Reliable change scores and their relation to perceived change in memory: implications for the diagnosis of mild cognitive impairment.

The relation between the subjective report of memory problems and objective evidence of the same has been debated with mixed results appearing in the literature. Less is known about the relation between objective change in test performance and the perceptions of cognitive change from family members/friends and trained clinicians. These relations were explored using 5-year longitudinal data from the population-based Canadian Study of Health and Aging. Statistically reliable deterioration in memory test performance was determined using a standardized regression-based (SRB) approach and a Reliable Change Index (RCI) that accounts for aging and practice effects. Among a subsample of persons with no cognitive impairment (NCI) at baseline, there was a moderate relation between reliable test score decline and ratings made by clinicians and informants. No relation, however, was found with the subjective reports of memory difficulties. These findings hold implications for current mild cognitive impairment (MCI) criteria which include subjective, informant and/or clinician ratings of cognitive decline.