Inter-identity autobiographical amnesia in patients with dissociative identity disorder

Background
A major symptom of Dissociative Identity Disorder (DID; formerly Multiple Personality Disorder) is dissociative amnesia, the inability to recall important personal information. Only two case studies have directly addressed autobiographical memory in DID. Both provided evidence suggestive of dissociative amnesia. The aim of the current study was to objectively assess transfer of autobiographical information between identities in a larger sample of DID patients.

Methods
Using a concealed information task, we assessed recognition of autobiographical details in an amnesic identity. Eleven DID patients, 27 normal controls, and 23 controls simulating DID participated. Controls and simulators were matched to patients on age, education level, and type of autobiographical memory tested.

Findings
Although patients subjectively reported amnesia for the autobiographical details included in the task, the results indicated transfer of information between identities.

Conclusion
The results call for a revision of the DID definition. The amnesia criterion should be modified to emphasize its subjective nature.