Cognitive function folates

Adverse effects include CNS symptoms (reversible blurring of vision, diplopia, dizziness and ataxia) and depression of cardiac AV conduction. Alimentary symptoms, skin rashes, blood disorders and liver and kidney dysfunction also occur. Osteomalacia by enhanced metabolism of vitamin D (enzyme induction) occurs over years so also does folate deficiency. Enzyme induction reduces the efficacy of combined and progestogen-only contraceptives. Carbamazepine impairs cognitive function less than phenytoin. 

Raman, G., Tatsioni, A., Chung, M., Rosenberg, I.H., Lau, J., Lichtenstein, A.H., and Balk, E.M., 2007. Heterogeneity and lack of good quality studies limit association between folate, vitamins B-6 and B-12, and cognitive function. Journal of Nutrition. 137 1789-1794. 

Vitamin B and folate supplementation in small doses over the long term is preferable to larger doses in the short term and leads to improvement in cognitive function. 

---