Figure 1. Sample Distribution of Age of First Exposure to Tackle Football and Decade Participants Began to Play Tackle Football.

CTE+ = the presence of chronic traumatic encephalopathy and comorbid neurodegenerative disease. The Figure on the right presents the distribution of AFE to tackle football by decade of play in the CTE+ participants. Decade of tackle football play refers to when the subject began to play tackle football and ranges from the 1920s to the 2000s.