Dissociative Identity Disorder and Temporal Lobe Involvement: Replication and a Cautionary Note.
William Sheehan, M.D., Barry Sewall, M.D.
Rice Memorial Hospital, Willmar, Minnesota, USA
Steven Thurber, Ph.D.
Woodland Centers, Willmar, Minnesota, USA
The patient is a 37 year old female. Between the ages of four and twelve, she reportedly was the victim of severe, repetitive abuse by her grandfather, both physical and sexual including insertion of sharp, painful objects (e.g., knives) into her vagina, and hanging her from pulleys. According to the patient, physical and sexual abuse occurred every weekend during this time period. The grandfather threatened to kill her if she ever revealed the abuse. It finally ended with the grandfather’s death. It is important to note that the patient’s parents were not able or were unwilling to corroborate these allegations nor could the patient provide any external confirmatory evidence.
The patient was diagnosed with Dissociative Identity Disorder (DID) by psychotherapists who had worked with her over a six year period. They indicated that “alters” usually emerged quite abruptly with marked changes in facial expression, tone, and prosody of voice, vocabulary, and gesture; there were also reportedly differences in handwriting, behavioral and affective expressions; some were more playful, informal, warm or witty than the patient’s adult persona.
The patient is currently an elementary school teacher who reported an initial alter enactment while instructing a class of students; a four year old girl emerged who began to color with the crayons she, as teacher, used with her students. Later, another alter emerged who began to trash the classroom because “she did not want to be back at school.”
The “alters” coexisted without full awareness of one another, and in particular, she as an adult could intuit but did not know directly what had been expressed by them when they enacted; it was like material from a kind of dream state. Nevertheless, as an adult, she was able to maintain control and appear to be an integrated person. When the “dominant personality” re-emerged, the patient would roll or close her eyes, seem semi-stuporous for a few moments, and then gradually regain orientation and awareness over about the next twenty or thirty seconds. There was a distinctly post-ictal quality to these re-emergences of the controlling “adult,” a returning back, as it were, from a trance or dream.
The patient had been subjected to much skepticism by mental health professionals and was eager to have her condition “validated” by the “objective” evidence from a Single Photon Emission Computed Tomography (SPECT) scan. For the first scan, she summoned “Emma,” a girl who purportedly suffered the most severe abuse at the age of ten. “Emma” was injected intravenously with 23.0 mCi of flow tracer 99m-technetium (neurolite) and imaging was obtained according to the usual protocol in a nuclear medicine department. A week later, she presented as her adult self and the procedure was repeated.
SPECT images were obtained in the axial, sagittal, and coronal planes. Inter-comparison showed a visually apparent increase of activity in the mesial temporal lobe on the left compared to the right in the scan performed on the “adult.” In the “Emma” state, activity in the left and right temporal lobes was indistinguishable. In contrast, the adult showed a significant asymmetry, with increased activity in the left temporal lobe, This was consistent with a previous SPECT study indicating the temporal lobes, -and the left temporal lobe, in particular-may mediate the phenomenon of dissociative identity disorder (Saxe, Vasile, Hill, Bloomingdale, & van der Kolk, 1992).
The involvement of the temporal lobes in DID is not surprising, in light of connections between the temporal lobe and the limbic system. The latter includes the amygdale, which is involved in the processing of emotional responses and in particular fear, and the hippocampus, which is vital to memory storage. In theory, the patient was able to induce dissociative states seemingly at will, presumably by increased volitional inputs involving neurons in other cortical areas-the temporal lobe has heightened sensitivity to electrical stimulation from other neurons—and when emerging from a dissociative state did appear confused and disoriented.
