Cognitive decline folates

In the methionine cycle, cobalamin also plays a central role, as the methyl group of 5-methyltetrahydrofolate is first transferred to the cobalamin molecule and then further transferred to homocysteine to form methionine. This reaction explains the close connection of folate and cobalamin metabolism, as 5-methyltetrahydrofolate cannot be used for other reactions over than the methylation of homocysteine. Mild deficiency of folate and cobalamin is also associated with cognitive decline due to the neurotoxic effects of increased... 

B Vitamins (Folate, and B22) in Relation to Stroke and its Cognitive Decline... 

Deficiencies of vitamin Bg, vitamin B12 and folate may play a role in the pathogenesis of cognitive impairment in the elderly. There are two biological mechanisms by which low levels of vitamin B12 or folate might result in dementia. First, vitamin B12 and folate are essential factors of methylation cycles involved in the synthesis of methionine from homocysteine. With decline in vitamin B status, homocysteine levels increase this is associated with increased prevalence of poor cognitive decline and increased risk of development of dementia and AD. The sequential inability to methylate homocysteine leads to SAH accumulation which is a strong inhibitor of all methylation reactions, competing with SAM for the active site on the methyl transferase... 

Low vitamin B12 and folate and hyperhomocysteinemia induce cognitive decline by impaired DNA synthesis, impair genomic and non-genomic methylation, homocysteine-induced DNA synthesis, neurotoxicity and oxidative stress. 

Fioravanti, M., Ferrario, E., Massaia, M., Cappa, G., Rivolta, G., Grossi, E., and Buckley, A.E., 1997. Low folate levels in the cognitive decline of elderly patients and the efficacy of folate as a treatment for improving memory deficits. Archives of Gerontology and Geriatrics. 26 1-13. 

Morris, M.C., Evans, D.A., Bienias, J.L., Tagney, C.C., Hebert, L.E., Scherr, P.A., and Schneider, J.A., 2005. Dietary folate and vitamin B12 intake and cognitive decline among community-dwelling older persons. Archives of Neurology. 8 657-678. 

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