Eliezer J. Sternberg M.D.

NeuroLogic

Fear

The Fear Factor in Somatization

What Harry Potter can teach us about irritable bowel syndrome (yes, really!)

Posted Aug 31, 2015

NatashaG/Pixabay
Source: NatashaG/Pixabay

In the twilight hours the night before an exam, medical students may have a peculiar experience: they start manifesting the symptoms of the diseases they are studying.  As they read their textbooks, they suddenly experience the jaw pain of giant cell arteritis or the numbness of Charcot–Marie–Tooth disease.  The phenomenon is so common that it’s actually been given a name: “medical student’s disease.”  Yet it’s really quite mysterious when you think about it.  How can words printed on a page in black ink induce actual, physical symptoms?  Oddly enough, a clue to the answer may reside in the pages of Harry Potter.

Consider the feeling of immersion you experience when you read passages like this: 

Harry lay listening to the muffled shouting next door and wondered why he didn't feel more scared. Sirius Black had murdered thirteen people with one curse; Mr. and Mrs. Weasley obviously thought Harry would be panic-stricken if he knew the truth.1 

A team of German researchers recently used neuroimaging to investigate the brain regions involved in “getting lost in a book.”2   They gathered twenty-four volunteers who had read at least one Harry Potter novel and presented them with a set of passages sampled from the books.  As the participants read the passages, their brain activity was monitored with fMRI (functional magnetic resonance imaging), a scan that can track brain activity in real time.  After completing the passages, the participants rated their own level of immersion in each passage on a scale of 1 (not at all immersed) to 7 (“I forgot the world around me while reading”).

It turned out that the participants’ subjective level of immersion followed a pattern: it was greatest while reading tense or frightening scenes and lowest while reading emotionally neutral ones.  Reading the scary passages activated an area of the brain known as the mid-cingulate cortex, which is part of the emotional system.  Specifically, the mid-cingulate is known as a place where two brain pathways overlap: the pathway for fear and the pathway for pain.  The theory is that the mid-cingulate cortex uses its access to these two neurological circuits to engender our fear of pain, allowing us to avoid whatever in our lives makes us hurt.3   This connection, however, can have some unintended effects.

Fear and the cingulate cortex happen to be central to one of the most elusive phenomena in medicine, known as somatization.  Somatization is the tendency to manifest psychological distress in the form of bodily symptoms.  Take irritable bowel syndrome (IBS), for instance.  People experience pain, bloating, and diarrhea or constipation, yet they have no medical problem with their bowels at all.  It’s caused by psychological stress.

In a recent study of IBS, German scientists used fMRI to track the relationship between anxiety and the painful bowel movements of IBS.4   Twenty-seven volunteers, fifteen of them with IBS, first underwent psychological testing to determine their level of anxiety and had testing to ensure they had no injury to the rectum that might cause pain.  Next came the task of quantifying their pain level during bowel movements.  The researchers created a simulation of the experience by using an expandable cylindrical balloon which, when inserted into the rectum, could apply gentle pressure and convince the local nerves that a bowel movement was occurring.  The participants then rated their level of discomfort using a numerical pain scale.  All the while, their brain activity was recorded by fMRI.

The results showed that the more anxious the participants were, the more pain they experienced.  That helped prove what we already know, that it’s the anxiety in IBS that’s responsible for the symptoms rather than a structural intestinal problem.  But what did the fMRI show?  Activation of the mid-cingulate cortex, precisely the same area that fires up when we read frightening scenes in Harry Potter.  

So, what does this mean?  As we said, the mid-cingulate is an intersection of the neurological pathways for fear and pain.  This crossover of brain circuitry may be part of the reason why the fear of pain, as in IBS, may manifest as actual pain.  The fear circuit may incidentally activate the pain circuit.  Fear leads to us to focus deeply on a thought or idea.  In its most mild form, it helps us become immersed in thrilling book as we throw ourselves into Harry’s quest to defeat Voldemort.  While memorizing disease symptoms for a test, some medical students may experience a more powerful, detrimental form of this immersion, leading them to begin manifesting the symptoms they’re studying.  Somatization may represent the most extreme segment of this immersion spectrum.  The focus on one’s bodily symptoms, exacerbated by fear and anxiety, is so severe that the symptoms become not only real, but debilitating.  The good news, however, is that managing fear and anxiety can go a long way in warding off somatization disorders and leaving disease symptoms where they belong: in textbooks.

REFERENCES

1.  Rowling, JK. Harry Potter and the Prisoner of Azkaban. New York: Scholastic, 1999, p. 67.
2.  Hsu et al. “Fiction feelings in Harry Potter: haemodynamic response in the mid-cingulate cortex correlates with immersive reading experience.” Neuroreport 25, 17 (2014): 1356-61.
3.  Vogt, B.A. "Pain and emotion interactions in subregions of the cingulate gyrus." Nature Reviews Neuroscience 6 (2005): 533–44.
4.  Elsenbruch S. et al. “Affective disturbances modulate the neural processing of visceral pain stimuli in irritable bowel syndrome: an fMRI study.” Gut 59, 4 (2010): 489-95.