PROJECT SUMMARY Alzheimer’s disease is a leading cause of functional disability among older adults worldwide. Despite the inevitability of functional impairment in Alzheimer’s disease, large heterogeneity in the rate and order that specific functions are lost suggests that there are undiscovered ways to slow the progression of functional decline. The majority of older adults are married or co-habiting with an intimate partner, and have daily routines that are interdependent (i.e. synchronous activities or complementary division of functions such as shopping and cooking). Despite strong evidence that interdependence in functioning exists in other older adult couples, there is very little dyadic research on functional decline in the context of preclinical or clinical Alzheimer’s disease. Longitudinal studies have established that the continuum of dementia-related functional decline begins years prior to diagnosis and at wide range of impairment in cognition for most functions. Other previous studies have demonstrated that frequency of engagement in daily activities begins to decline prior to loss of functional abilities. The overall goal of the “RSELVES Study: Remote Sensing of (older adult couples’) Engagement in Life and Variability in Everyday Support” is to examine the intra-dyadic patterns and change in daily life engagement and functional interdependence along cognitive and well-being trajectories in older adult couples at high-risk of developing Alzheimer’s disease. We will use an innovative digital data technology platform developed by the Oregon Center for Aging and Technology, and a dyadic approach informed by the Developmental-Contextual Model of Couple Synchrony to discover changes in life engagement and function in 100 older adult couples. The aims of this study are to characterize baseline interdependence in patterns of life engagement and function among couples with a partner who is at high risk for dementia (Aim 1); evaluate longitudinal dyadic change in life engagement (e.g. dyadic disengagement or partner compensation) and support (Aim 2); and determine the extent to which dyadic life engagement and support appraisals mitigate the influence of cognitive impairment on functional impairment and well-being in older adult couples (Aim 3). Reframing AD-related functional decline in couples as an interdependent process and measuring the degree of synchrony in activities digitally will uncover the early dynamics of changes in life engagement among older adult couples and highlight novel opportunities to target couples’ daily routines in order to delay the “cascade of losses” leading to functional dependence in persons living with AD and degradations to well-being.