Good man, for sure. Solid leader, and he ended up being, arguably, the best player from that weak 2005 class, and had some of the best "football smarts" I've seen.
I don't seem to recall his ever having shown concussion issues at ND, so I'm guessing that they occurred during his pro years, probably during his time as a special teams gunner.
I hope that all of that cumulative damage doesn't affect his ability to live a normal life, and wish him and his family the best.