Physical fitness as a protective factor for cognitive impairment in a prospective population-based study in Germany

To evaluate the predictive effects of subjective measures of physical activity (PA) and objective measures of physical fitness (PF) on dementia risk, Participants of the prospective population-based ILSE-study (*1930-1932; 12-year follow-up) were examined at three examination waves (t1 : 1993/94; t2 : 1997/98; t3 : 2005/07). 381 subjects of the original cohort (n = 500) were re-examined at t3. 29% of the subjects who were cognitively healthy at baseline received the diagnosis of mild cognitive impairment (MCI) and 7% of Alzheimer's disease (AD). Subjects were screened for physical and mental health using medical interviews, physical, and neuropsychological examinations. Participants completed a questionnaire on their current and past PA at t1. Subjects were classified as physically active if they reported a regular sport activity for at least 2 hours per week in the past year. Muscular strength (handgrip) and motor coordination (balance) served as objective indicators of PF. Subjects who passed the balance-test at t1 had a reduced risk of developing MCI/AD at t3 (OR = 0.35, 95%CI 0.19-0.66, p < 0.01) and performed significantly better on various neuropsychological measures. Muscular strength or subjective reports of PA did not predict MCI/AD development. Our results confirm the hypothesis that PF acts as a protective factor for the development of cognitive disorders. In our study, context, motor coordination served as a better predictor than muscular strength or self-rated PA. Since subjects with cognitive disorders due to cerebral and/or systemic disorders were excluded from the analyses, our findings suggest that the effect of skill-related PF extends beyond the reduction of cardiovascular risk factors.