One possible symtom of deficiency of folic acid (folate) or vitamin B₁₂ (cobalamin) is impaired cognition. Status of these two B-vitamins have been linked to cognitive performance also in various populations of subjects with no evident clinical deficiency (for example in “healthy elderly”). The present study investigated 60 nondemented patients (mean age 58 years) presented with mild cognitive impairment (MCI) or subjective memory complaints. Blood/serum folate, serum cobalamins, and total plasma homocysteine were determined and compared to age-normalized results on 14 cognitive tasks. 21 of the patients were re-examined one year later and follow-up data were compared to baseline data. Results for cobalamin and folate were inconclusive for baseline data, but for homocysteine significant associations were found for tasks of visual episodic memory and for perceptual speed and attention (higher concentration related to worse cognitive performance). In the longitudinal data cobalamin and folate were positively related to word fluency. The outcome is consistent with a negative long-term influence of homocysteine on cognition. However, from the present data it is not possible to conclude if the results are specific for the studied population.

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