Those #s are frightening at the glance but there are a couple of factors that were not mentioned.
1. All the "participants" were old old old and played when Ignazio's helmet from his profile pic was the latest in safety gear.
2. It seems generally the higher level you play the greater risk you have for CTE. The guys that only played high school had a much lower rate of diagnosis and the ones that did show signs - they indicate it was mild. Moving along to college and pro and nearly everyone showing signs. Is that due to the harder hits or the longer longevity of playing? I don't think they know.
I would like to see the study in 50 years with today's latest gear, non head leading tackling techniques and concussion protocols.