When we are mildly concerned (worried, afraid), the stress response produces a mild reaction in the body. When we are greatly concerned/worried/afraid, the stress response produces a dramatic reaction in the body. Since the stress response is directly proportional to the degree of worry, a panic attack and its symptoms are generally the result of serious worry, concern, and fear.
People with generalized anxiety disorder (GAD) display excessive anxiety or worry, most days for at least 6 months, about a number of things such as personal health, work, social interactions, and everyday routine life circumstances. The fear and anxiety can cause significant problems in areas of their life, such as social interactions, school, and work.