Autoimmune disease appears to be on the rise in the United States. A study published in the June Arthritis and Rheumatology found that the prevalence of serum antinuclear antibodies (ANA), the most common biomarker of autoimmunity, has increased significantly in the U.S. population in recent years. Previously, there was evidence that frequency of autoimmunity and incidence of specific autoimmune disease had increased over the last several decades, but research findings were limited owing to a lack of systematic data collection. In the current study, researchers collected data on the prevalence of ANA through the National Health and Nutrition Examination Survey during three separate time periods from 1988 to 2012. Findings showed serum ANA increased from one time period to the next, with a greater increase in recent years. Increases were seen in both men and women, in adults over age 50, and in non-Hispanic whites. Notably, adolescents demonstrated a marked rise in ANA levels in the second and third time periods. Factors such as obesity, smoking, and alcohol use did not explain the increases, researchers said. Future studies that focus on underlying causes of increased ANA could help determine underlying causes of autoimmunity as well as potential preventative measures.