In a study at the Division of Human Nutrition, Wageningen University, in the Netherlands, researchers randomly assigned 818 participants 800 mg daily oral folic acid or placebo for 3 years. The effect on cognitive performance was measured as the difference between the two groups in the 3-year change in performance for memory, sensorimotor speed, complex speed, information processing speed, and word fluency.
The 3-year changes in memory (difference in Z scores 0.132, 95% CI 0.032 to 0.233), information processing speed (0.087, 0.016 to 0.158) and sensorimotor speed (0.064, -0.001 to 0.129) were significantly better in the folic acid group than in the placebo group.
INTERPRETATION: Folic acid supplementation for 3 years significantly improved domains of cognitive function that tend to decline with age.
Article pulbished in The Lancet, Jan 20 , 2007
abstract here : http://www.ncbi.nlm.nih.gov/pubmed/17240287