Which Patients with Psychosis Might Have NMDAR-Antibody Encephalitis?

N-methyl-D-aspartate receptor (NMDAR)-antibody encephalitis is a rare cause of new-onset psychosis, mainly in young patients. Accurate diagnosis, which requires lumbar puncture (LP) for cerebrospinal fluid autoantibody testing because serum testing alone is inadequate, can enable immunotherapy or curative surgery (e.g., of occult ovarian teratoma). But knowing when to suspect this rare condition is often the first hurdle. Are there specific features in patients with psychosis that should prompt us to consider it? To find out, researchers compared 96 patients with NMDAR-antibody encephalitis (“cases”) to 145 patients (“controls”) who presented for early intervention for psychosis (general, rapid-onset, or postpartum).