Risk Factors:

As many as 25% of all American adults experience intense anxiety sometime in their lives. The prevalence of true anxiety disorders is much lower, although they are still the most common psychiatric conditions in the United States and affect more than 20 million Americans.

General Risk Factors for Anxiety Disorders

Gender. With the exception of obsessive-compulsive disorder (OCD), women have twice the risk for most anxiety disorders as men. A number of factors may increase the reported risk in women, including cultural pressures to meet everyone else's needs except their own, and fewer self-restrictions on reporting anxiety to doctors.

Age. In general, phobias, OCD and separation anxiety show up early in childhood, while social phobia and panic disorder are often diagnosed during the teen years. Studies suggest that 3 - 5% of children and adolescents have some anxiety disorder. Children and adolescents who have an anxiety disorder are at risk of later developing other anxiety disorders, depression, and substance abuse.

Personality Factors. Children's personalities may indicate higher or lower risk for future anxiety disorders. For example, research suggests that extremely shy children and those likely to be the target of bullies are at higher risk for developing anxiety disorders later in life. Children who cannot tolerate uncertainty tend to be worriers, a major predictor of generalized anxiety. In fact, such traits may be biologically based and due to a hypersensitive amygdala -- the "fear center" in the brain.

Family History and Dynamics. Anxiety disorders tend to run in families. Genetic factors may play a role in some cases, but family dynamics and psychological influences are also often at work. Several studies show a strong correlation between a parent's fears and those of the offspring. Although an inherited trait may be present, some researchers believe that many children can "learn" fears and phobias, just by observing a parent or loved one's phobic or fearful reaction to an event.

Social Factors. Several studies have reported a significant increase in anxiety levels in children and college students in the past two decades compared to children in the 1950s. In several studies, anxiety was associated with a lack of social connections and a sense of a more threatening environment. It also appears that more socially alienated populations have higher levels of anxiety. For example, a study of Mexican adults living in California reported that native-born Mexican Americans were three times more likely to have anxiety disorders (and even more likely to be depressed) as those who had recently immigrated to the U.S. The longer the immigrants lived in the U.S., the greater their risk for psychiatric problems. Traditional Mexican cultural and social ties seemed to protect recently arrived immigrants from mental illness.

Traumatic Events. Traumatic events generally trigger anxiety disorders in individuals who are susceptible to them because of psychological, genetic, or biochemical factors. The clearest example is post-traumatic stress disorder. Specific traumatic events in childhood, particularly those that threaten family integrity, such as spousal or child abuse, can also lead to other anxiety and emotional disorders. Some individuals may even have a biological propensity for specific phobias, for instance of spiders or snakes, that have been triggered and perpetuated after a single exposure.

Medical Conditions. Although no causal relationships have been established, certain medical conditions have been associated with increased risk of panic disorder. They include migraines, obstructive sleep apnea, mitral valve prolapse, irritable bowel syndrome, chronic fatigue syndrome, and premenstrual syndrome.

Specific Risk Factors for Generalized Anxiety (GAD)

GAD affects about 1 - 5% of Americans in the course of their lives and is more common in women than in men. It is the most common anxiety disorder among the elderly. GAD usually begins in childhood and often becomes a chronic ailment, particularly when left untreated. Depression commonly accompanies this anxiety disorder and depression in adolescence may be a strong predictor of GAD in adulthood.

Specific Risk Factors for Panic Disorder

Age and Panic Disorder. Studies indicate that the prevalence of panic disorder among adults is between 1.6 - 2% and is much higher in adolescence, 3.5 - 9%. Panic disorder usually first occurs either in late adolescence or in the mid-30s.

Gender and Panic Disorder. Women have about twice the risk for panic disorder as men. Panic attacks are very common after menopause. In one study, nearly 18% of older women reported panic attacks within a 6-month period, with over half of these attacks being full-blown. They tended to be associated with stressful life events and poor health. The effects of pregnancy on panic disorder appear to be mixed. It seems to improve the condition in some women and worsen it in others.

Specific Risk Factors for Obsessive-Compulsive Disorder (OCD)

Obsessive-compulsive disorder occurs equally in men and women, and it affects about 2 - 3% of people over a lifespan. Most cases of OCD first develop in childhood or adolescence, although the disorder can occur throughout the life span.

Specific Risk Factors for Social Phobias

Social anxiety disorder is currently estimated to be the third most common psychiatric disorder in the U.S. Studies have reported a prevalence of 7 - 12% in Western nations.

Age and Phobias. The onset of social anxiety disorder is usually during the early teenage years.

Gender and Phobias. Women are more likely to develop social anxiety disorder than men, although equal numbers of men and women seek treatment for it. Most people seeking treatment have had symptoms for at least 10 years.

Specific Risk Factors for Post-Traumatic Stress Disorder

A lifetime risk for PTSD in the U.S. may be as high as 8%. People exposed to traumatic events, of course, are at highest risk, but many people can go through such events and not experience PTSD. Studies estimate that 6 - 30% or more of trauma survivors develop PTSD, with children and young people being among those at the high end of the range. Women have the twice the risk of PTSD as men.

After the September 11 attack on the World Trade Towers, an estimated 7.5% of New York's population reported PTSD within the month of the event, which declined to 0.6% at 6 months.

Researchers are trying to determine factors that might increase vulnerability to catastrophic events and put people at risk for develop PTSD. Some studies report the following may be risk factors:

• Pre-existing emotional disorder. People are at higher risk for PTSD if they have a history of an emotional disorder, particularly depression, before a traumatic event.
• Drug or alcohol abuse
• A family history of anxiety
• A history of abuse, particularly that which threatens family integrity, such as spousal or child abuse. Studies of individuals who had suffered physical or sexual abuse or neglect as children suggest that up to one-third develop PTSD.
• An early separation from parents
• Lack of social support and poverty
• Sleep disorders. Insomnia and excessive daytime sleepiness even within a month after a traumatic event are important predictors for the development of PTSD. One specific sleep disorder -- sleep apnea -- may even intensify symptoms of PTSD, including sleeplessness and nightmares. Sleep apnea occurs when tissues in the upper throat (or airway) collapse at intervals during sleep, thereby blocking the passage of air. Sleep apnea has also been associated with a risk for panic disorder. [For more information, see In-Depth Report #65: Sleep apnea.]