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P1–205: Folate levels and cognitive performance. The Rotterdam Scan Study
Author(s) -
Lau Lonneke M.,
Refsum Helga,
Smith A. David,
Johnston Carole,
Breteler Monique M.
Publication year - 2006
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1016/j.jalz.2006.05.582
Subject(s) - homocysteine , psychomotor learning , cognition , effects of sleep deprivation on cognitive performance , dementia , medicine , population , episodic memory , atrophy , hyperintensity , confidence interval , psychology , audiology , magnetic resonance imaging , radiology , psychiatry , disease , environmental health
Background: Elevated homocysteine concentrations are associated with cerebral small vessel disease, hippocampal atrophy, worse cognitive performance and an increased risk of dementia. It is unclear whether these associations are due to effects of homocysteine itself, or rather to other factors involved in homocysteine metabolism, such as folate. Recent evidence suggests that folate may have beneficial effects on cognition, independent from its effects on homocysteine levels. Objective(s): To examine the independent association of plasma folate levels with cognitive performance, and to evaluate to what extent this effect is through vascular mechanisms. Methods: In the population-based Rotterdam Scan Study, 1,033 non-demented participants aged 60-90 years underwent extensive cognitive testing and brain imaging. We constructed compound scores for psychomotor speed, memory function, and global cognitive function and scored white matter lesions and hippocampal atrophy on brain MRI scans. We evaluated the relation between folate levels and cognitive performance by means of multivariate linear regression, with plasma folate as a continuous variable (expressed per standard deviation increase) and in quintiles. To examine the role of vascular mechanisms, we also evaluated the association between folate levels and white matter lesions and hippocampal atrophy. Results: Increasing folate levels were associated with higher scores for psychomotor speed and global cognitive function (adjusted difference in test score per standard deviation increase in folate for psychomotor speed 0.07 (95% confidence interval (CI), 0.02-0.12), for global cognitive function 0.04 (95% CI, 0.00-0.08)), but not with memory function. Analyses in quintiles suggested a linear relationship. Higher folate levels were associated with a lower prevalence of severe white matter lesions (adjusted Odds Ratio per standard deviation increase 0.82 (95% CI, 0.69-0.98)). Adjustment for homocysteine levels only slightly diminished these associations. No relation was seen between folate levels and hippocampal atrophy. Conclusions: Higher plasma concentrations of folate are associated with better cognitive performance, in particular psychomotor speed, regardless of homocysteine level. A significant inverse association between folate levels and presence of severe white matter lesions was found, while no association was observed for hippocampal atrophy. These findings suggest that the effect of folate on cognition is mediated through vascular mechanisms.