Acute stress disorder is a disorder that is similar to posttraumatic stress disorder (PTSD), but acute stress disorder occurs earlier than PTSD (within 4 weeks of the traumatic event) and remits within 2 days to 1 month after a trauma (not PTSD).

PTSD shows three domains of symptoms: reexperiencing the trauma; avoiding stimuli associated with the trauma; and experiencing symptoms of increased autonomic arousal, such as enhanced startle. Flashbacks, in which the individual may act and feel as if the trauma is recurring, represent a classic form of reexperiencing. Other forms of reexperiencing symptoms include distressing recollections or dreams and either physiological or psychological stress reactions on exposure to stimuli that are linked to the trauma. Symptoms of avoidance associated with PTSD include efforts to avoid thoughts or activities related to trauma, anhedonia, reduced capacity to remember events related to trauma, blunted effect, feelings of detachment or derealization, and a sense of a foreshortened future. Symptoms of increased arousal include insomnia, irritability, hypervigilance, and exaggerated startle. The diagnosis of PTSD is only made when symptoms persist for at least 1 month; the diagnosis of acute stress disorder is made in the interim.

Acute stress disorder is characterized by reexperiencing, avoidance, and increased arousal, similar to PTSD. Acute stress disorder (not PTSD) is also associated with at least three dissociative symptoms.

Disorders that may enhance the risk for the development of anxiety disorders include eating disorders, depression, and substance use and abuse. In contrast, anxiety disorders have been shown to elevate the risk of subsequent substance use disorders and may comprise a mediator of the link between depression and the subsequent development of substance use disorders in a clinical sample.

Several studies have also suggested that there is an association between anxiety disorders and allergies, high fever, immunological diseases and infections, epilepsy, and connective tissue diseases. Likewise, prospective studies have revealed that the anxiety disorders may comprise risk factors for the development of some cardiovascular and neurological diseases, such as ischemic heart disease and migraine.

A good prognosis for people with obsessive-compulsive disorder (OCD) is indicated by good social and occupational adjustment, the presence of a precipitating event, and an episodic nature of symptoms. About one-third of patients with OCD have major depressive disorder, and suicide is a risk for all patients with OCD. A poor prognosis is indicated by yielding to (rather than resisting) compulsions, childhood onset, bizarre compulsions, the need for hospitalization, a coexisting major depressive disorder, delusional beliefs, the presence of overvalued ideas (i.e., some acceptance of obsessions and compulsions), and the presence of a personality disorder (especially schizotypal personality disorder). The obsessional content does not seem to be related to the prognosis.

The results of community studies reveal that women have greater rates of almost all of the anxiety disorders. Despite differences in the magnitude of the rates of specific anxiety disorders across studies, the gender ratio is strikingly similar. Women have an approximately twofold elevation in lifetime rates of panic, generalized anxiety disorder, agoraphobia, and simple phobia compared with men in nearly all of the studies. The only exception is the nearly equal gender ratio in the rates of OCD and social phobia.

Studies of youth report similar differences in the magnitude of anxiety disorders among girls and boys. Similar to the gender ratio for adults, girls tend to have more of all subtypes of anxiety disorders irrespective of the age composition of the sample. However, it has also been reported that despite the greater rates of anxiety in girls across all ages, there is no significant difference between boys and girls in the average age at onset of anxiety.

Anxiety disorders have been shown to have the earliest age of onset of all major classes of mental and behavioral disorders with a median onset by the age of 12 years. This is far earlier than the onset of mood disorders or substance use disorders and comparable to that of impulse control disorders. Women have greater rates of anxiety disorders than men. This difference in gender rates can be seen as early as 6 years of age. Despite the far more rapid increase in anxiety disorders with age in girls than in boys, there are no gender differences in the mean age at onset of anxiety disorders (not higher in girls) or in their duration. Female preponderance of anxiety disorders is present across all stages of life but is most pronounced throughout early and mid-adulthood. The rates of anxiety disorders in men are also rather constant throughout adult life, but the rates in women peak in the fourth and fifth decades of life and decrease thereafter.

Studies show a three- to fivefold increased risk of anxiety disorders among first-degree relatives of persons with anxiety disorders. Twin studies reveal that panic disorder has the highest heritability and has been shown to have the strongest degree of familial aggregation, with an almost sevenfold elevation in risk.

Sigmund Freud viewed phobias as resulting from conflicts centered on an unresolved childhood oedipal situation. In adults, because the sexual drive continues to have a strong incestuous coloring, its arousal tends to create anxiety that is characteristically a fear of castration. The anxiety then alerts the ego to exert repression to keep the drive away from conscious representation and discharge. Because repression is not entirely successful in its function, the ego must call on auxiliary defenses. In phobic patients, the defenses, arising genetically from an earlier phobic response during the initial childhood period of the oedipal conflict, involves primarily the use of displacement—that is, the sexual conflict is transposed or displaced from the person who evoked the conflict to a seemingly unimportant, irrelevant object or situation, which has the power to elicit anxiety. The phobic object or situation selected has a direct associative connection with the primary source of the conflict and has thus come naturally to symbolize it. Furthermore, the situation or object is usually such that the patient is able to keep out of its way and by the additional defense mechanism of avoidance to escape suffering from serious anxiety.

