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Introduction

People who have received organ transplants have reported stark changes in their personalities. Some (truly outrageous) stories claim that people who receive organs from people then get some of their donor’s personality traits. There are a few explanations like cellular memory, psychological, physiological, neurological,, immunological, DNA/RNA/epigenetic explanations. I think that the cases of personality change post-transplant are the same as twin studies, reporting only where there is remarkable similarity. Nonetheless, I’m skeptical of such claims. And I don’t think that, even if they’re true, that dualism is harmed. I will conclude with a discussion of my cognitive interface dualism and how even if the proposed mechanisms to explain observed personality changes in organ transplant receivers would hold it wouldn’t undermine my theory of dualism.

Proposed explanations for personality change post-transplant

Psychological explanations—The psychological impact of receiving a new organ could lead to a change in behavior. They may feel a sense of gratitude or connection to the donor which could change their behavior. The emotional experience of having a transplantat could profoundly affect the patient’s personality before and after surgery. If people receive a heart from someone who was outgoing or adventurous and they then become adventurous, this is then attributed to the organ transplant, specifically in a kind of cellular memory (reviewed below). So the chain goes like this: transplant -> connection to donor -> change in personally

Physiological explanation—Medication used to prevent organ rejection could affect personality in virtue of affecting brain chemistry. People who are to undergo a transplant are given immunosuppressive medication, to prevent the rejection of the transplanted organ. These medications suppress the recipient’s immune system which then could have various effects on the body. Some could also pass the blood-brain barrier. Certain medications, too, could also influence neurotransmitter production like serotonin, norepinephrine, and dopamine. Having an organ transplant is a major surgery, and the body becomes inflamed after. So the physiological response to stress could affect organ systems after the transplant. So along with the stress on the body of organ transplantation along with immunosuppressive medications, both of these could lead to changes in hormonal levels and signaling pathways. The trauma of surgery and recovery could also affect a person’s mental states. Here’s the chain: immunosuppressive medication -> altered brain functioning -> brain chemistry/function changes could alter personality

Neurological explanation—Organ transplants can lead to trauma of surrounding tissue. The transplantation process along with the medications one had to take can then influence neurochemical activity in the brain. Surgical, pharmacological, immunological and psychological factors could interact to cause personality change. Here’s the chain: after transplantation, signals from organ interact with recipient nervous system -> the signals could affect neural networks associated with specific traits/memories -> over time these interactions compound to change personality.

Immunological explanation—Bidirectional communication between the immune system and CNS—known as neuroimmune crosstalk (Tian et al, 2012)—could also be responsible. Organ transplants and immunosuppressive medication could disrupt this crosstalk. Further, inflammation could also affect neural functioning. Here’s the chain: suppressed immune system so organ isn’t rejected -> immune cells could interact with CNS -> immunological interaction could make changes to brain physiology which leads to personality change.

There are quite a few explanations for why personality changes occur that don’t rely on cellular memory. Each of the proposed explanations offers potential mechanisms to explain observed personality changes. Whole the psychological explanation emphasizes the emotional and psychological aspects of organ transplantation, while the physiological explanation focuses on the broader physiological effects of transplantation on the recipient’s body. The neurological explanation goes into the direct effect of transplantation while the immunological explanation highlights the role of immune-mediated processes in influencing brain physiology.

Cellular memory—This is where organs, cells or tissues retain memories or information from their previous host which then influence the behavior of the new recipient of the organ. Of course this is a very speculative idea and there isn’t really much scientific evidence for the claim. I can see someone trying to say that the neurons in the transplanted organ somehow had an effect on the personality change.

Based on anecdotal reports along with case studies of organ recipients who claimed to have acquired new skills, personalities, or preferences following their transplants, such stories capture the imagination of people. Such reports often involve cases in which the recipient exhibits behaviors or preferences that are seemingly unrelated to past personal experiences but are related to their organ donor. (I will quote some people below on this and their experiences.) So these cases have pushed along the claim that cellular memories can be transferred along with transplanted organs.

