Autobiographical memory in normal aging and primary degenerative dementia (dementia of Alzheimer type).

Autobiographical memory of old people (71-89 years) was studied by a method of free narratives, with normal subjects as well as patients with primary degenerative dementia (SDAT) at three stages of development. The chronological distribution of memories across the life span in both groups showed a peak in adolescence and early adulthood, decrease in mid-life, and increase in recent years. This distribution is different from the results found with the prompt word method among normal old adults, but is similar to the chronological pattern reported for vivid memories. The distribution in the demented group was more flat, which contradicts theories of selective preservation of early memories. With the progression of dementia, autobiographical memory deficits were first evidenced by inaccessibility or loss of memories, and, at a later stage, by loss of details of the retrieved memories and impairment of temporal structure. Events that marked transitions in the lives of the patients ("landmarks") were less subject to forgetting than nontransitional events. The article argues for an approach to autobiographical memory that takes into account sociocultural and developmental determinants of memorability as well as internal mechanisms of the cognitive system.