Cognitive Benefits of Exercise for Seniors

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The brain is the most active organ in the body and therefore very sensitive to daily stresses. Getting the right amount of exercise, proper nutrition, cognitive stimulation and adequate sleep enhances brain structure and function throughout our lives.

Great minds over the ages have known that physical activity is necessary to keep the mind strong and clear. Aerobic exercise improves cognitive function in humans, produces increases in brain volume, stimulates neurogenesis and synaptogenesis, and increases neurotrophic factors in different areas of the brain. Physical exercise may protect the brain against reduction in cognitive functions in the elderly and delay the onset and slow down the progression of Alzheimer disease.

The loss of strength, cognitive function and stamina attributed to aging is in part caused by reduced physical activity. Inactivity increases with age. By age 75, about 1 in 3 men and 1 in 2 women engage in no physical activity. Among adults aged 65 years and older, walking and gardening or yard work are, by far, the most popular physical activities. Social support from family and friends has been consistently and positively related to regular physical activity.

Older adults should consult with a physician before beginning a new physical activity program. Physical activity need not be strenuous to achieve health benefits. Older adults can obtain significant health benefits with a moderate amount of physical activity, preferably daily. A moderate amount of activity can be obtained in longer sessions of moderately intense activities (such as walking) or in shorter sessions of more vigorous activities (such as fast walking or stair climbing). Additional health benefits can be gained through greater amounts of physical activity, by increasing the duration, intensity, or frequency. Because risk of injury increases at high levels of physical activity, care should be taken not to engage in excessive amounts of activity. Previously sedentary older adults who begin physical activity programs should start with short intervals of moderate physical activity (5-10 minutes) and gradually build up to the desired amount. In addition to aerobic activity, older adults can benefit from muscle-strengthening activities. Stronger muscles help reduce the risk of falling and improve the ability to perform the routine tasks of daily life.

This presentation provides a current summary of the human research on aerobic activity and cognitive function in seniors.

Mark Dreher PhD

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Cognitive Benefits of Exercise for Seniors

