Editor’s Note:
This interview was curated by Leandro Loriga, Ph.D. as part of the 🟡Expert Interview Series on BodyIntegrityDysphoria.com. Minor edits were made for grammar and flow, without altering the content of the responses.
I want to thank Prof. Dr. Erich Kasten for agreeing to take part in this interview and for providing thoughtful and detailed answers. His contribution marks an excellent beginning to this series.
Could you briefly introduce yourself? Tell us about your academic and professional background.
My name is Erich Kasten. I was born in Travemünde on the Baltic Sea of northern Germany and studied psychology in Kiel. My academic career spanned the university clinics in Lübeck, Magdeburg, and Göttingen, as well as the Psychological Institute of the Humboldt University in Berlin. I received my doctorate from the University of Halle and the venia legendi in medical psychology. For the past 10 years, I was a professor of neuropsychology at the Medical School in Hamburg and taught medical psychology in Berlin. I have been a professor emeritus since 2023.
What is your current position and where are you based?
Since leaving university at the age of 70, I have been working in my own practice as a behavioural therapist and neuropsychologist in Travemünde, Germany.
How did you first become interested in Body Integrity Dysphoria (BID)?Was there a particular event, case, or academic interest that sparked this?
In 2006, I published a book on Body Modification, specifically tattoos, piercings, branding, scarification, and other forms of altering one’s own body. One chapter dealt with apotemnophilia, which was then the old term for people who wanted an amputation. Shortly after the book’s publication, the first affected person contacted me, enthusiastic about the objective portrayal of this phenomenon. About a year later, I launched the first study on a small group of affected individuals.
How would you define BID in your own words?
The most common denominator of BID is probably the desire to undergo a physical modification that most other people would classify as a “disability,” such as e.g. amputation, paralysis, blindness, or deafness. However, those affected do not perceive this physical modification as a limitation; quite the opposite: They only feel complete when their external body corresponds to their internal, mental body image.
What do you think are the most misunderstood aspects of the condition?
Ordinary people on the street usually label someone who wants the amputation of an intact, healthy body part as “crazy.” No one can truly understand why a person would, for example, desire paralysis and only feel comfortable in a wheelchair. I keep hearing the phrase that these people must be completely lunatic. Unfortunately, even experts primarily classify the need for a disability as psychopathological. Based on everything we know today, however, it is more likely a congenital neurological malfunction.
How has the understanding of BID evolved since you began studying it?
When I began to intensively study the disorder (in 2006 still known as apotemnophilia or body integrity identity disorder), no one had a truly logical explanation. Initial theories were more psychoanalytically based, such as identification with a disabled person in early childhood or psychosomatic aspects, such as external disability as an expression of an internal disability. As my research progressed, however, it became clear that there were hardly any similarities at the psychopathological level; in our studies, we found virtually no similarities with regard to typical personality traits or related mental disorders. In contrast, there was increasing evidence that it was a neurological dysfunction. In 2011, A. Sedda published an article describing this development: “Body integrity identity disorder: from a psychological to a neurological syndrome.” The work by G. Saetta on neural correlates of BID, published since 2020, was certainly groundbreaking.
Could you describe the methods you employ in your research on BID—such as clinical interviews, surveys, neuroimaging, or case studies—and what insights each has offered?
Most of our work at the Medical School in Hamburg (MSH) was not financially supported; therefore, we conducted almost exclusively surveys with those affected. However, a great many of these surveys were made; unfortunately, only a portion of them have been published scientifically so far. The most important findings include:
- We found no significant parallels between personality structure and the need for disability: The majority of those affected by BID were within the average range of the respective personality trait.
- Those affected by BID are satisfied after an amputation; they do not want any further disabilities and do not regret their decision. Their quality of life improves; as far as possible, they continue to work.
- Psychotherapy can help those affected cope with BID for a long time; a true cure apparently cannot be achieved with it. Psychotropic medications provided little relief. Relaxation techniques can be helpful and improve body awareness, but for some, the symptoms worsen precisely because of the focus on the body.
