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Alzheimer’s Disease and Physical Activity

Bushman, Barbara A. Ph.D., FACSM, ACSM-CEP, ACSM-EP, ACSM-CPT; Pullen, Madison E. B.S., ACSM-EP

Author Information
ACSM's Health & Fitness Journal: 7/8 2021 - Volume 25 - Issue 4 - p 5-10
doi: 10.1249/FIT.0000000000000675
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Q: Are there any benefits of physical activity and exercise related to risk reduction for the development of Alzheimer’s disease or within a treatment plan for an individual with Alzheimer’s disease?

A: No cure currently exists for Alzheimer’s disease (AD), and thus lowering risk and slowing progression are focal areas (1). AD is named after Dr. Alois Alzheimer. In 1906, he identified brain tissue changes after the death of a woman with an unusual mental illness, including memory loss, problems with language, and behavior that was unpredictable (2). These brain changes, now referred to as amyloid plaques and tau tangles, along with loss of connections between nerve cells, are features of AD (2).

DEMENTIA AND AD

Dementia is a general term referring to the loss of cognitive functioning (i.e., thinking, remembering, and reasoning) and behavioral ability (i.e., daily activities) (2). Among older adults, the most common cause of dementia is AD (2). AD is a specific brain disease that makes up 60% to 80% of the cases of dementia (3). A visual to help clarify the relationship between dementia and AD is found in Figure 1 (3). AD is described as “an irreversible, progressive brain disorder that slowly destroys memory and thinking skills, and, eventually, the ability to carry out the simplest tasks” (2). Ten early signs and symptoms of AD are found in Box 1 (4). Given the progression of the disease, aging is a risk factor with most cases found in older adults, although AD can be found in individuals younger than 65 years of age (1). For statistics and additional background related to AD, see Box 2 (1,5,6). Figure 2 displays differences among racial and ethnic groups as well as the projected increase in the number of cases (7).

Figure 1
Figure 1:
Relationship between AD and dementia (source: https://www.alz.org/alzheimers-dementia/difference-between-dementia-and-alzheimer-s). Used with permission. Courtesy of the Alzheimer’s Association.
Figure 2
Figure 2:
Projections on future AD cases and effect of race and ethnicity (source: https://www.cdc.gov/aging/data/infographic/index.html, https://www.cdc.gov/aging/data/infographic/racial-ethnic-disparities-ad.html).

BOX 1: Ten early signs and symptoms of AD (taken from the Centers for Disease Control and Prevention [4], https://www.cdc.gov/aging/healthybrain/ten-warning-signs.html)

  1. Memory loss that disrupts daily life
  2. Challenges in planning or solving problems
  3. Difficulty completing familiar tasks
  4. Confusion with time or place
  5. Trouble understanding visual images and spatial relationships
  6. New problems with words in speaking and writing
  7. Misplacing things and losing the ability to retrace steps
  8. Decreased or poor judgment
  9. Withdrawal from work or social activities
  10. Changes in mood and personality

BOX 2: Numbers and background related to AD

  • In the United States, nearly 6 million Americans are living with Alzheimer’s dementia (5).
  • Approximately 200,000 Americans under the age of 65 years have younger-onset AD (1).
  • In the United States, AD is the sixth leading cause of death, but for older people, AD may rank third, just behind heart disease and cancer, as a cause of death (2).
  • AD accounts for 60% to 80% of dementia cases (1).
  • More than 95% of people with dementia have one or more other chronic conditions (5).
  • According to the World Health Organization (WHO), approximately 50 million people are living with dementia worldwide, with nearly 10 million new cases yearly (WHO). The numbers for those suffering from dementia in 2030 are projected to be around 82 million and 152 million in 2050 (6).
  • The Alzheimer’s Association, founded in 1980, is a voluntary health organization focused on care, support, and research. The color of the association is purple because it combines the calmness and stability of blue and the passionate energy of red (1).

