horror bloodclotting  article

Next up: A study to determine if the Lord of the Rings trilogy actually does take your breath away.

We’ve used a lot of exaggerated adjectives to describe horror movies over the years — shocking, petrifying, bone-chilling, and my personal favorite, bloodcurdling. Any word that combines an internal process with the mental image of cottage cheese is a particularly gruesome one, no doubt, but how much truth is there to it?

Well, according to research recently published in the British Medical Journal (by a team of Dutch researchers, if that makes any difference), our use of the term “bloodcurdling” to describe certain horror movies might not be that far-fetched after all.

The answer lies in a complex known as “protein factor VII,” which aids in the clotting of our blood. Over the course of our evolution as human beings, the increase of protein factor VII has served as one of our bodies first internal reactions to a potentially harmful situation, acting as a sort of preemptive bandage should we be injured. As you might have gathered, protein factor VII is released into our bodies at higher and higher rates when we become…frightened. If we’re watching a horror movie, for instance.

How did researchers go about proving this? They started by gathering 24 healthy volunteers under the age of 30, consisting of students, alumni, and employees of the Leiden University Medical Center. Roughly half of these participants (14) were assigned to watch a frightening movie, Insidious, followed by a “non-threatening movie,” the documentary A Year in Champagne, while the other 10 watched the same movies in reverse order. The movies were both approximately the same length and were viewed more than a week apart at the same time of day to eliminate any potential x-factors, and the volunteers were additionally asked to avoid alcohol and tobacco on movie days.

Each group had a blood sample taken 15 minutes before the first movie, two samples taken between the movies, and then a final sample was taken within 15 minutes of the end of the second movie. The results:

Coagulant factor VIII levels increased in 12 (57%) participants during the horror movie, but only in 3 (14%) during the educational movie. Levels decreased in 18 (86%) participants during the educational movie, but only in 9 (43%) during the horror movie.

The mean increase in factor VIII levels of 11.1 IU/dL associated with acute fear could be clinically relevant, as every 10 IU/dL increase in coagulant factor VIII levels is associated with a 17% (95% confidence interval 7% to 28%) increase in the risk of venous thrombosis.

Of course, there were drawbacks. One of the participants had to be removed from the study after passing out while giving blood, which given the study’s limited size sample to begin with, was a bit of a blow. There’s also the issue of how exactly our bodies have developed this protein complex and what biological function causes it to be released, both of which are still unknown. And while the researchers are confident in the results of their test, they made special note to confirm that watching horror movies does not actually heighten one’s chance of getting a blood clot.

The whole study is explained in a nifty video, so check it out below, then head over to The British Medical Journal to get all the nitty gritty details.

Source: The British Medical Journal

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