After a week layoff, here’s some more Linkage focused on that thin ellipse of the Venn Diagram where sports and science intersect.
Chicago Marathon: An Enormous Study of Trauma & Torture?
This Sunday marks the 32nd running of the Chicago Marathon, and as reported on this blog, at least one University of Chicago scientist will be in the field. But marathons are of interest as well to scientists who aren’t avid long-distance runners, and perhaps not in the way you think. Covered well by the excellent neuroscience blogs Mind Hacks and The Neurocritic this summer was a study out of Columbia University that used marathon runners as stand-ins for victims of violent trauma – the argument being that marathons are a voluntary (and thus, ethical to study) pool of people who subjected themselves to intense, long-duration stress.
The study focused on how long-term elevations in cortisol, often known as the “stress hormone,” affect memory. In the study, authors Teal S. Eich and Janet Metcalfe cite studies that found running a marathon produces cortisol levels equivalent to military interrogation, severe burn injury and “first-time parachute jumpers.” Fun! So marathon runners were asked to perform tests for two types of memory after running their 26.2 miles, and the results were compared to tests taken by marathon runners tested 1-3 days before their race.
As you may expect, the researchers found that people are significantly worse at remembering a list of words (which tests explicit memory) immediately after a four-hour jog. But implicit memory (measured by the completion of words when given the first three letters) was actually improved after the marathon. So high levels of cortisol over an extended period of time can inhibit your ability to recall facts, giving you a form of temporary amnesia. Meanwhile, the unconscious, quick-fire recall of implicit memory is enhanced – a sensible strategy for a brain faced with an emergency situation.
The loss of explicit memory after prolonged stress is more than just a party trick; it’s particularly relevant to the debate over the use of “military interrogation” (what some might less charitably call torture) as a valid form of collecting intelligence. The conclusion of the marathon researchers that elevating a person’s stress hormone for several hours is not the best way to get them to recall facts was echoed by a scientific article published in August by Shane O’Mara in the journal Trends in Cognitive Sciences (summarized nicely by Newsweek’s Sharon Begley). That paper reviewed neurobiological literature on what stress does to areas of the brain associated with memory and concluded “coercive interrogations involving extreme stress are unlikely to facilitate the release of veridical information from long-term memory, given our current cognitive neurobiological knowledge.” In other words: torture isn’t just morally questionable, it’s also ineffective.
So marathon runners: don’t study for any tests immediately before running this Sunday. And wait until you’re done to read this excellent article by my friend and fellow neuroscientist Tom Hummer on why Kenyans excel at running long distances.
Brain Damage on the Gridiron
One of my first stories as a proper journalist was to cover a National Football League meeting in Rosemont about the growing evidence that the violence associated with playing football was causing brain damage, Alzheimer’s-like symptoms and depression in its players. The association between concussions and brain injury, covered tirelessly by New York Times reporter Alan Schwarz over the last few years, had largely been downplayed publicly by the NFL, and that meeting was no different. While the league said in tightly-controlled press conferences that they were monitoring the studies (many taking place at the University of North Carolina’s Center for the Study of Retired Athletes), the meeting was held behind closed doors watched over by former football players turned security guards. Individual teams were no better; when I called the Chicago Bears to see what types of concussion tests they perform on players to see if they were suitable to return to the field, I was given a terse no comment.
Well, the case for a link between on-field violence and brain injury is only growing stronger, as last week a study commissioned by the NFL found an incredible 19-fold increase in memory deficits in retired players. There are still questions – the latest study has not yet been published, and it was conducted via telephone survey – but momentum continues to build, with NFL players now offering their brains up to scientists (presumably after death) to help the inquiries. Scarily, the specific type of brain injury seen in NFL players who died prematurely (called chronic traumatic encephalopathy, or CTE) has now been observed in high school players, suggesting the damage can occur with only a few years of hard hits on the field, not the 10-20 years the pros experience.
The science raises an interesting question: is football too dangerous to play? In researching the NFL summit, some experts suggested that changes in helmet design could minimize, if not eliminate, the risk of brain injury. But how low do the rates of serious brain damage need to be to make a sport acceptable to play? A Chicago Tribune article published just yesterday profiled what Chicago-area high schools are doing to prevent serious head injury to their players, but the testing protocol that NFL teams use (called ImPACT) is out of the price range of most schools. Despite new guidelines about how long players should sit out after suffering a concussion, the pressures on star players (such as, most recently, Florida’s Tim Tebow) to return quickly to the field make such recommendations almost meaningless. Could science make football obsolete?
Either way, I’m raising my kids to play soccer.