Evaluation and optimisation of a brief, intensive cognitive-behavioral intervention for patients with dissociative identity disorder (DID) and posttraumatic stress disorder (PTSD)

Dissociative identity disorder (DID) is a dissociative disorder, characterized
by amnesia and fragmented identity. Patients with DID often have a long
psychiatric history, a high level of suffering and several comorbid psychiatric
symptoms. International research shows a prevalence of 1,1-1,5% in the general
population and about 5% (range 0,4-14%) in psychiatric populations (*ar, 2007;
*ar, 2011). Research conducted in the Netherlands showed a prevalence of 2%
among admitted psychiatric patients (Friedl, & Draijer, 2000). Currently, there
is no evidence-based treatment guideline available for this disorder (Ganslev
et al., 2020), Accordingly, in the current Dutch guidelines for DID treatment
(Zorgstandaard Dissociatieve stoornissen, 2022), several treatment programs are
suggested, but more research is necessary to investigate which treatments are
effective. Secondly, current guidelines often suggest a phase-based treatment
approach. The first phase focuses on safety and symptom stabilization of
patients. The second phase focuses on processing the traumatic memories. The
third phase focuses on identity integration and rehabilitation (International
Society for the Study of Trauma and Dissociation, 2011; Zorgstandaard
Dissociatieve stoornissen, 2022). There is not sufficient evidence to determine
whether this phase-based treatment approach is necessary, or whether
trauma-focused therapy and treating the DID symptoms can be applied without a
stabilization phase. Results of a recent randomized controlled trial (RCT)
showed that combining a stabilizing group-treatment with individual therapy did
not result in a better outcome of the treatment of patients with complex
dissociative disorders compared to individual therapy alone (Baekkelund, 2022).
Considering the high level of suffering of patients and the high burden on the
mental health care system, the development of effective and efficient
evidence-based treatments of DID is necessary.
Results of previous research suggests that dissociation is used as a coping
mechanism to cope with the intense emotions evoked by traumatic memories
(Huntjes et al., 2014; Cloitre, 2012). Using dissociation, these emotions are
numbed. Therefore, dissociation and symptoms of dissociative identity disorder,
can be seen as avoidance behavior. In the regular treatment for posttraumatic
stress disorder (PTSD) changing trauma-related avoidance behavior is a main
focus. Previous research has shown that with intensive trauma-focused treatment
dissociative symptoms decrease (Zoet et al., 2018). However, symptoms regarding
a fragmented identity, a core symptom of DID, often remain. A
cognitive-behavioral treatment approach for DID was developed and illustrated
with a successful patient case (van Minnen & Tibben, 2021). The main assumption
behind this treatment approach is that dissociation is an avoidance strategy,
which was functional during traumatization but has become dysfunctional for
patients after trauma. Another assumption is that this avoidance behavior can
be changed. The effectiveness of this newly developed treatment approach for
DID has not yet been studied.
The current study focuses on the evaluation of a treatment program where
trauma-focused therapy is combined with the cognitive-behavioral treatment
approach for DID. Therefore, the first aim of this study is to determine the
effectiveness of this treatment approach. In addition, as a second aim, we will
be investigating factors that possibly have an effect on the effectiveness of
the treatment. Currently, very little is known about patients* opinions and
experiences regarding the function of their fragmented identity and the process
of parting with their identities. Gaining insight into patients* experiences
may provide information to optimize treatment. To gain more insight, a
qualitative study will be part of the current research.

The primary objective is to determine the effectiveness of a short-term,
intensive cognitive-behavioral intervention for patients with DID and PTSD.
The secundary objective is to determine possible factors that impact the
treatment efficacy and to gain insight into a patient's own opinions and
experiences regarding their dissociative symptoms.

The design of the study will be a single-case experimental design (SCED) in
which DID and PTSD symptoms will be measured in ten patients during three
phases: (1) baseline phase, (2) treatment phase and (3) follow-up phase (6
months post-treatment). All ten subjects will receive an intensive
trauma-focused therapy (treatment as usual, TAU) followed by an intensive
two-day treatment for DID at the Psychotrauma Expertise Center (PSYTREC
Bilthoven, the Netherlands). The DID treatment is a cognitive-behavioral
intervention combining exposure to all identities with a technique to allow
patients to part with their fragmented identities. Because the effectiveness of
this psychological intervention has not been systematically studied yet, and
the low prevalence of DID in clinical practice, we chose to start this
experimental study with a small group of patients. The ten patients will be
randomized during baseline. There will be three groups: (1) 4-6 weeks between
end of the intake procedure and start of the TAU, (2) 6-8 weeks between end of
the intake procedure and start of the TAU and (3) 8-10 weeks between end of the
intake procedure and start of the TAU.

Patients will first receive treatment as usual (TAU) for PTSD: four days
combining two 120-minute sessions of prolonged exposure (PE) and eye movement
desensitization and reprocessing (EMDR) sessions, two 120-minute sessions with
physical exercise, and 60 minutes of psycho-education on a daily basis. The TAU
is scheduled with two consecutive days of treatment, followed by a 60-minute
session to evaluate the therapy.
The new intervention under study will start after the TAU. Patients will
receive two consecutive days of treatment for DID with two 120-minute
individual therapy sessions and two 120-minute sessions with physical exercise,
per day. These two days of treatment will be followed by a 60-minute session to
evaluate the treatment. The treatment program follows a detailed treatment
manual. After explaining the rationale of the treatment, an inventory will be
made of all fragmented identities and their functions. After starting with a
relaxation-exercise, patients will be asked which of their identities they
would like to part with. After this exercise, patients are asked to expose
themselves to this identity, thank the identity for the function they once had
aloud, and part with them. This process is repeated for all the identities the
patient wants to part with. At one-month follow-up the treatment will be
evaluated with several questionnaires. To evaluate dissociative experiences, we
will administer the qualitative interview. At three-months follow-up symptoms
will be evaluated with the SCID-D, the CAPS-5 and several self-report
measurements. At six-months follow-up the treatment will again be evaluated
with the SCID-D, CAPS-5 and several questionnaires. To evaluate dissociative
experiences, we will administer the qualitative interview.

The current research can be classified as having *negligible risks*. The goal
of the DID treatment sessions is to change avoidance behavior, in this case
dissociation. Changing avoidance behavior is also the goal of the PTSD
treatment sessions, which has been proven to be safe. The exposure to their
alters and parting with them, will not be a bigger burden than the four hours
of trauma-focused therapy sessions that patients will have attended on a daily
basis during TAU. Secondly, DID is seen as a coping mechanism after traumatic
events. Patients will start with PE and EMDR to treat the traumatic memories.
Thus, we hypothesize that after adequately treating the traumatic memories,
patients will not need this coping mechanism as much. Furthermore, during the
TAU, patients learn to regulate their emotions and cope with stressful
situations. The hypothesis is that this makes them more resilient and better
equipped to participate in the sessions for the dissociative symptoms.
The additional interviews and questionnaires will require around 27 hours of
extra time between baseline and 6 months follow-up. However, patients at
PSYTREC are already taking part in the administration of questionnaires and
interviews and therefore are familiar with it. Furthermore, previous research
has shown that patients with PTSD generally report filling in questionnaires as
beneficial (Jaffe et al., 2015).