It is often assumed that when confronted with an emotional event, patients with DPD inhibit information processing. It is also thought that this fosters memory fragmentation. This hypothesis has not been tested in chronic depersonalization. The aim of this study was to investigate the temporal pattern of autonomic responding to emotional material in depersonalization disorder, along with concomitant deficits in subjective and objective memory formation (i.e., difficulties to form a coherent narrative consisting of an ordered sequence of events). Participants with depersonalization disorder (n = 14) and healthy control participants (n = 14) viewed an emotional video clip while their skin conductance (SC) levels were measured. Peritraumatic dissociation was measured before and after the clip, and memory performance was measured 35 min after viewing. Compared to controls, depersonalized participants exhibited a distinctly different temporal pattern of autonomic responding, characterized by an earlier peak and subsequent flattening of SCLs. Maximum SCLs did not differ between the two groups. Moreover, unlike the control group, depersonalized participants showed no SC recovery after clip offset. In terms of memory performance, patients exhibited objective memory fragmentation, which they also reported subjectively. However, they did not differ from controls in free recall performance. Apparently, emotional responding in DPD is characterized by a shortened latency to peak with subsequent flattening and is accompanied by memory fragmentation in the light of otherwise unremarkable memory functioning.
Depersonalization disorder (DPD) is characterized by persistent or recurrent episodes of “detachment or estrangement from one's self” (p. 530; American Psychiatric Association, 2000). The Diagnostic and Statistical Manual, Fourth Edition, Text Revision (DSM-IV-TR) (American Psychiatric Association, 2000) classifies DPD as one of the dissociative disorders, but some scholars have argued that it is an anxiety or mood disorder (Baker et al., 2003 and World Health Organization, 1992). However that may be, there is evidence that patients with DPD exhibit deficits in emotion processing. For example, Sierra et al. (2002) reported that DPD patients have reduced magnitudes and increased latencies of skin conductance responses to static aversive stimuli, as compared to both healthy controls and patients with anxiety disorder. It has also been suggested that the chronic state of depersonalization in DPD hampers the formation of emotional memories, thereby promoting memory fragmentation (van der Kolk and Fisler, 1995). Thus, when confronted with an emotional event, patients with DPD are thought to inhibit information processing (Ladwig et al., 2002), which in turn leads to difficulties to form a coherent narrative consisting of an ordered sequence of events. In line with this assumption, some trauma victims say they experience difficulties in recalling the temporal order of events (van der Kolk and Fisler, 1995) and patient with DPD report temporal disintegration of autobiographical memories (Simeon et al., 2007). Germane to this is also a PET study by Simeon et al. (2000) that is suggestive of deficient sensory integration in DPD. However, no study has directly looked at emotional memories in DPD using an objective measure of memory fragmentation (for a review, see Giesbrecht et al., 2008a).
With these considerations in mind, the aim of the present study was twofold. First, we wanted to investigate the time course of autonomic responding to emotional material in DPD. Specifically, we were interested in the dynamics of emotional responding during an emotional video clip of 12:30 min. An emotional stimulus with a relatively long duration as employed in the current study provides an opportunity to test the hypothesis that an initial and brief increase in arousal would be followed by shutdown and blunting in those who dissociate (Simeon, 2004). Such a process cannot be captured, and therefore has not been addressed, by the studies which have either used brief stimuli (Sierra et al., 2002 and Lemche et al., 2007) or peripheral neurohormonal measures obtained pre- and post-stress which only capture the “net” response to the stressor (Giesbrecht et al., 2007).
Second, we hypothesized that patients with DPD might exhibit memory deviations related to overall recall and temporal sequencing (i.e., fragmentation). In addition, we were interested in whether such changes would be associated with autonomic responsivity.