The most common symptom of AD is struggling to remember new information. This disease typically starts in the part of the brain that has to do with learning. According to the Alzheimer’s Association, nerve cell destruction ultimately causes “memory failure, personality changes, problems carrying out daily activities and other symptoms of Alzheimer’s disease” (1). Although various classification systems exist, the Alzheimer’s Association presents three general stages: early stage, middle stage, and late stage (1). Understanding disease status is important within an overall treatment plan. Within the early stage, mild symptoms include trouble remembering names or words, losing things, or difficulty with organization. This stage is an opportune time to encourage lifestyle actions to promote health and wellness. The middle stage involves progression of the disease with symptoms, including inability to remember events, mood changes or feeling withdrawn, wandering off, needing help using the restroom or dressing, and changes in personality. During this stage, assistance may be needed for daily activities, and the level of support required increases. In late-stage AD, the symptoms are severe with loss of ability to communicate or engage with others and difficulty with physical tasks. Support services, including hospice care, are valuable for both the individual with AD and those who are caregivers.

DIETARY FOCUS

AD requires a healthy diet, and as noted by the Alzheimer’s Association, “Eating a heart-healthy diet benefits both your body and your brain” (1). Two diets have been suggested to reduce risk of heart disease and dementia: the Dietary Approaches to Stop Hypertension (DASH) diet and the Mediterranean diet (1). The DASH diet focuses on reducing blood pressure, includes foods low in saturated fat, total fat, and cholesterol. This diet is high in fruits, vegetables, and low-fat dairy, along with whole grains, poultry, fish, and nuts while reducing consumption of fats, red meat, sweets, sugary beverages, and sodium. The Mediterranean diet emphasizes eating fruits, vegetables, nuts, and grains. The Mediterranean diet recommends replacing fats with healthy fats (e.g., olive oil), reducing red meat consumption, replacing salt with herbs to season food, and eating more fish and poultry. Another diet, reflecting aspects of DASH and Mediterranean diets, is the Mediterranean–DASH Intervention for Neurodegenerative Delay (MIND) diet; observational studies have shown an association between the MIND diet and the reduced AD risk and slower cognitive decline (8). For more on dietary aspects to consider, see “What do we know about diet and prevention of Alzheimer’s disease?” from the National Institute on Aging (8).

MEDICATIONS

Two types of drugs have been approved by the FDA for memory: cholinesterase inhibitors and memantine (1). Although these medications do not stop AD, there is the potential to lessen or stabilize symptoms. Cholinesterase inhibitors prevent acetylcholine breakdown; acetylcholine is involved with learning and memory given its role with communication among nerve cells (1). Memantine regulates glutamate, which is a chemical involved in processing, storing, and retrieving information (1). In addition, various medications for behavior and sleep changes may be prescribed (1). Medications will depend on the stage of the patient and symptoms. It is incumbent that exercise professionals working with individuals with AD are aware of all medications and the side effects of the medications. Given that medications are focused on symptom relief rather than a cure, exercise has been suggested as a valued treatment due to overall safety with relatively few side effects (9). The remainder of this article will focus on the potential effect of physical activity and exercise.

PHYSICAL ACTIVITY AND EXERCISE

The risk of AD is increased by a sedentary lifestyle; conversely, increasing physical activity is potentially protective against AD (10). Leisure-time physical activity, both current and past, was associated with lower risk of AD than when leisure activity was low throughout life (11). There is support for the value of lifelong physical activity in reducing cognitive impairment later in life, although other factors also may contribute (e.g., social factors, education level, and number of activities) (10). Relationships can be difficult to study, given the complex and interrelated factors; associations found in cohort studies (i.e., a longitudinal study that looks at group characteristics over time) cannot fully answer whether physical activity has a direct or indirect affect (12). Thus, from a wider perspective, recommendations for reducing risk of cognitive decline include physical activity, in addition to healthy diet, social engagement, and mentally stimulating activities (2). The effect of environmental enrichment, including physical, cognitive, and social stimuli, has been referred to as “brain reserve,” and the question remains if this may create a cognitive reserve that can compensate for processes that damage the brain (13).

One review of studies that included comparisons between a physical activity intervention group and an inactive control group noted insufficient evidence that physical activity alone can prevent cognitive decline, although physical activity did impart benefits compared with controls for some aspects (12). The authors of the review questioned whether available studies may have been too short in duration or with insufficient subject numbers (thus impacting ability to identify changes), suggesting that true long-term gains as supported by cohort studies may require a lifestyle of activity, started earlier in life leading to the conclusion: “Short-term interventions begun after decades of high-risk behavior likely are insufficient to reduce dementia incidence” (12). Another review article examined the efficacy of physical exercise among older adults with AD as it related to executive function improvement; many, but not all studies, demonstrated improvements with physical activity (variety of programs, including aerobic, resistance training, or combination of aerobic, resistance, and flexibility or balance) (14). Although exercise alone does not appear to prevent AD, physical exercise has been noted as foundational for other lifestyle interventions, including healthy diet, not smoking, adequate sleep, and cognitive engagement (15).