  1. 1. January 2014 Cognitive Benefits of Exercise for Seniors Mark Dreher PhD (January 2014)
  2. 2. “Lack of activity destroys the good condition of every human being, while movement and methodical physical exercise save it and preserve it.” - Plato “… from nothing else but the brain come joys, delights, laughter and sports, grief, despondency, and lamentation.” - Hippocrates “Walking is the best possible exercise. Habituate yourself to walk very fast.” “A strong body makes a strong mind.” -Thomas Jefferson “Physical fitness is not only one of the most important keys to a healthy body, it is the basis of dynamic and creative intellectual activity.” “A vigorous five-mile walk will do more good for an unhappy but otherwise healthy adult than all the medicine and psychology in the world.” “The Paul Dudley White Kenneth H. Cooper -John F Kennedy “The Father of American Cardiology” reason I exercise is for the quality of life I enjoy.” “the Father of Aerobics”
  3. 3. Brain Facts that Need to be Respected Every Day! Fact # 1: Although the human brain is only 2% of the body weight, it receives about: - 15% of the cardiac output - 20% of total body oxygen consumption - 25% of total body glucose utilization The brain is the most metabolically active organ and therefore prone to oxidative and inflammatory stress damage, which may deteriorate cognitive function. Fact # 2: The human brain is in a constant state of change such that: - Over the lifespan new neurons may be formed while others will die and new synapses are created while others are eliminated. - Brain cerebral systems are not purely hard-wired and can be significantly influenced by many non-genetic factors such as physical activity, cognitive activity, sleep and nutrition.
  4. 4. United States Physical Activity Report Card for Seniors The loss of strength, cognitive function and stamina attributed to aging is in part caused by reduced physical activity. Inactivity increases with age. By age 75, about 1 in 3 men and 1 in 2 women engage in no physical activity. Among adults aged 65 years and older, walking and gardening or yard work are, by far, the most popular physical activities. Social support from family and friends has been consistently and positively related to regular physical activity. http://www.cdc.gov/nccdphp/sgr/olderad.htm
  5. 5. How Much Aerobic Activity is Generally Recommended? Older adults should consult with a physician before beginning a new physical activity program. Physical activity need not be strenuous to achieve health benefits. Older adults can obtain significant health benefits with a moderate amount of physical activity, preferably daily. A moderate amount of activity can be obtained in longer sessions of moderately intense activities (such as walking) or in shorter sessions of more vigorous activities (such as fast walking or stair walking). Additional health benefits can be gained through greater amounts of physical activity, by increasing the duration, intensity, or frequency. Because risk of injury increases at high levels of physical activity, care should be taken not to engage in excessive amounts of activity. Previously sedentary older adults who begin physical activity programs should start with short intervals of moderate physical activity (5-10 minutes) and gradually build up to the desired amount. In addition to aerobic activity, older adults can benefit from muscle-strengthening activities. Stronger muscles help reduce the risk of falling and improve the ability to perform the routine tasks of daily life. http://www.cdc.gov/nccdphp/sgr/olderad.htm
  6. 6. Regular Physical Activity Health Benefits for Seniors  Helps to reduces symptoms of anxiety and depression and fosters improvements in mood and feelings of well-being. Reduces risk of developing neurodegenerative diseases, high blood pressure, colon cancer, and diabetes. Helps maintain the ability to live independently and reduces the risk of falling and fracturing bones. Can help reduce blood pressure in some people with hypertension. Helps people with chronic, disabling conditions improve their stamina and muscle strength. Helps maintain healthy bones, muscles, and joints. Helps control joint swelling and pain associated with arthritis. http://www.cdc.gov/nccdphp/sgr/olderad.htm
  7. 7. Cognitive Function Benefits Associated with Exercise for Seniors: Overview = Brain Mechanisms Associated with Exercise Cerebral Blood Flow increases to deliver more oxygen and nutrients and remove waste products from brain regions responsible for learning and memory. Neurogenesis spurs the growth of new nerve cells in an important brain memory center called the hippocampus. Angiogenesis creates new brain blood vessels to help maintain and expand volume in key regions such as the hippocampus that are associated with cognitive function. Neuroplasticity develops new brain connections by promoting changes in neural pathways and synapses for healthy development, learning, memory, and recovery from brain damage. Neuroprotection associated with increases in the body’s natural antioxidant defense system and other functions to defend brain health. Healthy Brain Signals increase levels of (1) brain-derived neurotrophic factor (BDNF), a chemical that improves brain synapses and (2) endorphins that promote a feeling of well-being. Potential Benefits of Exercise Helps to slow or reverse shrinkage of key cognitive brain regions such as the hippocampus, important for learning, planning, memory, reasoning and processing speed. Helps reduce the risk for neurodegenerative diseases. Helps to manage mood, anxiety and depression, and fosters feelings of well-being. Kirk-Sanchez and McGough. Clinical Interventions in Aging. 2014;4(9):51-62; Portugal et al. Neuropsychobiology. 2013; 68:1-4; Mind, Mood & Memory, Combating Memory Loss. Massachusetts General Hospital. 2012
