Body Image on the Brain
Last week, two interesting research papers were published that looked at the neurological origins of body image distortion in anorexia nervosa. And what researchers found was rather interesting.
The first article looked at not only how people with AN process body image, but it broke down that processing into two different steps: attitudes towards their body and how they experienced their own size (Mohr et al, 2009). Using fMRI, the researchers
"further demonstrated stronger activation of the insula and lateral prefrontal cortex during the satisfaction rating of thin self-images. This indicates a stronger emotional involvement when patients are presented with distorted images close to their own ideal body size. Patients also overestimated their own body size."
Furthermore, the researchers found a complex pattern of activation of the precuneus, an area of the brain that is thought to contain a sensory-based map of the body. Scientists hypothesized that people with AN have a deficit in their ability to pull up an accurate map of their bodies, leading to the body size overestimation so prevalent in AN.
I think it would be fascinating to compare fMRI scans of people with non-fat-phobic anorexia to those with AN and body dysmorphia. Perhaps this would help confirm that these different patterns are specific to body image and not related to anorexia in some other way.
The second paper looked at the role of the right parietal lobe in the formation of body image in people with AN (Nico et al, 2009). Part of the parietal lobe's job is to integrate sensory information from different points in the body, and stroke patients who have damaged right parietal lobes have difficulties with body representation and schema. Whereas people without AN and those with stroke damage to the left parietal lobe were able to estimate their bodies accurately, those with AN and stroke damage to the right parietal lobe were not. The researchers concluded that these results
"support the possibility for a neuropsychological component in the pathogenesis of anorexia, offering alternative approaches to treatment of the disorder."
Together, this research indicates that the body image difficulties in eating disorders go beyond seeing skinny models in magazines (though this doesn't help) and these neuropsychological differences play a role in the development of EDs.
6 comments:
Thanks for let us know about the two articles. I have one question associated with them. How are the neuropsychological differences explanations combined with the low incidence in males?
Thankyou for writing this phrase: "non-fat-phobic anorexia". I sometimes feel like the only anorexic in the world who looks in the mirror and sees a skinny person! It's helpful to know this is a recognised phenonemon.
Oh how interesting...I've always wondered if there was a quantitative difference between body dysmorphic and non-fat phobic anorexics too. I fall into the latter category like Motorina. Eating disorders make you feel isolated enough as it is, but not being able to relate to the main thing that the public thinks typifies anorexia, or to the thought processes of people who apparently have the same illness as you, is a very bizarre experience. It will be fascinating to see where they go next with this sort of research.
Another interesting post Carrie...
I fall into the category of non-fat-phobic anorexia nervosa like Motorina and Katie above. I posted a video about this type of anorexia nervosa on my youtube channel quite recently (http://www.youtube.com/watch?v=STCbFLwU9m0) because it is being debated for the preparation and production of DSM V.
For some people with anorexia nervosa, body dysmorphic disorder and body dissatisfaction are salient drivers for their ED; i.e. the personal 'meaning' of their ED is to create thinness or to avoid fatness.
However, for others (like me) ED behaviours have a different 'meaning'. My restriction and over-exercising created order and routine in my life. In turn, this order and routine made me feel 'in control' - of my world, my life and my emotions. Thinness was a 'side-effect' of the behaviours; not the goal.
Research in different aspects of the causes of EDs often helps to explain the disorder ONLY in a certain few sufferers. I feel that one problem some researchers have is that they assume that anorexia nervosa is a distinct illness and that patients all have similar thoughts and feelings.
I doubt that there will ever be a single, standard, effective psychological therapy for curing anorexia nervosa - simply because of the individuality of sufferers.
Carrie & CathyUK;
I <3 you both!
My 2cents is that the emerging picture is AN is primarily a disorder of interoception & executive emotional processing. Differing symptomology occurs across the AN population in large part because both due to the variability of which interoceptive circuits are affected, and because cultural milieu and personal experiences are highly variable and play key roles in how our prefrontal cortices do their jobs.
Much to ponder with the stuff being posted here.
I am off to NYC for the holiday.
Wishing you many blessings to be thankful for tomorrow!
Ex Ana,
There has been some interesting research going on in recent years about hormone exposure in utero and ED risk. It turns out that in male/female twin pairs, the males have a higher risk of ED than male/male twins, and the females have a lower risk than female/female twins, indicating that estrogen exposure triggers something in the brain, and testosterone may be more protective. This is supported by several clinical facts, namely that in pre-pubescent children, it's much closer to a 50/50 male/female distribution of sufferers, and the onset of AN and EDs is typically around puberty.
No doubt, there are cultural effects, too, and also a lower rate of diagnosis in men with EDs. Unfortunately, most of the brain imaging studies are women only due to difficulties in recruiting men with EDs.
Great question!
Motorina, Katie, and Cathy,
It's so great to hear the different experiences of people with AN. For me, I rarely thought I was fat but any weight loss just didn't register in my brain. If I did eat something "out of bounds" or didn't follow my rituals, I would get this horrible, anxiety-provoking "fat" feeling that really reminded me of the fears of contamination I would get with OCD. The brain is a mysterious thing. I often thought that I would like to specialize is neurology or psychiatry if I went to med school.
IrishUp,
Just got back from NYC and had a lovely time. I hope you do, too. And...I still want your brain. Just sayin'...
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