I doubt it. This article is kind of wacky. It claims that children who were raised as vegetarians have a higher IQ. They do not take into consideration that kids who eat a vegetarian diet are less likely to consume as much sugar as kids on a regular diet. I have a feeling they need to do more testing and find how much white sugar these people actually ate compared to how much meat and veggies.
I believe if they realized how much white sugar and white flour a person eats in a normal diet they'll find out that it has nothing to do with being vegetarian, but with poor choices in sweet foods. From what I know, most vegetarians eat whole grains as opposed to refined white flour and that could have a lot to do with it.
Read about it here.