Rao et al. reported hypomethylated cyclooxygenase-2 (COX-2) (one of the arachidonic acid (AA) cascade markers) and brain-derived neurotrophic factor (BDNF) promoter regions in AD brain, while the promoter region of cAMP response element-binding protein (CREB), which regulates the transcription of BDNF, was shown to be hypermethylated. This evidence concerns the gene PTGS2 and Alzheimer disease.