Patients with Dissociative Identity Disorder have difficulty recalling specific memories

The memories of people with Dissociative Identity Disorder (DID) do not work as was previously thought. This has implications for the distinction made between DID and PTSD (Post-traumatic Stress Disorder). Patients suffering DID appear to have difficulty remembering specific personal events. They tend to overgeneralize their recollections, remembering long-lasting situations or events that occurred more regularly. These are among the results of experiments carried out by Netherlands Organisation for Scientific Research (NWO) researcher Rafaele Huntjens from the University of Groningen. The results are published in the latest (May) issue of the Journal of Abnormal Psychology.

Dissociative Identity Disorder (DID) can occur in reaction to a traumatic experience. Until now, it was thought that a patient in a trauma identity (who has memories of the negative event he/she has experienced) was overwhelmed by specific negative memories. Patients in an avoidance identity (who have no memory of the traumatic experience) were assumed to overgeneralize their recollections, which enabled them to avoid painful emotions and make life more bearable. However, in practice this does not seem to be the case: ‘There is no difference between the identities in terms of tendency to overgeneralize recollections. I think we’ll have to amend our ideas about DID,’ concludes Rafaele Huntjens.

The DID patients taking part in the study were prompted to recall specific past events while in different identities, using key words such as ‘happy’ and ‘regret’. The results showed that it was not only people in the avoidance identity who had a generalized style of remembering; it was true of every identity. Examples of DID patients overgeneralizing memories from the past include ‘While I was at boarding school …’ or ‘Every time I was in his bedroom…’

Classify with post-traumatic stress disorder

The study was carried out on 94 female test subjects: people with Dissociative Identity Disorder or Post-traumatic Stress Disorder (PTSD) and healthy control subjects. The healthy people were easily able to recall memories relating to a specific time and place. But like the DID patients, the group of PTSD patients tended to have overgeneralized autobiographical memories. In view of the similarities in the recall style of people with both disorders, the researcher would advise classifying DID as a ‘trauma-related disorder’ in the same way as PTSD. Enhancing the specificity of autobiographical memory should be a goal when treating both PTSD and DID. Difficulty recalling specific autobiographical events is a problem as it impedes people’s ability to come to terms with negative past experiences.

Rafaele Huntjens was awarded a Veni grant by the Netherlands Organisation for Scientific Research (NWO) for this research. The study was conducted in association with Radboud University Nijmegen and KU Leuven.