. >> reporter: gina seau, junior's former wife to whom he remained close and his four children decidedis brain to the nih to try to understand why the man they loved and knew as an outgoing leader on and off the field changed so drastically in his final few years and ultimately ended it all, detached and alone. >> a lot of things towards the end of his life, patterns that we saw and things that worried us. his decision making and his ambition decreased. >> he would sometimes lose his temper. he would get irritable over very small things. kind of go off the grid for a couple weeks. >> reporter: all symptoms, experts say, of cte. >> impulsivity, aggressiveness, depression, sometimes suicidal. >> reporter: a once deeply respected and highly devoted family man, seau's behavior became confusing for his children. >> at the end, it just became more and more apparent that he was disconnecting, and i didn't understand, but i just took a different seat and just went with it. >> now do you understand? >> now i do. i had no idea it could be something this serious. >> reporter: the night before he