Epidemiology and Course

Anxiety disorders are the most prevalent category of mental health disorders. According to the National Comorbidity Survey Replication (NCS-R), specific phobia is the most common lifetime anxiety disorder (12.5 percent), followed by social anxiety disorder (SAD; 12 percent), panic disorder (PD; 5 percent), and generalized anxiety disorder (GAD; 6 percent). Agoraphobia without a history of PD is somewhat rare, with a prevalence of 2 percent.

Compared to mood and psychotic disorders, the age of onset is often earlier in life, and the course of illness is more chronic. SAD has a bimodal age of onset, typically occurring in adolescence or early adulthood, while PD, agoraphobia, and GAD have more variable ages of onset, with a median age of onset in the early to mid-twenties.

Comorbidities

Both psychological and medical comorbidities are common among individuals with anxiety disorders. Approximately half of individuals with a lifetime anxiety disorder meet the criteria for two or more distinct anxiety or traumatic stress disorders.

Mood and anxiety disorder comorbidity is also well documented. Results from the NCS-R indicate that compared to those without anxiety disorders, individuals with an anxiety disorder are approximately three to five times more likely to have a lifetime diagnosis of major depression, three to six times more likely to have a lifetime diagnosis of dysthymia, and four to six times more likely to have a lifetime diagnosis of bipolar disorder. For twelve-month prevalence rates, the strongest association between mood and anxiety disorders is found among PD, GAD, and SAD. Additionally, SAD, GAD, and PD have been found to be uniquely associated with a lifetime history of suicidal ideation and behaviors, highlighting the significant impact of these disorders on public health, with analyses by gender indicating that all three disorders are associated with suicidality in women, while only PD is uniquely associated with suicidality among men.

Individuals with anxiety disorders are also at higher risk for comorbid substance use disorders. Individuals with anxiety disorders in the past twelve months are shown to be three to four times more likely to have met criteria for alcohol dependence and three to nine times more likely to suffer from drug dependence in the last year, suggesting screening all patients with anxiety disorders for these issues is indicated. While alcohol dependence is strongly correlated with most anxiety disorders (with the exception of GAD), drug dependence tends to be most strongly associated with social and specific phobias.

Finally, anxiety disorders often co-occur with medical illnesses. Anxiety disorders have been shown to be associated with a number of somatic diseases such as respiratory conditions, gastrointestinal problems, allergies, atopic conditions, or migraine, even after controlling for the effect of depression. Although the direction of the causality varies and may not be well understood, patients presenting with anxiety disorders and somatic symptoms should undergo a review of systems and concurrent medical conditions should be considered in the differential diagnosis.

Impact

The social and economic burden of anxiety disorders is high. On an individual level, the presence of an anxiety disorder is associated with school dropout, marital discord, reduced educational attainment, and job dissatisfaction. All anxiety disorders, except specific phobia, are associated with lost economic productivity and reduced work efficiency. Furthermore, the cost of anxiety disorders in the United States during the 1990s was estimated to exceed $40 billion.

Panic Disorder

Panic disorder is a syndrome characterized by recurrent unexpected panic attacks about which there is persistent concern, or that are accompanied by significant behavioral changes such as extensive avoidance, for one month or more. Per DSM-V, panic attacks are discrete episodes of intense anxiety that develop abruptly, reaching a peak within minutes and associated with at least four symptoms across different domains including psychological (e.g., derealization, depersonalization, a fear of losing control or going crazy, or a fear of dying) and autonomic arousal (e.g., sweating, chills, or hot flashes), as well as cardiac (e.g., tachycardia, palpitations, chest pain, or discomfort), pulmonary (e.g., feeling of choking or shortness of breath), gastrointestinal (e.g., nausea or abdominal distress), and neurological symptoms (e.g., dizziness, lightheadedness, faintness, trembling and shaking, or paresthesias). Additional diagnostic criteria include persistent concern about having another attack or their consequences (e.g., losing control) and maladaptive behavior changes related to the attacks. In addition, the panic attacks are not accounted for by any other mental disorder (for example, panic attacks only during exposure to social situations in social anxiety disorder).

Whereas the initial panic attack is, by definition, unprovoked and spontaneous, panic attacks may also become linked to typical triggers, and apprehension frequently develops about future attacks (anticipatory anxiety). The age of onset is typically between late adolescence and the thirties, but many patients experience anxiety dating from childhood, often in the form of inhibited, anxious temperament or childhood anxiety disorders. In addition, many patients have limited symptom attacks (only 3 or fewer of the panic symptoms experienced); however, these subsyndromal symptoms are also associated with significant morbidity.

