Chronic traumatic encephalopathy: Derek Boogaard had it - What is it?

[Emily]

The condition was found upon autopsy in two professional sports players recently. One died of a drug overdose and one died of suicide.
Repeated head traumas are believed to cause to the progressive condition of brain degeneration that creates a buildup of an abnormal brain protein called tau. Much is unknown about the illness, such as why some people seem to be able to sustain the same level of head injuries without suffering the degenerative illness that affects others.

http://www.latimes.com/health/boostershots/la-heb-derek-boogaard-brain-20111206,0,4523141.story?track=rss

Derek Boogaard had chronic traumatic encephalopathy: What is it?
By Jeannine Stein, Los Angeles Times / For the Booster Shots blog

December 6, 2011, 2:26 p.m.
The brain of former National Hockey League player Derek Boogaard showed signs of early chronic traumatic encephalopathy, researchers report, shedding light on the neurological condition that may affect some athletes who sustain brain injuries during play....