At the still-ongoing (as of July 12, 2010) meeting of the American Alzheimer’s Association in Honolulu, four different papers were presented that validate components of the anti-aging firewalls regimen suggested in my treatise Anti-Aging Firewalls – The Science and Technology of Longevity and in previous blog entries including Diet and cognition, and Warding off Alzheimer’s Disease and things in my diet.. The regimen components concerned are exercise, drinking green tea and coffee, taking vitamin D and eating walnuts. “Evidence from three long-term, large-scale studies supports the association of physical activity and certain dietary elements (tea, vitamin D) with possibly maintaining cognitive ability and reducing dementia risk in older adults – (ref).” The AAA papers listed here were embargoed for release until yesterday and can be found here. I quote both from the papers and from the AAA ICAD press release. The highlights in italics of critical findings are my own.
The paper Physical Activity and the Risk of Dementia: The Framingham Study takes a longer-term look at the relationship between physical exercise and dementia than many of the earlier studies. It draws its date from the Framingham Study, “a population-based study that has followed participants residing in the town of Framingham, Massachusetts since 1948 for cardiovascular risk factors, and is now also tracking cognitive performance. Framingham is widely acknowledged as a premier longitudinal study; it has continued to yield valuable information for more than 40 years(ref).”
“Zaldy Tan, MD, MPH, of Brigham and Women’s Hospital, GRECC, VA Boston, and Harvard Medical School, and colleagues estimated the levels of 24-hour physical activity of more than 1,200 elderly participants from the Framingham Study (742 female; age 76 +\-5) during the study’s 20th examination cycle (1986-87) and followed them for the development of dementia. They divided the participants into five groups based on level of physical activity, from lowest (Q1) to highest (Q5). — Over two decades of follow-up (mean 9.9 +/-5 years), 242 participants developed dementia (of which 193 were Alzheimer’s). The researchers found that participants who performed moderate to heavy levels of physical activity had about a 40 percent lower risk of developing any type of dementia. Further, people who reported the lowest levels of physical activity were 45 percent more likely to develop any type of dementia compared to those who reported higher levels of activity. Similar results were seen when analyses were limited to Alzheimer’s alone. Analyses showed that the observed associations were largely evident in men in the study.”
A 40% risk reduction for developing dementia due to physical activity alone is not bad, so keep moving and exercising.
The second study of concern is Tea, coffee and cognitive decline in the elderly: The Cardiovascular Health Study. “Observational studies have shown associations between consumption of either tea or coffee and cognitive function in older adults, but data including long-term follow-up and rate of change in cognitive function are lacking. — Lenore Arab, PhD, of UCLA, and colleagues used data on more than 4,800 men and women aged 65 and older from the Cardiovascular Health Study to examine the relationship between consumption of tea, coffee, and change in cognitive function over time. Study participants were followed up for up to 14 years for naturally-occurring cognitive decline using the Mini-Mental State Examination (3MSE) administered at baseline and annually up to 8 times. People scored on the average 1.17 points less per year. Tea and coffee drinking were assessed using a food frequency questionnaire. — The researchers found that people who consumed tea at a variety of levels had significantly less cognitive decline (17-37 percent) than non-tea drinkers. More specifically, study participants who drank tea 5-10 times/year, 1-3 times/month, 1-4 times/week, and 5+ times/week had average annual rates of decline 17 percent, 32 percent, 37 percent, and 26 percent lower, respectively, than non-tea drinkers. — According to the scientists, coffee consumption did not show any effect except at the very highest level of consumption – where it was associated with significantly decreased decline of 20 percent(ref).”
So, If you consume both large quantities of green tea and exercise, what is the reduction in dementia? The question was not studied. Does drinking tea bump up the AD risk reduction from 40% to 60% or 70%?
The third paper of concern is Vitamin D and Cognitive Impairment in NHANES III. “3,325 adults aged 65 years or more completed cognitive assessments and provided blood samples in the Third National Health and Nutrition Examination Survey (NHANES III), a nationally representative cross-sectional study of the US non-institutionalized population. Cognitive impairment was assessed using measures of immediate and delayed verbal memory, orientation and attention (impairment was defined as the worst 10% of the distribution of combined scores).”
