Forms of Anxiety
The Different Forms of Anxiety Disorders
Anxiety can take many forms, but the fundamental characteristics of all anxiety disorders include:
- the presence of anxiety
- the avoidance behaviors designed to ward off the anxiety
Anxiety disorders include: Generalized Anxiety Disorder, Panic Disorder, Obsessive-Compulsive Disorder, Social Anxiety Disorder (Social Phobia), Specific Phobias, Posttraumatic Stress Disorder, Acute Stress Disorder. While the diagnostic criteria for each anxiety disorder includes distinctive symptoms, the symptoms of each disorder revolve around excessive, irrational fear and anxiety, apprehensiveness and dread. (For specific diagnostic criteria for each anxiety disorder, see: Assessing Anxiety Disorders.
Anxiety disorders are classified in The Diagnostics and Statistical Manual of Mental Disorders IV-TR as follows…
Generalized Anxiety Disorder (GAD)
Generalized Anxiety Disorder (GAD) is characterized by excessive anxiety, worry, and apprehensive expectation about a variety of everyday problems. To warrant a diagnosis of GAD, symptoms must be present for more than half the days of at least 6 months.
For people with GAD, the days are typically filled with worry after worry, even when there’s little or nothing to provoke worry. Small things are easily turned into big things, “mountains made out of molehills.”
They can’t seem to get rid of their worries, even though they’re usually aware that their intense anxiety is an overreaction. They tend to expect disaster and may be overly concerned about health issues, money, family problems, or difficulties at work. Sometimes even the very thought of getting through the day torques the anxiety.
People with mild GAD can usually function socially and occupationally, whereas people with severe GAD may struggle to perform even the simplest daily activity. People with GAD tire easily, can’t relax, startle easily, are prone to irritability and have difficulty concentrating. Often they have trouble falling asleep or staying asleep. Physical symptoms that often accompany the anxiety include: fatigue, headaches, muscle tension, muscle aches, difficulty swallowing, trembling, twitching, sweating, nausea, lightheadedness, frequent urination, feeling out of breath, and hot flashes.
Because the symptoms of GAD are common and relatively unfocused and the nervousness may be chronic but low-key, GAD can be difficult to diagnose. GAD affects around 3.1 percent (6.8 million) U.S. adults, and impacts twice as many women as men. The disorder develops gradually and can begin at any point in a person’s life, although it typically begins in childhood and becomes a chronic ailment when left untreated. GAD is the most common anxiety disorder among the elderly.
GAD rarely occurs alone, often co-occurring with other anxiety disorders, depression, or substance abuse. In fact, depression in adolescence may be a strong predictor of GAD in adulthood.
Who’s at Greater Risk for GAD?
Risk factors for GAD include:
- Genetics — GAD tends to run in families
- Depression in adolescence
- Childhood trauma (e.g., witnessing traumatic events), increases the risk of developing GAD in adulthood
- Chronic health condition or serious illness (e.g., cancer) that leads to constant worry about the future
- Experiencing a large, stressful event or a number of smaller stressful life situations
- People with neurotic personality types and some personality disorders, such as borderline personality disorder
- Substance abuse — drugs and alcohol worsen anxiety
Panic Disorder is a common anxiety disorder in which the person experiences panic attacks — usually many, but always more than one — and, for at least one month following an attack, persistently worries about having another attack, as well as the implications or consequences of having attacks.
What are the symptoms of a Panic Attack?
In a panic attack, the person develops an intense fear or discomfort in which four (or more) of the following symptoms developed abruptly and reached a peak within 10 minutes:
- palpitations, pounding heart, or accelerated heart rate
- trembling or shaking
- sensations of shortness of breath or smothering
- feeling of choking
- chest pain or discomfort
- nausea or abdominal distress
- feeling dizzy, unsteady, lightheaded, or faint
- derealization (feelings of unreality) or depersonalization (being detached from oneself)
- fear of losing control or going crazy
- fear of dying, impending doom
- paresthesias (numbness or tingling sensations)
- chills or hot flushes
Fearing one’s own unexplained physical symptoms can also be a symptom of Panic Disorder. People having panic attacks sometimes believe that they’re having heart attacks, losing their minds, or are about to die. They often can’t predict when or where the next attack might occur, and between episodes, they may worry intensely, dreading the next attack.
