He drank to cope, "entered a devastating cycle of depression and alcohol abuse," and became a manic, compulsive gambler in which he lost a "significant amount of money in an attempt to make back business losses," the lawsuit said.
Seau's family donated his brain to the NIH for research, and this month it released a statement saying "abnormalities were found that are consistent with a form of (CTE)."
According to the NIH's pathology report, five researchers -- two NIH neuropathologists and three independent experts -- examined slides of Seau's brain, and all confirmed that there were signs consistent with CTE. None of the researchers was aware that the brain they were examining was Seau's.
In a recent study, researchers found CTE in 34 of 35 deceased NFL players whose brains were donated by family members.
A brain with CTE is riddled with dense clumps of a protein called tau. Under a microscope, tau appears as brown tangles similar to dementia. However, the Boston study showed this progressive, tau protein array in football players much too young for a dementia diagnosis, which typically occurs in people in their 70s or 80s.