Research Strategy Design. The study investigators propose recruiting 40 middle-aged (45-65 years) participants from the Wisconsin Alzheimer's Disease Research Center's (ADRC) "IMPACT" cohort to participate in a 12 week diet and exercise intervention with a 6-month follow-up. The Wisconsin ADRC has a special emphasis in preclinical AD, and participants are recruited with the expectation of being approached for intervention studies. Since the treatment will be applied to groups of 10 participants each, consisting of a total of 4 groups, the study investigators will not be able simultaneously to roll out the treatment program in all groups. Subsequently, an incomplete stepped wedge cluster randomized trial (SWCRT)48,49 will be considered. The design allows each block (intervention group) to be randomized to the intervention in a stepped fashion, initially providing a baseline measure, as indicate by '0' in the design matrix below, then followed by the 12 week intervention 'X' with '.' indicating no measurement, and '1a' indicating measurement post-12 week diet and exercise intervention and '1b' 6 months after the intervention.