Patients with dissociative identity disorder find it difficult to recall specific memories

The memory of people with a Dissociative Identity Disorder (DID) works differently than was previously thought. This has consequences for the distinction that is drawn between DID and PTSD (Posttraumatic Stress Disorder). Patients with DID experienced difficulty in recalling specific personal events. They are inclined to an overgeneralised style of memory: they think back to events that cover a longer timespan or occur more frequently. This was revealed in experiments performed by NWO researcher Rafaele Huntjens from the University of Groningen. The research results were published in the most recent issue (May 2014) of the Journal of Abnormal Psychology.

A Dissociative Identity Disorder (DID) can occur as a response to traumatic experiences. Up until now it had been thought that a patient in a trauma identity (who carries the negative events experienced) is overwhelmed by specific negative memories. The patient in the avoiding identity (who knows nothing about the traumatic experiences) would be more inclined towards overgeneralised memories. With that he or she would be able to counteract the painful feelings experienced and make everyday life more 'bearable'. However, everyday practice reveals a different picture: 'The inclination towards overgeneralised memories does not differ between identities. It seems we need to adjust our picture of DID', concludes Rafaele Huntjens.

The participating DID patients in the study were asked to think back in different identities to specific events from the past based on keywords such as 'happy' and 'regret'. The results revealed that not just the avoiding identity assumed an overgeneralised style of remembering, but all the other identities as well. Formulations of DID patients such as 'When I was at boarding school …' or 'Every time I was in his bedroom …' are examples of overgeneralising manner of recollecting the past.

Merging with posttraumatic stress disorder

The research was carried out among 94 female study subjects: people with a Dissociative Identity Disorder or Posttraumatic Stress Disorder (PTSD) and healthy study subjects. The healthy study subjects had no difficulty in recalling memories that could be traced back to a specific time and place. However, both the group with PTSD and the group with DID were inclined towards an overgeneralised autobiographic memory. In view of the similarities between both disorders, in terms of the style of memory the researcher calls for DID it to be placed in the category 'trauma-related disorders' just like PTSD. In the treatment of both PTSD and DID it is advisable to increase the specificity of autobiographical memories. The difficulty in recalling specific autobiographical memories is problematic, as that hinders the processing of negative events from the past.