“Recent European studies suggest vitamin D deficiency is associated with increased odds of cognitive impairment and dementia in later life, although previous findings from the U.S. have been mixed. Interest in vitamin D has intensified recently as research has suggested that it may play a role in a variety of age-associated diseases. — David Llewellyn, PhD, of the University of Exeter Peninsula Medical School (UK), and colleagues examined information from 3,325 adults aged 65 years and older from the Third National Health and Nutrition Examination Survey (NHANES III), a study that was carefully designed to accurately represent the U.S. non-institutionalized population. Vitamin D levels were measured from blood samples and compared with performance on a measure of general cognitive function that incorporated tests of memory, orientation in time and space, and ability to maintain attention. — The researchers classified participants as being cognitively impaired if they scored in the worst 10 percent of older adults in the study. They found that the odds of cognitive impairment were about 42 percent higher in those people who were deficient in vitamin D, and 394 percent higher in people who were severely deficient. –“It appears that the odds of cognitive impairment increase as vitamin D levels go down, which is consistent with the findings of previous European studies,” Llewellyn said. “Given that both vitamin D deficiency and dementia are common throughout the world, this is a major public health concern(ref).”
So if you exercise a lot, drink green tea and take vitamin D supplements, what is the combined reduction in your risk of getting Alzheimer’s disease? Does it give you a 90% risk reduction for getting AD? Again, this is a highly practical but unstudied question.
The final paper of concern is not a large-population study like the others; it is a mouse study: Walnuts-rich diet improves memory deficits and learning skills in transgenic mouse model of Alzheimer’s disease.” Quoting the press release: “It has been suggested that oxidative stress may have a key role in Alzheimer’s disease. Oxidative stress occurs when the production of free radicals exceeds the antioxidant capacity of a cell. Reports have suggested that beta amyloid can increase oxidative stress leading to brain cell death. — Walnuts are source of a-linolenic acid (a plant-based omega-3 fatty acid) and have high content of antioxidants. In March 2004, the U.S. Food and Drug Administration said that “Supportive but not conclusive research shows that eating 1.5 ounces of walnuts per day, as part of a low saturated fat and low-cholesterol diet, and not resulting in increased caloric intake, may reduce the risk of coronary heart disease.”– Abha Chauhan, PhD, and colleagues at the New York State Institute for Basic Research in Developmental Disabilities, examined the effect of diet containing 6 percent or 9 percent walnuts (equivalent to 1 oz. and 1.5 oz. daily intake of walnuts in people) on the cognitive, emotional and motor functions in a transgenic mouse model of Alzheimer’s. The mice were fed custom-mix diets from the age of four months for nine to 15 months. Control mice were fed diet without walnuts. The experimental and control mice were examined at the age of 13 to 14 months and 18 to 19 months for spatial memory and learning ability, position discrimination learning ability, motor coordination, and anxiety-related behavior. — The researchers found that Alzheimer’s transgenic mice on the diet without walnuts at both testing periods showed memory deficits, anxiety-related behavior, and severe impairment in spatial learning ability, position discrimination learning ability and motor coordination. The Alzheimer’s transgenic mice on 6 percent walnuts diet and 9 percent walnuts diet showed significant improvement in learning, memory, emotional regulation and motor coordination compared to transgenic mice that did not eat walnuts. The effects of 6 percent and 9 percent walnuts diets were similar.”
So then, what is the impact on dementia risk reduction if older folks like me pursue all four interventions simultaneously: regularly exercise, drink green tea, take vitamin D3 and eat walnuts daily? How about also pursuing a Mediterranean diet and eating bitter dark chocolate snacks(ref)(ref)? And what would be the impacts of also taking the other anti-oxidant and dietary polyphenols in the combined combined supplement regimen and pursuing the other lifestyle regimen suggestions in my treatise and blog entries related to avoiding dementia? I conjecture that the probable benefits are highly synergistic and far exceed those of any of the individual interventions described in the papers reported here.