Suprising Right Hemisphere Deficits in Anorexia Nervosa

  • Suprising Right Hemisphere Deficits in Anorexia Nervosa

    Posted by Samuel Ford on February 10, 2024 at 8:42 pm

    Can you see the face hidden in the coffee beans?

    https://feastingonresearch.blogspot.com/2010/09/face-in-coffee-beans.html

    I couldn’t find it for ages – though I was looking for a sort of gestalt multi-bean-face when it turns out the face is just one of the coffee beans. Surprisingly, people with the eating disorder anorexia nervosa are very good at finding the face in the beans.

    Anorexia is mentioned several times throughout TMWT as a classic right-hemisphere deficit condition – I remember when reading TMWT that I was surprised at anorexia being linked to schizophrenia. Here’s a quote from page 219:

    “…it is the body schema that is aberrant in anorexia nervosa, so much so that a person who is in reality grossly underweight, and may be starving to death, sees herself as grotesquely obese. Although not usually classified as a psychotic illness, it is delusional, and other psychotic symptoms are not uncommon; anorexia can also occur in the prodrome of schizophrenia. Schizophrenia and anorexia nervosa are in fact genetically linked, and each is commoner in genetic lineages of the other.

    Quite apart from the clue given by the fact that the body schema lies in the right parietal cortex, in cases where anorexia was associated with a hemispheric lesion, the majority were right-sided; imaging and EEG studies of anorexia nervosa show hypofunction of the right hemisphere; psychological profiles of subjects with anorexia show typical right hemisphere deficits; and in one case a left-sided stroke caused the sudden remission of a patient whose life for years had been dominated by anorexia nervosa.

    (In the book this quote also includes many citations which I have not included)

    Anorexia is mentioned again in the chapter on space/matter and again in the chapter on value.

    From Space and Matter, pages 1548-1550:

    “…it is that perceptual distortions in space feed paranoid beliefs, and paranoid states lead to perceptual distortions of space. Schizophrenia, as we have seen, as well as autism, obsessive-compulsive disorder and anorexia, are all characterised by and essential preference for stasis and sameness over motion and change.”

    From Value, page 1785:

    People with conditions that are associated with right hemisphere deficits, such as schizophrenia, autism and anorexia nervosa, have an unusual predilection for, at least simple, symmetry.”

    In my more recent reading about anorexia, I found that several neuropsychological studies have found that those suffering from anorexia nervosa score consistently poorly on tests that measure set-shifting abilities and central-coherence. (review of many studies demonstrating this – https://jeatdisord.biomedcentral.com/articles/10.1186/s40337-019-0251-5).

    Definitions from the review:

    Set-shifting refers to the ability to move back and forward between different tasks or mental sets, and is often used as a measure of cognitive flexibility.” – clearly right-hemisphere dependent; switching attention or strategies.

    Central coherence refers to a bias towards processing details (local processing) at the expense of paying attention to the bigger picture (global processing).!!! – This is like McGilchrist right-hemisphere deficits 101; can’t see the forest for the trees, but can see that little hidden face in the beans.

    Here’s a different study that seems to confirm the right-hemisphere deficit understanding of anorexia – https://www.cambridge.org/core/journals/psychological-medicine/article/role-of-the-right-parietal-lobe-in-anorexia-nervosa/638DE775EBCF1505A35E3ADA4EDE2C64 – published back in 2009.

    In this study, subjects were sat facing a robot arm with an LED light in its finger-tip. The light would move then in a line towards the subject. Subjects had to predict whether the light would have hit their body or not if its trajectory continued. This was conducted on both left and right sides.

    8 anorexic patients were tested, and the various control groups were healthy right-handed individuals, two right-handed patients who had suffered a stroke in the right parietal lobe (the right parietal lobe being associated with the body image), and two right-handed patients who had suffered a stroke in the left parietal lobe.

    As expected the right-parietal lobe stroke patients had a typical kind of left-neglect; they thought their left ‘boundary’ (essentially their left shoulder) was closer to their midline than in reality (the healthy controls and the left-parietal stroke patients did not show this result). However, the anorexics scored similarly to the right-parietal lobe stroke patients (the result was smaller but still statistically significant) – they thought their left boundary/shoulder was closer to their midline than it was in reality, but, strikingly, they predicted their right boundary just like the normal controls.

    Quote from the discussion of the paper:

    By testing body size perception implicitly, using collision judgments, we could eliminate potential confounds due to psycho-affective attitudes towards body weight and size in AN. This allowed us to uncover an unsuspected neuropsychological aspect of anorexia; consistent deviations of body schema emerged but, strikingly, not in the direction predicted by the phenomenology of the disorder, or by patients’ reported feelings of being overweight (Table 1). By contrast, performance showed clear similarities with that of patients with right parietal damage.”

    (The authors also performed a control test that ruled out this being the result of differences in properly perceiving movement toward objects).

    From what I have read so far, anorexia nervosa has very high relapse rates (around 30-40% after 18 months of first being treated) and these rates have not really improved since its initial description. It is also exceptionally dangerous – it has the highest mortality rate of any prevalent mental health condition including depression, and is most common in adolescent women. Essentially it’s truly terrible and nobody has a treatment method that consistently helps these young vulnerable people recover fully. Many of us on this forum have thought about how Iain McGilchrist’s ideas can actually be applied in the real world (usually on a grand scale – politics, philosophy, science, culture, etc) but this seems a bit more straightforward and obviously worthwhile – can therapies that focus on regaining right-hemisphere function help save people from anorexia?

    Samuel Ford replied 2 weeks, 5 days ago 1 Member · 0 Replies
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