However, it contrasted with re-analysis of the data from two studies [67] that found that whereas low vitamin B12 was associated with cognitive impairment and dementia, and low vitamin B6 was associated with cognitive impairment, there was no relationship between brain function and folate, homocysteine or the MTHFR C677TT polymorphism. This evidence concerns the gene MTHFR and Cognitive impairment.