Regression is an unconscious defense mechanism in which a person undergoes a partial or total return to early patterns of adaptation. Condensation is a mental process in which one symbol stands for a number of components. Projection is an unconscious defense mechanism in which persons attribute to another person generally unconscious ideas, thoughts, feelings, and impulses that are undesirable or unacceptable in themselves. In psychoanalysis, isolation is a defense mechanism involving the separation of an idea or memory from its attached feeling tone. Dissociation is an unconscious defense mechanism involving the segregation of any group of mental or behavioral processes from the rest of the person’s psychic activity. Table 16.1 describes a more current view of seven of the psychodynamic themes in phobias.

Community studies have consistently found that rates of anxiety disorders in general are greater among those at lower levels of socioeconomic status and education level. Anxiety disorders are negatively associated with income and education levels. For example, there is almost a twofold difference between rates of anxiety disorders in individuals in the highest income bracket and those in the lowest and between those who completed more than 16 years of school and those who completed less than 11 years of school. In addition, certain anxiety disorders seem to be elevated in specific occupations. Anxiety disorders are higher in homemakers and those who are unemployed or have a disability. Several community studies have also yielded greater rates of anxiety disorders, particularly phobic disorders, among African Americans. The reasons for ethnic and social class differences have not yet been evaluated systematically; however, both methodological factors and differences in exposure to stressors have been advanced as possible explanations.

Generalized anxiety disorder (GAD) is a chronic (not mild) condition, and nearly half of patients who eventually recover experience a later recurrence. GAD is characterized by frequent, persistent worry and anxiety that is disproportionate to the impact of the events or circumstances on which the worry focuses. The distinction between GAD and normal anxiety is emphasized by the use of the words “excessive” and “difficult to control” in the criteria and by the specification that the symptoms cause significant impairment or distress. The anxiety and worry are accompanied by a number of physiological symptoms, including motor tension (i.e., shakiness, restlessness, headache), autonomic hyperactivity (i.e., shortness of breath, excessive sweating, palpitations), and cognitive vigilance (i.e., irritability). The ratio of women to men with the disorder is about 2:1 (not 1:2). The disorder usually has its onset in late adolescence or early adulthood, although cases are commonly seen in older adults. Also, some evidence suggests that the prevalence is particularly high (not low) in primary care settings. This is because patients with GAD usually seek out a general practitioner or internist for help with a somatic symptom. GAD is probably the disorder that most (not least) often coexist with another mental disorder, usually social phobia, specific phobia, panic disorder, or a depressive disorder.

According to current conceptualizations, PTSD is associated with objective measures of physiological arousal. This includes elevated baselines heart rate, increased blood pressure, and excessive sweating. Furthermore, evidence from studies of baseline cardiovascular activity revealed a positive association between heart rate and PTSD.

The finding of elevated baseline heart rate activity is consistent with the hypothesis of tonic sympathetic nervous system arousal in PTSD. Disturbance in autonomic nervous system activity in individuals with PTSD is characterized by increased sympathetic and decreased parasympathetic tone. Preliminary evidence suggests that this autonomic imbalance can be normalized with selective serotonin reuptake inhibitor treatment. There is no change in blood level of thyroxine in those with PTSD.

Unexpected panic attacks are required for the diagnosis of panic disorder, but panic attacks can occur in several anxiety disorders. The clinician must consider the context of the panic attack when making a diagnosis. Panic attacks can be divided into two types: (1) unexpected panic attacks, which are not associated with a situational trigger, and (2) situationally bound panic attacks, which occur immediately after exposure in a situational trigger or in anticipation of the situational trigger. Situationally bound panic attacks are most characteristic of social phobia and specific phobia. In generalized anxiety disorder, the anxiety cannot be about having a panic attack.

Some differences between the DSM-IV-TR and earlier versions in the diagnostic criteria of panic disorder are interesting. For example, no longer is a specific number of panic attacks necessary in a specific period of time to meet criteria for panic disorder. Rather, the attacks must be recurrent, and at least one attack must be followed by at least 1 month of anticipatory anxiety or phobic avoidance. This recognizes for the first time that although the panic attack is obviously the seminal event for diagnosing panic disorder, the syndrome involves a number of disturbances that go beyond the attack itself. Isolated panic attacks without functional disturbances are not diagnosed as panic disorder. Furthermore, isolated panic attacks without functional disturbance are common, occurring in approximately 15 percent of the population.