Panic attacks can be sneaky. They can occur at any time, even during sleep. (Some people awaken at night with panic attacks.) While an attack usually peaks within 10 minutes and lasts less than 30 minutes, some symptoms may linger much longer.
There are three subtypes of panic attacks:
- Unexpected or uncued panic attacks arise spontaneously, as in Panic Disorder, and are not associated with a specific situational or environmental stimulus, cue or trigger; for example, someone might experience a sudden, unprovoked panic attack while shopping at the grocery store… her heart starts pounding, she feels as if she can’t breathe and she doesn’t know why.
- Cued or situationally bound panic attacks. These attacks are triggered by specific cues or situational or environmental stimuli. These situations become cues or triggers for a panic attack, such as a fear of crossing a particular traffic intersection; or a person who fears enclosed spaces might experience a panic attack when entering, or thinking about entering, an elevator.
- Situationally predisposed attacks are those in which the person is at higher risk and often — but not always — becomes immediately panic-stricken when exposed to a feared situation or cue. For example, a person who fears social situations may not experience a panic attack in every social situation, or may have a delayed attack after being in that social situation for an extended period of time.
Full-blown Panic Disorder affects between 2.7 – 3.5 percent of the U.S. adult population (6 million adults) annually. Around 10 percent of the general population has suffered panic attacks. Twice as many women suffer from Panic Disorder than men. Panic attacks often begin in late adolescence or early adulthood; pathological panic attacks usually begin in the 20s. Not everyone who experiences panic attacks will develop Panic Disorder. Many people, in fact, will have only one attack in their lifetime.
Panic disorder is often accompanied by — and can mask — other conditions such as depression, drug abuse, or alcoholism. Panic attacks can be involved in several medical conditions, such as acute myocardial infarction or heart attack, which is the very condition that many people who suffer panic attacks fear most. Intoxication with psychoactive substances such as caffeine, marijuana and amphetamines can produce panic attacks.
Panic Attacks are not codable disorders in themselves; rather, they’re building blocks of several different anxiety disorders.
Who’s at Greater Risk for Panic Disorder?
Genes contribute to the risk for repeated panic attacks in fact, Panic Disorder is thought to have a strong genetic component, possibly as much as 40 percent of the risk for Panic disorder may be heritable.
Other risk factors include:
- Sleep apnea (a condition in which tissues in the upper throat or airway collapse at intervals during sleep, blocking air flow)
- Frequent stressful life events and/or an inability to cope effectively
- Poor health
- Pregnancy may worsen panic attacks for some women, though it seems to improve reduce panic attacks in others
Agoraphobia is not a codable disorder in itself. It occurs within the context of Panic Disorder, but may also occur in a person with no history of Panic Disorder.
About half the people who suffer panic attacks have symptoms of Agoraphobia — the fear of open spaces.
About one-third of agoraphobics become housebound, or are only able to confront a feared situation when accompanied by someone they trust.
Agoraphobic fears typically involve situations that require being outside the home alone and being in a crowd, standing in a line, on a bridge, or traveling in a bus, train, or automobile. Agoraphobics’ lives become so restricted that they avoid normal activities like shopping, driving or traveling, or at least endure them with marked distress and often the fear of having a panic attack. The agoraphobic’s fear often stems from anxiety about being in places or situations from which escape might be difficult or embarrassing and/or help may not be available if they were to suffer an unexpected panic attack or panic-like symptoms.
Around 0.8 percent or 1.8 million U.S. adults suffer from agoraphobia each year. Three times as many women suffer from Panic Disorder With Agoraphobia than men.
Who’s at Greater Risk for Agoraphobia?
Risk factors include:
- People who have Panic Disorder
- Stressful life events, including childhood sexual or physical abuse
- Having other anxiety disorders, especially social anxiety disorder or generalized anxiety disorder
- A substance abuse disorder
- Females, Native Americans, low-income populations, and people who are either widowed, separated, or divorced are at increased risk
Obsessive-Compulsive Disorder (OCD)
People who have Obsessive-Compulsive Disorder (OCD) are bothered by persistent, upsetting thoughts (obsessions), and they use rituals (compulsions) to control or neutralize the anxiety that those thoughts produce. But the rituals end up controlling them. For example, people who are obsessed with germs or dirt may develop a compulsion to wash their hands over and over again. Someone who develops an obsession with intruders may recheck the locks on their doors many times before going to bed. Someone who also has social anxiety may brush their hair compulsively in front of a mirror, perhaps even becoming mesmerized by their image in the mirror and unable to move away from it.
