Generalized anxiety disorder (GAD), however, is different from normal worry and is characterized by persistent, excessive worry and apprehensive expectation. People with generalized anxiety disorder worry that "terrible" things are going to happen most of the time, even when the probability of something bad happening is very low. They worry about a variety of things, and they find it difficult to control their worry. Many people with GAD also have physical symptoms that are chronic and interfere with their daily lives, such as tenseness, depression, restlessness, fatigue, phobias, insomnia and irritable bowel syndrome.

Research shows that only about 30% of the causes of generalized anxiety disorder are inherited. There are certain personaility characteristics that seem to make a person more vulnerable to develop GAD, such as depression, feeling inhibited, general nervousness, and low-frustration tolerance. People with GAD also report more recent life stresses than people without GAD. People with generalized anxiety disorder are often not as effective in everyday problem-solving as they could be and/or have interpersonal conflicts whereby they might not be as assertive or effective as they could be.