Assessing instrumental activities of daily living in people with mild‐to‐moderate dementia: Objective and subjective assessments and their cognitive correlates

Different methods of assessing instrumental activities of daily living (iADL) may show distinct relationships with cognition in dementia. This study investigated whether these relationships differed across objective, self-rated, and informant-rated assessments, with analyses of individual cognitive measures treated as exploratory. Thirty-seven people with mild-to-moderate dementia were recruited from National Health Service memory clinics in North Wales. Participants completed the objective Direct Assessment of Functional Status (DAFS), study-specific self-rated and informant-rated questionnaires based on the DAFS, and self-rated and informant-rated versions of the Functional Activities Questionnaire (FAQ). Cognitive assessment included measures of executive function, attention, memory, and global cognition. Univariable and forced-entry multiple regression analyses were conducted with Holm-Bonferroni correction for multiple comparisons. Objective iADL performance showed more frequent associations with cognition than questionnaire-based ratings. DAFS scores were associated with global cognition, immediate and delayed memory, Trail Making Test Part 4, and Design Fluency scores. In contrast, questionnaire measures showed few associations with cognition. FAQ self-ratings were associated with depressive symptoms, while FAQ informant ratings were associated with carer burden. In the multivariable model, global cognition remained the only significant cognitive predictor after correction. Across 20 comparisons with questionnaire-based iADL measures, correlations between cognition and the objective DAFS were larger in absolute magnitude, although only four differences remained significant after correction. The findings suggest that objective, self-rated, and informant-rated assessments may capture partially distinct aspects of everyday functioning and should not necessarily be considered interchangeable measures. Global cognitive measures may provide useful indicators of functional ability in mild-to-moderate dementia.