Physical exercise, aging, and mild cognitive impairment: a population-based study.

BACKGROUND: Physical exercise is associated with decreased risk of dementia and Alzheimer disease.

OBJECTIVE: To investigate whether physical exercise is associated with decreased risk of mild cognitive impairment (MCI).

DESIGN: Population-based case-control study.

SETTING: The Mayo Clinic Study of Aging, an ongoing population-based cohort study in Olmsted County, Minnesota.

PARTICIPANTS: A total of 1324 subjects without dementia who completed a Physical Exercise Questionnaire.

MAIN OUTCOME MEASURES: An expert consensus panel classified each subject as having normal cognition or MCI based on published criteria.

RESULTS: We compared the frequency of physical exercise among 198 subjects with MCI with that among 1126 subjects with normal cognition and adjusted the analyses for age, sex, years of education, medical comorbidity, and depression. The odds ratios for any frequency of moderate exercise were 0.61 (95% confidence interval, 0.43-0.88; P = .008) for midlife (age range, 50-65 years) and 0.68 (95% confidence interval, 0.49-0.93; P = .02) for late life. The findings were consistent among men and women. Light exercise and vigorous exercise were not significantly associated with decreased risk of MCI.

CONCLUSION: In this population-based case-control study, any frequency of moderate exercise performed in midlife or late life was associated with a reduced odds of having MCI.