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According to the DSM-IV-R, dissociative identity disorder is when "two or more
distinct identities or personality states recurrently take control of the individual's
behavior, accompanied by an inability to recall important personal information that is
too extensive to be explained by ordinary forgetfulness."
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Dissociative Identity Disorder can be compared to a place setting of dishes including a
dinner plate, a salad plate, a soup bowl, a cup and a saucer. If you have a complete
place setting, you are prepared to have a complete dinner or any individual experience
of dinner you may encounter. But if you separate the place setting into individual
dishes, each piece is still functional but in an incomplete way.
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If you had only a cup, for example, it would be difficult to put a hamburger or a steak or
a potato in it, though it functions for a cup of coffee or tea. If you had only a
plate, it would be difficult to have soup for dinner, though it functions for the above
foods. With dissociative identity disorder, each identity is equipped to deal with
certain situations or memories, but none functions as a complete person. For example,
one "neutral" identity may function well at school or at work but is limited in its
emotional responses to situations. Another identity may have memories of traumatic
experiences and be ill-equipped to function in a benign setting, as its affective
responses are limited to fear, numbness or anger (which were appropriate responses to
traumatic events). A person with dissociative identity disorder doesn't have a range of
emotions, cognition and integrative functions to equip her or him to deal with life.
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It is a controversial diagnosis, with many individuals in the mental health field taking
polarized views that it absolutely does exist or, alternatively, that it is a confabulated
state produced by demand characteristics of usually well-meaning therapists.
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Pope, et al (1999) conducted a survey of American board-certified psychiatrists which
concluded that only a third agreed that dissociative amnesia and dissociative identity
disorder should be included without reservation in the DSM-IV, 25% agreed that these
diagnoses were supported by strong evidence of scientific validity, and the modal response
was that the diagnoses should be included only as proposed diagnoses.
Coons and Chu (2000) countered that Pope, et al were biased as they were members of the
False Memory Syndrome Foundation's scientific advisory board, and that the sample used for
the survey was biased in favor of older, male, biological psychiatrists who had not been
trained in dissociation. They also pointed out that the same survey published by Pope,
et al concluded that only 9-15% responded that the diagnoses should not be included in the
DSM-IV and only 20% felt that the diagnoses had little or no scientific validity.
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Little research is available regarding the biological basis for the disorder, which is
generally assumed to be a defense mechanism used by the mind to cope with extensive
childhood trauma, usually in the form of repeated and pervasive physical, emotional and
sexual abuse.
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Teicher, et al propose a theory that dissociative identity disorder is
a result of a cascade of events in the development of the brain in the context of
continuing trauma. They posit that the mammalian brain is "designed to be sculpted
into its final configuration by the effects of early experience." Before birth, 50% of
immature neurons are eliminated by apoptosis. Those remaining arborize and myelinate in
an attempt to establish appropriate connections. During childhood development, pruning
of axons and dendrites occurs without cell death. According to Teicher, et al, "the
final configuration of the circuitry occurs by elimination of synapses based on cell
interactions."
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The overexposure of the developing brain to stress chemicals, especially
glucocortisoids, has a suppressive effect on brain volume and DNA content, resulting in
underdevelopment of the left hippocampus, increased dopamine levels and decreased serotonin
levels in the amygdala and the nucleus accumbens, frontotemporal EEG abnormalities, decreased
corpus collosum size resulting in diminished communication between the two hemispheres,
decreased perfusion of the cerebellar vermis resulting in increased limbic irritability,
precocial maturation of the prefrontal cortex which may result in failure to reach its full
adult capacity, and decreased development of the left cerebral hemisphere. Alteration in
hippocampal development may contribute to the "anxiogenic, dissociative, amnesic and
disinhibitory aspects" of dissociative identity disorder. Excessive amygdaloid activation
accounts for the increased fight-or-flight aspects. Right-left asymmetries in serotonin and
dopamine projections to the amygdala and prefrontal cortex are highly correlated with anxiety.
Personality shifts may be related to decreased hemispheric integration and abnormal
hippocampal development and limbic irritability may make possible the generation of
dissociative states.
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Kelly A. Forrest (2001) theorizes that the orbitalfrontal cortex is the locus of
dissociative identity disorder. Forrest's theory posits that consistent nurturing in the
mother-infant dyad facilitates the infant's integration of different experiences of the
self in different situations into a coherent, inclusive self-concept. The orbitalfrontal
cortex (OFC) is responsible for inhibitory control of information, and through its
dopaminergic innervation controls emotion, attention, movement, visceral functioning,
including "initiation of movements toward emotionally significant stimuli, the pleasure
quality of social interactions, and the delayed response function...[which] allows the
individual to act on the basis of stored representations, not on the immediate context."
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For its development, the OFC relies on the child's reciprocal affective interactions with
its caregiver. In the context of disorganized interactions, the OFC fails to develop the
ability to maintain a consistent global concept of self across constantly varying
situations. This is not a failure to distinguish internal from external worlds, but a
failure to incorporate the different concepts of self that arise in different
circumstances into an overall integrated concept of self. Forrest theorizes that there
are different neural networks correlated with different self representations and that
"these networks must be integrated for individuals to experience a unified sense of self."
The inhibitory function of the OFC blocks additional information which would distract from
the child's response to its current context. This theory posits that in a traumatic
environment, the OFC prioritizes behavioral responses demanded by the immediate temporal
environment over the organization of behavior across contexts. The priority of
contradictory demands by the abusive adult creates contradictory self concepts and
prevents the development of self or self-in-relation concepts into a consistent conceptual
system of a global self.
Neuroimaging studies such as PET scans and fMRI studies have purported to show the brain
areas involved in personality switching and differential access of different personality
states to autobiographical memories of childhood trauma.
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Sources
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Site last reviewed and updated: 7/17/2005
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Does Dissociative Identity Disorder really exist?
