Update on excess folic acid findings

A little over a year ago, my friend and I wrote a letter to the editor in which we expressed concern that excess folic acid was linked to the rise in attention-deficit hyperactivity disorder and autism spectrum disorders:

https://www.ncbi.nlm.nih.gov/pubmed/27346490: "Unintended consequences of inhibiting dihydrofolate reductase through folic acid supplementation: inattentive-type attention deficit hyperactivity disorder and ASD connections."

Two recent studies indicate that excess folic acid during pregnancy causes--in mice and people-- diminished cognitive function in the offspring:

https://www.ncbi.nlm.nih.gov/pubmed/28069796: "High dietary folate in pregnant mice leads to pseudo-MTHFR deficiency and altered methyl metabolism, with embryonic growth delay and short-term memory impairment in offspring."

https://www.ncbi.nlm.nih.gov/pubmed/28724645: "Effect of maternal high dosages of folic acid supplements on neurocognitive development in children at 4-5 y of age: the prospective birth cohort Infancia y Medio Ambiente (INMA) study."

I expect more studies will come out with similar results over the next few years. Folic acid just isn't a typical molecule in the human body or diet.