(CNN)Here's some background information about concussions in the National Football League. Reports show an increasing number of retired NFL players who have suffered concussions have developed memory and cognitive issues such as dementia, Alzheimer's, depression and chronic traumatic encephalopathy (CTE).
Most concussions occur without losing consciousness.
Loss of consciousness
(Preseason and regular-season practices plus games)
1994 - NFL Commissioner Paul Tagliabue creates the Mild Traumatic Brain Injury Committee. Dr. Elliot Pellman is named chairman despite not having experience with brain injuries.