A Novel Method for Establishing Functional Change in Older Adults with Cognitive Impairment

Objective: The aim was to set syndrome stage-specific (eg, cognitively unimpaired, severe dementia) metrics for functional change. Methods: We selected 18,097 individuals who participated in 2 National Alzheimer's Coordinating Center visits between June 2005 and May 2020, with completed collateral rating of functioning on activities of daily living assessed by the Functional Activities Questionnaire. Both distribution-based (ie, regression-based reliable change indices) and anchor-based (ie, typical change associated with advancing a syndromal stage for clinically meaningful difference) methods were applied for individuals classified as: unimpaired cognition, mild cognitive impairment, mild dementia, moderate dementia, or severe dementia. Results: There were marked differences in the distribution of functional ratings depending on their syndromal stage. There were also differences in the functional change associated with advancing across different syndromal stages. These informed stage-specific metrics for reliable change indices and clinically meaningful differences. Conclusions: Our indices provide a hitherto unavailable method that allows clinicians to determine whether observed functional change is reliable or meaningful based on syndromal stage.