Anxiety disorders, as a group, are the most common psychiatric disorders in the United States with the exception of substance abuse disorders.1 Anxiety disorders are divided into six different disorders with different clinical presentations, prevalence/incidence, pathophysiology, treatments, and prognosis. These include panic disorder (PD), generalized anxiety disorder (GAD), obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), social anxiety disorder (SAD), and specific phobic disorders. Specific phobia refers to an individual's phobia or fear of certain objects or situations and is rarely treated with medications.2 Specific phobia will not be addressed in this chapter. It should also be noted that for patients to be diagnosed with any of the anxiety disorders discussed below, the symptoms must not be due to a general medical condition or substance and the symptoms must cause significant impairment in social or occupational functioning.2
The lifetime prevalence of PD is 1.6% to 2.2%, although 10% to 15% of the population may experience a single panic attack during their lifetime.3 Panic disorder is characterized by at least two unexpected panic attacks with associated anticipatory anxiety for at least 1 month.2 Those with PD may have associated agoraphobia or the fear of being in a place or situation where escape may be difficult. Panic attack is characterized by somatic or cognitive symptoms such as chest pain, palpitations, sweating, shortness of breath, fear of dying, dizziness, or hot flashes. These symptoms appear suddenly and last about 10 minutes. While patients can have multiple panic attacks in their lifetime, they may not necessarily have a PD. Patients with PD have approximately 40% lifetime prevalence of comorbid major depressive disorder (MDD).4
Generalized Anxiety Disorder
Generalized anxiety disorder is experienced by 5% of individuals during their lifetime and lasts for at least 6 months. It is characterized by chronic excessive worry and anxiety about life events.2 Additional symptoms may include feeling restless, difficulty concentrating, muscle tension or sleep disturbance, and easy fatigueability. Generalized anxiety disorder is more common among women and usually has a long course of illness. There does not appear to be a genetic link to development of GAD and there is a high incidence of comorbidity with MDD.
The lifetime prevalence of OCD is 1.6% and men tend to have an earlier onset of symptoms than women.5 There is a strong genetic link for OCD, as well as an association with antistreptococcal antibodies in a subgroup of children with OCD or tic disorders.6 Patients with OCD have either obsessions, compulsions, or both obsessions and compulsions. Obsessions are marked by recurrent and persistent thoughts that are inappropriate and cause significant anxiety in the person.2 Compulsions are characterized by repetitive behaviors that a person feels driven to perform. Adults who have either obsessions or compulsions recognize that these feelings are excessive, ...