Experts don’t know the exact causes of generalized anxiety disorder. Several things — including genetics, brain chemistry, and environmental stresses — appear to contribute to its development.
Some research suggests that family history plays a part in making it more likely that a person will have physical symptoms of GAD. This means that the tendency to develop GAD may be passed on in families. But no anxiety genes have been identified, and families may also pass down the tendency through lifestyle or environment.
Brain chemistry. This is complex. GAD has been linked to problems with certain nerve cell pathways that connect particular brain regions involved in thinking and emotion. These nerve cell connections depend on chemicals called neurotransmitters that send information from one nerve cell to the next.
If the pathways that connect particular brain regions don’t work well, problems related to mood or anxiety may result. Medicines, psychotherapies, or other treatments that are thought to work on these neurotransmitters may improve the signaling between circuits and help to improve symptoms related to anxiety or depression.
Environmental factors. Trauma and stressful events such as abuse, the death of a loved one, divorce, and changing jobs or schools may contribute to GAD. The condition can also worsen when stress feels out of hand. The use of and withdrawal from addictive substances (including alcohol, caffeine, and nicotine) can also worsen anxiety.