Socio-Demographic and Clinical Characteristics of the Populations Underrepresented in Mental Illness Association...

To describe the sociodemographic characteristics of the PUMAS sample in Brazil, focusing on differences between case and control groups and ethnic variation across cities.

This case-control study included a convenience sample of patients with schizophrenia and bipolar disorder, alongside matched controls, from five brazilian cities: Belém, Fortaleza, Goiânia, Salvador, and São Paulo. The Diagnostic Interview for Psychosis and Affective Disorders (DIPAD) was used to confirm diagnoses and assess lifetime psychopathology and clinical data.

A total of 14,017 subjects (54.7% female, mean age 39.93 years, s.d. 12.88) were enrolled: 7,532 patients with either bipolar disorder (N=4,059) or schizophrenia spectrum disorders (N=3,473), and 6,485 controls. Over 70% self-identified as black, admixed (Pardos), or indigenous. Significant differences in self-identified skin color, according to brazilian official classifications, were observed across cities. Patients with schizophrenia showed significant socioeconomic disparities compared to those with bipolar disorders. A higher proportion of individuals with severe mental illness self-identified as admixed. Educational attainment was lower among patients, particularly those with schizophrenia.

This is the largest and most diverse sample in Brazil collected to investigate the genetic basis of schizophrenia and bipolar disorder. It will allow testing critical hypotheses within a socio-cultural and ethnic context underrepresented in large-scale genetic studies.