Psychotic disorders and Dissociation: underlying cognitive and neural mechanisms of dissociation

Schizophrenia and dissociative disorders are historically related and have
overlapping symptoms. However, they are currently considered as distinct
diagnostic categories with distinct treatments. The central question in this
project is whether dissociative symptoms in schizophrenia are comparable to
dissociative symptoms in dissociative disorders at a phenomenological level and
with respect to underlying mechanisms. In this project two explanations for the
symptoms of dissociation in schizophrenia are examined. 1) Dissociation is an
epiphenomenon of psychotic symptoms. 2) Dissociation is a reflection of a
comorbid dissociative disorder. This will be the second in a series of studies
performed by our research group testing these two explanations through
examining cognitive and neural mechanisms underlying dissociation in psychosis.
By doing so this project has the potential to not only increase our
understanding of both psychosis and dissociation, but also has implications for
differential diagnosis and treatment.

To examine whether symptoms of dissociation in schizophrenia are qualitatively
similar or different to symptoms of dissociation in dissociative disorders.

This study exist of two parts. Part A will examine whether high dissociative
schizophrenia patients, low dissociative schizophrenia patients and
dissociative disorder patients show distinct symptom networks. For this part
diagnostic interviews and symptom measures will be administered. Part B will be
an f-MRI experiment in which the neural connectivity and neural activity of
high dissociative schizophrenia patients, low dissociative schizophrenia
patients and healthy controls will be compared in resting state, during a
working memory task and during two alexithymia tasks.

Part A will take four hours to complete which will be done in two to four
sessions. Part B will take one and a half hours to complete. The
questionnaires, interviews and tasks that are used in this study have all been
previously used in this population without any adverse effects therefor we do
not believe there are any risks to either part of this study. The study can
lead to improvements in our understanding of schizophrenia and dissociative
disorders their differential diagnosis and treatment guidelines.