The most common patterns of obsessive-compulsive behavior are fear of contamination and fears or doubts that lead to excessive checking, touching or counting behaviors. Common obsessions include having frequent thoughts of violence and fears of harming loved ones, persistently thinking about performing sexual acts the person dislikes, or having thoughts that are prohibited by religious beliefs. People with OCD are often preoccupied with rules, order and symmetry. Some have difficulty discarding things, so they accumulate or hoard unneeded items.
People with OCD usually try to help themselves by avoiding situations that trigger their obsessions. Some may use alcohol or drugs to calm themselves. People who have this disorder are usually aware that these intrusive thoughts or rigid behaviors are senseless, unrealistic, and inappropriate, which only results in more anxiety and dread. Performing rituals is not fun. It’s exhausting and time-consuming. It may soothe the anxiety created by obsessive thoughts, but only temporarily. The obsessions return. And so does the anxiety.
OCD symptoms may wax and wane, ease over time, or get worse. But because OCD is chronic, it can become debilitating. Severe OCD can prevent a person from holding down a job or carrying out normal responsibilities at home. Obsessions can impede one’s ability to complete normal tasks; for example, if someone continues to check all the door locks repeatedly, it might take hours to get to bed every night. Someone who obsesses about being “worthless” or “dirty” might take a 45-minute shower every morning and change clothes ten times, requiring her to get up a couple of hours earlier each morning just to get to work on time.
It bears mentioning that mentally healthy people also engage in compulsive behaviors from time to time, such as double-checking to make sure that the door is locked. The difference is that people with OCD continue to perform their rituals excessively (more than an hour each day), even though they find the repetition distressing and the rituals interfere with daily life. And while these behaviors or mental acts (e.g., repeating words silently) are aimed at neutralizing distress or preventing some dreaded event or situation, they may not even be connected in a realistic way with what they are designed to neutralize or prevent.
OCD affects 2 to 3 percent of the U.S. population over a lifespan (around 1 percent or 2.2 million adults in a given year). OCD can be accompanied by eating disorders, other anxiety disorders or depression. It strikes men and women in roughly equal numbers and typically begins in childhood, adolescence, or early adulthood, though it can occur at any point across a life span. One-third of adults with OCD develop symptoms as children, and research suggests that OCD may run in families. Of all the anxiety disorders, OCD has the highest percent of severe cases (50.6 percent).
A diagnosis of OCD does not require both obsessions and compulsions. Some people with OCD only have obsessions, some only compulsions.
Who’s at Greater Risk for OCD?
Risk factors include:
- In women, cultural pressures to meet everyone else’s needs except their own increase risk for OCD
- Familial history of OCD
- Childhood abuse or trauma is a strong predictor of OCD; especially physical or sexual abuse
- Stressful life events that trigger the intrusive thoughts, rituals and emotional distress and decreased emotional functioning
- Neurological soft signs (NSS) — minor, non-specific disturbances in brain functioning, such as impaired reflexes and motor coordination, may be linked to increased risk of OCD (Grisham, J., 2011)
Social Anxiety Disorder (Social Phobia)
Social Anxiety Disorder (also called Social Phobia) is diagnosed when someone who is overwhelmingly anxious and excessively self-conscious in everyday social situations.
People with social anxiety have an intense, persistent and chronic fear of being scrutinized and judged by others. They avoid social situations because they’re afraid of behaving in a way (or revealing anxiety symptoms) that will be humiliating or embarrassing. For example, social phobics may worry that they’ll be unable to perform when speaking, singing or playing a musical instrument, or that they might choke while eating in public, appear clumsy or silly to others, or will not be able to think of anything to say to unfamiliar people. Social anxiety can be limited to one situation (such as talking to people, eating or drinking in public) or it may be so broad (as in generalized social phobia) that the person experiences anxiety around almost everyone other than family and close friends.
