PROJECT SUMMARY Delaying the onset of Alzheimer’s disease and related dementias (ADRD) by even a few years could amass substantial improvements in quality of life for individuals and families, independent living, and the cost of specialized healthcare. Positive cognitive outcomes associated with physical activity interventions conducted in middle-aged and older adults have increased the promise that primary prevention of ADRD may be achievable via lifestyle change. It may take years to decades of adherence to health promoting behaviors to realize appreciable gains in cognitive health span. Critically, while lifestyle interventions are supportive of behavior change in the short-term, longer-term maintenance of cognitive health promoting behaviors (i.e. continued enactment of these behaviors 6+ months after completion of the intervention) has proven difficult to achieve. The current project will leverage an mHealth approach using commercially-available technology (smart phones, wrist-worn activity monitors) to promote long-term maintenance of light intensity physical activity (LIPA) in middle-aged adults at increased risk for ADRD (adults with obesity). Following a health education session with a certified exercise physiologist, our approach will deliver the other intervention components: adaptive daily step goal setting (both arms), self-monitoring (both arms), and interim goal setting every 2-3 hours (treatment arm-only), on study smart phones, over the course of participants daily lives. We aim to demonstrate that the interim goal setting manipulation to the intervention can lead to greater long-term maintenance of LIPA by keeping LIPA goals active in the focus attention during each day of the intervention period and increasing LIPA self-efficacy through regular goal attainment. Goal maintenance (indicated by self- monitoring frequency) will be quantified via participant interactions with custom-integrated Fitbit wrist-worn activity monitors and the Mobile Monitoring of Cognitive Change (M2C2) component of the forthcoming NIH Mobile Toolbox. Fitbits will be configured with a custom-designed clockface that displays accumulated step counts when a ‘check my steps’ button is pressed. Logging and timestamping these interactions will allow for quantification of self-monitoring frequency. We propose that development of these adherence-promoting mechanisms (goal maintenance and self-efficacy) can act as a self-regulatory scaffold from which long-term health promotion gains can be realized. The current project will: 1) demonstrate the ability of interim goal setting to engage our proposed adherence-promoting targets (Aim 1); 2) test the efficacy of the interim goal setting manipulation to increase short- and long-term LIPA maintenance following the intervention through goal maintenance and increased self-efficacy (Aim 2); 3) examine how variation in cognition influences the ability of the intervention to engage goal maintenance (Aim 3); 4) explore the long-term salutary effects of the intervention on cognitive (change in ADRD risk) and physical health (change in weight, V02-max; Aim 4).

PROJECT NARRATIVE Reduction of risk for Alzheimer’s disease and related dementias (ADRD) may be possible through lifestyle change including increased physical activity. While novel and effective behavioral interventions targeting increased physical activity and positive cognitive outcomes have been developed over the past several decades, little is known about the mechanisms that lead to longer-term adherence to health-promoting levels of physical activity behavior (long-term “maintenance”). The proposed adherence-promoting mHealth intervention is designed to support the development of a psychological scaffold for long-term physical activity maintenance in midlife that will help promote cognitive health into older age.