In an effort to discover whether concussion injury occurrence and treatment had changed, researchers compared those two consecutive six-year periods to determine the circumstances of the injury, the patterns of symptoms, and a player's time lost from NFL participation. Those time periods were chosen because concussion statistics were recorded by NFL teams using the same standardized form. It recorded player position, type of play, concussion signs and symptoms, loss of consciousness and medical action taken.
Researchers found that in 2002-2007 there were fewer documented concussions per NFL game overall, especially among quarterbacks and wide receivers. But there was a significant increase in concussions among tight ends. Symptoms most frequently reported included headaches, dizziness, and problems with information processing and recall.
"There are a number of possible explanations for the decrease in percentages of players returning to play immediately and returning to play on the day of the injury as well as the increased days out after (a concussion) during the recent six year period compared to the first six year period," write authors Ira R. Casson, M.D.; David C. Viano, Dr. med.; Ph.D., John W. Powell, Ph.D.; and Elliot J. Pellman, M.D. "These include the possibility of increased concussion severity, increased player willingness to report symptoms to medical staff, adoption of a more cautious conservative approach to concussion management by team medical personnel and a possible effect of changes in neuropsychological (NP) testing."
Source: SAGE Publications and I. R. Casson, D. C. Viano, J. W. Powell, E. J. Pellman. Twelve Years of National Football League Concussion Data. Sports Health: A Multidisciplinary Approach, 2010; DOI: 10.1177/1941738110383963
See also: Football Players May Still Injure Brain Even Without A Concussion and Youth Sports Concussions Double In Last Ten Years