When terrorists attacked the World Trade Center on September 11, 2001, Cassie McCauley watched in horror from her classroom on the New Jersey side of the Hudson River. Her heart pounded faster and faster as she saw billowing clouds of dark gray smoke pour from the landmark buildings. When the first tower collapsed, she began feeling light-headed. By the time the second tower fell in on itself, Cassie was so nauseated and dizzy she had to sit down. Along with millions of people across North America and around the world, Cassie grieved for the families who lost relatives and friends. But she never anticipated the changes September 11 would cause in her own life. Soon she found herself unable to go to school and barely able to function. Cassie was experiencing an anxiety disorder. Anxiety disorders are the most common psychiatric illnesses in North America. Estimates are that at least one of every twenty Americans will suffer from an anxiety disorder at some time. These disorders can happen for many reasons. As in Cassie's case, they can be triggered by traumatic and devastating events. In other cases, they can appear seemingly without reason. Nearly everyone at one time or another experiences anxious feelings, so some people assume that an anxiety disorder is not a serious condition. In Anxiety Disorders, however, you will learn how serious anxiety disorders can be. Through Cassie's story, and the stories of other people like her, you will explore the many different forms of anxiety disorders, the impacts they have on people's lives, and the treatments available to help. Discover just how prevalent anxiety disorders are and learn about the new ways doctors are fighting these all-too common forms of mental illness.