According to a study led by Mass General Brigham investigators from McLean Hospital and the Spaulding Rehabilitation Network, former professional soccer players who reported experiencing concussion symptoms during their playing careers performed worse than non-players on a range of cognitive tests. The results of the study will be published on March 2ndndInArchive of Clinical Neuropsychologyj.
Of the more than 350 former National Football League (NFL) players surveyed an average of 29 years after the end of their playing careers, those who reported experiencing concussion symptoms during their careers scored lower on the episodic memory rating, sustained attention, processing speed and vocabulary. However, the number of concussions diagnosed by a doctor or length of playing career had no observed effect on cognition.
A follow-up analysis compared the former players to more than 5,000 male volunteers in the general population who did not play professional football and found that cognitive performance was generally worse among former players than non-players. While younger ex-gamers outperformed non-gamers on some tests, older retired gamblers were more likely to perform worse than controls on cognitive tasks.
The researchers who led the study said their findings underscore the importance of tracking concussion symptoms as opposed to diagnosed concussions in research. This work also provides evidence of the impact that a professional soccer career can have in accelerating cognitive aging.
“It is well known that people experience some degree of cognitive impairment in the hours and days after a concussion. However, looking decades ahead, the data on long-term effects is mixed,” said study lead author Laura Germine. PhD, Director of the Brain and Cognitive Health Technology Laboratory at McLean Hospital and Associate Professor of Psychiatry at Harvard Medical School. “These new findings, from the largest study of its kind, show that professional soccer players can still suffer from cognitive difficulties associated with head injuries decades after they have retired.”
Concussion Symptoms Associated with Cognitive Performance
For the study, 353 retired NFL players completed hour-long neuropsychological tests through an online platform called TestMyBrain, supported by McLean Hospital and Harvard Medical School. Players were completely remote and completed tests on a laptop or desktop that included assessments measuring processing speed, visuo-spatial and working memory, and aspects of short- and long-term memory and vocabulary.
Recalled concussion symptoms were measured by asking players how often they experienced any of the following symptoms after being hit to the head during play or practice: headache, nausea, dizziness, loss of consciousness, memory problems, disorientation, confusion, seizures, or vision problems an unsteady feeling on your feet. They were also asked if they had lost consciousness during their careers and if they had ever been diagnosed with a concussion by a doctor.
The results showed that the former players’ cognitive performance (e.g., on memory tasks) was associated with remembered football concussion symptoms. For example, the observed differences in visual memory scores between former players with the highest and lowest reported concussion symptoms were equivalent to the differences in cognitive performance between a typical 35-year-old and a 60-year-old.
Poor cognitive performance, however, was not associated with diagnosed concussions, years of professional sports experience, or age of first soccer experience. The researchers noted that many head injuries or sub-concussive punches may not have been diagnosed as concussion because players were uninformed or underreported the symptoms at the time.
Comparing the retired players with a group of 5,086 men who did not play soccer, cognitive performance was generally worse among former players. On two tests of processing speed, age-related differences in cognitive performance were greater in the ex-gamer group than in the non-gamer group, with older gamers performing worse.
This comparative data suggests that football exposure could accelerate age-related cognitive decline and result in greater disadvantages in older age, the researchers said, adding that more studies are needed to track former players’ cognitive performance as they age. Another possibility is that improved head injury awareness and management may have spared younger retired players more than older ones. The researchers also noted that this comparative result is limited by a lack of data on pre-head injury cognition, and that more research is needed that closely matches former players and non-players and measures their cognitive performance across their lifetime.
“For both former players and researchers, we can glean some important lessons from this study,” said Ross Zafonte, DO, principal investigator of the Football Players Health Study. “Former players can support their cognitive health as they age by taking proactive steps and continuing to consult with their providers and educate themselves about head injury symptoms. For researchers and providers, these findings support efforts to develop ways to improve the diagnosis and definition of long-term concussion episodes.” Zafonte is President of the Spaulding Rehabilitation Network, Sports Medicine Physician to Mass General Brigham, Professor of Earle P. and Ida S. Charlton and Chair of the Department of Physical Medicine and Rehabilitation at Harvard Medical School.
“The community-based participatory research (CBPR) approach taken in this study is the direction in which this field is moving,” said Germine. “We are grateful to the players and for how much they taught us. It would not have been possible to conduct a study like this without engaging and deeply involving their community.”
Research powered by input from former NFL players
Launched in 2014, the Football Players Health Study at Harvard University is a comprehensive research program dedicated to examining the multifactorial causes affecting the health of former NFL players. The research was led by the players themselves, who provided input on the health issues and conditions they face after a career in football. An interdisciplinary team of researchers from Harvard University and Harvard Medical School and their affiliated teaching hospitals, including those in the Mass General Brigham system, conducts research in neurology, cardiology, sports medicine, rehabilitation medicine, chronic pain and public health. While concussion and head injuries are of paramount concern, the study examines all aspects of player health across the lifespan. Former players can find important resources to support their health in this section of the study website.