For example,a cohort study of depressive patients and healthy controls found that MTHFR polymorphism were more common in the individuals with depression history compared to controls67, while a study over a 60-month follow-up with depressed subjects indicated that the CC genotype of MTHFR C677T were more likely to have more severe symptoms compared to TT genotype carriers68. This evidence concerns the gene MTHFR and major depressive disorder.