Social phobics may worry for days or weeks leading up to a dreaded social event. This fear may become so severe that it interferes with work, school, and other normal activities. Social anxiety may make it difficult to make and keep friends. Over time, they may end up with no social life because it doesn’t seem worth the suffering. While most people with social anxiety realize that their fears about being with others are excessive or unreasonable, they’re unable to overcome them. Even if they manage to control their fears and take steps to socialize with others, they’re usually highly anxious beforehand, intensely uncomfortable throughout the encounter, and worry about how they will be judged for hours afterward.
Physical symptoms often accompany social anxiety, including blushing, profuse sweating, hoarseness, trembling, nausea, and difficulty talking. Such noticeable symptoms make social phobics feel as if all eyes are focused on them, and some may even experience a panic attack during an anxiety-triggering event, or even while anticipating the event.
Social anxiety disorder is currently estimated to be the third most common psychiatric disorder in the U.S. The annual prevalence of social phobia in U.S. adults is around 6.8 percent. (15 million adults). Recent studies report a lifetime occurrence of social phobias to be around 10 percent of the general population. Women and men are equally likely to develop the disorder, which usually begins in childhood or early adolescence. Because social anxiety is often suffered in silence, many people who seek treatment have had symptoms for at least 10 years.
Social anxiety disorder is often accompanied by other anxiety disorders or depression. Substance abuse may develop, especially for those who attempt to self-medicate their anxiety.
Who’s at Greater Risk for Social Anxiety Disorder?
While there’s some evidence of genetic risk for social anxiety disorder, other risk factors include:
- Familial history of OCD
- People with parents who are controlling or protective
- People who were shy, timid, withdrawn or restrained in childhood when facing new situations
- New social or work demands, such as meeting new people, public speaking or giving a presentation, may trigger the initial social anxiety symptoms, usually for people who had childhood social anxiety
- Having a condition that draws attention and increases feelings of self-consciousness, such as facial disfigurement or stuttering
- An overreactive amygdala
People with specific phobias have excessive or unreasonable fears of specific objects or situations. A specific phobia is an intense, irrational fear of something that poses little or no threat.
Specific phobia subtypes include:
- Animal Type (e.g., spiders, snakes)
- Natural Environment Type (e.g., heights, storms, water)
- Blood-Injection-Injury Type (e.g., fear of blood, injuries, injections or other invasive medical procedures)
- Situational Type (e.g., airplanes, elevators, enclosed places)
- Other Type (e.g., phobic avoidance of situations that may lead to: choking, vomiting, or contracting an illness; in children, avoidance of loud sounds or costumed characters)
The most common specific phobias include: flying, heights, blood, being closed-in, and thunderstorms. Other common phobias include: water, dogs, spiders, snakes, tunnels, and driving on highways.
Some types of specific phobias (e.g., fear of spiders or snakes) may be triggered and perpetuated after a single traumatic exposure. Phobias related to the environment or personal injury first appear in childhood, as early as age 5. Fear of tunnels, elevators, bridges, flying, driving and other situational phobias usually develop by the mid-20s. A specific phobia can even develop as a result of associating a neutral stimulus with an anxiety response; for example, someone experiences a panic attack or intense anxiety response while driving on the highway and comes to associate the highway with the anxiety or panic attack. Once the avoidance behavior occurs (the individual begins to avoid driving on the highway), the individual learns to become phobic.
People with specific phobias are aware that their phobias are irrational or unreasonable. They might be able to snow ski down a tall mountain comfortably but be unable to ride an elevator above the third floor of an office building. Exposure to the phobic stimulus typically provokes an immediate anxiety response, which may take the form of a panic attack. Adults with phobias often find that facing the feared object or situation triggers immediate anxiety, panic or severe, generalized anxiety. When they even think about facing a feared stimulus, they immediately feel nervous and panicky, a condition known as anticipatory anxiety. They worry about how they might behave if they’re exposed to the feared stimulus — will they faint, panic, lose control? People with specific phobias involving blood, injury or injection often experience a vasovagal response, such as reduced heart rate and blood pressure, that can actually cause them to faint. And all phobics tend to recall the phobic situation as more dangerous than it actually was; for example, the snake was bound to be poisonous; the dog was remembered as larger, faster and more aggressive than it actually was.
As long as the degree of discomfort is mild, or the feared situation or object is easy to avoid, most phobics are unlikely to seek help. But anticipatory anxiety and avoiding feared situations tends to significantly interfere with their normal routine, occupational (or academic) functioning, social activities and relationships.
