Risk Factors

As many as 25% of all American adults experience intense anxiety at 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.

Gender. With the exception of obsessive-compulsive disorder (OCD) and possibly social anxiety, women have twice the risk for most anxiety disorders as men. A number of factors may increase the reported risk in women, including hormonal factors, 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. Indeed, this may be an underestimation, particularly since symptoms in children may differ from those in adults. One study indicated that if such children could be identified as early as 2 years of age they possibly could be treated to avoid later anxiety disorders.

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 run in families. Genetic factors play a role in some cases, but family dynamics and psychological influences are also often at work. For example, in a 2002 study, toddlers tended to avoid rubber snakes or spiders if their mothers indicated a negative response to these objects by their facial expressions. Girls had a stronger response than did boys. Studies are reporting the anxiety in new mother can affect their infants. One study reported a higher rate of crying and an impaired ability to adapt to new situations in infants of mothers who had been stressed and anxious during pregnancy. In another, infants of mothers with panic disorder had higher levels of stress hormones and more sleep disturbances than other children.

Social and Economic Factors. Several studies reported a significant increase in anxiety levels in children and college students in the past two decades compared to children in the 1950s. In two 2000 studies, anxiety was associated with a lack of social connections and a sense of a more threatening environment.

It follows then, that more socially alienated populations would 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. And the longer the immigrants lived in the U.S., the greater was their risk for psychiatric problems. Traditional Mexican cultural effects and social ties, appear to protect recently arrived immigrants from mental illness, even when they are poor. Eventually, however, the consequences of Americanization may lead to depression and anxiety, probably resulting from feelings of alienation and inferiority, not only in many Mexican Americans but also in other impoverished minority groups

Risk Factors for Generalized Anxiety (GAD)

GAD affects about 5% of Americans in the course of their lives and is more common in women than in men. Some experts believe that it is underdiagnosed and more common than any other anxiety disorder. It is certainly the most common anxiety disorder among the elderly. GAD usually begins in childhood and often becomes a chronic ailment, particularly when left untreated. Depression in adolescence may be a strong predictor of GAD in adulthood. Depression commonly accompanies this anxiety disorder in any case.

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%. In one study, 18% of adult patients with panic disorder reported the onset of the disorder before 10 years of age. In general, however, panic disorder tends to begin in late adolescence and peaks at around 25 years of age.

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.

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. About 80% of people who develop OCD show signs of the disorder in childhood, although the disorder usually develops fully in adulthood. The only group shown to be specifically at risk for OCD is women who have just given birth.

Risk Factors for Social Phobias

Social phobia 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 in adolescence, although most people with this disorder are not diagnosed and do not receive treatment until or unless they develop an accompanying anxiety disorder.

Gender and Phobias. Unlike their response to other emotional disorders, men are more likely than women to seek treatment for this disorder, probably because social phobias can interfere strongly with many jobs in white-collar professions. Some evidence suggests, however, that the actual rates of social phobia are higher in women.

Risk Factors for Post-Traumatic Stress Disorder

Studies estimate a lifetime risk for PTSD in the U.S. of up to 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.

Furthermore, PTSD can occur in people not directly involved with a traumatic event. For example, 17% of the US population outside New York City reported some symptoms of post-traumatic stress 2 months after the September 11 attack on the World Trade Towers. (In the city itself, where the attack occurred, 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 who have a history of an emotional disorder, particularly depression, before the traumatic event are at higher risk for PTSD.
• 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. In one study, 91% of crime victims with PTSD had either sleep apnea or a lesser condition that partially blocked the airways during sleep. In fact, in one study treatment of sleep apnea eased PTSD. Sleep apnea has also been associated with a risk for panic disorder. [For more information, see In-Depth Report #65: Sleep apnea.]