Multiple biological pathways lead to similar symptoms – NIH-funded study. Three biomarker-based categories, called biotypes, outperformed traditional diagnoses, such as schizophrenia and bipolar disorder with psychosis, in sorting psychosis cases into distinct subgroups on the basis of brain biology, report researchers funded by the National Institutes of Health. A hallmark of severe mental illness, psychosis is marked by hallucinations and delusions, or false, irrational beliefs.