Association of vitamin B12, folate, homocysteine and cognition in the elderly

Abstract

Normal and subnormal serum levels of vitamin B 12 and/or folate do not exclude functional deficiency, and elderly people are specifically exposed to deficiency owing to impaired nutrition, malabsorption, accompanying diseases and current medication. Several studies report that low levels of vitamin B 12 are more common in people with Alzheimer's disease (AD) than in non-demented people. Low levels of folate are also correlated with other types of dementia. Current studies suggest that low levels of vitamin B 12 as well as folate may be part of the aetiology in AD. A functional deficiency of vitamin B 12 /folate may be present despite serum levels within reference limits. The amino acid homocysteine (Hcy) is a sensitive but non-specific marker of deficiency of vitamin B 12 and folate and appears to have the strongest association with cognitive function. The association between Hcy levels and cognitive function is also stronger than that of the levels of vitamin B 12 /folate. The clinical manifestations of vitamin B 12 /folate deficiency are non-specific, but when they are connected with laboratory findings adequate investigation should be performed. A generous attitude to treatment with vitamin B 12 /folate is advocated, combined with a compulsory evaluation of treatment effect. Clinical regress of neuropsychiatric symptoms by cobalamin and folate therapy is dependent on the duration and severity of symptoms, but on a group level, not necessarily in individual patients.

Association between vitamin B12-containing supplement consumption and prevalence of biochemically defined B12 deficiency in adults in NHANES III (Third National Health and Nutrition Examination Survey)

“…Were such a programme implemented, there would be fewer patients with low serum B 12 and biochemically defined B 12 deficiency for clinicians to investigate. Several studies have reported that adults with suboptimal B 12 status have poorer cognitive functioning or could improve with supplementation(30-32). However, results from other B-vitamin supplement trials have failed to yield clinically measurable benefit(33,34).…”