When I first told my grandmother that I had started studying people who want to amputate their arms or legs, she was disgusted. She asked me whether they were crazy.

Grandma is 84. She cannot understand how a “normal” person could ask for a healthy limb to be amputated. And the way she feels is the same as most people when they first hear about Body Integrity Identity Disorder, the rare condition explored in the MATTER story Do No Harm.

As a neuroscientist, I could say these reactions are because people aren’t open-minded enough. But that’s not true: these reactions are grounded in our brains.

In 1994, scientist Paul Rozin and his colleagues published a paper in which it was demonstrated that violations to the “body envelope” (that is, harm caused to the body that somehow violates its usual status) elicit disgust.

Disgust is an emotion we all know: when we smell something spoiled, our nose wrinkles and we feel nauseous. What is less well-known is that during evolution, disgust changed a lot from its original core, which was centered on food rejection. Nowadays it also concerns the moral rejection of other types of unacceptable things — sometimes culturally dependent, sometimes not — that can harm or contaminate us.

We can experience this idea quite easily: what do you experience when you think about paedophilia? The usual reaction is that people say they are “disgusted” by the idea.

So what is the link between disgust and BIID? Disgust for body envelope violations comprises “surgery, puncture wounds, deformity, and other situations in which the normal exterior envelope of the body is breached or altered” (Haidt, et al, 1994). This explains why Grandma was disgusted by the idea of somebody amputating their own limbs: she was implicitly imagining what it would be like to do it to herself. The brain has developed several systems to warn you against such violations, because you need to stay away from death and disability.


Thinking about this, perhaps the issue of BIID can be looked at in a different way: what if the body envelope in BIID individuals comprises only one leg, or one arm?

If that’s the case, then a BIID sufferer’s reaction is appropriate: they are fighting against a violation of their brain’s representation of their ideal body — only in their case, the body envelope has three, not four, limbs.

And if that was the case, could the consequence of this be that amputation must be performed, or otherwise a person would be condemned to live their entire life in a pathological state?


Here comes the big problem. Are we really sure that the body representation is not the typical one in those with BIID? Are those few studies that have been performed enough to definitely convince us (neuroscientists and non-neuroscientists alike) that BIID is a neurological condition? And what do we really mean by neurological?

One parallel to understand the difficulty we face with BIID is depression.

Most of us know depression, and depressed people: the worst cases make those who are affected try to commit suicide. Today we’re convinced that depression is not an attitude, but something with a basis in brain dysfunction, involving serotonin pathways among other things. In fact, drugs have been developed based on this knowledge, which can be used to treat depression and make some patients lose their suicidal thoughts.

But guess what? In other patients these drugs don’t work. In fact, for some people, nothing seems to work. And if depression can’t be cured in these individuals, and they suffer because of it, is it ethical to allow them to die? My guess is that nobody would say yes. Instead, many attempts are made to try to find an alternative cure.

Similarly, with BIID, some individuals “treat” themselves by pretending to have the disability they desire when they are at home alone: they bind their leg, or go around in a wheelchair. For some, it’s enough to ease their anxiety — but not for everyone. However, the fringe cases of those who feel the need to act with surgery are the ones that make BIID such a big deal.

It’s quite hard to define what is ethical or not about treating a condition like BIID when we have only just started to explore it seriously. And it’s dangerous to state firmly that the condition is neurological based only on a few positive findings of experiments which can’t establish whether the brain dysfunction is the causing behaviour, or is the consequence of it.

Allowing people to disable themselves for their entire life is, objectively, a risk. More importantly, the biggest risk is not for the people who have had surgery and are happy to have done it: it is for the people who have not had surgery yet.

BIID research is highlighting more and more that this condition may not be a single entity, but could actually comprise many different varieties. Some BIID patients want to be paraplegic, others want to be blind. Have we established the same brain dysfunction for these forms? The answer is no: we have not even studied them yet. We have no proof, and we have no answers. The truth is that we just do not know enough about BIID.


Dr Anna Sedda is a postdoctoral fellow in the Department of Brain and Behavioural Sciences at the University of Pavia in Italy.

To read more about the science behind BIID, and to hear the stories of other BIID patients, read Do No Harm, a story from the new digital publisher MATTER. The story is free to access, but we rely on paid members to support the in-depth journalism we produce — and we’d greatly appreciate your support. Membership costs just 99c per month.