Cognitive Neuropsychiatry Lectures
Lecture 1 – Body Image in AN (Feb 10)
Introduction
- Is perception reality? perception of reality can really differ per person. The brain fools us
in how we perceive the world around us (blue/gold dress, colors rubics cube).
- For patient with AN, their body perception is their reality!
AN = ED
(1) restriction of energy intake leading to significant low body weight,
(2) fear of gaining weight or becoming fat, interfering weight gain,
(3) and have disturbed body image, often are UW. They perceive their body as normal of
oversized. This disturbed body perception only happens for themselves, not when seeing
other people.
- Restricting type (without bingeing/purging, weight loss by restriction/exercise)
- Binge eating/purging type = beinge eating/purging
- Partial remisseion = A criterion not met anymore, B & C still met for some time
- Full remission = No criteria met for sustained period
Body perception disturbances in AN
Statistics = very rare dx:
- 0.6% of young females have AN.
- 35% relapse.
- 50% remain chronically ill.
- 5-15% mortality rate (highest of all psychiatric dx)
After being UW for many years, brain function is affected (eg frontal areas). If they get to a
healthier weight (BMI 17/18+), therapy works better due to being able to think and feel
emotions.
Tube feeding doesn’t solve the ED, but mainly keeps their body alive (18+ can’t be
forced but can be court ordered > RM or IBS).
Research:
Most research was on the cognitions of seeing they’re fat. However, they can literally feel
that they’re fat, which hasn’t been the focus of research a lot (not really acknowledged in
clinical practice > “fat is not an emotion, only the other B’s”).
= Big discrepancy between knowing that you’re UW (eg. knowing BMI), and still feeling fat).
Clinical practice = more use of questionnaires (EDE)
But neuropsychology & neuroscience angle focuses more on sensory parts.
The body in the brain
Representation of body in brain = Abstract collection of all body-related information.
- bodily cognitions (emotions, attitudes, semantics)
- bodily perception (visual, tactile perception)
- bodily action (planning/EF of motor action)
,Input from multiple senses contributes to building a blueprint of the body and its size in the
brain. (Even auditory info contributes to body perception)
Homunculus information is rescaled via mental body representation (not known where it’s
located > several areas: connected to parietal cortex).
Body representation in daily life need to know where your body is located relative to
objects in your environment (proprioception). Eg: walking up stairs, typing, shaking
hands. Body is making calculations based on the body representation in daily life. We
don’t have conscious knowledge of these calculations.
During evolution we never developed a body representation main function is making sure
we can use and move our body to keep yourself safe. Determining whether you are
fat is not the aim of your body representation!
Body representation in AN
Body representation:
- Internal model of our body (blueprint)
- Constructed from multisensory information
- Abstract information (not just an image) > location of position of joints.
- Crucial in daily life for bodily cognition/affect; bodily perception and motor action.
So, it’s also semantics about body, etc.
AN patients mainly struggle with body size
Especially body size representation is disturbed it likely to affect multiple senses/modality
- Cognition & affect is disturbed
- Visual perception
- Tactile perception
Measuring distance of two touchpoints on forearm and stomach. Participants were
blindfolded and they had to make a size estimate.
Results ‘Two-point representation task: controls underestimated size on
arm and stomach (less receptor density). AN patients significantly
overestimated size of arm and even more of stomach (they have more
sensitive receptors so more sentive to touch, but they’re less specific).
= AN patients literally feel bigger with their body (perceive touch to
skin differently). The two touch points the distance must be further
apart for them to feel 2 separate points. So, they need a lot of space,
but they easily feel very light touches: very sensitive (maybe due to
heightened attention?)
- Motor planning and EF
Body scaled action (body movement):
Experiment:
People must walk through a ‘door opening’. Some openings wider and some smaller, so the
body had to be turned to fit through.
o HC: rotated shoulders when opening was 25% wider than their shoulders.
o AN: rotate shoulders when the opening is 40% wider than their shoulders.
, o ‘Estimated shoulder width’ then they rotate the same as HC (25% wider).
So, they estimated their shoulder width as larger.
= Shows that they move as if they’re bigger than they actually are.
Conclusion: AN patients don’t only see themselves as fat, they literally feel fatter and move
their body as bigger (so it’s much more severe than previously assumed.
Can we change body size experience in AN patients through
(complementary) treatments or experiments? (YES!)
Rubber hand illusion:
o Synchronous condition > gives experience that hand is part of your body
o Asynchronous conditions > not an experience of hand ownership.
AN estimate their hand size as smaller (!) after asynchronous condition they estimate
their hand size more realistically, but in synchronous condition they estimate it less
realistically.
Whole body illusion (see article VR)
o Virtual body seen through VR > in reality a movement sensor (virtual brush), which
was a hand in the VR view (both synchronous & asynchronous).
o VR avatar is bigger than AN patients’ body, but they see the avatar as thinner as
themselves!
Results: before they’d overestimate body size. After they still showed some overestimation,
but it did improve. After a while: 3 hours later the effect still exists
So, body size perception in AN is flexible…
- Even for emotional body parts
- Improved body size estimation remains over time!
…however:
- Also improvement in control condition (so nothing to do with illusion of changed
ownership.)
- Results are not very uniform
- How do patients feel emotionally? (wasn’t included in study)
VR is NOT a therapeutic intenvention.
Hoop training (Keijzer, A., Bonekamp, J., Engel, M., Elburg, A.)
- 8 hoops selected randomly.
- AN patient must choose (2) hoops per session they think they would precisely fit through.
- Ask what they see when they lift the hoop around the hips: “how do you feel? Is there is lot
of room or not?” maybe next time select a smaller hoop? Almost impossible for ED
to come up with excuses.
- Multiple points addressed:
o Seeing hoops
o Thoughts about hoops
o Move through hoops
o Feel the hoops
Lots of treatment is based on cognitions (telling what they’re seeing), but their feeling
doesn’t change, so hoops give them body tactile/sensory feedback.
