https://www.ncbi.nlm.nih.gov/pubmed/28392301
Anecdotally, reminds me of one of our local characters who was as religiously and politically fundamental as you could get.
His contemporaries told me that he wasn't that way until he got kicked in the head by a horse.
His other cognitive abilities were quite sharp and he would gladly discuss things with you all day long and make well arranged arguments. But eventually you'd figure out that he hadn't heard one thing you said and you'd grow tired of the game.
