No linear association between number of concussions or years played and cognitive outcomes in retired NFL players

Objective: The aim of the current study is to examine whether concussion history and years played are linearly associated with cognitive outcomes in retired National Football League (NFL) players. Method: Thirty-five retired NFL players over the age of 50 who had sustained at least one concussion completed a clinical interview and brief neuropsychological battery. Correlational analyses were conducted between exposure variables [number of total concussions, concussions with loss of consciousness (LOC), and years played] and cognitive performance as characterized by cognitive composite scores based on performance on neuropsychological measures (attention/processing speed, language, memory, and overall composite scores). Results: Correlational analyses corrected for multiple comparisons did not reveal any statistically significant correlations between exposure variables and cognitive outcomes. Conclusions: We did not find a significant linear association between cognitive outcomes and either number of total concussions, concussions with LOC, or years played in the NFL. These findings do not support a dose–response relationship between sports-related exposure to head impacts and cognitive outcomes later in life. Rather, the findings suggest that cognitive difficulties experienced by some retired players later in life are not directly linearly associated with quantified exposure to head impacts sustained throughout a football career, but related to factors or combinations of factors that have yet to be elucidated.