Exercise is associated with reduced risk for incident dementia among persons 65 years of age and older (2006)

Background: Alzheimer disease and other dementing disorders are major sources of morbidity and mortality in aging societies. Proven strategies to delay onset or reduce risk for dementing disorders would be greatly beneficial.

Objective: To determine whether regular exercise is associated with a reduced risk for dementia and Alzheimer disease.

Results: During a mean follow-up of 6.2 years (SD, 2.0), 158 participants developed dementia (107 developed Alzheimer disease). The incidence rate of dementia was 13.0 per 1000 personyears for participants who exercised 3 or more times per week compared with 19.7 per 1000 person-years for those who exercised fewer than 3 times per week. The age- and sex-adjusted hazard ratio of dementia was 0.62 (95% CI, 0.44 to 0.86; P 0.004). The interaction between exercise and performance-based physical function was statistically significant (P 0.013). The risk reduction associated with exercise was greater in those with lower performance levels. Similar results were observed in analyses restricted to participants with incident Alzheimer disease.

Limitations: Exercise was measured by self-reported frequency. The study population had a relatively high proportion of regular exercisers at baseline.

Conclusion: These results suggest that regular exercise is associated with a delay in onset of dementia and Alzheimer disease, further supporting its value for elderly persons.