People with social anxiety disorder do not believe that their anxiety is related to a mental or physical illness. This type of anxiety occurs in most social situations, especially when the person feels on display or is the center of attention. Once a person avoids almost all social and public interactions, it can be said that the person has an extreme case of social anxiety disorder, more commonly called Avoidant Personality Disorder. People with social anxiety disorder have an elevated rate of relationship difficulties and substance abuse.