Memory Impairment and Awareness of Memory Deficits in Early-Stage Alzheimer's Disease

Abstract

In addition to their memory impairment, individuals with Alzheimer's disease (AD) often suffer from deficits in self-awareness. Awareness of memory deficits or metamemory is a multifaceted function, comprising on-line self-monitoring, generalized self-beliefs of memory efficacy, and generalized knowledge about memory functions. Awareness of memory problems in early-stage AD is a matter of clinical importance from a humanistic point of view, because higher levels of awareness may be associated with better future outcomes. Current methods of measuring awareness tend to fall into two categories, i.e., to introduce a questionnaire assessing patient/caregiver discrepancies; or to ask a patient to prospectively predict or retrospectively postdict their own memory performances. Characteristics of each measure as well as relationship between the two measures were discussed. For the performance prediction/postdiction paradigm, we used recognition memory of auditory verbal learning tests and awareness of memory deficits were examined in 24 individuals with early-stage AD. In addition to their significantly impaired recognition memory, individuals with AD displayed underawareness of memory deficits even at this early stage. They retrospectively overestimated memory performance after actual performance, but appeared to benefit from feedback and displayed intact on-line awareness of memory dysfunction, leading to normal prediction of the second session. However, individuals with AD again failed to retrospectively incorporate incidents of memory failure into generalized self-belief systems. Brain/behavior correlational analyses suggest that the prefrontal cortex and posterior dorsomedial regions including the precuneus may be involved in self-awareness.