Exercise: a potential contributing factor to the relationship between folate and dementia.
OBJECTIVE
To investigate whether exercise confounds the relationship between folate and cerebrovascular events, all-cause dementia, and Alzheimer's disease.


METHODS
Prospective cohort study.


METHODS
Multiple centers in Canada.


METHODS
In the Canadian Study of Health and Aging, 466 people reported exercise levels, had folate measurements, and were not demented at baseline. After 5 years, 194 had adverse cerebrovascular events, and 65 had dementia (Alzheimer's disease in 47).


METHODS
Associations between folate and cerebrovascular outcomes were examined using logistic regression in the presence and absence of exercise and other confounders.


RESULTS
Folate was associated with greater risk of Alzheimer's disease (odds ratio (OR)=2.12, 95% confidence interval (CI)=1.01-4.54) and cerebrovascular outcomes (OR=2.05, 95% CI=1.11-3.78) in adjusted analyses before the inclusion of exercise and neared significance with all-cause dementia (OR=1.80, 95% CI=0.94-3.45). After the inclusion of exercise, the association between folate and dementia and Alzheimer's disease was 29% and 25% lower, respectively, and neither association was any longer significant (Alzheimer's disease: OR=1.91, 95% CI=0.89-4.11; all-cause dementia: OR=1.62, 95% CI=0.84-3.15). Exercise was a significant confounder in the relationship between folate and Alzheimer's disease (P=.03) and dementia (P=.003) but not cerebrovascular outcomes (P=.64). Unlike folate, exercise was significantly associated with Alzheimer's disease (OR=0.43, 95% CI=0.19-0.98) and dementia (OR=0.35, 95% CI=0.17-0.72) in adjusted analyses.


CONCLUSIONS
Exercise seems to account for much of the relationship between folate and incident dementia and Alzheimer's disease.
Middleton
Laura E
LE
Division of Geriatric Medicine, Dalhousie University, Halifax, Canada.
Kirkland
Susan A
SA
Maxwell
Colleen J
CJ
Hogan
David B
DB
Rockwood
Kenneth
K
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D002170:Canada / Q000453:epidemiology; D003071:Cognition / Q000502:physiology; D003704:Dementia / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D015444:Exercise / Q000502:physiology*; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D016017:Odds Ratio; D011379:Prognosis; D011446:Prospective Studies; D012044:Regression Analysis; D012307:Risk Factors; D011795:Surveys and Questionnaires; D015996:Survival Rate
D015415:Biomarkers; D005492:Folic Acid