Readers react to a rare visual disorder, microplastics in arteries and more


Let’s face it

Scientists re-created the demonic distortions that a patient with prosopometamorphopsia, or PMO, sees when looking at faces, Anna Gibbs reported in “Here’s what faces can look like to people with a rare visual disorder” (SN: 4/20/24, p. 32).

Reader John Henderson asked whether research on facial blindness could help scientists better understand PMO.

The two disorders have been linked to similar regions in the brain, including the right occipital lobe and fusiform face area, says neurologist Jason Barton of the University of British Columbia in Vancouver. So studying one disorder could help illuminate the other.

Henderson also found it interesting that people’s faces but not necessarily their hair are distorted in PMO.

The brain may process faces and hair using different mechanisms, say Brad Duchaine and Antônio Mello, neuropsychologists at Dartmouth College. They point to a 1997 paper about a patient who suffered brain damage that left him unable to recognize objects. The injury did not affect his recognition of the internal face — the region containing the eyes, nose and mouth — but did impair his ability to identify people from their hair and other external facial features.

Reader Gary Wilson asked if there are disorders that distort senses other than vision.

Absolutely. In addition to distorting vision so that objects look too large, too small or warped, Alice in Wonderland syndrome can affect how a person senses time or feels their own body, Barton says.

There are also common sensory distortions like tinnitus in the ear, Duchaine and Mello say. And some psychiatric disorders, such as schizophrenia, can induce auditory hallucinations.

Microplastic perils

Patients with microplastics in their arteries had a roughly quadrupled risk of heart attack, stroke or death, Meghan Rosen reported in “Tiny plastics turn up in arterial clogs” (SN: 4/20/24, p. 6).

Microplastics form when plastics in the environment break down over time. Reader Eric E. Sabelman wondered whether medical equipment made with plastic, such as some hip prostheses or IV bags and tubes, could shed microplastics within the body.

This is very likely, says Laurens Mandemaker, a chemist at Utrecht University in the Netherlands. Hip prostheses, for instance, undergo constant abrasive wear when the hip moves. Studies have shown that hip prostheses that consist of metal and plastic parts experience heavier wear than metal-only prostheses. Microplastics could form inside the body as those plastic parts degrade over time, he says.

What this means for health is still unclear. If microplastics pose serious, long-term health risks, scientists need to find alternative materials for such medical equipment, Mandemaker says. But patients who need prostheses, dialysis or blood transfusions would probably consider the risks of microplastics a lower priority than addressing an urgent and severe health problem, he says.


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