In light of the many other established health improvements linked to physical activity, along with potential benefit to cognition, physical activity is a worthy public health recommendation (10). Relationships between cognitive decline and vascular conditions (e.g., heart disease, stroke, and hypertension) or metabolic conditions (e.g., obesity and diabetes) are of interest to researchers (2); the value of physical activity related to each of these conditions is well documented (16).

Currently, an explanation of how exercise may confer benefits to brain health is not fully known. Researchers continue to explore the mechanism(s) that contribute to a protective effect of exercise, including reducing blood pressure and obesity, improving lipid profiles and endothelial function, enhancing cerebral blood flow and oxygenation of various areas in the brain that are related to cognitive function, and providing neuroprotection by increasing various factors such as brain-derived neurotrophic factor (BDNF), which is linked to the development/survival of neurons and synapses (17). Exercise may affect the brain in various areas, including vascular aspects, volume of the hippocampus, and neurogenesis (9,18). The higher volume of the hippocampus (an area in the brain) is related to improved cognition, and exercise appears to protect against loss of volume (18). In addition, blood flow to the brain is higher with exercise (18).

EXERCISE TESTING

The American College of Sports Medicine (ACSM) includes guidance related to working with individuals with AD in the newest edition of ACSM’s Guidelines for Exercise Testing and Prescription (GETP11) (19). Safety is always a top consideration and remains so with exercise testing in individuals with AD given concerns with comorbid conditions (e.g., cardiovascular disease and type 2 diabetes) (19). In addition, severe cognitive impairments may interfere with safe administration of exercise testing because of the individual’s inability to remember the steps or required actions of the test (19). Consultation with an individual’s health care team (physician and/or neuropsychologist) who are aware of the level of impairment is vitally important (19).

EXERCISE AND PHYSICAL ACTIVITY RECOMMENDATIONS

Early intervention appears to be valuable with various studies showing improvements in cognition, memory, and processing speed tasks (10). Aerobic exercise has the potential to attenuate cognitive impacts of AD by lowering cerebrovascular risk factors (20); many risk factors for cerebrovascular diseases and AD are shared (17). A combination of aerobic and resistance training has been shown to be beneficial for individuals with dementia, although not all studies have shown improvements in cognition (10). The key elements of successful programs appear to include multiple modes of exercise, including an aerobic component of at least 150 minutes per week, in addition to incidental movement throughout the day (10). Physical exercise may allow for improved ability to engage in activities of daily living, along with improvements in aerobic fitness and functional abilities related to strength, balance, agility, and flexibility (21). Additional benefits of exercise include reduced risk of falling and improvement in other chronic conditions that may occur along with AD such as type 2 diabetes (19). The social aspect of a physical activity program also may be valued (21). In one study, there was a correlation between the caregiver’s and the care recipient’s physical activity level, with expectations regarding the outcome of activity being strongly associated with the level of physical activity of the care recipient. Caregivers are integral in promoting physical activity in individuals with AD (22).

Potential concerns related to the effect of cognitive impairment within an exercise environment include the distraction and overestimation of capacity by the individual with AD (19). ACSM suggests that exercise can be safely implemented with appropriate progression and supervision; consultation and ongoing communication with the individual’s health care team are keys for feedback on the severity of the cognitive impairment and any other chronic health conditions (19). See Box 3 for a suggested list of questions to discuss with the health care provider (23). Programs that include a variety of lower-intensity activities as well as inclusion of multiple modes of exercise are recommended (19). A summary of the exercise prescription recommendations is found in the Table adapted from GETP11 and includes aerobic fitness, muscular fitness, and flexibility (19). As with any exercise program, a warm-up and a cool-down should be included to promote safety (19).