Panic disorder is often a chronic disease, with rates of relapse after discontinuation of treatment as high as 60 percent. Untreated panic disorder is often complicated by persistent anxiety and avoidant behavior, social dysfunction, marital problems, alcohol and drug abuse, as well as by increased utilization of medical services, and an increased mortality rate (from cardiovascular complications and suicide). Avoidant behavior often leads to a progressive constriction of a patient’s social interactions. Patients may experience chronic distress and demoralization which can trigger depression. Although alcohol can temporarily alleviate symptoms of anxiety, patients who abuse it may experience rebound anxiety, tolerance, and withdrawal, which may all exacerbate anxiety.

Agoraphobia

While Agoraphobia was associated with panic disorder in DSM-IV, it is no longer the case in DSM-V. Agoraphobia involves fear or anxiety in two or more of these situations from which ready escape might be difficult (or embarrassing), or where help may be unavailable in the event of a panic attack or in case of incapacitation: (1) outside home alone; (2) public transportation; (3) open spaces, including large parking lots or markets; (4) enclosed spaces (stores, theaters, or cinemas); and (5) standing in line or a crowd. The clinical significance criterion includes either avoidance of agoraphobic situations, or the need of a companion to face these situations, or intense worry and alarm in the situations. To meet the diagnosis, the fear or anxiety also needs to be out of proportion to the danger posed and typically persist for more than 6 months. Agoraphobia therefore significantly restricts a patient’s daily activities, with individuals occasionally becoming homebound.

Generalized Anxiety Disorder (GAD)

GAD was introduced in 1980 as a “catch-all diagnosis” for disorders not fitting in another category. Patients with GAD suffer from excessive anxiety or worry that is out of proportion to situational factors. As per DSM-V, the worry over a variety of concerns, must occur on more days than not for longer than six months and be associated with three associated symptoms including: muscle tension, restlessness, insomnia, difficulty concentrating, easy fatigability, and irritability. The anxiety must cause significant distress or impairment in function. Finally, the worry must not be related to features of other disorders, and the anxiety is not attributed to an organic cause (e.g., substance use, medical condition). Typically, people with GAD have been worrying excessively for years with the level of severity of anxiety, ruminations and other symptoms waxing and waning over time.

Specific Phobia

A phobia is an irrational fear related to a specific stimulus. On exposure to that stimulus, the individual reliably manifests an anxiety response. A patient may suffer from a specific phobia of any specific stimulus. Although specific phobias commonly generate circumscribed symptoms, they may interfere with some aspect of a patient’s functioning due to avoidance of the phobic stimulus or perseverance in the face of great discomfort (e.g., fear of flying leading to difficulty with travel). To meet the diagnosis, the fear or anxiety also needs to be out of proportion to the danger posed, typically persist for more than 6 months, and interfere with the person’s normal routine or cause marked distress.

When making the diagnosis, specific subtypes (e.g., animal, natural environment, blood-injection-injury, situational) should be specified.

Social Anxiety Disorder (SAD) or Social Phobia

Patients with SAD exhibit marked fear or anxiety about social situation(s) in which they are the focus of attention or might be scrutinized publicly. The patient fears that he or she will act in a way (or show anxiety symptoms) that will be negatively evaluated (e.g., leading to humiliation or embarrassment). This perception leads to persistent fear and ultimately to avoidance or endurance with intense distress of the social situation. To meet the diagnosis, the fear or anxiety also needs to be out of proportion to the danger posed, typically persist for more than six months, and interfere with the person’s normal routine or cause marked distress. The anxiety can be limited to circumscribed performance situations, like “performance anxiety” (e.g., public speaking); although discomfort related to public speaking is relatively frequent, significant distress or impairment is still required to warrant the diagnosis of the performance only subtype of SAD.

Patients frequently report early onset during childhood. The course of the disease is chronic but may fluctuate as symptoms may be worsened by stress as well as the level of exposure to social and performance activities. Finally, the symptoms should not be better accounted by an organic condition or by another mental disorder (e.g., trembling in Parkinson’s disease, stuttering); however, if the fear due to such condition is excessive, SAD may be diagnosed.