Homocysteine, vitamin B 12 and folate in Alzheimer's and vascular dementias: the paradoxical effect of the superimposed type II diabetes mellitus condition.

BACKGROUND Increased concentration of plasmatic homocysteine (tHcy) and decreased vitamin B 12 (B12) and folate (FOL) are associated with Alzheimer's (AD) and vascular (VaD) dementias, with type II diabetes mellitus (DM), and reported as risk factors of these diseases. METHODS The sample (n=122; males=60; mean age=73+/-7 years) comprised AD and VaD patients without DM, with a concomitant DM (AD+DM, VaD+DM), DM alone and controls (CTR), resulting in 6 groups. tHcy, B12 and FOL were determined in duplicate. RESULTS The one-way ANOVA yielded significant differences between groups for all variables: tHcy p<10(-12); B12 p<10(-3); FOL p<10(-4). Significance for comparisons between groups was set at alpha=0.05, using the Bonferroni's statistic. The comparisons: DM vs. CTR, AD+DM vs. AD, VaD+DM vs. VaD, and DM demented vs. DM non-demented resulted significant for all variables, except for B12 in 2 comparisons. CONCLUSIONS In demented and control subjects, tHcy and FOL exhibit extreme differences, not so marked between DM and controls. Demented patients with concomitant diabetes are closer to controls than their non-diabetic counterparts. Diabetes affects tHcy and FOL values, which are changed with opposite sign to non-demented. These results suggests a paradoxical phenomenon when diabetes is superimposed to dementias.