Imagine waking up one morning and finding that every face you see is distorted into demonic proportions, with pointy ears, narrow eyes and a terrifying grin. That’s a reality for some patients with a rare condition called prosopometamorphopsia (PMO), and a unique case study has now given us a glimpse at what those hallucinations look like.
Faces are such an important part of our everyday life that the brain has networks dedicated purely to processing them. It’s evolutionarily important to be able to quickly sort out people we know and trust from strangers who might mean us harm, and read their expressions to make an informed guess about whether it’s flowers or a knife they’re hiding behind their back.
That also means that when something goes wrong in this very specific part of the brain, our ability to perceive faces can become impaired even if every other part of our vision processing is fine. For example, a condition called prosopagnosia (commonly known as “face blindness”) prevents sufferers from recognizing any familiar faces, sometimes even including their own.
But prosopometamorphopsia is an even stranger condition, causing faces to appear disturbingly distorted. The exact appearance differs from patient to patient, but generally faces will have more prominent eyes and mouths, features will look stretched or squashed, or in the wrong place. Only about 75 cases have ever been reported in scientific literature, with about half saying it affects the whole face and the other half seeing it only on one side or the other. It can last days, weeks, years or even a lifetime, and creepiest of all, it can come on suddenly.
It’s been hard to recreate these visions, because if a patient is asked to confirm whatever 'police sketch' a researcher might produce, they end up seeing that face distorted as well. But now, a patient with a unique variation on the condition has helped scientists finally visualize what PMO patients are seeing.
The patient in question is a 58-year-old man who had reportedly been living with PMO for almost two-and-a-half years. Every face he saw in the real world appeared, as he described it, “demonic,” with severely stretched features and deep grooves carved into their forehead, cheeks and chin. He reported no distortions when looking at other objects, and importantly, he was still able to recognize known faces, even when distorted.
But the really bizarre thing, in a story full of bizarre things, is that the patient would only see distorted faces in the real world – those on a screen or on paper looked normal. So for the new study, researchers at Dartmouth College took advantage of this to develop an experiment.
The patient was shown photos of people on a screen, while the same person sat in front of him in the room. The researchers then edited the photos until the patient said they resembled the distorted face of the real-life person. The results, which you can see above, are very unnerving – especially when you remember this is how he, and other people with PMO, see faces down the street, in the supermarket, and in their own home. As you might expect, the condition can be distressing for patients, especially if it starts suddenly.
“We’ve heard from multiple people with PMO that they have been diagnosed by psychiatrists as having schizophrenia and put on antipsychotics, when their condition is a problem with the visual system,” said Brad Duchaine, senior author of the study. “And it’s not uncommon for people who have PMO to not tell others about their problem with face perception because they fear others will think the distortions are a sign of a psychiatric disorder. It’s a problem that people often don’t understand.”
As such, the researchers say that the aim of the study is not just to gain a better understanding of PMO, but to raise awareness of the condition to help people suffering from it. Damage or abnormalities in certain parts of the brain have been associated with developing PMO – in this case, the patient reported a history of bipolar and PTSD, a major head injury about 12 years before the onset of the condition, and "possible carbon monoxide poisoning" four months before PMO onset. MRI scans also revealed a small lesion in his left hippocampus, but this part of the brain isn't involved in facial processing. Whether any of these are related to the condition remain to be seen.
The team is currently seeking more participants with PMO on their website.
The research was published in the journal The Lancet. The research is described in the video below.
Source: Dartmouth
