Head Injuries and Psychiatric Symptoms in Football Players

Repetitive brain injury can lead to marked behavioral changes.

Posted Oct 25, 2017

There has been significant media coverage of a 2017 publication by Ann McKee, Jesse Mez, and colleagues in the Journal of the American Medical Association (JAMA) entitled “Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football.” The press focused on the finding that 110 of 111 former National Football League (NFL) players included in the study exhibited neuropathological signs of chronic traumatic encephalopathy (CTE) at the time of their deaths. Marked cognitive changes are associated with the neurodegeneration that occurs in this condition. In addition, there are profound behavioral changes.

CTE is a progressive neurodegeneration associated with repeated head trauma. In the JAMA paper, the authors report findings from 202 American football players who played the game at various levels from high school to professional. After the players died, their brains were donated by their families for research.

Of the 202 participants in this study, 177 exhibited post-mortem signs of CTE. A diagnosis of CTE was made by neuropathological examination of brain tissue according to nationally recognized consensus criteria. There are four stages of CTE severity as defined by the level of changes in the brain. Stages I and II are considered mild; stages III and IV are considered severe.

The research team also performed retrospective clinical evaluations of study participants using online surveys and telephone interviews with informants, usually close family members. Both the interviewers and the informants were unaware of the neuropathological results at the time of the interviews.

The individuals with CTE had manifested two groups of symptoms during their lives: cognitive symptoms and behavioral symptoms. Most of these individuals eventually experienced both groups of symptoms. The cognitive symptoms, including memory problems, attentional problems, and executive function difficulties, often progressed to dementia

The behavioral symptoms were not subtle. Eighty-seven percent of those with behavioral symptoms demonstrated impulsivity, 63 percent depressive symptoms, 55 percent apathy, 54 percent anxiety, 53 percent hopelessness, 55 percent explosivity, 45 percent verbal violence, 37 percent physical violence, and 36 percent suicidality.

Interestingly, behavioral symptoms were the first manifestations of CTE in about 43 percent of individuals; about 42 percent exhibited cognitive symptoms first. Almost everyone who had CTE had behavioral symptoms at some point. Ninety-six percent of those who died during the mild stages of the condition had a history that included behavioral symptoms.

The median age at death for those with mild CTE was 44, and the most common causes of death were suicide (27 percent), dementia-related and parkinsonian-related neurodegeneration (16 percent), cardiovascular disease (11 percent), and motor neuron disease (9 percent).

Many of the participants whose condition presented with behavioral symptoms had a substance use disorder, history of suicidality, and/or family history of psychiatric disorders. Perhaps, individuals with an individual or family history of psychiatric illness are more susceptible to developing early behavioral changes from chronic head injuries.

In summary, chronic brain injuries can result in profound behavioral changes in addition to marked cognitive changes that can progress to dementia. This report by Mez and colleagues examined individuals who were American football players. CTE is also associated with head trauma sustained in other contact sports, for example, boxing, and it also occurs in some individuals who were exposed to head injuries while serving in the military.

It is important to acknowledge several limitations of this study. First, families of the participants made the decision to join the study and they may have been motivated by the presence of symptoms in their loved ones. Thus, the sample is biased toward people who exhibit symptoms. Second, the study sample was not representative of all football players in that the percentage of professional players was much higher than in the general football-playing population. Nonetheless, the finding of CTE in football players across a range of levels particularly among those who played the sport at collegiate and professional levels is sobering and has individual, familial, and societal implications.

CTE is a disorder that can occur in individuals who voluntarily participate in activities associated with repeated head trauma. It can lead to behavioral changes that are harmful to the individual and to those around them. As a result of cognitive changes, individuals with CTE may require assistance with activities of daily living. Thus, substantial costs are associated with taking care of these individuals. Who should be responsible for paying for these costs? Should it make a difference if the disorder resulted from voluntary participation in certain sports or head injuries sustained while serving in the military? What costs should be borne by the organizations (professional and collegiate) that profit from these sports? This is likely to be an evolving story with major societal implications.

This post was written by Eugene Rubin MD, PhD and Charles Zorumski MD


Mez, J., Daneshvar, D.H., Kiernan, P.T., Abdolmohammadi, B., Alvarez, V.E., Huber, B.R., Alosco, M.L., et al. (2017). Clinicopathological evaluation of chronic traumatic encephalopathy in players of American football. JAMA 318(4): 360-370.