Persistent retrograde, amnesia following a minor trauma.

A 19-year-old man showed dense retrograde amnesia (RA) for autobiographical and public events covering his entire life, following a motor car accident that caused no apparent brain damage. His learning abilities remained excellent and permitted him to recover knowledge of the past, based on information gathered from other people and the media, although he never reacquired the sense of personal experience. At the onset he also showed occasional gaps in his semantic memory, e.g., he failed to recognize a few objects and was unable to provide factual information about sports he had long been playing. Eventually, his amnesia was predominantly restricted to autobiographical events or facts. After 29 months the deficit has remained unchanged. CT, MRI and PET were negative. Psychogenic amnesia was considered, but eventually ruled out for want of any evidence pointing to emotional problems, stressful situations or secondary gains. We posit that for reasons unknown a mild trauma can cause functional inhibition of the access to the engrams that are already stored, leaving intact the ability to encode and retrieve new memories.