Schizophrenia is a common, chronic and debilitating neuropsychiatric syndrome affecting tens of millions of individuals worldwide. While rare genetic variants play a role in the etiology of schizophrenia, most of the currently explained liability is within common variation, suggesting that variation predating the human diaspora out of Africa harbors a large fraction of the common variant attributable heritability. However, common variant association studies in schizophrenia have concentrated mainly on cohorts of European descent. We describe genome-wide association studies of 6152 cases and 3918 controls of admixed African ancestry, and of 1234 cases and 3090 controls of Latino ancestry, representing the largest such study in these populations to date. Combining results from the samples with African ancestry with summary statistics from the Psychiatric Genomics Consortium (PGC) study of schizophrenia yielded seven newly genome-wide significant loci, and we identified an additional eight loci by incorporating the results from samples with Latino ancestry. Leveraging population differences in patterns of linkage disequilibrium, we achieve improved fine-mapping resolution at 22 previously reported and 4 newly significant loci. Polygenic risk score profiling revealed improved prediction based on trans-ancestry meta-analysis results for admixed African (Nagelkerke’s R2 = 0.032; liability R2 = 0.017; P < 10−52), Latino (Nagelkerke’s R2 = 0.089; liability R2 = 0.021; P < 10−58), and European individuals (Nagelkerke’s R2 = 0.089; liability R2 = 0.037; P < 10−113), further highlighting the advantages of incorporating data from diverse human populations.

Perceived discrimination has been found to increase risk for depression in emerging adulthood, but explanatory cognitive mechanisms have not been well studied. We examined whether the brooding and reflective subtypes of rumination would mediate the relation between perceived discrimination and depressive symptoms among racial/ethnic minority, versus White, emerging adults, and whether a strong ethnic identity would buffer against this effect. Emerging adults (N = 709; 70% female; 68% racial/ethnic minority), ages 18–25, completed measures of perceived discrimination, rumination, depressive symptoms, and ethnic identity. Perceived discrimination was positively associated with depressive symptoms among racial/ethnic minority and White participants. Brooding – but not reflection – mediated this relation only among racial/ethnic minorities. Ethnic identity, though negatively associated with depressive symptoms, did not buffer against the mediating effect of brooding on the discrimination-depression relation. Interventions for depression among racial/ethnic minority emerging adults should address maladaptive cognitive responses, such as brooding, associated with perceived discrimination.

Previous research suggests that cognitive inflexibility prospectively increases vulnerability to suicidal ideation, but the specific cognitive factors that may explain the relation have not been examined empirically. The present study examined the brooding subtype of rumination and hopelessness as potential mediators of the prospective relation between cognitive inflexibility and suicidal ideation. Fifty-six young adults who completed a measure of cognitive inflexibility and suicidal ideation at baseline were followed up 2-3 years later and completed measures of brooding, hopelessness, and suicidal ideation. Cognitive inflexibility at baseline predicted suicidal ideation at follow up, adjusting for baseline ideation. This relation was mediated by brooding but not by hopelessness. However, there was an indirect relation between perseverative errors and suicidal ideation through brooding, followed by hopelessness, such that brooding was associated with greater hopelessness and hopelessness, in turn, was associated with greater suicidal ideation. Cognitive inflexibility may increase vulnerability to suicidal thinking because it is associated with greater brooding rumination, while brooding, in turn, is associated with hopelessness.