Don't stress out too much about them. My guess is they are addressing poorly treated PKU. There are definitely symptoms to poor control of diet later in life. Many of these studies were done because those of us who are older were told that we could go off diet after childhood. Doctors learned that diet needs to be for life. Because of that, there are many adults with PKU who still don't manage their diet. It's hard to go back on after years of eating normal. As your son gets older, you just want to make sure he understands the importance of being on diet for life. I have been off diet for periods of time. During those times, yes, I do have some issues WHEN I'm off-diet. I have symptoms similar to ADHD & bi-polar disorder. The symptoms do go away completely when I manage my diet properly. As long as your son stays on diet he will have no problems. I prefer my life on diet, which is why I'm very strict with myself now. Feel free to e-mail me if you have specific questions.