Twisted faces

One of the most terrifying episodes The X Files ever did was called "Folie à Deux."  In the opening scene, a man sees his boss not as a human but as a hideous-looking insectile alien who is, one by one, turning the workers in the company into undead zombies.

The worst part is that he's the only one who sees all of this.  Everyone else thinks everything is perfectly normal.

The episode captures in appropriately ghastly fashion the horror of psychosis -- the absolute conviction that the awful things you're experiencing are real despite everyone's reassurance that they're not.  In the show, of course, they are real; it's the people who aren't seeing it who are delusional.  But when this sort of thing happens in the real world, it is one of the scariest things I can imagine.  As I made the point in my neuroscience classes, your brain is taking the information it receives from your sensory organs and trying to assemble a picture of reality from those inputs; if something goes wrong, and the brain puts that information together incorrectly, that flawed picture becomes your reality.  At that point, there is no reliable way to distinguish reality from hallucination.

I was, unfortunately, reminded of that episode when a friend and loyal reader of Skeptophilia sent me a link yesterday to a story in NBC News Online about a man with prosopometamorphopsia, a (thank heaven) rare disorder that causes the patient's perception of human faces to go awry.  When he looks at another person, he sees their face as grotesquely stretched, with deep grooves in the forehead and cheeks.

Computer-generated images of what the patient describes seeing [Image credit: Antônio Mello, Dartmouth University]

Weirdly, it doesn't happen when he looks at a drawing or a photograph; only actual faces trigger the shift.  A moving face -- someone talking, for example -- accentuates the distortion.

Some people with prosopometamorphopsia (PMO) have it from birth; most, though, acquire it through physical damage to the brain, such as a stroke or traumatic brain injury.  The patient who was the first subject of this study shows up in MRI images with a lesion on the left side of his brain that is undoubtedly the origin of the distorted perception.  As far as the origin of that, he had a severe concussion in his forties (he's now 59), but also suffered from accidental carbon monoxide poisoning four months before the onset of symptoms.  Which of those is the root cause of the lesion, or if it's from something else entirely, is unknown.

At least now that he knows what's going on, he has been reassured that he's not going insane -- or worse, that he's seeing the world as it actually is, and like the man in "Folie à Deux," become convinced that he's the only one who does.  "My first thought was I woke up in a demon world," the patient told researchers, regarding how he felt when the symptoms started.  "I came so close to having myself institutionalized.  If I can help anybody from the trauma that I experienced with it and keep people from being institutionalized and put on drugs because of it, that’s my number-one goal."

I was immediately reminded of a superficially similar disorder called Charles Bonnet syndrome. (Nota bene: Charles Bonnet is no relation.  My French great-grandfather's name was changed upon arrival in the United States, so my last name shouldn't even be Bonnet.)  In this disorder, people with partial blindness, often from macular degeneration, start putting together the damaged and incomplete information their eyes are relaying to their brains in novel ways, causing what are called visual release hallucinations.  They can be complex -- one elderly woman saw what appeared to be tame lions strolling about in her house -- but there's no actual psychosis.  The people experiencing them, as with PMO, know (or can be convinced) that what they're seeing isn't real, which takes away a great deal of the anxiety, fear, and trauma of having hallucinations.

So at least that's one upside for PMO sufferers.  Still, it's got to be disorienting to look at the world around you and know for certain that what you're seeing isn't the way it actually is.  My eyesight isn't great, even with bifocals, but at least what I am seeing is real.  I'll take that over twisted faces and illusory lions any day.

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