TABLE - Exercise Prescription Recommendations for Individuals with AD
Aerobic Exercise Resistance Training Flexibility Exercises
Frequency 3 days per week 2 to 3 days per week Daily is most effective, at least 2 to 3 days per week minimum
Intensity Individualize based on the severity of disease: light with progression to moderate based on individual response For beginners, consider 40% to 50% of 1-RM; for more advanced, consider 60% to 70% 1-RM. Modify levels as needed based on the severity of disease or other conditions Stretch to point of slight discomfort
Time Starting point may be less than 10 minutes, progress should be individualized. Continuous or accumulated aerobic exercise up to 30 to 60 minutes per day One or more sets of 8 to 12 repetitions, or for beginners 10 to 15 repetitions Static stretches should be held for 10 to 30 seconds and repeated 2 to 4 times for each exercise
Type Large, rhythmic muscle group activity such as walking, cycling, swimming, and dancing Focus on weight machines and other devices such as bands or body weight exercises rather than free weights Target all major muscle groups with slow static stretches
Adapted from ACSM’s Guidelines for Exercise Testing & Prescription, 11th edition.

BOX 3: Exercise Prescription Considerations

Good communication between the health care team (physician and/or neuropsychologist) and the fitness professional is key to understand the severity of AD as well as any other coexisting conditions (e.g., heart disease, hypertension, and fall history). Some suggested areas to discuss include the following (23):

  • What type(s) of physical activities will be best?
  • What physical activities should be avoided?
  • How frequent should the activity sessions be and for what duration?
  • What is the recommended intensity?

Individuals in early stages may be able to exercise independently, but given the progressive nature of AD, this ability will change. As the disease progresses, supervision becomes important to monitor safety as well as to encourage and support the individual (19). Exercise sessions will need to be modified and individualized based on the stage of the disease and other related health conditions (19). Time of day may be a consideration as morning sessions may be most beneficial given that symptom severity tends to be lower earlier in the day (19). Listed below are some additional aspects to consider (23):

  • Keep it simple. As AD progresses, remembering how to do more complicated movements may be difficult and, thus, could become a safety issue. Establish a routine program that is consistent and manageable.
  • Check the environment. Address trip-and-fall hazards like poor lighting, rugs, and cords. Installing a grab bar in the exercise area may be helpful if balance is an issue. A calm, quiet environment that is familiar to the person can increase comfort with the activity setting.
  • Make it fun. Find enjoyable activities to maintain and promote the habit of activity.

CONCLUSION

Much is still unknown regarding the mechanism by which physical activity and exercise may lower risk of AD, or slow the progression. Associations between higher amounts of physical activity and reduced risk of AD are encouraging. Improvement in cognitive function for those with AD due to a physical activity program is not yet fully established, and more research is needed to examine this potential effect of various physical exercises. Current ACSM recommendations include aerobic exercise, resistance training, and flexibility with the understanding that programs must be individualized in consultation with the health care team to ensure disease severity and coexisting conditions are addressed appropriately, with a focus on improving quality of life.

References

1. Alzheimer’s Association Web site [Internet]. Chicago (IL): Alzheimer’s Association; [cited 2020 Dec. 10]. Available from: https://www.alz.org/alzheimer_s_dementia.
2. National Institute on Aging Web site [Internet]. Alzheimer’s Disease Fact Sheet. Bethesda (MD): National Institute on Aging; [cited 2020 Dec 15]. Available from: https://www.nia.nih.gov/health/alzheimers-disease-fact-sheet.
3. Alzheimer’s Association Web site [Internet]. Chicago (IL): Alzheimer’s Association; [cited 2020 Dec. 15]. Available from: https://www.alz.org/alzheimers-dementia/difference-between-dementia-and-alzheimer-s.
4. Centers for Disease Control and Prevention Web site [Internet]. 10 Warning Signs of Alzheimer’s. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2020 Dec 17]. Available from: https://www.cdc.gov/aging/healthybrain/ten-warning-signs.html.
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7. Centers for Disease Control and Prevention Web site [Internet]. Infographics. Atlanta (GA): Centers for Disease Control and Prevention; [cited 2020 Dec 17]. Available from: www.cdc.gov/aging/data/infographic/index.html.
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RESOURCES FROM THE WEB

Video showing how AD changes the brain: https://www.nia.nih.gov/health/video-how-alzheimers-changes-brain

Resources for caregiver health and support: https://www.alz.org/help-support/caregiving/caregiver-health

Information on medications related to AD, see https://www.alz.org/alzheimers-dementia/treatments.

Dietary considerations, including the MIND diet, see www.nia.nih.gov/health/what-do-we-know-about-diet-and-prevention-alzheimers-disease

Information on many aspects of AD: www.cdc.gov/aging/aginginfo/alzheimers.htm

Information on dementia from the World Health Organization: https://www.who.int/news-room/fact-sheets/detail/dementia

Copyright © 2021 by American College of Sports Medicine.