Plasma total homocysteine levels, dietary vitamin B6 and folate intake in AD and healthy aging

PURPOSE: To study the association between Alzheimer's disease (AD) and plasma total homocysteine (tHcy), dietary folate and vitamin B6. METHODS: 64 AD patients were matched by gender, age, and smoking status to 64 healthy controls, tHcy was determined using an automated immunoassay. Dietary patterns for three age periods (20-39, 40-59, and 60 + yrs) were assessed using a questionnaire adapted from the Block Health Habits and History Questionnaire. Respondents (cases by proxy) reported food frequencies, which were translated into estimated daily nutrient intakes. APOE genotype, cognitive performance (CDR, MMSE), blood lipids, and albumin were obtained for patients and controls. RESULTS: tHcy did not differ significantly between controls (11.5 ± 3.7 mmol/L) and AD patients (12.3 ± 4.3 mmol/L)(p=0.25). tHcy levels were not related in AD patients or controls to education, CDR, MMSE, blood lipids, albumin or ApoE genotype (p>0.15). There was a negative correlation between plasma tHcy and triglyceride levels in AD patients (p=0,023), but not in controls. AD patients consumed significantly less dietary vitamin B6 (p=0.05) and folate (p=0.001) after age 60 than controls. CONCLUSIONS: Although plasma tHcy levels were higher in cases than controls, this difference was not significant. tHcy levels were not related to cognitive status. Plasma tHcy was inversely correlated with triglyceride levels in AD patients but not in controls.