1. Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
2. Matthew A. Gfeller Sport-Related Traumatic Brain Injury Research Center, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
3. Center for the Study of Retired Athletes, Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
4. College of Medicine, Florida State University, Tallahassee, Florida