Dear Doctor: Being physically fit in middle age can decrease the risk of dementia, according to my sister-in-law. She walks four miles a day and runs on the weekends, so I imagine she's covered. But I work full-time and am a single mom to three busy kids, so I'm short on free time. Just how much exercise is enough?
Dear Reader: Your sister-in-law appears to be referring to a study conducted in Sweden, which has yielded some rather dramatic findings. According to the researchers, middle-aged women who had a very high degree of physical fitness were almost 90 percent less likely to develop dementia when they reached old age compared to women with medium or poor physical fitness. When women from the "very fit" group did develop dementia, it was at about age 90 rather than 79, a full 11 years later than the average age at which cognitive decline appeared in members of the less-fit groups.
The study, published online in the medical journal Neurology in March, began in 1968. That's when researchers tested the level of physical fitness of a group of 191 women between the ages of 38 and 60. The women's peak cardiovascular capacity was gauged via a test on a stationary bicycle, which they were asked to ride in several stages until they reached a point of exhaustion. They were then sorted into sub-groups based on their levels of cardiovascular fitness. Over the course of the next 44 years, the women who remained in the study underwent periodic cognitive screening.
During that time, 44 study participants went on to develop dementia. Of those, just 5 percent came from the group deemed "very fit." In the group of women who tested as moderately fit, 25 percent developed dementia. Among the women with the lowest degree of physical fitness, almost one-third of them went on to develop dementia.
When it comes to translating those results into daily life, it's important to note that the most pronounced reduction of dementia risk was observed among the women with the very highest levels of cardiovascular fitness. The women who were unable to complete the bicycle test without taking a break went on to have the highest rates of dementia. And lest the findings seem like a fluke, the authors refer to a number of other studies, both in the United States and in Europe, that associate increasing levels of physical fitness with lowered risk of cognitive decline.
As mothers ourselves, we understand the challenge of finding time for exercise. But a mounting body of research suggests that every minute you put into physical fitness now will pay off for years to come. For general health, current guidelines suggest at least 30 minutes of physical activity per day. When it comes to improved fitness and cardiovascular health, which was linked to lowered dementia rates in the study, the goal becomes up to 60 or 90 minutes per day. This can be broken up into 10- or 15-minute segments. It sounds daunting, but we know from personal experience that, with planning and determination, it's possible and worth the effort.
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