I read the whole thing, several times, years ago and also recently. I have also shared it with my colleagues who run human subject research for our firm. With unanimity, like most people who have commented here, we believe it's complete and utter garbage.
It is deeply flawed, biased, cherry-picked samples, no control group, conflicts of interest galore, completed while kids were in the program and their responses could lead to longer detention, no follow up, etc., etc., etc. This work would not pass the most cursory examiniation in peer review and has never been published, indicating the authors know it doesn't pass muster.
In summation, it's bunk. The very first post in this thread completely invalidates the work.