Physical Activity as Protective Factor against Dementia: A Prospective Population-Based Study (NEDICES)

The aim of this study was to analyze whether physical activity (PA) is a protective factor for the incidence of dementia after 3 years of follow-up. The Neurological Disorders in Central Spain (NEDICES) is a prospective population-based survey of older adults (age 65 years and older) that comprised 5278 census-based participants at baseline (1994-1995). A broad questionnaire was used to assess participants' sociodemographic characteristics, health status, and lifestyle. Subsequently, a modified version of Rosow-Breslau questionnaire was applied to classify individuals' baseline PA into groups (i.e., sedentary, light, moderate, and high). Cox regression models adjusted for several covariates (age, sex, education, previous stroke, alcohol consumption, hypertension, health related variables) were carried out to estimate the association between the PA groups and risk of dementia at the 3-year follow-up (1997-1998). A total of 134 incident dementia cases were identified among 3105 individuals (56.6% female; mean age = 73.15 +/- 6.26) after 3 years. Hazard ratios (HRs) of the light, moderate, and high PA groups (vs. sedentary group) were 0.40 (95% confidence interval {CI} [0.26, 0.62]; p < .001), 0.32 (95% CI [0.20, 0.54]; p < .001) and 0.23 (95% CI [0.13, 0.40]; p < .001), respectively. Even after controlling for covariates and the exclusion of doubtful dementia cases, HRs remained significant. However, a supplementary analysis showed that the dose-effect hypothesis did not reach statistical significance. PA is a protective factor of incident dementia in this population-based cohort.