disorder is thought to be markedly less than  for transient symptoms, although precise es-
timates for the disorder are unavailable. In general, approximately one-half of all adults
have experienced at least one lifetime episode of depersonalization/derealization. How-
ever, symptomatology that meets full criter ia for depersonalization/derealization disor-
der is markedly less common than transient sy mptoms. Lifetime prevalence in U.S. and
non-U.S. countries is approximat ely 2% (range of 0.8% to 2. 8%). The gender ratio for the
disorder is 1:1.
Development and Course
The mean age at onset of depersonalization/derealization disorder is 16 years, although the
disorder can start in early or middle childhood; a minority cannot recall ever not having had