Here is a link to a great article that appeared in the Wall Street Journal. "A Gut Check for Many Ailments." Each year we are learning more and more about the health importance of the "gut." They are linking more and more issues that deal with mental problems that appear to have a link with gut problems.
This past month the article states they have just discovered a certain bacterium, Sutterella, that appears to be part of the problem in digastric issues found with Autistic children. Studying the gut is leading to new ways research is being pursued for Parkinson's and for Depression. Interesting stuff.