The option that defines anxiety disorder is a blanket term that covers several forms of abnormal fears, worries, and phobias. Anxiety is not an illness, it is a disorder that can be treated with visits to a psychologist who is there to help you heal your brain. Anxiety can manifest in mild worries, when you are nervous about something that is supposed to happen, or can be so stressful that you cannot continue living your normal life the way you used to.