Prevalence and Course
The one-year prevalence for any panic attack, whether unexpected or situationally cued, is approximately 28%. Lifetime prevalence rates for unexpected panic attacks and agoraphobia are approxi-mately 4 and 9%, respectively. The National Comorbidity Survey Replication (NCS-R) found lifetime prevalence rates of 4.7% for panic disorder and 1.4% for agoraphobia without panic (Kesseler et al., 2005). Investigations of unexpected panic attacks in col-lege student samples using self-report methodology have revealed similar rates, ranging from approximately 5 to 11%.
The National Comorbidity Study (Eaton et al., 1994) has reported the lifetime prevalence of panic disorder (with or with-out agoraphobia) in the general population to be 3.5%. However, despite uncertainty as to the reason, this rate is somewhat of an anomaly in the literature. Most epidemiological studies, includ-ing those based on Epidemiologic Catchment Area and other data sources, have consistently shown lifetime rates between 1 and 2%. The National Comorbidity Survey Replication (NCS-R) found lifetime prevalence rates of 4.7% for panic disorder and 1.4% for agoraphobia without panic (Kesseler et al., 2005). In treatment seeking individuals, the prevalence of panic disorder is considerably higher. Approximately 10% of patients in mental health clinics and between 10 and 60% in various medical spe-cialty clinics (e.g., cardiology, respiratory, vestibular) have panic disorder. Panic disorder with agoraphobia is more common than panic disorder without agoraphobia in clinical samples.
Age of onset for panic disorder is distributed bimodally, typically developing between 15 and 19 or 25 and 30 years. The clinical features of panic disorder such as number and severity of symptoms are much the same across the sexes. However, women are diagnosed with panic disorder more than twice as often as men. Recent research indicates that women are more likely to have panic disorder with agoraphobia and that they are more likely to have recurrence of symptoms after remission of their panic attacks than are men (Yonkers et al., 1998). Men, on the other hand, are more likely to have panic disorder without agora-phobia (Yonkers et al., 1998) and are more likely to self-medicate with alcohol than are women. The literature remains unclear as to why these sex differences exist but alludes to the possible role of biological and/or socialization factors.
Panic disorder symptoms may wax and wane but, if left untreated, the typical course is chronic. Data from a sample of patients assessed and treated through the Harvard/Brown Anxi-ety Disorders Research Program and followed prospectively over a 5-year period indicated remission rates in both men and women to be 39% (Yonkers et al., 1998). In general among those receiv-ing tertiary treatment, approximately 30% of patients have symp-toms that are in remission, 40 to 50% are improved but still have significant symptoms, and 20 to 30% are unimproved or worse at 6 to 10 years follow-up.