HEALTH – THE BRAIN – ALZHEIMER’S & DEMENTIA – EXERCISE


6 RESEARCH ARTICLES + 1 GRAPHIC – CLICK ON IMAGE TO ENLARGE



ALZHEIMER’S AND EXERCISE – 2017


– Alzheimer’s is the leading cause of dementia in late adult life
– Because of mixed effectiveness of medications, exercise has been considered as a treatment for pre-clinical AD, late stage AD, and as a prevention strategy
– Exercise appears to improve brain blood flow, increase hippocampal volume, and improve neurogenesis
– Higher physical activity levels are associated with a reduced risk of development of disease
– Exercise as a treatment for AD shows improvement in cognitive function, decreased neuropsychiatric symptoms, and a slower decline in activities of daily living (ADL)


MEDIATION OF COGNITIVE FUNCTION IMPROVEMENTS BY STRENGTH GAINS IN OLDER ADULTS WITH MILD IMPAIRMENT – 2016


OBJECTIVES
To determine whether improvements in aerobic capacity (VO2peak) and strength after progressive resistance training (PRT) mediate improvements in cognitive function
DESIGN
– Community-dwelling older adults (aged ≥55) with mild cognitive impairment (MCI) (N = 100)
– PRT and cognitive training (CT), 2 to 3 days per week for 6 months
– Alzheimer’s Disease Assessment Scale–cognitive subscale (ADAS-Cog); global, executive, and memory domains; peak strength (1 repetition maximum); and VO2peak.
RESULTS
1. PRT increased upper, lower and whole-body strength and percentage change in VO2peak significantly more than sham exercise
2. Higher strength scores, but not greater VO2peak, were significantly associated with improvements in cognition
3. Greater lower body strength significantly mediated the effect of PRT on ADAS-Cog improvements and global domain but not for executive domain
CONCLUSION
– High-intensity PRT results in significant improvements in cognitive function, muscle strength, and aerobic capacity
– Strength gains, but not aerobic capacity changes, mediate the cognitive benefits of PRT


ASSOCIATION BETWEEN AEROBIC FITNESS AND COGNITIVE FUNCTION IN OLDER MEN MEDIATED BY FRONTAL LATERALIZATION – 2016


AIM
– to reveal the relationship between aerobic fitness, cognitive function, and frontal lateralization
METHOD
60 male older adults each performed a submaximal incremental exercise test to determine oxygen intake (View the MathML sourceO2) at ventilatory threshold (VT)
– They performed a color–word Stroop task while prefrontal activation was monitored using functional near infrared spectroscopy
CONCLUSION
These results suggest that higher aerobic fitness is associated with cognitive function via lateralized frontal activation in older adults


EXERCISE TO PREVENT DEMENTIA – 2015


EXERCISING IN MID-LIFE
(1) Combining the results of 11 studies shows that regular exercise can significantly reduce the risk of developing dementia by about 30%
(2) For Alzheimer’s disease specifically, the risk was reduced by 45%
(3) One study looked at health behaviours of over 2,000 men in Wales, and followed them for 35 years:
– Of 5 behaviours assessed (regular exercise, not smoking, moderate alcohol intake, healthy bodywt, healthy diet), exercise had the greatest effect of reducing dementia risk
– Overall, people who followed 4 or 5 of the above behaviours were up to 60% less likely to develop dementia
(4) In the short term, aerobic exercise can also improve the performance of healthy adults on thinking tests:
– Results of 29 clinical trials shows a month or more of regular aerobic exercise resulted in improvements in memory, attention and processing speed when compared with regular non-aerobic exercise such as stretching and toning
EXERCISING IN LATER LIFE
(1) Although less research has been done with healthy older people, there is evidence to show older people can also reduce risk of dementia with regular exercise
(2) Study: 716 people average age 82 yrs; those in bottom 10% of daily physical activity were >2x as likely to develop Alzheimer’s as those in the top 10%
(3) A literature review found 27 studies looking at the effect of physical activity on brain function in people over 60 yrs of age:
– In 26 of the studies there was a clear link between physical activity levels and cognitive performance
(4) Aerobic exercise has also been shown to affect the brains of healthy older people:
– Study: 1 yr of aerobic exercise resulted in a small increase in the size of the hippocampus (the key brain area involved in memory), which was the equivalent of reversing 1 to 2 yrs of age-related shrinkage
– Study: 638 people in Scotland; those physically active at age 70 experienced less brain shrinkage over 3 yrs than those who were not


ASSOCIATION OF MUSCLE STRENGTH WITH THE RISK OF ALZHEIMER’S – 2009


OBJECTIVE
– To test the hypothesis that muscle strength is associated with incident AD and MCI
– Alzheimer disease (AD) or mild cognitive impairment (MCI)
DESIGN
– More than 900 community-based older persons without dementia at the baseline evaluation
– Strength was measured in 9 muscle groups in arms and legs, and in the axial muscles and summarized into a composite measure of muscle strength
RESULTS
1. During a mean follow-up of 3.6 years, 138 persons developed AD
2. Each 1-U increase in muscle strength at baseline was associated with about a 43% decrease in risk of AD
3. Muscle strength was associated with a decreased risk of MCI, the precursor to AD
CONCLUSION
– These findings suggest a link between muscle strength, AD, and cognitive decline in older persons


CARDIORESPIRATORY FITNESS AND BRAIN ATROPHY IN EARLY ALZHEIMER’S – 2008


J. M. Burns, MD, H. Swerdlow, M et al
BACKGROUND
– In normal aging physical fitness appears to mitigate functional and structural age-related brain changes
– Whether this is observed in AD is not known
METHODS
– Subjects without dementia (n = 64) and subjects with early-stage AD (n = 57)
– Peak oxygen consumption (VO2peak), the standard measure of cardiorespiratory fitness, was assessed during a graded treadmill test
– Normalized whole brain volume, a brain atrophy estimate, was determined by MRI
– Pearson correlation and linear regression were used to assess fitness in relation to brain volume and cognitive performance
CONCLUSIONS
– Increased cardiorespiratory fitness is associated with reduced brain atrophy in Alzheimer disease (AD)
– Cardiorespiratory fitness may moderate AD-related brain atrophy or a common underlying AD-related process may impact both brain atrophy and cardiorespiratory fitness


 

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