Relation of higher folate intake to lower risk of Alzheimer disease in the elderly.

BACKGROUND Higher intake of folate and vitamins B6 (pyridoxine hydrochloride) and B12 (cyanocobalamin) may decrease the risk of Alzheimer disease (AD) through the lowering of homocysteine levels. OBJECTIVE To relate intake of folate and vitamins B6 and B12 to AD risk. DESIGN AND PATIENTS We followed up 965 persons 65 years or older without dementia at baseline for a mean +/- SD period of 6.1 +/- 3.3 person-years after the administration of a semiquantitative food frequency questionnaire. Total, dietary, and supplement intake of folate and vitamins B6 and B12 and kilocalorie intake were estimated from the questionnaire responses. We related energy-adjusted intake of folate and vitamins B6 and B12 to incident AD using the Cox proportional hazards regression model. MAIN OUTCOME MEASURE Incident AD. RESULTS We found 192 cases of incident AD. The highest quartile of total folate intake was related to a lower risk of AD (hazard ratio, 0.5; 95% confidence interval, 0.3-0.9; P=.02 for trend) after adjustment for age, sex, education, ethnic group, the epsilon4 allele of apolipoprotein E, diabetes mellitus, hypertension, current smoking, heart disease, stroke, and vitamin B6 and B12 levels. Vitamin B6 and B12 levels were not related to the risk of AD. CONCLUSIONS Higher folate intake may decrease the risk of AD independent of other risk factors and levels of vitamins B6 and B12. These results require confirmation with clinical trials.