Fact or factitious? A psychobiological study of authentic and simulated dissociative identity states

Abstract

Background: Dissociative identity disorder (DID) is a disputed psychiatric disorder. Research findings and clinical observations suggest that DID involves an authentic mental disorder related to factors such as traumatization and disrupted attachment. A competing view indicates that DID is due to fantasy proneness, suggestibility, suggestion, and role-playing. Here we examine whether dissociative identity state-dependent psychobiological features in DID can be induced in high or low fantasy prone individuals by instructed and motivated role-playing, and suggestion.

Methodology/principal findings: DID patients, high fantasy prone and low fantasy prone controls were studied in two different types of identity states (neutral and trauma-related) in an autobiographical memory script-driven (neutral or trauma-related) imagery paradigm. The controls were instructed to enact the two DID identity states. Twenty-nine subjects participated in the study: 11 patients with DID, 10 high fantasy prone DID simulating controls, and 8 low fantasy prone DID simulating controls. Autonomic and subjective reactions were obtained. Differences in psychophysiological and neural activation patterns were found between the DID patients and both high and low fantasy prone controls. That is, the identity states in DID were not convincingly enacted by DID simulating controls. Thus, important differences regarding regional cerebral bloodflow and psychophysiological responses for different types of identity states in patients with DID were upheld after controlling for DID simulation.

Conclusions/significance: The findings are at odds with the idea that differences among different types of dissociative identity states in DID can be explained by high fantasy proneness, motivated role-enactment, and suggestion. They indicate that DID does not have a sociocultural (e.g., iatrogenic) origin.

Figure 1. Graphical representation of averages and direction of subjective emotional experiences, subjective sensori-motor experiences, and cardiovascular responses.

The dashed line depicts the response of the neutral identity state (NIS) when listening to the neutral or trauma-related memory script (MS). The solid line depicts the response of the traumatic identity state (TIS) when listening to the neutral or trauma related MS. All three groups are presented per variable: the dissociative identity disorder patients (DID) in pink, the high fantasy prone DID simulating controls (CH) in cyan and the low fantasy prone DID simulating controls (CL) in blue. See Table 1 for the statistical values.

Figure 2. “Glass brain” renderings showing the dissociative identity state main effects, both for the trauma-related identity state (TIS) and for the neutral identity state (NIS), for the dissociative identity disorder (DID) group (left) and the comparison of this group to the high (middle) and low (right) fantasy prone DID simulating controls (CH and CL respectively).

See Table 2 for the specific areas.

Figure 3. “Glass brain” renderings show differences in the processing of the trauma-related text (indicated with a small ‘t’) and the neutral text (indicated with a small ‘n’) within the trauma-related identity state (TIS).

Differences in regional cerebral blood flow patterns for the dissociative identity disorder (DID) group (left) and the comparison of this group to the high (middle) and low (right) fantasy prone DID simulating controls (CH and CL respectively) are depicted. See Table 3 for the specific areas.

Figure 4. The brain areas indicated with the blue cross (i.e. the peak voxel) are (from top left to bottom right):

the left amygdala, the left insula, the left precuneus, and the right occipitotemporal sulcus. These areas have the most significant rCBF differences between the dissociative identity disorder patients and high and low fantasy prone DID simulating controls (CH and CL respectively) and is shown both in directionality, i.e. the bar graphs, and location, i.e. shown on a coronal overlay (left in the picture is left in the brain). Results show the differential processing of the trauma-related text versus the neutral text within the TIS, when comparing the DID groups to the high fantasy prone control group (left) and low fantasy prone control group (right).

Figure 5. “Glass brain” renderings show differences in the processing of the trauma-related text (indicated with a small ‘t’) between the trauma-related identity state (TIS) and the neutral identity state (NIS).

Differences in regional cerebral bloodflow patterns for the dissociative identity disorder (DID) group (left) and the comparison of this group to the high (middle) and low (right) fantasy prone DID simulating controls (CH and CL respectively) are depicted. See Table 4 for the specific areas.

Figure 6. The brain areas indicated with the blue cross (i.e. the peak voxel) are (from top left to bottom right): the right caudate nucleus (dorsal part) (2x), the left precuneus, and the right occipitotemporal sulcus.

These areas involve the most significant rCBF difference between the dissociative identity disorder patients and high and low fantasy prone DID simulating controls (CH and CL respectively) and is shown in both directionality, i.e. the bar graphs, and location, i.e. shown on a coronal overlay (left in the picture is left in the brain). Results show the differential processing of the trauma-related text between the TIS and the NIS, when comparing the DID groups to the high fantasy prone control group (left) and low fantasy prone control group (right).