According to the “Global Prevalence of Dementia: a Delphi Consensus Study”, appearing in the Lancet (2005; 366(9503): 2112-7), the number of people with dementia in developed countries will double between 2001 and 2040. There are over 23 million people with dementia worldwide, with a new case coming every seven seconds. There are 4.6 million new cases every year.

There is evidence that physical activity reduces the risk for developing dementia. A prospective, cohort study appearing in the Archives of Internal Medicine (2006; 144(2): 73-81) looked at the exercise habits in 1,740 subjects over the age of 65. Over the course of the study, those who exercised three or more times each week had a lower incidence of dementia.

Other research appearing in The Journals of Gerontology Series A: Biological Sciences and Medical Sciences (2008; 63(5): 529-35) also found that exercise decreased the likelihood of developing dementia. The subjects in this cohort study were 2,263 men between the ages of 71 and 92.

In the Archives of Neurology (March 2001;58:498-504) 9,008 men and women over the age of 65 and without any cognitive impairment or dementia were studied. Of that number, 4,615 were available for a five-year follow-up. In the five year follow-up 436 of the subjects were found to be cognitively impaired and 285 were found to have actual dementia. It was found that regular exercise decreased the risk for both cognitive impairment and dementia. Also, the protection was proportional—the greater the amount of activity, the lower the incidence of cognitive impairment or dementia.

Exercise even improves brain power according to a report presented at the annual meeting of the Society of Psychophysiological Research in Montreal, Canada October 18, 2001. The study looked at the thinking ability of 20 subjects between the ages of 18 and 24 after running for a half-hour. After the exercise the subjects were connected to an electroencephalogram (EEG), a device designed to measure brain waves. They were given computer tests before and after the exercise. The brain wave measurements showed that the decision making process was faster after the exercise.