Dissecting football and brain injury
Evidence continues to accumulate linking chronic traumatic encephalopathy (CTE) to participation in American football.
CTE is defined by unique changes in brain tissue that is examined at autopsy. CTE results from repeated brain injury, most commonly concussion, which may occur as a result of military service, domestic violence and contact sports.
Concussion results from sudden deceleration or torsion of the brain, which then strikes the inner surface of the rigid skull. Many concussions are not reported or are ignored by athletes who do not wish to be removed from play. Lesser brain injury, which does not rise to the level of a concussion, may contribute to the development of CTE.
A recent study in the Journal of the American Medical Association (JAMA 2017;318:360-370) was based upon rigorous evaluations of the brains of 202 former football players. Brains were donated for study by spouses or other family members or referred for evaluation by medical examiners. Studies were conducted by a team of experts in Boston with extensive experience with CTE. Using strict microscopic criteria, 177 of the brains were diagnosed with CTE.
Severity of CTE was graded from 1 to 4 based on the number, distribution and severity of abnormalities. Categories 1 and 2 were considered “mild,” while 3 and 4 were considered “severe.”
Detailed case histories for each player were obtained through standardized, online and telephone interviews with closest kin. Interviewers, who had professional training in neurology or psychology, were not aware of pathology findings at the time of gathering clinical data.
A progressive or worsening clinical course was common. Changes in behavior, including depression, anxiety, explosive outbursts and suicidal thoughts were reported in a majority of cases. Decline in memory and mental function generally were common, more so in severe CTE. Dementia was common at the time of death.
The median age at death for mild CTE victims was 44 years (range 29-64). Median age for severe CTE victims was 71 (range 64-79).
Suicide was the most common cause of death (27 percent) in subjects found to have mild CTE. Degenerative brain disease accounted for 47 percent of deaths in subjects with severe CTE.
Age at first exposure to organized football ranged from 8 to 14 years. The highest level of play for three affected athletes was high school. Of 48 affected college players, 21 showed mild CTE; 27 showed severe CTE. Of 110 NFL players, 15 showed mild changes; 95 showed severe changes.
Length of time in organized football correlated with severity of CTE. Players with mild CTE played an average of 13 years versus 15.8 years for players with severe CTE.
Linemen — both offensive and defensive — linebackers, running backs and defensive backs suffered the highest incidence of CTE in this study. Tights ends, wide receivers, and punters had the lowest incidence.
An important, as yet unanswered, question: Once CTE begins, is the process progressive even in the absence of further participation in football?
The frequency of CTE cannot be determined since there is no means for diagnosing the disorder during life. Patterns of behavior or cognitive decline that occur in former football players may raise suspicions of CTE, which can only be diagnosed with certainty after death.
Perhaps advances in brain-scanning technology will permit early diagnosis of CTE. A player with these findings could be advised to cease further playing. Close clinical followup might mitigate symptoms associated with CTE. Tests on blood or spinal fluid might be developed to detect abnormalities diagnostic of CTE.
While the science of CTE evolves, research could lead to changes in football equipment to lessen the shock waves to the brain following a hard block or collision with another player or the playing surface.
Changes in the rules of the game could lessen the intensity of hits. The ban on helmet-to-helmet contact must be strictly enforced. Hard, blindside hits on quarterbacks and pass receivers must be banned.
Practice protocols can be altered to reduce the number of hard contacts with blocking dummies and teammates.
More comprehensive evaluation of players experiencing concussion is in order. If a player is observed to be wobbly or dizzy after a play, he should be removed from the game at once for an appropriate examination. The notion of “playing hurt” must be discouraged.
When should children be exposed to tackle football? The Centers for Disease Control and Prevention is gathering data to answer that important question.
The National Football League and the National Collegiate Athletic Association should fund and promote efforts to make American football safer for participants at all levels.