Sedentary Lifestyle
Conditions
Keywords
physical activity, aging, cognition, brain, exercise
Brief summary
Although exercise is known to delay cognitive decline and decrease our risk of Alzheimer's Disease, there is a lack of understanding of how exercise protects the aging brain. The proposed research takes a novel approach to this problem by testing the concept that there are acute, direct effects of exercise in the same brain regions that are affected by chronic exercise training. If the investigators are successful, the acute paradigm will allow us to determine the critical exercise parameters that modulate brain function in humans using only a single exercise dose.
Detailed description
Given the rising proportion of older adults worldwide and the progressive decline in brain function with advancing age, there is a pressing need to develop novel interventions that protect the aging brain. The predominant approach for implementing exercise training to improve brain function is to increase cardiovascular fitness. However, there is mixed empirical support for the effectiveness of this approach. Further, there are also acute effects of exercise within one hour of the cessation of a single exercise session. These effects occur before adaptations related to fitness could occur and animal studies have shown they occur in the same brain regions that benefit from longer-term exercise training. Therefore, the investigators propose the acute paradigm is a tool to probe this early, direct response from exercise in order to determine how best to maximize the long-term benefit of exercise training on the aging brain. This presents a critical need to determine the mechanistic relation between acute and long-term effects of exercise on the aging brain. Our long-term goal is to determine how exercise protects the brain from the adverse effects of aging. In turn, our specific objective in this R21 proposal is to support or refute the concept that a single session of exercise produces acute increases in functional synchrony of clinically relevant brain networks that are related to accrued exercise-training effects in the same brain systems. Our central hypothesis is that the effects of moderate intensity exercise will increase the functional synchrony of the hippocampus with the Default Mode Network, and the Prefrontal Cortex with the Fronto-Executive Network, in the same fashion as a 12-week moderate intensity exercise training program. This hypothesis is based on data showing acute effects of exercise on factors related to neuronal plasticity and excitability in the same brain regions that show long-term effects of exercise in animals. The contribution of the proposed research is significant because it will determine the extent to which the acute exercise paradigm can provide insight into how regular exercise protects the brain from adverse effects of aging. The proposed research is innovative because for the first time the investigators will examine the overlapping neural systems and outcomes associated with acute and chronic exercise in the same individuals. Overall, success in this project will enable future research to study how varying exercise parameters such as mode or intensity affect exercise-induced change in brain function and the timecourse of these effects, as well as the neurobiological mechanisms associated with the direct effects of exercise on the aging brain.
Interventions
BEHAVIORALCycling
The experimental group will complete a 3 month exercise program that includes working up to cycling at a moderate intensity for 50 minutes/session 3 times a week. The comparison group will complete a 3-month exercise program that includes intermittent cycling (alternating between passive and moderate intensity) for 50 minutes/session 3 times a week. Both groups will exercise in our laboratory at Spence Labs, and will be supervised by an exercise trainer that is trained in working with elderly and special populations.
Sponsors
University of Iowa
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
BASIC_SCIENCE
Masking
SINGLE (Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
60 Years to 80 Years
Healthy volunteers
Yes
Inclusion criteria
* Eligible to participate in an aerobic exercise intervention based on the Physical Activity Readiness Questionnaire, and corrected vision of 20/40. * Because our older adult sample is over the age of 40, we will also require completion of a detailed health history questionnaire and further eligibility for the exercise intervention will be determined following approval from a physician that monitored electrocardiography (ECG) response during a maximal aerobic fitness test that is part of the second study visit described below.
Exclusion criteria
* Not between the ages of 60 and 80 years old * Not fluent in English * Score \< 26 (out of 30) on the Montreal Cognitive Assessment (MoCA) * Inability to comply with experimental instructions * Qualify as high risk for acute cardiovascular event by the published standards of the American College of Sports Medicine * Left-handed * Previous diagnosis of neurological, metabolic, or psychiatric condition, and no previous brain injury associated with loss of consciousness * Inability to complete an MRI
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Functional brain network integrity: the strength of the correlation between fluctuating functional magnetic resonance imaging (fMRI) signal in different brain regions of the Default Mode Network (DMN) and the Executive Control Network (ECN) at rest | Change from baseline functional network integrity at 12-weeks | Resting state brain networks known to be vulnerable to decline with normal aging |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Motor learning rate | Change from baseline learning rate at 12-weeks | Learning rate parameter expressing rate of reaction time speeding in an alternating serial reaction time task (ASRTT) |
| Explicit paired associates learning rate | Change from baseline learning rate at 12-weeks | Learning rate parameter expressing rate of improvement in accuracy in a paired associates learning task |
| Executive function composite measure | Change from baseline executive function performance at 12-weeks | Composite score from performance (speed and accuracy) on four executive function tasks, including Trails A and B, Go/No-Go dual task, a modified flanker task, and a non-verbal working memory n-back task |
| Cardiovascular fitness measured as Vo2 max from a cycle ergometer test | Change from baseline fitness at 12-weeks | The ability of the heart and lungs to supply oxygen to working muscle tissues and the ability of the muscles to use oxygen to produce energy for movement |
Countries
United States
Outcome results
None listed