Browsing by Author "González-Valderrama, Alfonso"
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Item Duration of untreated psychosis and acute remission of negative symptoms in a South American first-episode psychosis cohort.(Wiley Publishing Asia Pty Ltd., 2015) González-Valderrama, Alfonso; Castañeda, Carmen Paz; Mena, Cristián; Undurraga, Juan; Mondaca, Pilar; Yáñez, Matías; Bedregal, Paula; Nachar, RubénAIM: To determine the association between duration of untreated psychosis (DUP) and symptoms remission in a hospitalized first-episode psychosis cohort. METHODS: Inpatients with a first-episode non-affective psychosis were recruited. Subjects were divided into two groups of long and short DUP using a 3-month cut-off point, and this was related to remission at 10 weeks of treatment. Multivariate analyses were performed. RESULTS: Fifty-five inpatients were included. There were no differences in remission rates of positive symptoms. Up to 76.5% of the patients with a short DUP (<3 months) achieved remission of negative symptoms versus 31.6% in the DUP ≥ 3 months group (P = 0.003). After controlling for relevant factors, patients with a shorter DUP were still three times more likely to achieve negative symptoms remission (HR: 3.04, 95% CI 1.2-7.5). CONCLUSIONS: DUP is a prognostic factor that should be considered at an early stage to identify a 'high risk' subgroup of persistent negative symptoms.Item Early treatment resistance in a Latin-American cohort of patients with schizophrenia(2018) Mena, Cristian; González-Valderrama, Alfonso; Iruretagoyena, Bárbara; Undurraga, JuanBackground: Failure to respond to antipsychotic medication in schizophrenia is a common clinical scenario with significant morbidity. Recent studies have highlighted that many patients present treatment-resistance from disease onset. We here present an analysis of clozapine prescription patterns, used as a real-world proxy marker for treatment-resistance, in a cohort of 1195 patients with schizophrenia from a Latin-American cohort, to explore the timing of emergence of treatment resistance and possible subgroup differences. Methods: Survival analysis from national databases of clozapine monitoring system, national disease notification registers, and discharges from an early intervention ward. Results: Echoing previous studies, we found that around 1 in 5 patients diagnosed with schizophrenia were eventually prescribed clozapine, with an over-representation of males and those with a younger onset of psychosis. The annual probability of being prescribed clozapine was highest within the first year (probability of 0.11, 95% confidence interval of 0.093-0.13), compared to 0.018 (0.012-0.024) between years 1 and 5, and 0.006 (0-0.019) after 5years. Age at psychosis onset, gender, dose of clozapine used, and compliance with hematological monitoring at 12months, was not related to the onset of treatment resistance. A similar pattern was observed in a subgroup of 230 patients discharged from an early intervention ward with a diagnosis of non-affective first episode of psychosis. Conclusions: Our results highlight that treatment resistance is frequently present from the onset of psychosis. Future studies will shed light on the possible different clinical and neurobiological characteristics of this subtype of psychosis.Item Imaging Social and Environmental Factors as Modulators of Brain Dysfunction: Time to Focus on Developing Non-Western Societies(2019) Crossley, Nicolas A.; Alliende, Luz Maria; Ossandon, Tomas; Castañeda, Carmen Paz; González-Valderrama, Alfonso; Undurraga, Juan; Castro, Mariana; Guinjoan, Salvador; Díaz-Zuluaga, Ana M.; Pineda-Zapata, Julián A.; López-Jaramillo, Carlos; Reyes-Madrigal, Francisco; León-Ortíz, Pablo; Fuente-Sandoval, Camilo de la; Sanguinetti Czepielewski, Leticia; Gama, Clarissa S.; Zugman, Andre; Gadelha, Ary; Jackowski, Andrea; Bressa, RodrigoSocial and environmental factors are known risk factors and modulators of mental health disorders. We here conducted a nonsystematic review of the neuroimaging literature studying the effects of poverty, urbanicity, and community violence, highlighting the opportunities of studying non-Western developing societies such as those in Latin America. Social and environmental factors in these communities are widespread and have a large magnitude, as well as an unequal distribution, providing a good opportunity for their characterization. Studying the effect of poverty in these settings could help to explore the brain effect of economic improvements, disentangle the effect of absolute and relative poverty, and characterize the modulating impact of poverty on the underlying biology of mental health disorders. Exploring urbanicity effects in highly unequal cities could help identify the specific factors that modulate this effect as well as examine a possible dose–response effect by studying megacities. Studying brain changes in those living among violence, which is particularly high in places such as Latin America, could help to characterize the interplay between brain predisposition and exposure to violence. Furthermore, exploring the brain in an adverse environment should shed light on the mechanisms underlying resilience. We finally provide examples of two methodological approaches that could contribute to this field, namely a big cohort study in the developing world and a consortium-based meta-analytic approach, and argue about the potential translational value of this research on the development of effective social policies and successful personalized medicine in disadvantaged societies.Item Implementing psychosocial evidence-based practices in mental health: are we moving in the right direction?