Diet and obsessive thoughts

I have an Aspberger's nephew who exhibits the same tendency to fixate as his father. His father's fixations have been terrible for family relationships for the past few years, and the son really, really doesn't want to fixate, too. So I've been delving into the PubMed database for findings related to obsessive thoughts.

The research repeatedly shows apparent connections between lower levels of GABA & GABA receptors and OCD. See this, this, this, this, this, and this. The GABA(A) receptor is decreased when homocysteine is elevated (which fits with MTHFR defects being associated with autism, for MTHFR defects negatively impact conversion of homocysteine to methionine). Myo-inositol has been shown to help protect subunits of GABA(A) receptors in the hippocampus, and some people on Amazon are reporting that it helps them with OCD thoughts. 

The research thus supports a two-pronged dietary approach to lessening fixations that consists of 

• supporting homocysteine conversion by making sure to consume enough betaine, zinc, B12 (but not the cyanocobalamin form), and folate (definitely avoid folic acid, though; too much of it apparently causes pseudo-MTHFR deficiencies)
• protecting GABA(A) receptors from internal or external antagonists by consuming enough myo-inositol (it seems prudent to limit caffeine consumption, as caffeine appears to interfere with at least one inositol-related function)

What we eat can't change our genetics, but it definitely affects our phenotypes. Fresh fruits and vegetables, whole grains, and moderate intake of animal products (at least after childhood--babies need milk!), combined with avoidance of excess intake of anything, keep popping up as keys to long-term health.