Thestudy, conducted by University of North Carolina at Chapel Hillresearchers and colleagues, found that retired National Football Leagueplayers also faced a 37 percent higher risk of Alzheimer’s than otherU. S. males of the same age.
A report on the findings, which arebeing presented at a Congress of Neurosurgery scientific meeting inBoston today (Oct. 10), appears in the October issue of the journalNeurosurgery. Lead authors are Drs. Kevin M. Guskiewicz, professor ofexercise and sport science in the UNC College of Arts and Sciences, andStephen W. Marshall, associate professor of epidemiology at the UNCSchool of Public Health and of orthopaedics at the UNC School ofMedicine. Guskiewicz also chairs the exercise and sport sciencedepartment, directs the university’s Center for the Study of RetiredAthletes and Sports Medicine Research Laboratory and holds a jointappointment in othopaedics.
"In this unique study, we had somevery interesting findings," Guskiewicz said. "Our data suggest that ahistory of recurrent concussions and probably sub-concussive contactsto the head may be risk factors for the expression of late-life memoryimpairment, mild cognitive impairment and earlier expression ofAlzheimer’s disease. Research like this is important since more than300,000 sport-related concussions, many of which are recurrentinjuries, occur annually in the U.S. and more than 1.2 millionAmericans suffer head injury each year."
The study involvedsurveying by mail 3,683 retired professional football players whobelonged to the NFL Retired Player’s Association about their overallhealth and analyzing the results.
Of those, 2,552 returnedquestionnaires or had their spouses or other close relatives do so forabout a 70 percent response rate. Players averaged almost 54 years oldand had an average professional career spanning 6.6 years.
Researchersthen surveyed a subset of 758 players aged 50 and older and asked moredetailed questions about concussions and diagnosed dementia-relatedimpairments. Spouses and close relatives also participated and assistedin confirming responses provided by the retired players.
"Whenconsidering prevalence of previous concussions, 1,513, or 60.8 percent,of the retired players reported having sustained at least oneconcussion during their professional playing career, and 597, or 24percent, reported sustaining three or more concussions," Guskiewiczsaid.
Among retired players who sustained a concussion duringtheir professional careers, more than half reported experiencing lossof consciousness or memory loss from at least one of their concussions,he said.
"We asked the retired players for their subjectiveassessment of the long-term consequences of their injuries," Guskiewiczsaid. "Of the retirees who sustained at least one concussion, 266, or17.6 percent, reported that they perceived the injury to have had apermanent effect on their thinking and memory skills as they havegotten older. The findings showing a relationship between diagnosedmild cognitive impairment and history of concussions -- three or more-- suggest that a true memory effect is present."
Retired playerswith three or more concussions had a five-fold greater chance of havingbeen diagnosed with mild cognitive impairment and a three-foldprevalence of reported significant memory problems compared to thoseplayers without a history of concussion, he said. Physicians haddiagnosed 33 players with Alzheimer’s. The higher prevalence of thememory-destroying disease was more noticeable in the younger age groups-- those below age 70 than in those over that age.
Co-authors ofthe report are Dr. Julian Bailes of the West Virginia University Schoolof Medicine, Dr. Michael McCrea Waukesha Memorial Hospital and theMedical College of Wisconsin in Milwaukee, Dr. Robert C. Cantu ofEmerson Hospital in Concord, Mass., and Brigham and Women’s Hospital inBoston, Dr. Christopher Randolph of the Chicago Neurological Instituteand Loyola University Medical School in Maywood, Ill., and Barry D.Jordan of Burke Rehabilitation Hospital in White Plains, N.Y.
Thestudy’s chief limitation was that it was based on self-reported answersto the health questions, and the accuracy of remembering memoryproblems could not be verified completely.
"Future prospectivestudies should implement genetic testing since genes are known toaffect memory," Guskiewicz said. "Also, there needs to be more rigorousdiagnostic criteria, historical documentation of injuries and periodicevaluations such as neurophysiologic testing and functionalneuroimaging to clarify the effects of concussion on lifetime risk ofdementia or other neurologic disorders."
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