This study will examine the possible relationship between certain antibodies found in patients with systemic lupus erythematosus (SLE) and cognitive (thought processing) impairment in these patients. Antibodies are proteins produced by cells of the immune system to fight foreign invaders such as bacteria and viruses. In autoimmune diseases like SLE, however, the immune system produces antibodies against the body's own healthy tissues. Antibodies targeting the brain may cause cognitive dysfunction. Many patients with SLE have mild to severe cognitive impairment involving, for example, short- or long-term memory, thought processing and relating objects in time and space.