Autoimmune encephalitis is a group of conditions that involve inflammation of the brain. Inflammation is one of the ways that our immune system protects the body from infection. But in autoimmune encephalitis, the immune system mistakenly attacks healthy brain cells and this leads to neurologic and psychiatric symptoms. People with AE have a wide range of symptoms, and not everyone with AE will have the same symptoms. However, certain symptoms and the pattern of symptoms may lead your doctor to suspect this diagnosis.
No one knows exactly why people get AE. Some cases are associated with certain cancers, (paraneoplastic AE) and some are linked to infections (such as herpes simplex virus), but many patients have no known trigger for their AE. AE usually occurs in previously healthy people, but it may be more likely in those with other autoimmune diseases or a strong family history of autoimmune disease. Researchers are exploring whether there are genetic changes that increase the risk of people developing an autoimmune disease when they are exposed to a trigger in the environment, such as an infection.