Life Experiences - What Causes Anxiety: Mental Health

Content provided by the Faculty of the Harvard Medical School

Life experiences

People who are extremely anxious may think that a trying experience has given them reason to feel that way. And to a large degree, they're right.

Lingering effects

As mentioned earlier, a traumatic event is often a trigger for acute stress disorder, post-traumatic stress disorder, and specific phobias. Either of the two stress disorders usually begins within days of a terrifying experience. While a phobia may not develop immediately after a traumatic event, it can often be traced back to one. For example, many adults who fear dogs were attacked by dogs as youngsters.

There is growing evidence that highly stressful experiences, especially those that occur early in life, increase the risk for anxiety by impairing a person's ability to negotiate emotional bumps in the road later on. Such experiences include abuse or neglect, emotional deprivation, and the loss of or separation from one's mother. Studies show that rat pups separated from their mothers for just several minutes early in life have a much greater startle response than other pups when faced with stress several months later.

Traumas seem to alter the brain in a way that makes it more susceptible to anxiety. In addition to making the HPA axis hypersensitive (see "Hormones and the HPA axis"), they may also change the structure of the brain. The hippocampus, which works closely with the amygdala (the brain's "fear" center), is smaller in some people with post-traumatic stress disorder, as well as some who have endured extreme, prolonged stress (see "Hippocampus").

Acting in concert

Of course, not everyone who has survived a traumatic event develops an anxiety disorder. That's where an individual's genes and brain chemistry come in. One theory is that some people are genetically or biologically more susceptible to anxiety, but that it often takes a traumatic life event to serve as the catalyst. In the study of the 5-HTT gene (see "One anxiety gene uncovered"), people with a particular gene variation all developed anxiety symptoms only after facing a fear-inducing situation.

In some cases, the trauma or stress is not apparent. Some people seem to develop an anxiety disorder "out of the blue." But when they seek help, a mental health professional discovers clues suggesting an undiagnosed anxiety disorder experienced in childhood. For example, a 20-year-old with generalized anxiety disorder may have been a 3-year-old who had a hard time being away from her parents when they left for work (separation anxiety). However, trauma is not always a trigger. Some people who develop an anxiety disorder have not endured particularly stressful events.

Last updated:	September 05, 2008