- There are clear parallels between BID and transgender identity. Both have suffered from the feeling of living in the wrong body since early childhood and are seeking surgical reassignment.
- In some people, both transgender and BID, a surprising erotic component can be found. There is some overlap between mancophilia (i.e. deformation fetishism) and BID.
- Amputation and monoleggedness are perceived as attractive by those affected by BID. Depending on their needs, they may perceive a disability as beautiful.
- There are no tangible similarities in childhood—no overprotective behaviour from the mother, no neglect or abuse. The only parallel we could find was that those affected by BID could recall encounters with people with disabilities precisely. Unlike normal children, they were not frightened, but fascinated.
In your experience, how do people with BID typically describe their experience? Are there common themes across cases?
People with BID actually suffer from having one intact, but superfluous body part or sensory function. The disorder progresses in phases, with long periods in between where they are largely symptom-free and can suppress the need. The pressure almost always increases around the age of 50; either they acquire their disability now or they are eventually too old for it. Almost all of them remember incidents when, as a child, they first saw a disabled person and immediately felt: I want to be like that. Many exhibit pretending behaviour, i.e. mimicking the disability (e.g., elevated leg, wheelchair use), which helps them and brings a certain catharsis, but is also embarrassing and usually only done in secret. Walking with crutches gives them the feeling of being “whole,” while using a wheelchair is downright ecstatic. People with the need for blindness feel comfortable and safe when they can no longer see. After undergoing amputation, I have only heard stories of complete satisfaction. After surgery many withdraw from the scene because they are cured of BID.
In your 2014 pilot study on BIID, you noted that psychotherapy appeared to reduce psychological strain but did not diminish—and in some cases was associated with an increase in—the desire for disability. Given the time that has passed since that initial investigation, have you observed any shifts in clinical practice or patient outcomes that indicate a change in how BIID is therapeutically approached—and how effective those approaches are?
Unfortunately not. Even today, psychotherapy does not seem to bring a cure, only relief. Many sufferers learn to block the need for disability from their minds by defocusing away from the unpleasant physical sensation and focusing on other thoughts and activities. But it comes back. I know of one treatment with hypnosis that was initially successful, but as far as I know, BID returned after a few years. Ultimately, this is consistent with other physical changes. Even transgender people cannot be convinced with psychotherapy that their innate gender is perfectly fine. In the case of obesity, for example, it is not really helpful to make those affected proud of being overweight. With these disorders, healing occurs when the external body matches the mental state. In my view, the effectiveness of psychotherapeutic methods is limited here. I have little hope that anything will change in the future.
Reference: Kröger, K., Schnell, T., & Kasten, E. (2014). Effects of psychotherapy on patients suffering from Body Integrity Identity Disorder (BIID). American Journal of Applied Psychology, 3(5), 110– 115.
In your 2023 study, you mention that a significant proportion of individuals manage their BID symptoms through ‘pretending’ and never pursue surgery. Do you see this as a stable long-term coping strategy, or do you think it potentially delays more intensive interventions that may be inevitable for some?
The pretending behaviour displayed by many affected individuals is problematic. They mimic the desired disability and feel comfortable in this state. They often do this secretly in distant cities where no one knows them, moving around on crutches or in a wheelchair. This usually has a lasting effect, meaning they feel comfortable even days after such an outing as a pseudo-disabled person. As an intervention, when the psychological pressure of BID becomes too great, pretending behaviour can actually save the person from performing self-harm. Unfortunately, there is also a negative side. Moving around with crutches, in a wheelchair, or as a blind person is an intensely positive experience. In the sense of operant conditioning, the rewarded behaviour becomes ingrained in the brain, and the desire to feel this experience more often increases. However, this reinforces the need to be truly disabled and not just to imitate it.
If you want to mitigate BID, you should stop engaging with it altogether and avoid displaying imitative behaviour. Pretending behavior is, therefore, both positive and negative.
However, it must be admitted that BID is not the same as BID. Like other disorders, BID can vary greatly in severity. Some sufferers cope with the attacks throughout their lives without seriously considering amputation or permanent wheelchair confinement. However, BID can also be so severe that sufferers can no longer bear it; I know of at least one case where they placed their legs on railway sleepers and waited for the train. People with mild forms do indeed cope well with the occasional act of pretending; for others, this does not help at all; they seek a genuine surgical solution to their problem.
