Which autoantibodies that are most likely to be relevant for patients with psychotic symptoms?

We often do not check autoantibodies when making the diagnosis of primary psychosis unless we think the psychotic symptoms are due to a systemic illness which can be associated with autoantibodies. E.g. psychotic symptoms may be present in systemic vasculitis or systemic lupus erythematosus and ANA will be the most common autoantibody found (very sensitive) but not specific for these disease.

Since psychotic symptoms can be present secondary to brain disorders, such as Alzheimer's, Parkinsonian dementia, autoimmune encephalitis, infections, etc., but also can be seen in psychiatric disease such as schizophrenia; antibody testing would be based on additional clinical features to pinpoint etiological underpinnings.