Abstract
INTRODUCTION: Functional decline in activities of daily living (ADL)-advanced (AADL), instrumental (IADL), and basic (BADL)-is a hallmark of Alzheimer's disease (AD). However, integrated clinical-neuroanatomical evidence on progression across the AD continuum remains limited, particularly in Latin American populations. METHODS: We studied 138 older adults with subjective cognitive complaints (SCCs), mild cognitive impairment (MCI), and Alzheimer's disease dementia (ADD). ADL domains were assessed using the Technology-Activities of Daily Living Questionnaire. Structural magnetic resonance imaging data were analyzed using voxel-based morphometry (VBM) to identify gray matter (GM) correlates of ADL performance. RESULTS: A hierarchical decline from AADL to IADL to BADL differentiated clinical stages. SCC and MCI differed mainly in AADL performance, whereas ADD showed decline across all domains. VBM revealed GM correlates consistent with this hierarchy, with distinct but partially overlapping substrates for each ADL domain. DISCUSSION: These findings underscore a diagnostically informative and anatomically organized progression of ADL decline.