Relationship among Plasma Homocysteine, Folate, Vitamin B12 and Nutrient Intake and Neurocognitive Function in the Elderly

ABSTRACT

This study examined the relationship among plasma homocysteine, folate, and vitamin B12 levels and neurocognitive function in 118 community-dwelling elderly subjects (mean age, 75.1 +/- 6.7 years). The Mini-Mental State Examination (MMSE-KC) was used to screen and assess neurocognitive function in the participants. Dietary intake data including the use of dietary supplements were obtained using the 24-hour recall method by well-trained interviewers. Plasma folate and vitamin B12 concentrations were analyzed by radioimmunoassay, and homocysteine was assessed by a high performance liquid chromatography-fluorescence method. The proportions of participants with suboptimal levels of plasma folate ( 15 micromol/L) were 16.1%, 5.9%, and 21.2%, respectively. A multiple regression analysis showed that plasma homocysteine was negatively associated with plasma folate and vitamin B12 levels. The MMSE-KC test scores were significantly associated with plasma homocysteine and folate, but not with vitamin B12, after adjusting for age, gender, body mass index, living with spouse, education, current smoking, energy intake, and chronic diseases such as hypertension, diabetes, thyroid disease, dyslipidemia, stroke, and cardiovascular disease. A general linear model adjusted for covariates revealed that MMSE-KC test scores increased from the lowest to the highest quartiles of vitamin B1, vitamin B2, vitamin B6, vitamin B12, and vitamin C intake (p for trend = 0.012, 0.039, 0.014, 0.046, 0.026, respectively). These results indicate that the problem of folate inadequacy and hyperhomocysteinemia are highly prevalent among community-dwelling elderly people and that dietary intake of the B vitamins and vitamin C is positively associated with cognitive function scores.