  8. 8. Exercise and Cognition Research Highlights: Older Healthy Adults (55 years and older) In 2008, a report evaluated the effects of aerobic activity and cognition on healthy people 55+ years and concluded that the data was insufficient to confirm the benefits of aerobic activity on cognition in older adults. Eight of these 11 studies found that aerobic exercise improved at least one aspect of cognitive function such as speed, auditory and visual attention, but the cognitive benefits were not the same in each study and many comparisons were insignificant. (Angevaren et al. Cochrane database of Systematic Reviews 2008;3) Since 2008 the research focus on aerobic activity and cognitive function in older adults has increased several fold, so now the evidence supporting the benefits of aerobic fitness and cognition is much stronger , examples of new research are summarized below: Issue 1: Brain hippocampal volume can shrink 1–2% annually in healthy older adults, and this loss of volume increases the risk for developing cognitive impairment: Research shows that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood and improving memory function (Erickson et al. Proc Nat Acad Sci. 2011;108(7):3017-3022). Literature indicates that aerobic fitness is associated with healthier brain volume and white matter integrity in older adult (Hayes et al. Frontiers in Aging Neuroscience. 2013;5(31):1-16). Issue 2: The memory, executive function, visuospatial skills and processing speed decline in normal aging adults is likely associated with reduced brain blood flow in key cognitive brain regions such as the frontal cortex and hippocampus: Research suggests that aerobic exercise in sedentary adults (57-75 years of age) can improve cognitive/brain health. Physical activity augmented three domains; brain function resting regional cerebral blood flow, cognition (i.e., memory),and cardiovascular fitness (VO2max and RPE). The benefits were measured after 12 weeks of 3 x 60 minute sessions per week of aerobic exercise. (Chapman et al. Frontiers in Aging Neuroscience. 2013; 5(75):1-9). Study findings show that physical activity seniors (at the recommended levels) attenuated the age-related declines in aerobic fitness and cerebral blood flow compared to sedentary seniors. These findings highlight the importance of maintaining aerobic fitness throughout the lifespan given its capacity to improve cerebral hemodynamics in later-life (Bailey et al. Stroke. 2013; 44:3235-3238). Study finds that when men and women (aged 62-67 years) randomly assigned to an aerobic training sessions of 50 minutes 3-4 times a week compared to the control (non-exercise) group, they had significantly improved middle cerebral artery blood flow (Vicente-Campos et al. J Sports Med Phys Fitness. 2012; 52(5):537-544). When study participants were assigned by stratified randomization within gender (male or female) and age group (young: 19–39 years, middle age: 40–64 years, older age: 65 years or older) to either the exercise or control, the exercised adults had a faster cognitive response time and a lower response to less important cognitive noise across the age spectrum (Hogan et al. Phychol Aging. 2013;28(2):587-594). A cross-sectional study of women (50-90 years), found that physically fit women had higher cerebrovascular blood flow than sedentary women. Overall cognition was positively correlated with VO₂max., which is a predictor of higher resting cerebrovascular blood flow (Brown et al. Neurobiol Aging. 2010;31(12):2047-57).
  9. 9. Seniors Who are More Active have a Lower Risk of Cognitive Decline The results of observational studies support a dose-dependent neuroprotective relationship between physical exercise and cognitive performance in older adults:  The Honolulu–Asia Aging Study followed about 2,500 men from middle adulthood to late life for three decades to assess changes in physical activity and onset of dementia. Those who walked less than 1 mile per day were at significantly double the risk for developing dementia compared to men who walked more than 2 miles per day (Abbott et al. J Am Med Assoc.. 2004;292(12):1447-1453).  The Nurses’ Health Study followed about 20,000 women (aged 70–81) for 10–15 years. The research found that women who walked 90 minutes per week had cognitive scores significantly higher than those who walked less than 40 minutes per week (Weuve et al. JAMA. 2004;292(12):1454-1461). A cross-sectional study estimated the influence of exercise level on age related brain atrophy. Estimates of exercise engagement over the previous 10 years and MRI-based measures of whole and regional brain volumes were obtained in a sample of 52 healthy older adults aged 55 -79. Higher levels of exercise (roughly equivalent to moderate exercise for 30 minutes five times per week) resulted in larger frontal and temporal lobe brain volumes, which are key areas for memory and executive function. In contrast, there was significant age-related atrophy observed for older adults who engaged in low levels of exercise. Bugg and Head. Neurobiol Aging. 2011;32(3):506-514.  Cardiovascular Health Study followed about 300 older adults over 9-years. In this cohort, walking activity over a 1week period at baseline was predictive of greater gray matter volume at end of the study. A relatively long distance at baseline (72 blocks/week) was necessary to maintain brain volume. Greater gray matter brain volume was associated with reduced risk of cognitive impairment over the 9-year period. Erickson et al. Neurology. 2010;75(16):1415–1422.  A meta-analysis of 15 prospective cohort studies up to 2010 including in total of about 35,000 healthy adults evaluated for 1-12 years found that subjects with a moderate level exercise were significantly protected against cognitive decline during the follow-up by about 35%. (Sofi, et al.J Intern Med 2011; 269: 107-117). Kirk-Sanchez and McGough. Clinical Interventions in Aging. 2014;4(9):51-62
