Goal Setting to Promote Physical Activity Adherence in Midlife to Reduce Risk of Alzheimer's Disease and Related-Dementias: A Randomized Mechanistic Proof-of-Concept Trial - Project Summary More than 6 million U.S. adults live with diagnoses of Alzheimer's Disease and Related Dementias (AD/ADRD), with projections as high as 13.8 million cases by 2050. There are no cures for AD/ADRD, making lifestyle factors key targets for reducing risk, as they account for at least a third of AD/ADRD cases. Engaging in regular physical activity (PA), particularly in midlife, is associated with reduced risk for AD/ADRD. Yet nearly half of midlife adults (48%) do not meet national PA guidelines of 150 minutes/week of moderate-intensity PA. Goal setting is a commonly used behavior change strategy to increase PA. Key psychosocial mechanisms believed to underpin the use of goal setting to promote PA include self-regulation and self-efficacy. Yet, the most effective goal setting technique to enhance these psychosocial mechanisms for the successful promotion of PA and adherence to national PA guidelines remains unclear. In the proposed study, we will use a two- phased approach to empirically test three goal setting techniques to enhance psychosocial mechanisms of self- regulation and self-efficacy for the successful promotion of PA and adherence to national PA guidelines among insufficiently active midlife adults with obesity. In the R61 phase, a Phase 1 pilot study will establish feasibility and help refine the intervention. In the R33 phase, a Phase 2 9-month 4-arm proof-of-concept mechanistic trial (6-month active intervention and 3-month no contact follow-up) will be implemented to establish preliminary efficacy of goal setting techniques to increase PA and promote adherence to national PA guidelines. All participants will receive a Fitbit to self-monitor PA and engage in PA action planning sessions with a study interventionist. In addition, participants will be randomly assigned to 1 of 4 groups: i) static weekly goal of 150 minutes/week of moderate-intensity PA, which most closely resembles the approach of public health campaigns and care providers; ii) weekly self-selected PA goals, which allows for self-determination and adaptation of the goal; iii) modest incremental weekly PA increase goal (i.e., researcher determined PA goal that 20% minutes/week greater than the minutes/week of PA in the previous week); or iv) non-goal setting control group. Based on Goal Setting Theory, it is hypothesized that participants in the incremental goal group will have the greatest increases in self-regulation and self-efficacy, which in turn, will lead to the greatest improvements in PA and adherence to national PA guidelines over the 9-month intervention. Further, individuals with the greatest PA adherence are expected to experience the greatest improvements in AD/ADRD risk factors, including cognitive functioning (memory, executive functioning, processing speed), AD plasma biomarkers (plasma amyloid 42/40 ratio. plasma phosphorylated tau 231), and measures of cardiometabolic disease risk (BMI, blood pressure, plasma glucose, TG, total cholesterol, LDL-C, HDL-C, VLDL-C, IDL-C, insulin and insulin sensitivity).
