
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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 Fourcade, Eduardo Andres; 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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    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.