You're right, I used to know a few vegetarians who often supplement their diets with Vitamin B-12 which theoretically could help boosting and balance their cognitive ability vs. meat eaters. I personally did not notice any cognitive problems in those people at least.

Our DNA contains the sequence of folding steps instruction for each protein to fold. So for a protein to misfold itself, could this mean it must have received an incorrect instruction from the source? As we know, damages to DNA are often a result of foreign agents or coming from external environmental factors. Prevention is always better than a cure so it is probably a lot easier to figure out the source and eliminate that rather than trying to change the structure of these molecules which is extremely difficult.