When she was 24 years old, Caroline Walsh started having disturbing symptoms, like forgetfulness and sudden behavior changes. Doctors incorrectly diagnosed her several times before she was properly diagnosed with autoimmune encephalitis, a disease in which the body attacks itself and targets the brain. New research suggests the disease may affect up to 90,000 people each year. There's a blank year in 26-year-old Caroline Walsh's once-spotless memory. She's pieced parts together from stories her friends have told her and a collection of photos on Facebook.