Around 6.3 percent of U.S. adults are specific phobics; annual prevalence of specific phobias in U.S. adults is around 8.7 percent. Around 10 percent of all adults have suffered from a specific phobia at some point in their lives. Specific phobias are twice as common in women as men. They usually appear in childhood, the late teens or early 20s, and tend to persist into adulthood.
Who’s at Greater Risk for Specific Phobias?
Risk factors include:
- Familial history; parents often pass along specific phobias to children, such as a fear of spiders or snakes
- Direct exposure to a traumatic event (known as direct learning experience), such as being trapped in an elevator or attacked by an animal, may trigger the development of a phobia
- Witnessing a traumatic event (known as observational learning experience); i.e., witnessing others experience a traumatic experience or display fear and anxiety in specific situations; for example, witnessing someone falling from a building can trigger a phobia of high places
- Hearing or reading about dangerous situations (known as informational learning) can cause someone to develop a specific phobia; for example, a flying phobia can be triggered by frequently hearing of plane crashes
Posttraumatic Stress Disorder (PTSD)
Posttraumatic Stress Disorder (PTSD) can result when people experience or witness a traumatic event that involved actual or threatened death or serious physical injury to themselves or others and feel intense fear, helplessness, or horror as a result of the experience.
In general, the worse or more enduring the trauma, the greater the likelihood of developing PTSD. PTSD symptoms seem to be worse if the event that triggered them was deliberately initiated by another person, as in a mugging or a kidnapping.
The posttraumatic syndrome is typically experienced like this…
During or after the distressing event, the person experiences dissociative symptoms, such as detachment, depersonalization, decreased awareness, derealization (sense of unreality, the world seems unreal), feeling dazed or numb, or even amnesia (inability to recall an important aspect of the trauma). This physical and emotional numbing is often short-lived, followed by a flood of emotions (e.g., rage and grief) and physiological reactions. They began to relive the event, persistently reexperiencing it in recurrent images, thoughts, dreams, illusions, flashbacks, or distress triggered by reminders of the event. Each time, they have a sense of reliving the experience all over again through dreams, illusions, hallucinations, and dissociative flashback episodes. They may strongly avoid trauma-related stimuli (e.g., thoughts, feelings, conversations, activities, places, or people associated with the trauma) and exhibit emotional unresponsiveness. They experience physiological reactions (e.g., rapid heartbeat, elevated blood pressure) to internal or external cues that symbolize or resemble an aspect of the traumatic event. They experience anxiety and hyperarousal; for example, they may be irritable, restless, hypervigilant and startle too easily. They may have difficulty sleeping and concentrating.
Combat survivors are the most frequent victims, but PTSD can occur in people who have survived any type of catastrophic event — from bombings, assaults, kidnappings, rapes and car crashes to natural disasters such as floods, earthquakes and hurricanes. PTSD can also develop in people who did not directly experience the traumatic or harmful event; for example, someone who may have witnessed harm to a loved one or an event that threatened the lives of strangers. Children can develop PTSD as a result of an inappropriate sexual experience, even if there was no actual physical injury. In children, the helplessness and horror of trauma may be expressed by disorganized or agitated behavior.
People suffering from PTSD may feel lonely and isolated and have the sense that their lives will be foreshortened or unfulfilled.
Their behaviors can be easily misinterpreted. They may seem to have an inappropriate lack of feeling (“Why isn’t he more upset?”). Or they may be perceived as coping better than they actually are (“He’s so strong, he didn’t let it get to him!”).
Predominant symptoms in most people with PTSD include repeatedly reliving the traumatic event in flashbacks and desperately trying to avoid thinking about it or talking about it.
During a flashback, the person may lose touch with reality and believe that the traumatic event is happening all over again. Flashbacks are often triggered by ordinary occurrences that resemble some aspect of the trauma, such as a door slamming or a car backfiring. PTSD victims often assume guilt or responsibility for the event, feeling that they could have prevented it.
We all experience distracting emotions from time to time, but people with PTSD are often completely unable to control emotional intrusion into their thoughts. They get caught up in an endless loop between the amygdala, where we process emotions, and the hippocampus, which processes memories. The emotion triggers the memory, the memory triggers the intense feelings again, and they’re trapped in a painful cycle.
