Affiliations: [a]
Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
| [b] Faculty of Social Welfare, Yamaguchi Prefectural University, Yamaguchi, Yamaguchi, Japan
| [c]
Physical Fitness Research Institute, Meiji Yasuda Life Foundation of Health and Welfare, Hachioji, Tokyo, Japan
| [d] Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan
Correspondence:
[*]
Correspondence to: Kenji Tsunoda, PhD, Faculty of Social Welfare, Yamaguchi Prefectural University, 6-2-1 Sakurabatake, Yamaguchi, Yamaguchi 753-0021, Japan. Tel./Fax: +81 83 929 6221; E-mail: ktsunoda@yamaguchi-pu.ac.jp.
Abstract: Background:Moderate- to vigorous-intensity physical activity (PA) may reduce the risk of dementia; however, few studies have examined the effects of PA intensity on dementia risk. Objective:To prospectively examine the dose-response relationship of PA intensity with the incidence of suspected dementia in community-dwelling older adults. Methods:We conducted a baseline mail survey with an 8-year follow-up of 3,722 older adults in Japan. We assessed PA levels using the International Physical Activity Questionnaire short form and calculated the amount of time per week spent performing moderate- and vigorous-intensity PA (VPA). Information regarding suspected dementia was obtained from the city database during the follow-up period. Cox proportional-hazard models with age as time scale, and delayed entry and restricted cubic spline regression as variables were used to estimate risk of developing suspected dementia, excluding cases occurring < 1 year after baseline evaluation. Results:The cumulative incidence of suspected dementia during the follow-up period was 12.7%. Compared with those who did not practice moderate-intensity PA (MPA), those who practiced≥300 min (hazard ratio, 0.73; 95% confidence interval 0.56–0.95) of MPA showed a lower risk of developing suspected dementia. Furthermore, when the dose-response relationship was examined, the hazard of developing suspected dementia decreased almost linearly with MPA. A significantly lower hazard was observed from 815 minutes/week. There was no significant association between VPA and suspected dementia. Conclusion:This study suggested that MPA is often practiced in older adults and this PA intensity has a sufficiently favorable effect on dementia prevention.
