Anxiety is a specific unpleasurable state of tension that forewarns the presence of danger, real or imagined, known or unrecognized, and is often verbalized as an intense feeling of worry. Anxiety is often a normal adaptation to life events or stressors, and in many circumstances, could be considered appropriate given the context and would represent a reasonable emotional response to a perceived threat or circumstance. Even extreme levels of anxiety could be considered appropriate given the level of perceived threat. An anxiety disorder, however, describes a condition in which a response to a given circumstance or threat becomes significantly disproportionate or uncontrollable, leading to the deterioration of performance and an inability to cope. As the level of dysfunction increases, the patient is much more likely to have a true anxiety disorder. Anxiety disorders are considered to be among the most prevalent of mental health behavioral and emotional disorders worldwide.

Acute anxiety is common in emergency department (ED) patients who have primary anxiety disorders, concomitant anxiety disorders, and crisis situations. Emergency physicians are frequently called upon to diagnosis and treat anxiety disorders in the ED and therefore need to be familiar with both the diagnostic criteria as well as the differential diagnoses and treatment modalities. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for anxiety disorders include general anxiety disorder, panic disorder, agoraphobia, and specific phobia. Obsessive-compulsive disorders (OCD), post-traumatic stress disorder (PTSD), and acute stress disorder, which have now been moved to their own category in the DSM-5, will also be discussed in this chapter.

The most recent available national statistics on past-one-year and lifetime prevalence of anxiety disorders amongst adults (age 18 or older) is derived from the National Comorbidity Study Replication (NCS-R) originating from the Harvard Medical School National Comorbidity Survey (NCS). Data updated as of 2007 reveals 19.1% past-year prevalence with a female predominance (23.4% versus 14.3%) and an overall lifetime prevalence of 31.1% among all adults in the United States (US).

Many patients seeking primary health care have significant mood and anxiety symptoms, such as panic disorder, generalized anxiety disorders (GAD), and depression, but almost half of these symptomatic patients never receive appropriate treatment. Patients with chronic illness and those who make frequent medical visits have higher rates of anxiety and depression. The prevalence of anxiety disorders surpasses that of any other mental health disorder, including substance abuse. There is a close relationship between alcohol abuse and anxiety disorders.

Anxiety disorders in children and adolescents lead to anxiety disorders in adulthood, but anxiety disorders often go unrecognized and untreated in the pediatric population. The same is true of geriatric patients with a prevalence rate of 1.2% to 15%. Except for generalized anxiety disorder and agoraphobia, anxiety disorders typically start earlier in life.

The incidence of specific anxiety disorders varies: specific phobia is 7% to 9%, social anxiety is 7%, panic disorder is 3%, and GAD is 3%. The lifetime risk for post-traumatic stress disorder (PTSD) is about 9%, but the 12-month prevalence is approximately 4%. Substance or medication-induced anxiety and anxiety due to a medical condition have an unknown prevalence but may be relatively high in those seeking emergency medical care.

A different form of anxiety related to fear of suffering from an illness, now known as illness anxiety disorder (formerly hypochondriasis), may be as high as 8% in ambulatory medical populations. In these cases, patients may disguise their anxiety, presenting with a physical complaint rather than bear the perceived stigma associated with psychiatric complaints. This is distinct from patients with a somatoform disorder.

There are many forms of anxiety disorders and the precise mechanisms underlying the development of anxiety have not been fully established. However, the serotonin, noradrenergic gamma-aminobutyric acid (GABA) and dopaminergic systems are the most studied neurotransmitter systems implicated in anxiety disorders (see Box 98.1 ). It is hypothesized that low serotonin system activity and elevated noradrenergic system activity may play a role, and thus selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs) are frequently used as treatment. There is also considerable comorbidity with depressive disorders, with evidence showing genetic and neurobiologic similarities, especially related to serotonin.

The well-established effectiveness of benzodiazepines in the treatment of anxiety has led to the study of the GABA system and its relationship to anxiety. GABA is the principal inhibitory neurotransmitter in the central nervous system, and benzodiazepines act on the GABA _A receptors. Studies have also focused on the role that corticosteroids may play in fear and anxiety. Steroids are thought to induce chemical changes in select neurons that strengthen or weaken certain neural pathways to affect behavior under stress.

Family research suggests that genetic factors play a role in anxiety, but the precise nature of the inherited vulnerability is unknown. Five major anxiety disorders (panic disorder, GAD, phobias, OCD, and PTSD) share genetic and environmental risk factors. Psychological and environmental factors also contribute to the generation of anxiety in biologically predisposed individuals.

