I had soo many of the mental/cognitive symptoms and although they weren't the worst anyone has seen, they were pretty severe. I had extreme bouts of paranoia (like you describe), lost all working memory (short and long term), couldn't follow patterns, couldn't follow instructions, couldn't get the words out that made any sense and so much more.
For many people these are signs of ammonia build up in their brains. There was a good conversation going about
this here:
www.healingwell.com/community/default.aspx?f=30&m=2994845