Capturing functional change in early Alzheimer’s disease: Comparing instruments and scoring techniques to detect subtle decline

Background Functional decline is a gradual process occurring along the Alzheimer’s disease (AD) continuum, starting years before dementia onset. Different instruments, such as the ADCS‐ADL and the Amsterdam Instrumental Activities of Daily Living Questionnaire (A‐IADL‐Q) aim to capture early functional changes. In the current study, we compared measurement instruments and scoring techniques to find the optimal measurement technique for detecting functional impairment in early AD. Method Study partners of participants from the international ‘Capturing Changes in Cognition’ study cohort completed both the A‐IADL‐Q and ADCS‐ADL over the course of one year (mean follow‐up 10.8±2.3 months). For both measures, we computed the following scores: (1) sum score, (2) weighted average, and (3) number of items with maximum score. For the A‐IADL‐Q, we also computed item response theory (IRT) scores, using predetermined parameters that take into account varying difficulty of included items (see Jutten et al., 2017). To compare the ability to detect changes over time for each scoring method, we performed linear mixed modeling, adjusted for sex and baseline age. Result We included 159 individuals (72.2±8.4 years old, 45% female) with subjective cognitive decline (SCD, N=12), mild cognitive impairment (MCI, N=66) or mild dementia (N=81). Overall, a significant decline in functioning was detected with all scoring techniques (all p