Aspartame is one of the most exhaustively studied ingredients in the human food supply; studies like these need to be much more concrete to raise concern.
I have for some time suspected that I was somehow sensitive to artificial sweeteners, so I have largely stopped consuming them. I don't have a good description of what happens, but something is off either the next day or the day after, if I drink a large bottle of Pepsi Max for example.
meh. I don't think it proves much. What would be so hard about taking a survey of people who drink a lot of diet drinks about their anxiety levels? That would be more effective I think.