In a set of 3 studies, see how exercise and sleep lowered Alzheimer's, while sitting around and watching TV resulted in significantly worse brain health.
1. ExerciseModerate Exercise in Middle Age Is Associated with Decreased Risk of Dementia
Of the growing body of research concerning lifestyle and brain health, and also the possibility of reduced risk of Alzheimer's and other dementias, perhaps the strongest and most consistent evidence exists for regular physical activity.
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Yonas E. Geda, M.D. and colleagues at the Mayo Clinic investigated the relationship between timing of exercise (mid-life/50-65 vs. late-life/70 and above) and risk of new cases of dementia in 280 older adults (median age=81) with mild cognitive impairment (MCI) from the Mayo Clinic Study of Aging, and reported on their findings at AAIC 2014.
A person with mild cognitive impairment (MCI) has a slight but noticeable and measurable decline in cognitive abilities, including memory and thinking skills. These changes are serious enough to be noticed by the individuals experiencing them or to other people, but they are not severe enough to interfere with daily life or independent function. People with MCI are at an increased risk of developing Alzheimer's disease.
Study participants completed a questionnaire on the frequency and intensity of exercise during their lifetime. After following the participants for about three years, the researchers found that a history of moderate physical exercise in middle age was associated with a significantly decreased risk of MCI progressing to dementia. (The association did not hold for either light or vigorous exercise in middle age, or for any level of physical activity in late life.)
In a second study reported at AAIC, the researchers looked at the timing of physical exercise and the risk of new cases of MCI. The study participants were 1,830 older adults with normal cognition from the Mayo Clinic Study of Aging. Participants underwent neurological evaluations, cognitive tests, and a self-reported questionnaire about physical exercise habits in mid-life and late-life, and were followed for an average of 3.2 years. The scientists observed that light physical exercise in mid-life and late-life were associated with decreased risk of incident MCI. Additionally, vigorous mid-life as well as moderate late-life physical exercise were associated with decreased risk of incident MCI.
“In our studies, we found that physical exercise at various levels, especially in mid-life, is beneficial for cognitive function,” Geda said. “These are intriguing results, but they are not yet conclusive. More research is needed to determine the extent and nature of physical activity in protecting against MCI and dementia.”
2. SleepPoor Sleep Is Associated with Higher Dementia Risk In Veterans; PTSD More Than Doubles That Risk
It is known that sleep disturbance is a risk factor for cognitive decline and dementia, but this association has not been carefully investigated in older veterans. At AAIC 2014, Kristine Yaffe, M.D. of the University of California, San Francisco and colleagues reported on the results of a retrospective study of sleep disturbance and dementia among 200,000 veterans age 55 and older, 96.5 percent of whom were male.
The researchers examined eight years of the veterans' medical records. After controlling for variables such as gender, income, education, and health status, they found that veterans who had a diagnosis of non-specific sleep disturbance, apnea, or insomnia at baseline had a 30 percent increased risk of dementia compared with veterans with no diagnosed sleep problems. They also found that veterans with both PTSD and sleep disturbance had an 80 percent increased risk of dementia.
“This is the first investigation into the link between sleep disturbance and dementia in a large cohort of older, mostly male veterans,” said Yaffe. “Further research is needed to clarify the role of sleep disturbance as either a risk factor for, or an early symptom of, dementia among veterans, and in other populations as well.”
3. TV & Loafing AroundLow Physical Activity and High TV Viewing are Associated with Worse Cognitive Function
Physical activity in later life is generally considered a protective factor against cognitive decline and possibly Alzheimer’s and other dementias, but little is known about the role of physical activity in early adulthood.
“Understanding this relationship in early adulthood may be particularly important because global data suggests that levels of physical inactivity and sedentary behavior are increasing,” said Tina Hoang, MSPH, of the Northern California Institute of Research and Education (NCIRE), San Francisco, with her mentor, Kristine Yaffe, MD, of the University of California, San Francisco.
Yaffe, Hoang and colleagues investigated the association of long-term patterns of low physical activity and high television viewing time over 25 years with cognitive function at mid-life. The study population included more than 3,200 black and white adults, 18-30 years old, in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Physical activity and television viewing were assessed at repeated visits (≥3 assessments) over 25 years. Low physical activity was defined as activity below 300 kcal/50 min session, 3 times per week; high television viewing was defined as more than 4 hours per day.
A long-term pattern of each behavior was defined as meeting these cutoffs for more than two-thirds of visits. 17% of participants reported a long-term pattern of low physical activity, 11% a long-term pattern of high television viewing, and 3% reported both. At year 25 of the study, participants were assessed for memory, executive function and processing speed using well-established tests.
At AAIC 2015, Yaffe, Hoang and colleagues reported that study participants with low levels of physical activity over 25 years had significantly worse cognition in mid-life, adjusting for age, race, sex, education, smoking, alcohol, BMI, and hypertension. Similarly, participants with high levels of TV watching over 25 years also had significantly worse mid-life cognitive function. Study participants with both long-term low physical activity and high television viewing were almost two times more likely to have poor cognitive function in mid-life.
“Our findings demonstrate that even early- and mid-adulthood may be critical periods for promotion of physical activity for healthy cognitive aging,” Hoang said. “Sedentary behaviors, like TV viewing, could be especially relevant for future generations of adults due to the growing use of screen-based technologies. Because research indicates that Alzheimer’s and other dementias develop over several decades, increasing physical activity and reducing sedentary behavior beginning in early adulthood may have a significant public health impact.”