Panic disorder (PD) is a diagnosis of exclusion, even in patients with known psychiatric illness, because several mental illnesses cause panic attacks as a secondary manifestation. For a diagnosis of panic disorder, one must experience recurrent, unexpected panic attacks ( Box 98.3 ), as well as either persistent concern of future attacks or a maladaptive behavioral change related to the attacks. As with other disorders, the disturbance should not be better explained by substance use, another medical condition, or another psychiatric illness.

A panic attack, differentiated from panic disorder, is an abrupt fear or discomfort that reaches a peak within minutes and has associated physical and cognitive symptoms. ^2. It may occur with any anxiety disorder or as part of another psychiatric or other medical disorder. A panic attack is not a diagnosis but rather an indication of an underlying disorder. The presence of panic attacks often influences the treatment and outcome of the primary illness. An attack can be replicated by intentional hyperventilation, which can be distinguished from medical hyperventilation by its irregularity and interruptions. When there is doubt, formal psychiatric evaluation is indicated, particularly before a potentially dangerous or addictive drug therapy is prescribed.

GAD is defined as excessive worry that occurs most days over a 6-month period involving several events or activities. The anxiety must cause significant distress or impairment in functioning. GAD has been linked to overuse of medical services and often is not recognized, which leads to ineffective treatment.

PTSD is caused by experiencing or witnessing a highly traumatic event. Those with PTSD manifest symptoms of re-experiencing the event, avoidance of triggers, changes in cognition and mood, and changes in arousal and reactivity ( Box 98.4 ). Rates of PTSD are higher among military veterans and those whose occupation involves risk of traumatic exposure. ED staff are also at risk for experiencing PTSD related to unusual traumatic events and unexpected deaths. Those suffering from PTSD may also be suffering from other disorders such as OCD, personality disorders, and substance use disorders, and may even exhibit suicidal ideations.

A phobia is an irrational fear that results in avoidance behavior. Phobia becomes a disorder when it interferes with day-to-day function in an individual’s life. Social phobia, now termed social anxiety disorder, is characterized by clinically significant anxiety about one or more social situations in which the individual may be scrutinized. This fear often leads to avoidance or other changes in behavior for such activities, such as public speaking, performing, visiting people, sitting in classrooms, attending social events using public showers or restrooms, or eating in public places.

OCD is characterized by recurrent, intrusive, unwanted thoughts (obsessions), such as fears of contamination, or compulsive behaviors or mental acts (compulsions) that a person feels compelled to perform, such as handwashing or counting. OCD is considered an anxiety disorder because (1) anxiety or tension is often associated with obsessions and resistance to compulsions, (2) anxiety or tension is often immediately relieved by yielding to compulsions, and (3) OCD often occurs in association with other anxiety disorders. In summary, the obsessions and intrusive thoughts increase anxiety, and the compulsions and repetitive behaviors decrease anxiety but with significant disruption of one’s life.

Hyperventilation syndrome is a disorder characterized by intermittent episodes of increases in minute ventilation, together with feelings of doom and anxiety, associated with somatic symptoms such as dyspnea, chest pain, lightheadedness, perioral numbness and tingling, and muscle spasm of the hands and feet. Underlying conditions that may cause or contribute to this syndrome include primary psychological or neurologic dysfunction as well as cardiopulmonary etiologies. The diagnosis of hyperventilation syndrome may be challenging since there are no widely accepted diagnostic criteria. Patients presenting with new-onset hyperventilation require an extensive history, as well as physical examination and screening laboratories to rule out lethal etiologies. Patients with known hyperventilation syndrome from a psychological etiology can benefit from reassurance, breathing therapy, and low doses of benzodiazepines. A study of patients presenting to an ED with hyperventilation syndrome found 30% had previous episodes and more than 50% had a psychiatric comorbidity.

Although not necessarily categorized as anxiety disorders, this group of disorders has an undefined but established link to anxiety and depressive disorders and includes somatic symptom disorder, illness anxiety disorder (formerly hypochondriasis), conversion disorder (formerly functional neurological symptom disorder), and psychological factors affecting other medical conditions. With somatic disorders, the patient will complain about one or more physical symptoms, which cause impairment notwithstanding a negative evaluation. These symptoms are not intentionally feigned, as in the case of malingering or factitious disorder. A high utilization of medical services is correlated with these disorders, independent of comorbidity. Patients with somatoform disorders may seek as much psychiatric attention as do those with panic disorder.