I too have wanted hard info re: carbidopa/toxicity, since Peter's neuro had a similar reaction. He did not, however, question that not so much was needed, and assented readily to a reduction in amount. As for the book mentioned by a doc with PD, McGoon, we read it a year or so ago, but don't have it or recall the title. Our support group may have a copy. A call to a bookstore asking them to check under author's name in "Books in Print" should produce the info. Will be glad for any references anyone has, as SJS requested in original post. Camilla Flintermann,CG for Peter,78/7 Ohio