  10. 10. Timing Required for Exercise to Show Improved Cognitive Function Benefits A duration of at least 16–20 weeks may be needed to sufficiently improve aerobic fitness in older adults, and exercise durations of 6–12 months are often needed before cognitive changes are detected. Exercise methods to facilitate long-term exercise participation should be incorporated into the design of exercise programs for older adults, such as individual exercise plans that address physical limitations, activity preferences, and social needs. Kirk-Sanchez, McGough. Clinical Interventions in Aging. 2014; 9:51-62
  11. 11. Case Study #1: Aerobic Exercise Increases Size of the Brain Hippocampus Region for Improved Memory in Older Adults Background:  As older adults age, they can experience a 1-2% hippocampus shrinkage per year.  Shrinkage of the brain’s hippocampal region precedes and leads to memory impairment in late adulthood and increased risk for dementia.  Hippocampal and medial temporal lobe volumes are larger in higher-fit adults, and physical activity training increases hippocampal function, but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood needs more research. Methods:  120 older adults (mean age about 65 years) without dementia were randomly assigned to a moderate aerobic exercise group (n = 60) or to a stretching control group (n = 60).  Magnetic resonance images were collected before the intervention, after 6 mo, and again after 1 year.  The groups did not differ at baseline in hippocampal volume or attendance rates. Results/Conclusions:  Aerobic exercise training increased the size of the hippocampus, leading to a better memory.  Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 years. Increased hippocampal volume is associated with greater serum levels of brain-derived neurotrophic factor (BDNF), a mediator of brain neurogenesis.  Hippocampal volume declined in the control group. These findings indicate that aerobic exercise training can reverse hippocampal volume loss in late adulthood and improve memory function. Erickson, et al. Proceedings National Academy Science. 2011;108(7):3017-3022.
  12. 12. Case Study #2: Moderate Aerobic Exercise Improves Brain Health in Older Adults with Mild Cognitive Impairment Background: Evidence from neuropsychological and neuroimaging studies has suggested that mild cognitive impairment (MCI) represents a clinical risk for degenerative dementias such as Alzheimer’s disease (AD). Several randomized controlled trials (RCTs) have been conducted to investigate the effects of physical activity on cognitive function in older adults with MCI. Methods: Investigators evaluated 100 older healthy Japanese adults (mean age, 75 years) with MCI. The subjects were randomized to either a multi-component aerobic exercise or no exercise control group.  The moderate aerobic exercise group included 90 minutes a day sessions for 2 days a week or 40 times for 6 months. Results/Conclusions:  The aerobic exercise group had significantly better cognition (as measured by the Mini-Mental State Examination) and logical memory scores, and reduced whole brain cortical shrinkage compared to the control group.  The effects of exercise were most pronounced for logical memory and general cognitive function in older adults with MCI.  The results suggested that a moderate level of exercise is beneficial for brain health in older adults even if started later in life. Suzuki, et al. PLOS ONE. 2013; 8(4):e61483.
  13. 13. Case Study #3: Moderate Aerobic Exercise Improves Cognition and Brain Health in Older Healthy Adults Background:  Physical exercise, particularly aerobic exercise, is documented to slow cognitive declines including memory, executive function, visuospatial skills, and processing speed in normally aging adults.  Aging studies have focused largely on the effects of extended (>6 months) exercise programs.  Little is known about the cognitive and brain plasticity gains possible in healthy but sedentary seniors from shorter term aerobic exercise training. Methods:  37 cognitively normal adults (mean age of 64.0 [ 57–75 years of age]) were randomized into two different groups: physical training or no training control.  The training regimen consisted of three 60 min sessions of moderate aerobic exercise training per week for 12 weeks.  Participants’ cognitive, cardiovascular fitness and resting cerebral blood flow were assessed at baseline, mid and post-training time points. Results/Conclusions:  The exercise group showed cognitive gains in immediate and delayed memory performance over the course of the 12 week training program, which was associated with a significant increase in hippocampal blood flow compared to the control group.  This study suggests that even shorter term aerobic exercise can facilitate neuroplasticity to reduce negative cognitive consequences of aging and promote brain health in older sedentary adults. Chapman et al. frontiers in Aging Neuroscience. 2013; 5(75):1-10.
  14. 14. “To keep the body in good health is a duty… otherwise we shall not be able to keep our mind strong and clear.” - Buddha “If we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health.” - Hippocrates

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