Dementia & Diabetes Prevention Program (DDPP)

This is a multicenter, randomized 2-arm clinical trial of two lifestyle interventions varying in intensity and format, in 400 older African American and non-Hispanic whites at increased risk of cognitive decline and dementia in the East San Francisco Bay Area. The trial will include two lifestyle interventions that differ in intensity and format:

1. Aerobic Exercise (AEx) Intervention that involves aerobic activities with in-class walking workouts and tutorials and carried out at the East Oakland Sports Center (EOSC) and Tice Creek Fitness Center (TICE).
2. Dietary counseling to support adherence to the Mediterranean-Diet Approaches to Stop Hypertension (DASH) Intervention for Neurodegenerative Delay (MIND) diet to encourage increased consumption of berries, green leafy and other vegetables, whole grains, nuts, fish, poultry, beans and olive oil, and to reduce consumption of fried/fast foods, red meat, whole fat cheese, sweets, butter and trans-fat margarines.

The 8-month diet and AEx regimens used here are theoretically motivated by implementation science and use the best available practices to treat multisystemic disabling processes. The recent Centers for Disease Control (CDC) review of Diabetes Prevention Program (DPP) implementation literature found that 1 hour per week is the optimal length and frequency to balance cost and attentional demands of the participants. DPP class structure generally involves a 10-min weigh-in, a discussion of adherence to personal weight loss and exercise goals, formal DPP content delivery, and lastly a discussion of barriers to adherence. Diet module content focuses on calorie restriction by altering the composition of participants' meals. These goals include reducing trans-fats, saturated fats, sodium, and carbohydrates and increasing fruits, vegetables, whole grains, and fiber. Participants set weight reduction goals for themselves with personalized goals between 5% and 10% of total body weight dependent on the participant's level of obesity - effectively replacing prepared foods with traditional (Mediterranean) diet.

Because cognitive abilities do not appear to change without a corresponding improvement in cardio respiratory (CR) fitness, the 8-month AEx module content optimizes CR fitness improvement with in-class walking workouts and tutorials. All health instructors at TICE and EOSC will have at least an Associates level degree in exercise physiology and be required to have personal training certification. They will always be under the direct supervision of the PI. Direct supervision of the participants by these health instructors will occur for all exercise sessions until the weekly duration target of 150 minutes a week is reached (Week 6). We introduce more flexibility in scheduling exercise when the participant is consistently and safely meeting their goals by allowing unsupervised exercise sessions at the facility when exercise trainers may not be available (i.e. early morning, nights, and weekends). Participants are still required to have at least one directly supervised exercise session per week to maintain contact with program staff and encourage adherence to the program. Unsupervised exercise sessions are conducted similarly to supervised exercise and session data will be reviewed by the exercise instructor at the weekly supervised session.

Per a well-developed literature on DPP best practices,159,160 we will limit intervention class sizes to about 20 people. Over the course of 5 years, we will run 30 to 35 full DPP groups, each session meeting weekly for 20 consecutive weeks of diet-focused or AEx-focused intervention.

Previous studies suggest that salivary hormones such as cortisol, alpha-amylase and testosterone all measure glucocorticoid (GC) sensitivity, a potent biomarker of age-related stress. We will measure three stress markers in spit before and after a participant exercises during the 6-minute walk challenge at baseline and at each follow-up visit. Because better fitness is believed to improve one's reaction to stressful events, changes in these hormones may reflect the adaptation of a person's ability to cope with emotional and physical stress as they become more cardiorespiratory fit.