A study of retired professional football players by researchers at UT Southwestern Medical Center found that their cognitive abilities did not differ significantly from a control group of similarly aged men who did not play football, nor did those abilities show significant change over one to five years. The findings, published in Brain Injury, suggest that exposure to concussions and head injuries among National Football League (NFL) players is not a predictor of neurocognitive decline later in life.
“This is the first study, to our knowledge, that has measured cognitive functioning over time in older NFL retirees, and it provides evidence that the degree of head-injury exposure does not relate to neurocognitive changes over time compared to carefully matched peers,” said the study’s senior author, Munro Cullum, Ph.D., Professor of Psychiatry, Neurology, and Neurological Surgery and Chief of Psychology at UTSW. “This is important given some of the media portrayal of cognitive impairment being routinely associated with a history of playing professional American football.”
The effect of concussions and repeated hits to the heads on NFL players has been a source of heightened concern in recent years since a number of deceased former NFL players were found to have had chronic traumatic encephalopathy (CTE). CTE, a neuropathologic condition that has been linked to repetitive head trauma, has been identified in some former football players and boxers as well as military veterans exposed to explosive blasts. But its actual cause is unknown, and it can only be diagnosed through autopsy.
Medical experts have been challenged to better understand how repeated head traumas and other factors might contribute to degenerative changes in the brain. Previous studies have reported mixed findings on the relationship between head-injury exposure and neuropsychological functioning later in life. While some investigations have suggested former NFL players may exhibit lower verbal memory and executive function scores, others have not found differences compared to control groups, according to a review of the literature .
The latest investigation, by faculty and trainees from UTSW’s Departments of Psychiatry, Neurology, Neurological Surgery, and Physical Medicine and Rehabilitation, included 53 former NFL players age 50 or older as well as 26 healthy controls and 83 individuals with mild cognitive impairment or dementia who did not play collegiate or professional contact sports and matched as closely as possible to the NFL retirees by age and education. The participants underwent clinical interviews that included concussion histories, neuropsychological testing, neuroimaging, and neurological exams. Twenty-nine players had follow-up evaluations ranging over one to five years.
The retired players in the study had an average of 5.63 concussions, 8.89 years in the NFL, and 115.12 games played.
The researchers report that retired football players had slightly lower memory scores compared to healthy peer controls but did not find this to be significantly associated with head-injury exposure. The findings held true whether the athletes had played non-speed positions (quarterback, lineman, linebacker) or those involving speed (running back, defensive back, receiver) during their playing careers. And the results did not significantly change in the follow-up evaluations.
“These results underscore that not all NFL retirees will have cognitive problems later in life, and they add to the complex and mixed literature on whether there is a clear dose-response relationship between head-injury exposure and later cognitive impairment,” said Jeff Schaffert, Ph.D., Assistant Professor of Psychiatry at UTSW and the study’s lead author. “Our finding that some NFL retirees may have slightly lower memory scores is not clinically meaningful and importantly did not relate to any measure of head-injury exposure we could evaluate.”
Dr. Schaffert, who is a neuropsychologist, added that these latest findings are not the end of the story. “Future research will be critical to determine whether there is a subset of former athletes who may be most at risk,” he said.
