Vitamine B9, vitamine B12, homocystéine, et fonctions cognitives

The prevalence of vitamin B9 and/or vitamin B12 deficiency is high among older people. Inadequate dietary intake and impaired absorption remain the main causes of deficiency among elderly, respectively for vitamin B9 deficiency and vitamin B12 deficiency. The lack of the two vitamins leads to an elevated serum homocysteine level that is a well-known independent cardiovascular risk factor. Low vitamin B9 and vitamin B12 serum levels (and elevated serum homocysteine) have been associated with poor cognitive function, cognitive decline and dementia. Despite this epidemiological association, there is today no clear evidence from randomized controlled trials that supplementation with vitamin B12 and not folate will improve cognitive decline or dementia, even though it might return homocysteine levels to normal.