(2015) González-Valderrama, Alfonso; Mena, Cristián; Undurraga, Juan; Gallardo, Carlos; Mondaca, PilarOne of the main goals of research in health sciences is to provide clinically relevant information aimed at generating effective interventions in the patients’ care. Many ways to bring the new knowledge into daily practice have been implemented: clinical guidelines, reviews in journals, continuing medical education (CME), courses and seminars, easy access to online information, and thers (1). However, there is a gap between evidence-based knowledge and clinical practice in different medical settings.Publication Intra and inter-individual variability in functional connectomes of patients with First Episode of Psychosis(2023) Tepper, Angeles; Vásquez Núñez, Javiera; Ramirez-Mahaluf, Juan Pablo; Aguirre, Juan Manuel; Barbagelata, Daniella; Maldonado, Elisa; Díaz Dellarossa, Camila; Nachar, Ruben; González-Valderrama, Alfonso; Undurraga, Juan; Goñi, Joaquín; Crossley, NicolásPatients with Schizophrenia may show different clinical presentations, not only regarding inter-individual comparisons but also in one specific subject over time. In fMRI studies, functional connectomes have been shown to carry valuable individual level information, which can be associated with cognitive and behavioral variables. Moreover, functional connectomes have been used to identify subjects within a group, as if they were fingerprints. For the particular case of Schizophrenia, it has been shown that there is reduced connectome stability as well as higher inter-individual variability. Here, we studied inter and intra-individual heterogeneity by exploring functional connectomes’ variability and related it with clinical variables (PANSS Total scores and antipsychotic’s doses). Our sample consisted of 30 patients with First Episode of Psychosis and 32 Healthy Controls, with a test–retest approach of two resting-state fMRI scanning sessions. In our patients’ group, we found increased deviation from healthy functional connectomes and increased intragroup inter-subject variability, which was positively correlated to symptoms’ levels in six subnetworks (visual, somatomotor, dorsal attention, ventral attention, frontoparietal and DMN). Moreover, changes in symptom severity were positively related to changes in deviation from healthy functional connectomes. Regarding intra-subject variability, we were unable to replicate previous findings of reduced connectome stability (i.e., increased intra-subject variability), but we found a trend suggesting that result. Our findings highlight the relevance of variability characterization in Schizophrenia, and they can be related to evidence of Schizophrenia patients having a noisy functional connectome.Item The incidence of non-affective psychotic disorders in Chile between 2005 and 2018: results from a national register of over 30 000 cases(2020-08) González-Valderrama, Alfonso; Jongsma, Hannah E.; Mena, Cristián; Castañeda, Carmen Paz; Nachar, Rubén; Undurraga, Juan; Crossley, Nicolás; Aceituno, David; Iruretagoyena, Bárbara; Gallardo, Carlos; Mondaca, Pilar; Monje, Matías; Irarrazaval, Matías; Zavala, Cynthia; Valmaggia, Lucia; Kirkbride, James B.Background. Evidence suggests the incidence of non-affective psychotic disorders (NAPDs) varies across persons and places, but data from the Global South is scarce. We aimed to estimate the treated incidence of NAPD in Chile, and variance by person, place and time. Methods. We used national register data from Chile including all people, 10–65 years, with the first episode of NAPD (International Classification of Diseases, Tenth Revision: F20– F29) between 1 January 2005 and 29 August 2018. Denominators were estimated from Chilean National Census data. Our main outcome was treated incidence of NAPD and age group, sex, calendar year and regional-level population density, multidimensional poverty and latitude were exposures of interest. Results. We identified 32358 NAPD cases [12136 (39.5%) women; median age-at-first- contact: 24 years (interquartile range 18–39 years)] during 171.1 million person-years [crude incidence: 18.9 per 100 000 person-years; 95% confidence interval (CI) 18.7–19.1]. Multilevel Poisson regression identified a strong age–sex interaction in incidence, with rates peaking in men (57.6 per 100 000 person-years; 95% CI 56.0–59.2) and women (29.5 per 100 000 person-years; 95% CI 28.4–30.7) between 15 and 19 years old. Rates also decreased (non-linearly) over time for women, but not men. We observed a non-linear association with multidimensional poverty and latitude, with the highest rates in the poorest regions and those immediately south of Santiago; no association with regional population density was observed. Conclusion. Our findings inform the aetiology of NAPDs, replicating typical associations with age, sex and multidimensional poverty in a Global South context. The absence of asso- ciation with population density suggests this risk may be context-dependent.Item Uso de cannabis en jóvenes hospitalizados por un primer episodio de psicosis: un estudio caso-control(2020) Castañeda, Carmen Paz; Iruretagoyena, Bárbara; Nachar, Rubén; Mancilla, Felipe; Díaz, Camila; Gallardo, Carlos; Mena, Cristián; Ramírez-Mahaluf, Juan Pablo; Undurraga, Juan; González-Valderrama, Alfonso; Crossley, Nicolás A.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% confi-dence 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 legisla-tion and the public policies currently being discussed in Chile.