Not like we didn't already know about this, but damn:
Dead athletes' brains show damage from concussions
[U]sing tissue from retired NFL athletes culled posthumously, the Center for the Study of Traumatic Encephalopathy (CSTE), at the Boston University School of Medicine, is shedding light on what concussions look like in the brain. The findings are stunning. Far from innocuous, invisible injuries, concussions confer tremendous brain damage. That damage has a name: chronic traumatic encephalopathy (CTE).
[...] CSTE studies reveal brown tangles flecked throughout the brain tissue of former NFL players who died young -- some as early as their 30s or 40s.
McKee, who also studies Alzheimer's disease, says the tangles closely resemble what might be found in the brain of an 80-year-old with dementia.
"I knew what traumatic brain disease looked like in the very end stages, in the most severe cases," said McKee. "To see the kind of changes we're seeing in 45-year-olds is basically unheard of."
The damage affects the parts of the brain that control emotion, rage, hypersexuality, even breathing, and recent studies find that CTE is a progressive disease that eventually kills brain cells.
There are such powerful incentives to play sports that it's unlikely that studies like this will prompt the dissolution of the NFL, but, well let's just say that my kids will not be encouraged to play organized football.