Thanks and a hat tip to Marty R....
The link between MTHFR mutations, mood disorders and neurodevelopmental problems is not new information to scientists, even though adoption of testing by the broader medical community appears to be a rarity.
Studies have shown homocysteine levels can predict the length someone might suffer from post-traumatic stress disorder, that B vitamins have been observed to relieve premenstrual anxiety, and that MTHFR variations are associated with major depression, bipolar disorder and schizophrenia.
A study in Northern Ireland found a MTHFR variation was associated with an increased risk of depressive episodes. A 2011 study reported a possible link between a different MTHFR variation and ADHD.
A recent study in Arkansas, published in the journal Molecular Psychiatry, found that a group of children with autism who were treated with folinic acid showed significant improvements in verbal communication, receptive and expressive language, attention and stereotypical behaviour. About one third of treated children demonstrated moderate to much improvement.
Studies that definitively prove a link with anxiety are thinner on the ground.