RESUMO
BACKGROUND: Treatment resistance is a common issue among schizophrenia patients undergoing antipsychotic treatment. According to the American Psychiatric Association (APA) guidelines, treatment-resistant status is defined as little or no symptom reduction to at least two antipsychotics at a therapeutic dose for a trial of at least six weeks. The aim of the current study is to determine whether ethnicity and migration are associated with treatment resistance. METHODS: In a sample of 251 participants with schizophrenia spectrum disorders, we conducted cross-sectional assessments to collect information regarding self-identified ethnicity, immigration and treatment history. Ancestry was identified using 292 markers overlapping with the HapMap project. Using a regression analysis, we tested whether a history of migration, ethnicity or genetic ancestry were predictive of treatment resistance. RESULTS: Our logistic regression model revealed no significant association between immigration (ORâ¯=â¯0.04; 95%CIâ¯=â¯0.35-3.07; pâ¯=â¯0.93) and treatment resistant schizophrenia. White Europeans did not show significant association with resistance status regardless of whether ethnicity was determined by self-report (ORâ¯=â¯1.89; 95%CIâ¯=â¯0.89-4.20; pâ¯=â¯0.105) or genetic analysis (ORâ¯=â¯-0.73; 95%CIâ¯=â¯-0.18-2.97; pâ¯=â¯0.667). CONCLUSION: Neither ethnicity nor migrant status was significantly associated with treatment resistance in this Canadian study. However, these conclusions are limited by the small sample size of our investigation.