bination of careful questioning as to the sequence of events preceding or leading up to the
attack and the individual’s own judgment of wh ether or not the attack seemed to occur for
no apparent reason. Cultural interpretation s may influence the assignment of panic at-
tacks as expected or unexpected (see section “Culture-Related Diagnostic Issues” for this
disorder). In the United States and Europe , approximately one-half  of individuals with
panic disorder have expected panic attacks as  well as unexpected panic attacks. Thus, the
presence of expected panic attacks does not rule out the diagnosis of panic disorder. For
more details regarding expected versus unexpected panic attacks, see the text accompa-
nying panic attacks (pp. 214–217).
The frequency and severity of panic attacks vary widely. In terms of frequency, there
may be moderately frequent a ttacks (e.g., one per week) for months at a time, or short
bursts of more frequent attacks (e.g., daily) separated by weeks or months without any at-
tacks or with less frequent attacks (e.g., two per month) over many years. Persons who
have infrequent panic attacks resemble person s with more frequent panic attacks in terms
of panic attack symptoms, demographic charac teristics, comorbidity with other disorders,
family history, and biological data. In terms of severity, individuals with panic disorder
may have both full-symptom (four or more symptoms) and limited-symptom (fewer than
four symptoms) attacks, and the number and type of panic attack symptoms frequently
differ from one panic attack to  the next. However, more th an one unexpected full-symp-
tom panic attack is required for the diagnosis of panic disorder. 
The worries about panic attacks or their co nsequences usually pertain to physical con-