They establish the causative role that the 5LO pathway plays on this biological effect both in vivo and in vitro, and elucidate a novel mechanism in which high Hcy-dependent 5LO DNA hypomethylation results in 5LO pathway up-regulation, which then is responsible for increased Aβ formation, tau phosphorylation and worsening of behavioral deficits in a relevant mouse model of AD. This evidence concerns the gene MAPT and Alzheimer disease.