Exercise and Alzheimer’s Disease
Adapted from the Medical Fitness Specialist Certificate Program by Alzheimer’s Research and Prevention Foundation: Alzheimer’s Disease Prevention and Intervention.
(Article 3 in a 3-part series about Alzheimer’s disease.)
In the first article in this series, it was noted that:
- although there are natural physiological changes that occur with age, memory loss is neither normal nor a natural process of aging.
- there is no medication at this time that cures fatal Alzheimer’s disease, so prevention is the best line of defense against the disease.
- exercise plays a very important role in prevention of cognitive decline and brain health.
In the second article, prevention for cognitive decline and Alzheimer’s was discussed with The 4 Pillars of Prevention, a program researched and developed by the Alzheimer’s Research and Prevention Foundation.
This article will look at evidence-based information about the role of exercise in prevention and intervention of Alzheimer’s disease and cognitive impairment.
There are now dozens of research studies that look at the effect of exercise for prevention and intervention for cognitive decline and the risk for developing Alzheimer’s. The evidence supporting exercise continues to grow, as more studies are conducted. Exercise continues to prove to be an important therapeutic strategy for prevention of cognitive decline and Alzheimer’s.
“Although at this time, medications have no proven neuroprotective effect on dementia, an evolving literature documents significant benefit of long-term regular exercise on cognition, dementia risk, and perhaps dementia progression.” (Ahlskog 2011 metanalysis) Many studies suggest that exercise reduces the effects of dementing neurodegenerative mechanisms.
Currently, research significantly indicates that exercise is associated with a reduced risk of cognitive impairment and dementia. This appears to happen in two ways: (Ahlskog 2011)
- A convergence of evidence from both animal and human studies indicate that aerobic exercise seems to reduce the risk of degeneration of brain processes and seems to protect the brain from biological and neurological decline.
- The cardiovascular benefits of aerobic exercise reduce vascular risk improving cerebrovascular (carotid and brain artery) health, reducing plaque build-up, and maintaining better circulation to the brain.
There are several types and doses of exercise being researched in association with brain function in order to determine the type and dose of exercise that produces beneficial results. Moderate physical activity was reported in many studies to improve brain function. Moderate exercise was quantified in different ways including:
- the number of blocks walked over 1 week. Walking 72 blocks/ week was necessary to detect beneficial increased gray matter.(Erickson 2010)
- working at a duration of 40 minutes in a target heart rate zone of 50-60% for the first 7 weeks and then 60-75% for the remainder of the program determined by Karvonen method provided beneficial brain and memory changes. (Erickson 2015)
- moderate exercise 30 minutes per day for at least 5 days per week showed less accumulation of “beta amyloid plaque” (proteins that build up on brain with Alzheimer’s Disease), less shrinkage of the hippocampus, and less reduction in use of glucose in the brain. They also had fewer neurofibrillary tangles (twisted fibers inside brain cells) and did better on memory tests. (Bernstein 2014 review)
- current levels of Recommended Physical Activity (RPA). Subjects wore an accelerometer and were categorized as having met physical activity recommendations or not based on the US Department of Health and Human Services recommendations of 150 minutes of moderate-to-vigorous physical activity per week. (Dougherty 2016)
- sedentary lifestyle (<5 hours activity per week) was significantly associated with more than double the risk for dementia. A physically active status was determined as 5 hr/wk or more of light activity and at least occasional moderate to vigorous activity. (Norton 2012)
Other types of physical activity such as resistance training, moderate intensity cycling, and strenuous activity are being studied to determine their value in maintaining cognitive function in aging. In particular, the dose-response relationship is being explored. If minimum physical activity requirements are found to be neuroprotective, investigation continues to see if higher doses of exercise training are more beneficial. At this time, mixed results have been found.
A clear dose-response relationship exists between exercise and cardiorespiratory fitness. Cardiorespiratory fitness is an indicator for brain health. Adherence to more strenuous exercise programs may be problematic for many older adults. (Vidoni 2015) Health-fitness professionals need to work with clients of all ages, carefully balancing fitness gains and intensity/volume with program adherence.
The ultimate goal for quality of life and good health is not realized if your client does not build healthy exercise behaviors to adhere to exercise long term, at least at minimal physical activity requirements. It is important for the general public, and especially the older adult population, to be properly informed of the benefit to risk relationship for the exercises they choose, and most importantly, for those which they can tolerate and adhere long term.
When looking at the research, it is very difficult to say that exercise is not beneficial to brain health. In fact, it appears to be critical to brain health. Research substantially supports that the currently accepted minimum physical activity requirements are neuroprotective. This gives health-fitness professionals a good starting point from which to build programs with clear minimum requirements.
At this time, other intensities and types of exercise are being researched in relation to brain health. As fitness as medicine continues to evolve and develop, it is imperative for health-fitness professionals to consider all aspects of exercise behavior including exercise tolerance and adherence. The art of exercise prescription is creating and fostering long term adherence for good health through the life span.
For more information about Prevention of cognitive decline and dementia, visit the ARPF website at www.alzheimersprevention.org.
The information in this article is taken from the “Exercise Prescription for Alzheimer’s Prevention and Intervention” course, the second course in a two-course 11 hour Medical Fitness Specialist Certificate Program: Alzheimer’s Disease Prevention and Intervention.
Alzheimer’s Disease Prevention and Intervention Medical Fitness Specialist Certificate