Autoimmune encephalitis (AE) symptoms can vary but may include memory loss, changes in thinking, changes in behavior, and seizures. For a definitive diagnosis, an autoantibody must be identified in the blood or cerebrospinal fluid (the fluid that surrounds the brain and spinal cord); however, some AE patients are not positive for these autoantibodies. Most patients are severely affected in the acute stages of the disease, and, while long-term outcomes are often good, long-term effects such as anxiety, fatigue, and cognitive problems may affect quality of life.