Reference: Kasten E. The Girl Who Wants to Get Rid of Her Left Leg-Body Identity Dysphoria. Healthcare (Basel). 2023 Jun 30;11(13):1901. doi: 10.3390/healthcare11131901. PMID: 37444736; PMCID: PMC10340271.}
In one of your 2015 study, you found a significantly higher number of childhood experiences with disabled individuals among BIID participants compared to controls. How do you interpret the potential causal or shaping role of these experiences? Do they trigger a shift in body identity early on, or do they resonate with a pre-existing neuropsychological disposition?
From my point of view, it works according to the lock-and-key principle. It is probably a malfunction in the brain that began during pregnancy. A body part was not properly integrated into body awareness; you can move and feel it, but in some strange way it does not belong to your own body. Perhaps comparable to a dental bridge: you can chew with it, but it is still a foreign object in your mouth. The BID-affected brain is basically prepared for it, but as a child, you cannot really deal with the discrepancy in your feelings. Only the first encounter with someone who has exactly this disability triggers the typical feeling of fascination that almost all BID people report. One person told me that he heard a story from his hairdresser about a motorcyclist who had lost a leg in an accident. Instead of reacting with shock or sadness, he was electrified and spent days painting only people with one leg. The brain seems to be prepared for this and reacts differently. So, as with transgender/transidentity, I believe there is a neural basis already present before birth that is then further shaped by life events.
Reference: Obernolte, C., Schnell, T., & Kasten, E. (2015). The role of specific experiences in childhood and youth in the development of body integrity identity disorder (BIID). American Journal of Applied Psychology, 4(1), 1–8.
In your 2025 expert survey, you found broad support for surgical solutions to BID when all other therapies fail, despite longstanding ethical objections in many countries. Do you see this as a shift in expert opinion? If so, what factors do you think have contributed to this change?
I was sceptical at first and suspected that some people were trying to take us, scientists, for fools by saying they wanted to have a perfectly healthy body part amputated. I have to admit, my first impression was that someone like that must be absolutely crazy. Meeting a large number of those affected has taught me that they are completely normal people. Normal, apart from their need for disability, of course. Most of them go to work, pay their taxes and have a partner. There is basically nothing unusual about them. I think most scientists who have real contact with those affected feel the same way. These people simply do not have an overarching mental illness. Over the last two decades, this has brought about a clear shift from the perspective of psychological to that of a neurological malfunction in the brain.
In addition to getting to know each other personally, studies from the 2020s that used fMRI examinations to demonstrate the existence of organic brain changes are, of course, crucial for this paradigm shift. On the other hand, the search for personality changes has never yielded anything significant; each affected person is different.
Reference: Kasten, E. (2025). Body integrity dysphoria (BID): Survey of experts and development of a diagnostic guideline. Medical Sciences, 13(1), 26.
What is one thing you wish more professionals, or the general public understood about BID?
I would like both the person on the street and many professionals to understand that those affected by BID are not to blame for their disorder; they did not choose this condition. Ultimately, in my view, they are victims of an obviously innate, incorrect wiring of body awareness in the brain. They do not deserve to be ridiculed or portrayed as mentally ill. They need the understanding of those around them. I heard stories of those affected having sought psychotherapy in order to at least speak openly with someone about their need for amputation and paralysis, and that the professionals, of all people, have reacted without understanding or have even tried to place the affected person in a secure psychiatric hospital because of the risk of self-harm (sometimes even successfully). In my mind, that is not the right approach.
Looking ahead, how do you envision research on Body Integrity Dysphoria evolving—what directions do you believe it should take in the next 10 to 20 years to deepen understanding and improve support or treatment?
