Benefits of Exercise - Dementia

In this section, we present results from two studies on the impact of exercise on dementia in men and women (references 8 and 9).

In the first study (ref 8), men of Japanese ancestry in Hawaii were tracked for approximately 5 years. At the start of the study, there ages were between 71 to 93 years. Only men who were physically capable of walking, who were not employed, and who did not have dementia at the start were included. The development of dementia was determined by a rigorous cognitive function test. During followup, a total of 158 cases of dementia were identified, equating to a total risk of 16 cases per 100 people in 10 years.

Compared with men who walked more than 2 miles a day, men who walked the least (less than 0.25 miles per day) had an increased risk ratio of 1.77 (1.04 to 3.01 margin of error). We note that there is a very broad margin of error, that includes values close to 1.00, implying in our opinion that more studies are needed to corroborate this result.

Ref 9 presents a study involving almost 19,000 women aged 70 to 81 years. Unlike the previous study, it doesn't categorize the participants as becoming demented (or not) - rather, it determines a score of cognitive performance, and compares scores for women who are physically active to women who are not.

The study finds that women with a higher level of long term physical activity have an average higher score on the cognitive test, and less cognitive decline. They find that greater physical activity was similar in extent to being about 3 years younger in age, and associated with a 20% lower risk of cognitive impairment. The activities did not need to be vigorous to achieve the improvement - walking at least 1.5 hours a week at a 21-30 minute-per-mile pace was also associated with better cognitive performance.

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