Psychosis is a potential symptom of lupus, albeit uncommon. Some people with lupus have been misdiagnosed with Schizophrenia, and more generally there are signs

Psychosis is a potential symptom of lupus, albeit uncommon. Some people with lupus have been misdiagnosed with Schizophrenia, and more generally there are signs of immune dysfunction in many cases of Schizophrenia. I'm not sure about this particular scenario, but psychosis is also a potential symptom of meningitis, and brain inflammation can definitely cause weird behaviors (e.g. the account in the book Brain on Fire). It's not "severe damage" in the traditional sense, but depending on illness and treatment timeline there can be irreversible life-altering psychiatric consequences from brain inflammation.