Dissociative and Somatoform Disorders 335
Some people may spontaneously remember the forgotten experiences or infor-mation, particularly if their amnesia developed in response to a traumatic event and
they leave the traumatic situation behind, as when a soldier with localized amnesia
in response to combat leaves the battlefi eld. Anna O. recovered her ability to speak
German at the end of her treatment with Dr. Breuer, after she reenacted a traumatic
nightmare that she’d had when at her father’s sickbed (and that marked the start of
her problems).
Understanding Dissociative Amnesia
The following sections apply the neuro psychosocial approach as a framework for
understanding the nature of dissociative amnesia. Unfortunately, because the dis-
order is so rare, not much is known about either the specifi c factors that give rise
to it or how those factors might infl uence each other. In examining what is known
or hypothesized about the origins of this disorder, we’ll begin with neurological
factors and focus on the possible role of the hippocampus (a brain structure that
is crucial for storing new information in memory) and then consider the possible
role of hormones. Next, we’ll consider psychological factors, specifi cally the effects
of traumatic events and the nature of dissociation itself. Finally, we’ll turn to social
factors and explore the possible role of abuse.
Neurological Factors: Brain Trauma?
Neurological factors are clearly involved in cases of amnesia that arise following
brain injury, such as that suffered in a car accident (Piper & Merskey, 2004a).
However, when amnesia follows brain injury, it is not considered to be dissociative
amnesia. Neurological factors that may contribute to dissociative amnesia are less
clear-cut, as we’ll see.
Brain Systems Some researchers have suggested that dissociative amnesia may result
in part from damage to the hippocampus, which is critically involved in storing
new information about events in memory. These researchers assume that periods of
prolonged stress affect the hippocampus so that it does not operate well when the
person is highly aroused (Joseph, 1999). The arousal—which typically accompa-
nies a traumatic event—will impair the ability to store new information about that
event. Later, this process would lead to the symptoms of dissociative amnesia for
that event.
However, the idea that damage to the hippocampus underlies dissociativeamnesia cannot explain all cases of the disorder. Because such damage would
prevent information from being stored in the fi rst place, the subsequent amnesia
would not be reversible: There would be no way to retrieve the memories later
because the memories would not exist (Allen, Console, & Lewis, 1999). That is, the
Table 8.2 • Dissociative Amnesia
Facts at a GlancePrevalence- Dissociative amnesia is rare, and its
prevalence is unknown.
Comorbidity- Depression, anxiety, and substance-
related disorders may be present along
with dissociative amnesia. (Note: If the
amnesia is a result of substance use,
dissociative amnesia will not be the
diagnosis.)
Onset- Children or adults can develop this
disorder.
Course- Patients may have one or multiple epi-
sodes of amnesia.
Gender Differences- No gender differences in the prevalence
of dissociative amnesia have been
reported.
Cultural Differences- Dissociative amnesia may be a culture-
related diagnosis; there are no reported
cases of this disorder (due to a traumatic
event by itself, in the absence of brain
damage resulting from the trauma) prior
to 1800 (Pope et al., 2007).
Source: Unless otherwise noted, the source is
American Psychiatric Association, 2000. For more
information see the Permissions section.
CASE 8.1 • FROM THE OUTSIDE: Dissociative Amnesia
Mrs. Y, a 51-year-old married woman... had a two-year history of severe depressive episodes
with suicidal ideation, and reported total loss of memory for 12 years of her life... from the
age of 37 to 49. [The amnesia began at age 49 when] she had had a car accident from which
she sustained a very minor injury, but no loss of consciousness [nor any] posttraumatic stress
symptoms.... She remembered what happened in the accident, and immediately preceding
it, but suddenly had total loss of memory for the previous 12 years.
Mrs. Y had no problems recalling events which had occurred since the accident. She also
had good autobiographical memory for her life events up to the age of 37.
Her parents and her grown-up children had told her that the... 12 years were painful for
her. They would not tell her why, as they thought it would distress her even more. She was not
only amnesic for these reputedly painful events, [but was unable] to recognize any of the
friends she had made during that time. This included her present man friend, who was
the passenger in her car at the time of the accident. Her family had told Mrs. Y that this
gentleman (Mr. C) had been courting her for six years prior to the accident.
(Adapted from Degun-Mather, 2002, pp. 34–35)P SN