Anti-NMDA receptor encephalitis: an autoimmune disorder in which antibodies are produced against NMDA (N-methyl-D-aspartate)-type glutamate receptors in the brain. This condition was first described in 2007 and is characterized by neurologic and psychiatric symptoms that include agitation, delusions, hallucinations, mania, disorganization, speech changes, movement disorders, and seizures. Other symptoms that can occur include flu-like symptoms, memory problems, sleep disorders, vision and hearing problems, and reduction in breathing requiring a ventilator. The condition has been found in association with tumors (predominantly ovarian teratomas) and therefore has sometimes been termed a paraneoplastic syndrome (a collection of symptoms that occurs in association with a tumor). Still, a tumor has not been identified in all of those with the disease. Anti-NMDA receptor encephalitis affects predominantly women; 80% of those affected are female. It can affect people of any age, although younger people are more commonly affected.