Memory impairment and Alzheimer's disease pathology in individuals with MCI who underestimate or overestimate their decline

Objectives: The aim of this study was to examine whether the discrepancy between participant and informant estimation of memory decline can predict MCI prognosis. Methods: Analyses involved data from individuals with MCI enrolled in the Alzheimer's Disease Neuroimaging Initiative (ADNI) who filled the Everyday Cognition questionnaire. Participants who underestimated (N = 112) and overestimated (N = 157) their memory decline were compared on memory tasks, brain volume, and cerebrospinal markers, at study entry and after 24 months. Results: Individuals who underestimated their memory decline performed more poorly on memory tests, had smaller hippocampus volume, and greater Alzheimer's disease pathology than did individuals who overestimated their cognitive decline. Longitudinal comparisons demonstrated that individuals who underestimated their decline deteriorated more significantly in memory and in brain measures. Conclusions: Underestimation of memory decline should raise clinicians' suspicion of the existence of AD pathology in individuals with MCI.