Memory anosognosia in early Alzheimer’s disease: A memory clinic study

Abstract

Background Unawareness or anosognosia of memory impairment is a common phenomenon in patients with Alzheimer's disease (AD). Different findings have been reported regarding its presentation, assessment procedure, and cognitive correlates. Objective To assess memory awareness of early AD patients predictively (before memory testing) and online (immediately after performing a memory test). Methods All participants were outpatients of a memory clinic. AD patients were compared with participants having mild cognitive impairment (MCI) and a group with normal cognitive aging (NC). We used a performance-based assessment procedure to measure self-perceived memory abilities. An anosognosia ratio was calculated by matching self-estimates with objective memory scores derived from the Consortium to Establish a Registry for Alzheimer's disease Neuropsychological battery. Results Memory anosognosia in terms of self-overestimation was found in almost half of the AD sample, only rarely in MCI, and was not present in NC. Most AD patients had both, a low prediction and also a deficient online accuracy of self-estimation. Memory overestimators were older, less educated, and had significantly poorer neuropsychological scores. A stepwise linear regression analysis showed that memory anosognosia was predicted by age, everyday functional abilities and neuropsychological variables, including executive and mnestic abilities. Conclusions Poor cognitive and memory functions combined with memory anosognosia are a hallmark of early AD. Further, mnemonic anosognosia as assessed by performance based measures separates AD patients already in the early disease stage from subjects with MCI or normal controls. Our findings highlight the importance of assessing memory self-appraisal in subjects attending a memory clinic, in addition to clinical and cognitive variables.