Neuromodulation for Exercise Adherence

Background: Fall-related hospitalizations and consequent morbidity and mortality continue to rise despite the availability for over two decades of evidence-based fall-prevention programs. This is a major problem since more than 2.5 million older adults are treated annually for fall-related injuries in the US. Fall-prevention programs focusing on strength and balance exercises have been successful in facility settings but exercise programs are ineffective at home due to lack of adherence. Estimates indicate that only 1 in 5 individuals adhere to home exercise programs for fall prevention. Thus, there is an urgent need to improve adherence to exercise performed at home by older adults seeking to improve balance for the sake of fall prevention. Behavioral interventions have failed to consistently improve adherence to exercise. Biological reasons for poor exercise adherence, such as executive dysfunction, have not been explored. Adherence to long-term exercise is dependent on executive function (EF), which is controlled by the [dorsolateral prefrontal cortex (DLPFC)] of the brain. EF influences choices in scheduling, forgoing competing activities, enduring subtle costs of time and inconvenience, and the ability to delay gratification. Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive neuromodulation increasingly used for neural network specific interventions. rTMS of the DLPFC improves EF, memory, motivation, and mental flexibility. rTMS studies to date have stimulated the motor cortex for gait and balance improvements. The role of DLPFC in exercise adherence has not been explored. The proposed study will be the first to test DLPFC stimulation for improving exercise adherence.

Objective: The study objective is to determine the effects of rTMS treatment of the dorsolateral prefrontal cortex compared to sham on: [1. Short-term (2-wk) changes in executive function;] 2. Long-term (24-wk) adherence to a home-based exercise program; 3. Long-term (24-wk) changes in balance and gait; and [4. Short-term (2-wk) changes in self-efficacy and delay discounting.]

Methods: Sedentary community-dwelling older Veterans (age 60 years and older, [N=106]) will participate in a double-blind randomized sham-controlled three-phase study. The proposed study will use Nintendo Wii-Fit exercises. Phase I will include two weeks of facility-based exercise for safety assessment and learning the program, followed by 12 weeks of home-based exercises. [Subjects with poor adherence and those with good adherence with low EF] will then be randomized to rTMS or sham treatments. Phase II will include ten consecutive weekdays of rTMS or sham treatment along with exercise training for subjects with poor adherence [and for those with good adherence and low EF] and continuation of home-based exercises for those with good adherence and EF. Phase III includes 24-weeks of a home-based exercise program. All subjects will exercise for 45 minutes five days/week. [Objective measure of adherence collected from Wii-Fit console and Conner's continuous performance test for EF will be the primary outcome measures.] Balance and gait will be assessed. [Self-efficacy, delay discounting along with fear of falls, and falls incidence will be assessed. Outcome measures will be assessed at baseline, and at 14, 16, and 40 weeks.]

Significance: This project may have a major impact in improving adherence to an exercise program and in turn, improve balance in sedentary community-dwelling older Veterans. Knowledge gained about the adherence to home-based exercises would be applicable to multiple conditions such as diabetes. Since Wii-Fit and rTMS are readily available, translation of the study results to clinical practice would be expeditious.