tative functions and inter-episode remissions.  A diagnosis based on a single episode is
possible, although the disorder is a recurrent one in the majori ty of cases. Careful consid-
eration is given to the delineation of normal sadness and grief from a major depressive ep-
isode. Bereavement may induce great suffering, but it does not typically induce an episode
of major depressive disorder. When they do occur together, the depressive symptoms and
functional impairment tend to be more seve re and the prognosis is worse compared with
bereavement that is not accompanied by majo r depressive disorder. Bereavement-related
depression tends to occur in persons with other vulnerabilities to depressive disorders,
and recovery may be facilitated by antidepressant treatment.
A more chronic form of depression, persiste nt depressive disorder  (dysthymia), can be
diagnosed when the mood disturbance continues for at least 2 years in adults or 1 year in
children. This diagnosis, new in DSM-5, includes both the DSM-IV diagnostic categories of
chronic major depression and dysthymia.
After careful scientific review of the evid ence, premenstrual dy sphoric disorder has
been moved from an appendix of DSM-IV (“ Criteria Sets and Axes Provided for Further
Study”) to Section II of DSM-5. Almost 20 years of additional of research on this condition
has confirmed a specific and treatment-responsi ve form of depressive  disorder that begins
sometime following ovulation and remits within a few days of menses and has a marked
impact on functioning.
A large number of substances of abuse, some prescribed medi cations, and several
medical conditions can be associated with de pression-like phenomena. This fact is recog-
nized in the diagnoses of substance/medicati on-induced depressive disorder and depres-