The perception of appearance is abnormal in anorexia and dysmorphophobia. These two psychiatric illnesses are thought to be associated with abnormal visual cortex activity.
Anorexia and dysmorphophobia: two diseases which have in common an alteration in the perception of appearance. A study published in Psychological Science suggests that the visual cortex of people with either of these psychiatric disorders may process visual information in an abnormal way.
Fall in cortical activity
Anorexia nervosa and dysmorphobia are two closely related psychiatric disorders. In the first, patients go without food to achieve an ideal of thinness. In the second, patients are sickly obsessed with a detail of their appearance that they consider to be a flaw. Researchers at the University of California in Los Angeles (United States) performed MRI scans and electroencephalograms on 45 people separated into three groups: participants in good health, anorexia and dysmorphophobia. They showed them the photos of faces of strangers and houses.
MRIs reveal abnormal brain activity in the last two groups. In the first moments when the brain processes a visual signal, the visual cortex reacts abnormally: the regions involved in analyzing the overall image are less active, while those involved in processing details soar. In people with dysmorphophobia, the more active these latter areas, the less attraction participants felt for the face shown in the photo. According to the researchers, this suggests a distorted perception of appearance in general, not personal.
People with anorexia (green) and dysmorphophobia (blue) show less activity in areas of the brain that process “general” information when looking at houses (left) and faces (right). Source: Wei Li, UCLA
A very quick reaction
The most telling result is the speed at which these abnormalities in brain activity occur. These changes occur within 200 milliseconds of the image being picked up by the eye and therefore below the perception threshold. This detail is crucial according to the authors of the study, to understand at what level the origin of the disorder is located. “We now know that these abnormalities occur at a very early stage, when the brain begins to process visual signals,” comments Wei Li, the study’s first author. “The distortions of perception that we find in anorexia nervosa and dysmorphophobia could have a neurobiological origin”, adds this doctoral student at UCLA.
“Now that we know the timing, it becomes clearer that these distortions of perception are probably rooted very early in the visual system”, analyzes the lead author of the study, Jamie Feusner. “The fact that the results were recorded while the participants looked at the faces of other people and houses suggests that this may be an overall anomaly in the processing of visual signals. “
This discovery therefore opens a new therapeutic horizon in anorexia and dysmorphophobia. Patients could benefit from behavioral therapy that re-educates perception. Participants are encouraged to focus on a more general view and to focus less on details.
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