Physical activity as a protective factor in a prospective ageing study in Germany

Introduction: There is growing epidemiological evidence that physical activity (PA) reduces the risk of dementia. We asked if this protective effect was present in the Interdisciplinary Longitudinal Study on Adult Development and Aging (ILSE) and thus modulated the risk of developing mild cognitive impairment (MCI) or Alzheimer's disease (AD). Methods: 500 participants of the ILSE were examined in 1993–1996 (t1), 1997–2000 (t2) and 2005–2008 (t3). In all examination waves, participants were carefully screened for physical and mental health through extensive medical interviews, physical and neuropsychological examinations. In addition at t1, all the participants completed a questionnaire about current and past PA and were asked to balance on one foot for 15 seconds as an objective index for PA. The participants were classified as physically active if they reported a regular sport activity since at least one year and at least once a week for at least 2 hours per week. Results: 381 participants of the cohort were re-examined at t3. Prevalence of MCI increased from 13% to 23% and 29% over time; in addition, 7% of the participants developed AD at t3. Subjects who passed the one-foot-balance-test at t1 showed a reduced risk for developing MCI or AD in the 12 year follow-up (odds ratio [OR]=0.38, 95% confidence interval [CI]=0.24–0.70, p<0.01) compared to healthy controls (scores adjusted for gender, education, socioeconomic status and depressive symptoms). Self-rated physical activity did not predict MCI/AD development in our sample. Conclusion: Our findings confirm the hypothesis that PA constitutes a protective factor for the development of MCI and AD.