Posttraumatic symptoms last longer than a month. PTSD is diagnosed as acute if the symptoms last less than 3 months — chronic if they last longer than 3 months. It’s not uncommon for people with PTSD to experience a delayed onset. Symptoms may not appear until 6 months after the traumatic event. PTSD is often accompanied by depression, substance abuse, or other anxiety disorders.
PTSD affects nearly 3.5 percent (8 million) adults each year in the U.S., but it can occur at any age, including childhood. Women are more likely to develop PTSD than men, and older adults are less likely to develop symptoms than are younger ones.
Who’s at Greater Risk for PTSD?
While there is some evidence to support a genetic susceptibility to PTSD, traumatic events are the primary risk factor. After the September 11 attack on the World Trade Towers, for example, around 7.5 percent of New York City’s population reported PTSD within one month of the event, which declined to 0.6 percent at 6 months (A.D.A.M., 2012).
Other risk factors include:
- Pre-existing emotional disorder before a traumatic event, particularly depression.
- Drug or alcohol abuse
- A family history of anxiety
- A history of physical abuse, sexual abuse or neglect
- Early separation from parents
- Lack of social support or poverty
- Sleep disorders — Insomnia and excessive daytime sleepiness within a month after a traumatic event are significant predictors of PTSD. PTSD symptoms such as sleeplessness and nightmares may be intensified by sleep apnea, a condition in which tissues in the upper throat (airway) collapse at intervals during sleep, blocking air flow.
More than one-fourth of combat survivors are at high risk for PTSD, as are two-thirds of prisoners of war. And combat significantly elevates stress not only in soldiers, but in the families they leave behind. Children with military parents have higher blood pressure, heart rates and general stress levels during wartime than their peers. Since 2001, there has been a threefold increase in self-reported posttraumatic stress symptoms among combat-exposed U.S. military personnel. New onset PTSD symptoms are reported by up to 87 per 1000 combat-deployed personnel and up to 21 per 1000 non-combat deployed personnel, suggesting that a substantial number of new cases can be expected from combat in Iraq and Afganistan. PTSD incidence is higher among females who are divorced, enlisted, and have a drinking problem. 40 to 50 percent have persistent symptoms, which indicates that it may take several years to resolve PTSD symptoms (BMJ, 2008).
Acute Stress Disorder (ASD)
Acute Stress Disorder (ASD) is characterized by the development of severe anxiety and dissociative or other symptoms within one month after exposure to a traumatic stressor, such as witnessing a death or serious accident.
Typically, people who develop ASD were exposed to an event that involved actual or threatened death or serious injury, or a threat to the physical integrity of themselves or others and they responded to the stressor with intense fear, helplessness, or horror.
Acute Stress Disorder (ASD) symptoms are similar to those of PTSD, and, in fact, ASD includes all the elements required for PTSD. The distinction, however, is that ASD begins during or immediately after a stressful event, and only lasts for two days to one month.
(For details about the posttraumatic stress syndrome, see Posttraumatic Stress Disorder above.)
Who’s at Greater Risk for ASD?
Risk factors for developing ASD:
- A previous history of traumatic events
- A previous history of PTSD and/or other mental health disorders
- A tendency to exhibit certain symptoms when confronted with traumas, such as not knowing who or where you are
Does ASD predict PTSD? It often does. Some studies suggests that over 80 percent of people with ASD will develop PTSD within six months (Dept. of Veterans Affairs, 2007). Other studies indicate that between 4 to 13 percent of trauma survivors who don’t develop ASD in the first month after a trauma will develop PTSD in later months or years.
A.D.A.M. HealthCare Commission. New York Times Health Guide. Last reviewed 2-8-2012 by: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Grisham, J. R., Fullana, M. A., Mataix-Cols, D., Moffitt, T. E., Caspi, A., Poulton, R. Risk Factors Prospectively Associated With Adult Obsessive-Compulsive Symptom Dimensions and Obsessive-Compulsive Disorder. Psychological Medicine 41.12 (2011): 2495-506. Print.
Post Traumatic Stress Has Tripled Among Combat-exposed Military Personnel. British Medical Journal (2008, January 17).
United States Dept. of Veterans Affairs. 2007.