According to the “Global Prevalence of Dementia: a Delphi Consensus Study,” published in The Lancet (2005; 366(9503):2112–2117), the number of people with dementia in developed countries is expected to double between 2001 and 2040. Worldwide, more than 23 million people are living with dementia, with a new case occurring approximately every seven seconds, totaling about 4.6 million new cases each year. Evidence suggests that physical activity may help reduce the risk of developing dementia. A prospective cohort study published in the Archives of Internal Medicine (2006; 144(2):73–81) examined the exercise habits of 1,740 adults over the age of 65 and found that individuals who exercised three or more times per week had a lower incidence of dementia. Similar findings were reported in The Journals of Gerontology Series A (2008; 63(5):529–535), which followed 2,263 men aged 71 to 92 and found that higher levels of physical activity were associated with a reduced likelihood of developing dementia. Additional research published in the Archives of Neurology (March 2001; 58:498–504) followed 9,008 adults over age 65 without cognitive impairment at baseline; among the 4,615 available for five-year follow-up, regular exercise was associated with a lower risk of both cognitive impairment and dementia, with greater activity linked to greater protection. Exercise may also influence short-term cognitive performance. A report presented at the annual meeting of the Society of Psychophysiological Research in October 2001 described a study of 20 adults aged 18 to 24 who completed 30 minutes of running; electroencephalogram measurements and computer-based testing showed faster decision-making and changes in brain wave patterns after exercise.