Hippocampal Volumes in a Sample of Trauma Patients: A Possible Neuro- Protective Effect of Dissociation

Background: We sought to determine hippocampal volumes in a sample of inpatients in a Trauma Program specializing in posttraumatic stress disorder and dissociative disorders. Methods: We measured whole brain and left and right hippocampal volumes on MRI in a sample of 20 inpatients in a Trauma Program and 20 controls. Results: There were no differences between the two groups. Nineteen inpatients also completed a set of diagnostic and symptom measures; 16 met criteria for posttraumatic stress disorder (PTSD); the average score on the Dissociative Experiences Scale was (M = 45.4, SD = 20.1); and the average score on the secondary features of dissociative identity disorder section of the Dissociative Disorders Interview Schedule was (M = 9.1, SD = 4.9). Conclusion: We hypothesized that dissociation may have a neuro-protective effect, which accounts for the normal hippocampal volumes in the patients, despite their PTSD and trauma histories.