The Neurocritic covers some fascinating research on how marathon runners could be a scientific window into the neuropsychology of trauma owing to the fact that they experience extremely high levels of the stress hormone cortisol.
In their study, psychologists Teal Eich and Janet Metcalfe note that cortisol levels recorded 30 minutes after a marathon have been found to be similar to those in soldiers during military training and interrogation, rape victims just after the attack, severe burn injury patients and first-time parachute jumpers.
This suggests that marathon runners could be studied in a more systematic way than would would be ethical with victims of trauma, giving an important insight into the brain under extreme stress.
Eich and Metcalfe were particularly interested in the effect of stress on memory and wanted to see if there were any differences between explicit memory – memories that you can consciously call to mind, and implicit memory – the influence of past information on a task even if you’re not aware of doing any remembering.
They tested a group of runners about half an hour after they completed a marathon and a group who were just about to run a marathon.
In comparison to the about-to-runs, those who had completed the marathon had worse explicit memory but better implicit memory. In other words, their conscious memory was reduced but their unconscious memory seemed to be sharper.
This is interesting because chronically high cortisol levels from trauma are thought to affect the hippocampus, a brain area known to be key in conscious memory. The researchers suggest that a similar process may be temporarily reducing explicit memory in runners.
The authors are a little more cautious in suggesting why implicit memory may have been improved, but one possibility is that cortisol is known to affect fear conditioning – the unconscious linking of fright with the situation it occurred in.
Interestingly, this is known to work differently in men and women. Cortisol boosts unconscious fear learning in men, but not women. The researchers didn’t compare male and female marathon runners directly, but it would be interesting to know whether general unconscious learning that wasn’t associated with fright was also sex-specific in their study.
There’s more on the research over at The Neurocritic and the full text of the study is available online as a pdf if you want an in-depth look at the experiment.