There is evidence that physical activity may reduce the risk of developing Alzheimer’s disease and dementia. However, few reports have examined the physical activity-dementia association with objective measures of physical activity. Cardiorespiratory fitness (hereafter called fitness) is an objective reproducible measure of recent physical activity habits.

Purpose:

We sought to determine whether fitness is associated with lower risk for dementia mortality in women and men.

Methods:

We followed 14,811 women and 45,078 men, ages 20-88 at baseline, for an average of 17 years. All participants completed a preventive health examination at the Cooper Clinic in Dallas, Texas during 1970-2001. Fitness was measured with a maximal treadmill exercise test, with results expressed in maximal metabolic equivalents (METs). The National Death Index identified deaths through 2003. Cox proportional hazards models were used to examine the association between baseline fitness and dementia mortality, adjusting for age, sex, examination year, body mass index, smoking, alcohol use, abnormal ECGs, and health status.

Results:

There were 164 deaths with dementia listed as the cause during 1,012,125 person-years of exposure. Each 1-MET increase in fitness was associated with a 14% lower adjusted risk of dementia mortality (95% confidence interval, CI 6%-22%). With fitness expressed in tertiles, adjusted hazard ratios (HRs) for those in the middle and high fitness groups suggest their risk of dementia mortality was less than half that of those in the lowest fitness group (respectively: HR 0.44, CI 0.26-0.74; HR 0.49, CI 0.26-0.90).

Conclusion:

Greater fitness was associated with lower risk of mortality from dementia in a large cohort of men and women.