Somatoform dissociation discriminates among diagnostic categories over and above general psychopathology.

OBJECTIVE: The primary aim of this study was to investigate the hypothesis that somatoform dissociation would differentiate among specific diagnostic categories after controlling for general psychopathology.
METHOD: The Somatoform Dissociation Questionnaire (SDQ-20), the Dissociative Experiences Scale, and the Symptom Checklist-90-R were completed by patients with DSM-IV diagnoses of dissociative disorders (n = 44), somatoform disorders (n = 47), eating disorders (n = 50), bipolar mood disorder (n = 23), and a group of consecutive psychiatric outpatients with other psychiatric disorders (n = 45), mainly including anxiety disorders, depression, and adjustment disorder.
RESULTS: The SDQ-20 significantly differentiated among diagnostic groups in the hypothesised order of increasing somatoform dissociation, both before and after statistically controlling for general psychopathology. Somatoform dissociation was extreme in dissociative identity disorder, high in dissociative disorder, not otherwise specified, and increased in somatoform disorders, as well as in a subgroup of patients with eating disorders. In contrast with somatoform dissociation, psychological dissociation did not discriminate between bipolar mood disorder and somatoform disorders.
CONCLUSIONS: Somatoform dissociation is a unique construct that discriminates among diagnostic categories. It is highly characteristic of dissociative disorder patients, a core feature in many patients with somatoform disorders, and an important symptom cluster in a subgroup of patients with eating disorders.