Schizophrenia is a mental illness that affects Humans. A person with this disease may have delusions and see hallucinations. Schizophrenia is a hereditary disease (i.e. one that can be inherited). It cannot be cured but can be treated with medications.
Captain Samantha Carter once incorrectly referred to schizophrenia as a "multiple personality disorder." She (incorrectly) likened it to the mind of a Tok'ra host. (SG1: "The Tok'ra, Part 1")
Dr. Daniel Jackson was thought to have hebephrenic schizophrenia at one point, but it turned out to be a weapon designed by Ma'chello to fight the Goa'uld. (SG1: "Legacy")
Kelownan scientists including Dr. Kieran and Dr. Tomis Leed, who were working on the Kelownan Naquadria bomb suffered from schizophrenia after being exposed to excessive quantities of Naquadria radiation. (SG1: "Shadow Play")