Age of first exposure to football and later-life cognitive impairment in former NFL playersAuthor Response

Editors' Note: The study “Age of first exposure to football and later-life cognitive impairment in former NFL players” raised several concerns among Neurology ® readers. Maroon et al. pointed out methodologic limitations, Andrikopoulos raised questions about inaccuracies in definitions and references cited, and Larrabee et al. suggested that premorbid impairments may have been misinterpreted as brain injury effects. The authors of the study answer those inquiries in detail, acknowledging some of the limitations while rebutting others. They also point out that this is a preliminary study and encourage future research on this important issue. —Chafic Karam, MD, and Robert C. Griggs, MD The study by Stamm et al.1 may contain some methodologic limitations. The small sample was not representative of the general youth football player because most youth players do not go on to play professional football. In addition, the way football was played by the study subjects in the 1960s to 1980s is not representative of the improved, safer practices of modern-day youth football programs. Second, the authors need to more clearly outline their assessment of important variables such as normal score ranges of the outcome variables and choice of age group cutoff of 12 years and its relevance to the outcome variables. Most importantly, the retrospective research design and lack of proper control variables may explain group differences aside from early head impact. Parenting style (as to age at football participation) and socioeconomic factors could also explain group differences. Furthermore, these factors can interact with the type and likelihood of post head impact care, such as health care access or parents who encourage kids to “toughen up” vs “rest,” amplifying alternative explanations of group differences. Other limitations include the use of a suboptimal neuropsychological battery—the Wide Range Achievement Test, 4th edition (WRAT-4) reading subtest—and no proper determination …