In the coming decades, scientists should continue to strive to understand better the neurological changes in the brains of those affected. Unfortunately, such fMRI studies are very expensive, and the equipment is besieged by scientists from many disciplines. The group of BID patients is small, and they play a minor role in society. Therefore, it is difficult to obtain funding for such studies. However, it is important to note that studies on such individuals in particular teach us something about how body awareness develops in the brain—and what can go wrong in the process. Ultimately, these studies are also basic research and should be better funded.
If you had a microphone that could transmit your words to every person living with BID—across languages, cultures, and experiences—what would you want to say to them, drawing from all you have learned through your years of research and clinical work?
“Dear BID sufferers, we scientists are working on solving your problem. We are sorry it is taking so long. In the last 20 years, BID (at first still called BIID) has emerged from the dark corner of “crazy” and is recognised as a neurological disorder nowadays. None of you are mentally ill, and no one is to blame for this strange need for a disability. Body Integrity Dysphoria is now listed in the International Classification of Diseases (ICD-11), a huge advance that we ultimately owe to science. In the long term, the healthcare system must now offer treatment. Perhaps, and we scientists are also working on this, it will function similarly to transgender identity, meaning that once you have completed all stages of diagnosis and therapy, there should be legal surgery. It is a scandal that those affected suffer under the pressure of BID for several decades, but the healthcare system prohibits amputation. Everyone owns their own body and should be free to decide what they do with it.”
“If I had such a voice, I would also urge those affected to form self-help groups. Come out of your hiding places! Only through associations is there a possibility of political action and pressure on the healthcare system to allow the legal surgical solution. Here in Germany, there is the VFSK (Association for the Promotion of Studies on Body Perception Studies). The association has already organised conferences on this topic and supported research projects. This only has weight with many members who support it.”
Suppose you were given the opportunity to shape the future of BID research—with full access to international collaboration, cross-disciplinary expertise, and outreach infrastructure. What would be the very first step you would take to move the field forward?
I would be very interested to know how BID is distributed worldwide. Currently, we only have access to countries with a high level of technological advancement. There are almost no studies from developing countries. Is BID perhaps a luxury problem that can be afforded because, for example, Europe has such a good social system that one can live well even with a disability? Or is BID also present in the poor countries of the world, where an amputee might starve to death?
What are you currently working on—BID-related or not—and why does this topic matter to you at this stage of your career?
Unfortunately, I had to leave university at the age of 70. Here in Germany, the retirement age is 67. I did not tell anyone how old I was and happily was able to work for another three years. Today, without university support, it is unfortunately difficult to continue working on research projects for me. With the support of the VFSK, I conducted a survey of professionals; unfortunately, this will probably be the last study. In particular, the publication fees for online journals are so high (often much more than 2,000.- $$) that I cannot afford them privately. As a result, my own research has largely come to a standstill, which I am sad about. But that is how it is with getting old.
As a final word, is there anything you would like to share about your broader journey in research, what drives you, or what you hope to contribute moving forward?
I am a neuropsychologist and I study the brain and its functions. In this field, I have spent a long time studying visual hallucinations: what causes the brain to see things that are not there. I have also developed many neuropsychological therapy materials, including computer programs for training patients with brain damage. It has been a very fulfilling scientific life, one that I look back on with some pride. One particular question has always been how the brain manages to create an image of its own body. The foot belongs to me, the shoe does not. Nevertheless, when riding a motorcycle, I had the feeling that the high-powered BMW was an extension of my own body. Only then can you really navigate into and out of curves of the country road. BID was an absolutely fascinating journey into a territory where body awareness can be misdirected, and you suddenly perceive body parts that belong to you as foreign. Conversations with those affected have given me many profound insights into how our brain can create its own reality. I would not have wanted to have been without this understanding.
Looking back over your academic and professional path, is there a particular lesson, turning point, or guiding principle that continues to shape how you approach your work today?
Perhaps the most important point is that there is no such thing as reality. What we perceive as reality is a delicate construction of the human brain (…that undoubtedly makes life easier). In hallucinations, the brain sees things that are not there. With BID, you have the feeling that body parts attached to you do not belong to your own body. The brain creates its own reality. But ultimately, I always tell patients in my practice: “You are not a slave but the boss of your head; you decide what your brain thinks about and how you see things.”
