The theoretical bipartite model for dissociation was clinically confirmed in a sample of schizophrenia patients and might represent a dissociation subtype of schizophrenia, a recent study shows.
The bipartite model proposes that dissociative detachment and dissociative compartmentalization are two different types of dissociation rather than variations found on a dissociation continuum. Dr. Matthias Vogel of the Clinic for Psychosomatic Medicine and Psychotherapy at the Medical University of Rostock, Germany, and his associates reported that "around 25% of the variance in clinical symptoms of schizophrenia are explained by detachment equivalents and compartmentalization equivalent" (J. Trauma Dissociation 2013;14:1-15).
Previous estimates of the prevalence of a theoretical dissociative subtype of schizophrenia have been between 25% and 40% of patients diagnosed with schizophrenia. The researchers had set out to test the bipartite model of dissociation in a clinical sample while seeking potential overlap of dissociation among schizophrenia patients.
The clinical sample included 74 patients who were diagnosed with schizophrenia spectrum disorders based on the DSM-IV and were receiving treatment at a northern Germany psychiatric university clinic. Among the patients were 60 with paranoid schizophrenia, 5 with residual schizophrenia, and 9 with schizoaffective disorder; 25 (33.8%) patients were female, and the patients’ mean age was 39.
The Positive and Negative Syndrome Scale (PANSS), and the Association for Methodology and Documentation in Psychiatry (AMDP) scale for dissociation were used to interview the patients. Then, the researchers conducted a factor analysis for the 15 items on the AMDP-dis, seeking detachment and compartmentalization equivalents scores among the patients.
Compartmentalization dissociation refers to the temporary loss of control of specific systems of the brain related to memory, senses, and motor functions, which clinically presents as "dissociative amnesia or medically unexplained neurological symptoms." Meanwhile, detachment dissociation refers to a patient’s "unreal" or dreamlike feeling of being separated from his or her body, self, or the environment. The former specifically relates to disrupted memory function, and the latter is an altered state of consciousness.
The mean scores of the patients on the PANSS included 23.48 (SD 6.33) on the positive subscale, 24.22 (SD 7.33) on the negative subscale, and 47.12 (SD 10.74) on the general symptom subscale. The mean dissociation total score was 9.81 (SD 7.81). In the factor analysis with the AMDP-dis, a mean of 4.75 (SD 4.84) was identified for the detachment equivalents, and a mean 4.99 (SD 4.08) was identified for the compartmentalization equivalents.
The analysis confirmed discrete types of detachment and compartmentalization dissociative states, thereby confirming the bipartite dissociation model. "Consistent with the study hypothesis, dissociation as measured using the AMDP module was not on a continuum in the present sample but was discontinuous with detachment equivalents distinct from compartmentalization equivalents," the authors wrote.
Further, the authors found correlations between the detachment equivalents, and both positive symptoms and general schizophrenia symptoms. The compartmentalization equivalents were correlated with all three PANSS subscales.
Multiple regression analyses, however, found "intense interactions between detachment equivalents and positive symptoms of schizophrenia and between compartmentalization equivalents and negative symptoms of schizophrenia," thereby confirming the potential for both kinds of dissociation to comprise a dissociative subtype of schizophrenia. "This pattern of specific association linking schizophrenia and dissociation by subtype is also confirmed by the finding of a nonspecific association with the general symptoms subscale of the PANSS," Dr. Vogel and his associates wrote.
The researchers noted that the overlapping subtypes of dissociation and schizophrenia symptoms suggest a "link between detachment equivalents and psychotic symptoms." They suggest that this pattern is not indicative of a comorbidity but rather possibly a common disease process that potentially involves neurobiological mechanisms, or a bidirectional interaction between dissociation and psychosis.
The clinical implications of their findings are that additional treatment might be appropriate for schizophrenia patients experiencing dissociation. "Dissociation is an important part of the schizophrenic patient’s suffering, at the same time offering the advantage of an additional therapeutic access," they wrote. "The current results add to the findings that indicate the need of patients diagnosed with schizophrenia for such specific antidissociative treatment in addition to the standard of care for schizophrenia.
The study was limited by the high percentage of paranoid schizophrenia patients in the nonrepresentative sample.
Dr. Vogel reported no disclosures.