Risk factors for Alzheimer's disease: a population-based, longitudinal study in Manitoba, Canada.
BACKGROUND
Current knowledge of risk factors for Alzheimer's disease (AD) is limited. Data from a longitudinal, population-based study of dementia in Manitoba, Canada were used to investigate risk factors for AD.


METHODS
Cognitively intact subjects completed a risk factor questionnaire assessing sociodemographic, genetic, environmental, medical and lifestyle exposures. Five years later, 36 subjects had developed AD and 658 remained cognitively intact.


RESULTS
Older subjects or those who had fewer years of education were at greater risk of AD. After adjusting for age, education and sex, occupational exposure to fumigants/ defoliants was a significant risk factor for AD (relative risk [RR] = 4.35; 95% CI : 1.05--17.90). A history of migraines increased the risk of AD (RR = 3.49; 95% CI : 1.39--8.77); an even stronger effect was noted among women. Self-reported memory loss at baseline was associated with subsequent development of AD (RR = 5.15; 95% CI : 2.36--11.27). Vaccinations and occupational exposure to excessive noise reduced the risk of AD.


CONCLUSIONS
Some well-known risk factors for AD were confirmed in this study and potential new risk factors were identified. The association of AD with a history of migraines and occupational exposure to defoliants/fumigants is of particular interest because these are biologically plausible risk factors.
Tyas
S L
SL
PhD Program in Gerontology, Sanders-Brown Center on Aging and Kentucky School of Public Health, University of Kentucky 40356-0230, USA. styas@uky.edu
Manfreda
J
J
Strain
L A
LA
Montgomery
P R
PR
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics; D004781:Environmental Exposure; D020022:Genetic Predisposition to Disease; D006801:Humans; D008019:Life Style; D008137:Longitudinal Studies; D008350:Manitoba / Q000453:epidemiology; D016273:Occupational Exposure; D012307:Risk Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires