A degenerative brain disease that has been linked to concussions and other head trauma common in military combat and contact sports, CTE has been diagnosed in more than 100 former NFL players and arisen as an existential threat to the United States’ most powerful pro sports league.

Shane Devon Tamura, who killed at least four people in N.Y.C. before turning the gun on himself, claimed in his suicide note that he had brain disease CTE

Meiko Locksley, one of 152 athletes diagnosed with CTE before even reaching the age of 30 as part of the Boston University CTE Center’s 2023 study, never made it past college football and began exhibiting signs of the disease in his 20s.