Anxiety disorder due to a medical condition includes symptoms of intense anxiety or panic that are directly caused by a physical health problem. Generalized anxiety disorder includes persistent and excessive anxiety and worry about activities or events.They are a group of mental illnesses, and the distress they cause can keep you from carrying on with your life normally. For people who have one, worry and fear are constant and overwhelming, and can be disabling.anxiety disorders run in families, and that they have a biological basis,much like allergies or diabetes and other disorders. Anxiety disorders may develop from a complex set of risk factors, including genetics, brain chemistry, personality, and life events.Anxiety disorders are characterized by a variety of symptoms. One of the most common is excessive and intrusive worrying that disrupts daily functioning. Other signs include agitation, restlessness, fatigue, difficulty concentrating, irritability, tense muscles and trouble sleeping.