Autobiographical memory and executive function in early dementia of Alzheimer type

We studied executive function and autobiographical memory in a cohort of 33 DAT patients [divided into minimal (MMSE 24-30) and mild (MMSE 17-23) groups] and in 30 normal controls. Autobiographical memory, as assessed by autobiographical fluency and the Autobiographical Memory Interview (AMI), was impaired in DAT patients, even those with minimal disease. There was evidence of a gentle temporal gradient on the incident but not the personal semantic component of the AMI, suggesting that the two components are dissociable. Executive function was assessed by two separate dual performance tasks and letter fluency. Although there was a trend for minimal DAT patients to be impaired on executive tasks, this only reached significance for the mild group. Regression analysis suggested that the divided attention component of working memory was involved in the retrieval of personal semantic autobiographical memory, but verbal fluency was more important in the retrieval of autobiographical incidents. There was thus a dissociation in the type of executive function implicated in different subcomponents of autobiographical memory, arguing for subcomponents within executive function and autobiographical memory. The autobiographical memory deficit in DAT reflects, we argue, both impairment in retrieval processes, linked to executive function, and a loss of memory stores.