Associations between serum homocysteine, holotranscobalamin, folate and cognition in the elderly: a longitudinal study

Abstract

Objectives. To examine the associations between serum homocysteine (tHcy), holotranscobalamin (holoTC, the biologically active fraction of vitamin B12) and folate and cognitive functioning in a longitudinal population-based study of Finnish elderly subjects.Subjects and design. tHcy, holoTC and folate were measured at baseline in 274 dementia-free subjects aged 65-79 years from the Cardiovascular Risk Factors, Aging and Dementia study. Subjects were re-examined 7 years later, and global cognition, episodic memory, executive functioning, verbal expression and psychomotor speed were assessed. Increased holoTC levels were related to better performance on global cognition: 1.09 (95% CI 1.00-1.19); executive functions: 1.11 (95% CI 1.01-1.21); and psychomotor speed: 1.13 (95% CI 1.01-1.26). After excluding 20 cases of incident dementia, increased tHcy remained associated with poorer performance in episodic memory, execution functions and verbal expression. Higher holoTC levels tended to be related to better performance in executive functions and psychomotor speed, while elevated serum folate concentrations were significantly related to higher scores in global cognition and verbal expression tests.Conclusions. tHcy, holoTC and folate levels are related to cognitive performance 7 years later even in nondemented elderly subjects. Randomized trials are needed to determine the impact of vitamin B12 and folate supplementation on preventing cognitive decline in the elderly.

Emerging roles for folate and related B-vitamins in brain health across the lifecycle

“…Indeed, a review by Smith (41) some years ago reported that 90 out of 100 published cross-sectional and prospective studies showed a link between elevated homocysteine and/or low B-vitamins concentrations with cognitive dysfunction. Most of these studies have focused on elevated plasma homocysteine concentrations (42)(43)(44)(45)(46) , and/or a combination of suboptimal status of folate and vitamin B 12 (47)(48)(49)(50)(51)(52)(53)(54) and to a much lesser extent on vitamin B 6 ( 55,56) . To the authors' knowledge, no published study thus far has focused on riboflavin alone as a potential contributor to cognitive health.…”

Helicobacter pylori and Hematologic Diseases

“…In addition to its close association to the etiology of pernicious anemia [105] and subacute combined degeneration [106], vitamin B 12 deficiency is related, through homocysteine, with dissimilar diseases such as Alzheimer's disease [107,108], dementia [109,110], depression [111], stroke [112,113], pulmonary embolism [114,115], acute myocardial infarction, and coronary heart disease [116].…”

Possible biochemical mechanisms involved in beneficial and adverse effects of folates

“…Большинство исследований демонстрируют корре-ляцию между низкой концентрацией фолиевой кис-лоты и высоким уровнем гомоцистеина с умственной неполноценностью, высоким риском развития демен-ции и болезни Альцгеймера [12,22].…”