Psychometric evaluation of the multiscale dissociation inventory (MDI): A replication and extension in two trauma-exposed samples

Dissociation, defined as a disruption in the normal integration of mental processes, involves a wide range of symptoms that can occur following exposure to traumatic events. The accurate assessment of dissociative symptoms in trauma survivors is important both for understanding the link between dissociation and trauma and for developing effective treatments for posttraumatic dissociation. In the present study, we conducted a psychometric evaluation of the 30-item Multiscale Dissociation Inventory (MDI; Briere, 2002) in two trauma-exposed samples (367 community adults; 448 undergraduate students). We examined the MDI's (a) internal consistency; (b) convergent and discriminant validity, using measures of trauma-related dissociation, posttraumatic stress disorder, childhood trauma, depression, anxiety, physical aggression, well-being, appetite, and achievement; and (c) factor structure, using exploratory structural equation modeling (ESEM). In both samples, the MDI demonstrated high internal consistency and strong convergent and discriminant validity. ESEM replicated the 5-factor structure of the MDI (Disengagement, Identity Dissociation, Emotional Constriction, Memory Disturbance, and Depersonalization/Derealization) and identified one factor (Memory Disturbance) and several items that may benefit from further construct validation and/or refinement. We discuss considerations for future research and use of the MDI in trauma-exposed populations.