Alzheimer’s disease is a growing public health concern with the current number afflicted of 5 million in the US expected to triple by 2050. Since there is currently no cure or preventive pharmacological treatment, AD prevention research is now recognized as an important enterprise, with a goal to identify modifiable lifestyle factors that can reduce AD risk or delay its onset. Among these, increased physical activity, healthier food choices, more cognitive stimulation, better sleep quality, stress management, and social engagement have been identified as reasonable targets for behavioral intervention. A smartphone application-based behavioral intervention targeting these six behavioral domains was recently developed and a six-month randomized controlled trial was conducted, both to determine feasibility and compliance with technology usage and to test its efficacy. This study, titled the Gray Matters Study, was conducted in Cache County, Utah, enrolling a sample of 146 middle-aged participants (aged 40 to 64 years) randomized to treatment or control condition. Under the Health Belief Model, individuals who perceive a greater susceptibility to a particular health condition are hypothesized to be more likely to engage in more positive behaviors to reduce disease risk. Following this model, perceived threat of AD (operationalized by fear of AD, family history of AD, and metacognitive concerns) was examined for prediction of behavioral change over the six-month Gray Matters intervention period in these same six behavioral domains. Persons with a moderate level of fear of AD made significantly greater improvements in physical activity than those with low or high levels of fear. Family history was not a significant predictor of health-related behavioral change. However, persons with a moderate level of metacognitive concerns made significantly greater improvements in both physical activity and food quality than those with low or high levels of concerns. This is the first study to examine these psychological constructs related to AD risk and the extent to which they predict health-related behavior change. Future studies should extend the length of follow-up to at least one full year, include a more diverse sample of participants to expand generalizability, and build upon these findings to personalize supportive behavioral change interventions in order to be sensitive to these psychological factors.