The more hits that former high school and college football players took, the higher their likelihood of experiencing problems such as depression, apathy, or memory loss years later, a new study by School of Public Health and School of Medicine researchers says.
The study in the Journal of Neurotrauma, reports the most rigorous evidence to date that overall exposure to contact by former players could predict their likelihood of experiencing neurological problems. The findings are not conclusive, the authors wrote, as such mental problems can stem from a variety of factors.
The paper represents researchers’ first attempt to precisely calculate cumulative lifetime exposure to contact in living players. Previous estimates had relied in part on former players’ memories of concussions, or on number of years played. The new paper uses more objective measures, including data from helmet accelerometer studies.
The researchers estimated exposure to contact in 93 former players, ages 24 to 82. The estimate was based on the number of seasons played, the position, and the average number of hits expected for that position, at each level of play, beginning in youth leagues.
A hit was defined as an impact causing 10 times gravitational acceleration, including blows not directly to the head.
The study found that the greater the number of hits in a player’s career, the higher the likelihood of problems later in life. The cumulative number of hits also was a better predictor of later-life impairments than other measures, such as a player’s concussion total.
“I think of the study as just the beginning of trying to characterize exposure in a more precise way,” co-author Michael McClean, an associate professor of environmental health, told the New York Times in an interview.
Repetitive head impacts (RHI) refer to cumulative exposures to concussive and sub-concussive events. Although RHI is believed to increase risk for later-life neurological consequences (including chronic traumatic encephalopathy), quantitative analysis of the relationship had not yet been examined due to a lack of validated tools to quantify lifetime exposure.