GRIN2A and Alzheimer disease: -Homocysteine level significantly elevated in malnourished (p<0.05) - Homocysteine levels and malnourishment results in AD - Betaine able to reduce hyperphosphorylation of Tau protein and increase phosphatase activity (P<0.05) -Betaine increases memory-related protein (NR1 & NR2A) (P<0.05) and synaptic proteins - Betaine cause a significant improvement in recall of words, visuospatial capacity, recognition of dual words.