Mild Exercise May Counter Dementia

Moderate physical activity — even an unhurried 30-minute stroll a day — may diminish the risk for vascular dementia among the elderly, according to a new study published this week in the online journal Neurology.

Researchers from the University Hospital S. Orsola-Malpighi in Bologna analyzed the exercise habits of 749 rural Italians over age 65 during a period of four years. At the beginning of the study, none had memory problems; by the last check up, 85 participants had developed some form of dementia — including Alzheimer's and vascular dementia, which is associated with decreased blood flow to the brain.

While the researchers discovered no noticeable impact of exercise upon development of Alzheimer's — the neurodegenerative disease that accounts for roughly 70% of all cases of dementia — they found a marked impact on the risk of developing vascular dementia, the second most common variation after Alzheimer's. As its name implies, vascular dementia is a condition where restricted blood flow to certain parts of the brain impacts cognitive abilities, affecting the tissue like a series of small strokes.

Study participants who burned the most calories per week while walking — as few as 209 extra calories per week — had a 27% lower risk of vascular dementia than people who did little to no exercise. Those who expended the most energy during moderate activities like biking or yard work had a 29% lower risk. "It means that even small amounts of inexpensive and easy-to-perform exercise — just walking — can be of help to protect you against brain vascular damage," says Dr. Giovanni Ravaglia, the study's lead author, "and this is a type of exercise that even older disabled people with chronic disease can do without too much trouble."

The finding is in keeping with current research about the impacts of healthy lifestyle habits on the risk for developing cognitive impairment conditions later in life. "I'm not surprised by this study," says Dr. Zaldy Tan, director of the Memory Clinic at Beth Israel Deaconess Medical Center in Boston. "I think more and more researchers like myself are realizing that prevention is the most effective way of curbing the incidence of Alzheimer's disease and vascular dementia."

The study's authors suggest that exercise lowers the risk for cerebrovascular disease by increasing blood flow to the brain; exercise may also enhance the brain's ability to build "functional reserves" against damage by building elasticity in synapses and decreasing the secretion of stress hormones that negatively impact brain tissue. Still, the authors note that like many observational studies, theirs has limitations. It's possible, for example "that exercise, in our study, was a proxy for other, unaccounted for lifestyle habits or environmental influences," says Ravaglia. People who are regularly active are "more likely to be more careful of their health, what they eat, smoking, alcohol, and so on, reducing their general risk of cardiovascular disease and atherosclerosis," he says.

Though the current study does not definitively show that exercise prevents dementia (as opposed to being a symptom of general well-being), researchers note that regular exercise boosts health in many other important ways, including weight control and prevention of coronary disease. "I think it's premature to specifically prescribe exercise to prevent dementia, but it's not premature to prescribe exercise to prevent heart disease," says Tan. "A lot of the things that have been proven to be good for the heart, now there's accumulating evidence that these work for the brain."