PROJECT SUMMARY/ABSTRACT Early detection of cognitive decline in older adults (OA) is a public health priority. The pathology of Alzheimer's disease (AD) begins more than 20 years before memory loss develops, but dementia diagnoses often occur late in the process of cognitive decline. AD is a progressive disease and early detection of cognitive decline may slow disease progression by providing appropriate treatments earlier. There is growing evidence to suggest the possibility that depression in OA is a risk factor for cognitive decline and AD, potentially acting through perceived stress. However, it remains unknown whether depression in OA is a prodrome, a cause, or a consequence of cognitive decline. Moreover, we often rely on cognitive assessments in the lab, and could instead leverage real-world behaviors to detect early shifts in cognition. This study seeks to fill this knowledge gap through three aims: (Aim 1) identification of cross-sectional and longitudinal relationships between cognitive performance, perceived stress, and psychiatric symptoms in an existing sample from the Indiana Alzheimer's Disease Research Center; (Aim 2) development of natural language processing algorithms to detect and quantify risk factors for depression in midlife and OA; and (Aim 3) ecological momentary assessment of the daily cognitive functioning, emotions, and stress in OA, using validated mobile cognitive tasks. Completion of these aims will provide a test of the relationship between cognitive aging and depression in OA using a multimodal approach. Dr. Rutter's overarching K01 career development goal is to develop a naturalistic paradigm for early detection of cognitive decline. Aim 1 will define the theoretical framework for this paradigm; Aims 2 and 3 then apply this framework to real-world stimuli to determine whether these provide more sensitive measures of detecting cognitive decline. The integrated training and research plans proposed here will provide Dr. Rutter with advanced training in several critical areas needed to position here as an expert on aging. The mentorship and guidance from her team of national leaders will allow Dr. Rutter to achieve targeted training in the following domains: (1) cognitive aging, AD, depression and wellbeing in OA, and technology use in OA (Krendl & Holden), (2) natural language processing approaches to understanding risk factors for depression in midlife and OA (Bollen), (3) implementation of ecological momentary assessment and analysis of intensive longitudinal cognitive data in OA (Finn & Germine), and (4) career development skills in grantsmanship, leadership, and research (Krendl, Holden, & Hawkins). These training objectives will be achieved through a combination of coursework, conferences, workshops, directed readings, mentorship meetings, and completion of the primary K01 study. Indiana University Bloomington provides an outstanding environment for these training and research objectives. This K01 award will p...