by Dana Martin
|(From left) Dr. Linda Teri, |
Dr. David Buchner, and
Dr. Rebecca Logsdon.
We’ve all heard that exercise is good for us — right up there with the adage of eating an apple a day for the preservation of health. But can exercise really make a person smarter? And does exercise actually help prevent Alzheimer’s disease and even help those who have been diagnosed with the disease?
The relationship between exercise, physical health and cognitive function was the focus of the 22nd Annual Alzheimer’s Disease Research Center (ADRC) Public Forum, held June 13 at North Seattle Community College.
Dr. Linda Teri, UW ADRC Education Director and Professor of Psychosocial & Community Health, kicked off the evening with an overview of the ADRC. “We try to cover the waterfront in understanding the disease process,” said Teri. The Center’s mission is to conduct cutting-edge research, to help provide care, and to educate the public, including those caring for people with Alzheimer’s.
Dr. David Buchner, chief of the Physical Activity and Health Branch at the Centers for Disease Control and Prevention, was this year’s featured speaker. He began his presentation, “Surprising Links Between Physical Activity, Brain Health, and Healthy Aging,” by describing a 2001 study that enrolled almost 6,000 women over the age of 65. A test that measures memory and cognitive function was administered to each woman when she enrolled and repeated six to eight years later to measure how much cognitive function changed. The amount of physical activity was also measured by asking each woman how many blocks she walked in a week. The investigators found that more walking at baseline was significantly associated with less cognitive decline six to eight years later. In fact, women in the highest physical activity group had 34 percent less cognitive decline compared with the least- active women.
Although vigorous activity is good, the benefits of moderate activity are enormous and are less likely to lead to injury in older adults, noted Buchner. A simple test to determine your level of activity is that if you can sing while you’re walking, your exercise is light. If you can talk but not sing, it’s moderate. And if you’re gasping for air, you are doing vigorous activity.
“A surprising finding is that if you exercise moderately for three 10-minute intervals throughout the day, you get the same benefit as if you exercise for 30 minutes in a row,” Buchner said. That means instead of trying to pack all your physical activity into one session, you can break it up over the day, which makes it easier to work it into your daily routine. For example, you can reach your physical activity goal by taking a brisk 10-minute walk in the morning, spending 10 minutes raking or digging in the garden, and then lifting weights for 10 minutes while watching the evening news.
Research consistently points to the power of exercise to promote physical and mental health. Buchner cited a study with older adults in which walking two or more miles a day reduced mortality by more than 50 percent. “Do you know of anything else you can do that’s that easy and can reduce your rate of premature mortality by 50 percent? You’re not going to get a drug from your doctor, I don’t think, that’s going to reduce your rate of mortality by that much,” Buchner said.
As for the effects of exercise on memory and thinking, Buchner focused on whether physical activity improves cognitive ability in adults, whether it prevents cognitive decline in individuals at risk for dementia, and whether it improves function in those who already have cognitive impair-ment. A recent meta-analysis that included data from 18 high-quality research studies showed that, in adults, exercise has the greatest effect on skills like complex problem-solving and reasoning ability. Benefits were greatest in studies that included aerobic, strength and flexibility training — many women benefited more than men from exercise.
As far as preventing or delaying cognitive decline in older adults, a recent study conducted in Seattle by Dr. Eric Larson and colleagues found that habitual walkers had a 40 percent decreased risk of developing dementia compared to non-exercisers. Furthermore, adults who were less healthy and who had poorer physical function seemed to benefit the most. Dr. Buchner identified several possible underlying causes for this outcome, including increased blood flow to the brain, increased brain volume and reductions in metabolic inflammatory markers. “So we have now this list of possible mechanisms. There are about 10 to 15 studies about [exercise and] Alzheimer’s disease prevention, and most of the literature is positive,” Buchner said.
For those who already have Alzheimer’s disease or other dementias, exercise also appears to confer many benefits. For example, in 2006, Dr. Teri published results of a randomized controlled trial involving 153 community-living Alzheimer’s patients who received either an in-home exercise and caregiver education program or routine medical care. Participants who received the exercise and education program had better physical function, decreased depression and were less often placed in an institution due to behavioral disturbance than those who received routine care. In addition, a recent meta-analysis of physical activity and dementia showed that a variety of physical activity programs were consistently associated with a 30 to 50 percent reduction in adverse cognitive, behavioral and affective outcomes in individuals with dementia.
What specific changes occur in the brain that may be producing these exercise-related effects on cognition? Dr. Buchner cited a 2004 study that used functional magnetic resonance imaging (fMRI) to study brain activity in adults when performing a cognitive task. The fMRIs showed that subjects who were aerobically trained had enhanced brain function compared with non-exercisers. These findings are consistent with laboratory studies which have shown that exercise-trained rats solve mazes faster than sedentary rats and that exercise-trained rats actually grew new neurons in an area of the brain called the dentate gyrus of the hippocampus (an area affected by Alzheimer’s disease in humans). Research has also shown that exercise has beneficial effects on brain neurotransmitters such as dopamine, serotonin and acetylcholine. Several Alzheimer’s disease drugs (such as donepezil, rivastigmine, and galantamine) increase brain acetylcholine levels. Research shows that exercise might have the same effect.
Dr. Buchner concluded that the old tried-and-true recommendation for us to all take a walk every day has been proven to have tremendous health benefits, both physical and mental. “In my humble opinion, the evidence is not conclusive, but probably physical activity, especially aerobic physical activity, has a moderate effect on cognition in healthy and cognitively mpaired adults, and it prevents or delays the development of cognitive impairment, including impairment caused by Alzheimer’s disease.” He added that although much remains to be learned, “We already have more than enough reasons to be physically active. And it looks like to me we’re going to have another big reason as this research goes forward.”
“We have a chronic disease epidemic in this country, and mainly what’s driving it is our lifestyles.”
Q: What percent of Americans in 2000 reported a healthy lifestyle in that they:
CURRENT PHYSICAL ACTIVITY GUIDELINES
At least 30 minutes a day of moderate physical activity at least five days a week.
To view Dr. Buchner’s presentation, go to: http://depts.washington.edu/adrcweb/forum2007.shtml