Anxiety disorders are real illnesses with real causes and are not the result of personal weakness, a character flaw, or poor upbringing. Ongoing scientific research is making it clear that many of these disorders are caused by a combination of factors, including changes in the brain, environmental stresses, and genetics.
Studies have shown that severe or long-lasting stress can change the functioning of circuitry in the brain that regulates mood. Other studies have shown that people with certain anxiety disorders have changes in brain structures that control memory or mood. In addition, it has been shown that anxiety disorders run in families, which means that they can be inherited from one or both parents. Moreover, certain environmental factors -- such as a trauma or significant event -- may trigger an anxiety disorder in people who have an inherited susceptibility to developing the disorder.
As with most illnesses, some people are more susceptible than others. Close relatives of people with panic disorder have a four to seven times increased risk of getting panic disorder.