One possible interpretation of these observations would be that the dissociative condition was in fact a form of temporal lobe seizure. This is of interest in that the temporal lobe is more prone to seizure activity than any other lobe of the cortex (Engle, 1996). Patients with temporal lobe epilepsy may exhibit traits that define the Geschwind syndrome (Benson, 1991): Hypergraphia, emotional volatility, altered sexuality (usually decreased), over-inclusiveness, and extreme talkativeness related to excessive attention to detail. The patient in both her baseline and altered states exhibited all of these traits; her hypergraphia was especially noteworthy wherein she produced numerous letters by her dominant self and purportedly by her “alter” enactments. In addition, temporal lobe seizures are notable for producing states of altered consciousness, including those in which the sense of personal identity may disappear and a person may experience “out of body” experiences as well as free-floating feelings of doom or ecstasy (see Geschwind, 1977). Indeed, behaviors that give the verisimilitude of personality change can be evoked in individuals with temporal lobe epilepsy (Ahern, Herring, Tackenberg, & Seeger, 1993).We do not claim that the patient in our study evinced temporal lobe seizures; but her ostensive changes of identity did have aspects that seemed “seizure-like;” indeed,
behaviors that give the verisimilitude of personality change can be evoked in individuals with temporal lobe epilepsy (Ahern, Herring, Tackenberg, & Seeger, 1993). This suggests as a possible avenue of intervention the use of medication (that has not been tried hitherto) such as Trileptal, which is useful in the treatment of temporal lobe epilepsy.
Another possible lead in trying to understand the phenomenon of dissociation relates to the possibility of regarding alter enactments as a condition in which selective removal of inhibition of the more verbal left temporal lobe results in “paradoxical functional facilitation” of the more intensely visual right temporal lobe activity. This refers to the notion that reduction in left temporal lobe functioning (as in fronto-temporal dementia) may render decreased inhibition of the more right-sided visual systems (Miller, Boone, Cummings, Read, & Mishkin, 2000). This would account for the finding that the increased activity of the left temporal lobe was found in our patient in relation to the more verbally sophisticated “adult” persona. A reduction of left temporal activity accompanied by a loss of semantic knowledge and increased visual revivifying of early life experiences (visual and emotional) seemingly occurred with the ten year old child enactment.
Our data converge with five other independent investigations using SPECT, electroencephalography, or functional magnetic resonance imaging in supporting the association between DID and temporal lobe functioning (Semiz, Ebrinc, Cetin, Narin, & Ozguven, 2000; Hughes, Kuhlman, Fichtner, Gruenfeld, & Brain, 1990; Mesulam, 1981; Saxe, Vasile, Hill, Bloomingdale, & Van der Kolk; Tsai, Condie, Wu, & Chang, 1999).
Dissociative Identity Disorder (erstwhile Multiple Personality Disorder) remains highly controversial. It has been characterized as a creation of psychotherapy and the media, for example, rather than a genuine dysfunction (Spanos, Weekes, & Bertrand, 1985). Moreover, neuroscientists and practitioner blithely attribute the symptoms of DID to antecedent traumatic events albeit this connection has never been scientifically corroborated; hence the posttraumatic model of DID, presumed in this article, lacks construct validation (Piper & Merskey, 2004). It also appears that routinely practitioners and researchers accept the patient’s self report of child abuse without any type of corroborating evidence (as we did in this study). Moreover, they have failed to confirm the existence of DID symptoms prior to psychotherapy (again, we too are at fault). The latter is important given the possibility of iatrogenic etiology of DID (see Spanos, 1994). Researchers in this area have also, in the main, failed to acknowledge competing explanations for the temporal lobe-DID relationship. For instance, it is possible that a connection between imagined or false memories of abuse and later manifestations of DID may be mediated by the temporal lobe similar to reported transcendental experiences, extraterrestrial visitations, pseudocyesis, and alien abductions (see Persinger and de Sano, 1986; Persinger, 1989, Persinger, 1996).Further, persons with temporal lobectomies are deficient in accurate attributions as to the source of experiences, imagined or perceived (Schwerdt & Dopkins, 2001).
It is concluded that corroboration of temporal lobe involvement in the phenomenon of dissociative identity disorder does not reify this diagnostic classification, but does suggest promising hypotheses for future investigations. Perhaps a better avenue for construct validation is the study of interpersonality amnesia. For example, there are extant data suggesting an absence of transfer of information from identity-specific processing to other personality enactments (Eich, Macaulay, Loewenstein, & Dihle, 1997). Nevertheless, regardless of the controversial scientific status of the DID construct, we would aver that consistent findings of temporal lobe involvement in persons who claim and demonstrate symptoms of DID are results with theoretical import, with possible concatenations to implausible beliefs and experiences, suggestibility, and childhood pseudo-memories, as well as brain physiology.
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First Published September 12th 2005