In stool samples from 61 people with schizophrenia and 69 healthy controls, researchers found clear differences not just in bacteria, but also in gut fungi and archaea, with significantly lower archaeal diversity and altered fungal profiles in schizophrenia. A combined panel of 39 microbial species (9 archaea, 8 fungi, 22 bacteria) distinguished schizophrenia from controls with an AUC of 0.74, showing fungi added real diagnostic signal rather than noise. Specific fungal and archaeal species also tracked with symptom severity scores, strengthening the case that gut fungi are measurably involved in schizophrenia biology, not just bystanders.