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 ...