One hypothesis is neural network transfer. Memories or information stored in the brain of the organ donor could be transferred to the recipient through neural connections which are established through the transplantation process. So neural networks associated with memories or learned behaviors could be preserved within the transplanted organ leading to an influence in the recipient’s brain functioning.

A small number of donor cells could persist in the transplanted organ, which then could involve microchimerism. The donor cells could then interact with the recipient’s tissues and cells and then influence behavioral or physiological characteristics.

Epigenetic modifications which regulate gene expression without a change to the genome could play a role in cellular memory. Changes in gene expression patterns could persist in the recipient which then leads to behavioral changes.

Finally, psychological changes like the placebo effect and expectations could contribute to the perception of cellular memory. They could unconsciously or consciously adopt behaviors of the organ donor due to psychological or social influence.

But the anecdotal reports of cellular memory fall prey to post hoc rationalization, the placebo effect, and selective reporting. Moreover, neural network transfer and microchimerism lack evidentiary support to substantiate their role in the behavioral changes in the donor. There is a lack of a causal relationship between recipient experiences and donor characteristics. Factors like the recipient’s pre-existing beliefs, psychological adjustment to transplantation and social support networks more than likely play a significant role in shaping the post-transplant experiences of the donor.

One study found that 3 patients reported changes in their personality post-heart transplant (Bunzel et al, 1992). One online survey of 47 transplant recipients (23 heart and 24 organ) found that 89 percent of the donor’s experienced personality changes (Carter et al, 2024) (which was substantially higher than that of the results of Bunzel et al).

One white man was given a heart from a black kid who was gunned down in a drive-by shooting, and he loved classical music. After the man’s transplant, he began liking classical music after previously hating it. He stated that he know it wasn’t his heart because “a black guy from the ‘hood wouldn’t be into that’…and now [classical music] calms my heart” (Christopher, 2024). The recipient’s wife then said that the donor was socializing more with black coworkers at work and he began to love classifical music post-transplant. She said “He even whistles classical music songs that he could never know. How does he know them? You’d think he’d like rap music or something because of his black heart.”

In another case, a 19 year old woman was killed in a car accident. She was also a vegetarian and owned a health food restaurant. As she was dying, she said to her mother that she could feel the impact of the car hitting her. So the organ recipient was a 29 test old women who reported two things occurring post-transplant—she said she could feel the impact of the accident on her chest and she began hating meat after her surgery, saying that “now meat makes me throw up” (Christopher, 2024). Before her transplant she was a lesbian and then after, she was into men.

A 3 year old died in an accident at a family pool. The recipient—a 8 year old—loved the water before his surgery but after it, according to his mother, he was “now deathly afraid of water” (Christopher, 2024).

A 14 year old girl died in a gymnastics accident, and per her mother she had a “silly little giggle”. She was also kind of anorexic with food. Her recipient was a 47 year old man. After his surgery, the recipient’s brother states that he was acting “like a teenager” and that he’s “like a kid.” He also reported that when they went bowling he “yells and jumps like a girl” and that he “had a girls laugh.” He was also nauseous all the time and his doctor had a concern about his Wright (Christopher, 2024).

In the last case Christopher (2024) discussed, a cop was murdered by a drug dealer after being shot in the face. In his mug shot, the cop’s wife stated that the drug dealer looked like some depictions of Jesus. After the heart transplant, the donor stated that he would have dreams of seeing a “flash of light right in my face and my face gets real, real hot. It actually burns. Just before that time, I would get a glimpse of Jesus. I’ve had these dreams and now daydreams ever since: Jesus and then a flash” (Christopher, 2024). Finally a girl received a transplant from a teenage boy who died in a motorcycle accident. After her surgery her mother stated that she began liking KFC, “walking like a man“, and she wanted to drink beer. Come to find out, these were some things the boy who died liked to do. There is also a recent article on Psychology Today talking about cellular memory.

All of these cases could simply be an artifact of selective reporting or coincidence.

Conclusion

While these cases are no doubt interesting and if true means that we need to propose different mechanisms of the like as in with cellular, DNA/RNA, epigenetic and protein memory (Pearsall, Schwartz, and Russek, 2000), I think current evidence points it to be just coincidences or post hoc rationalization. Now of course, if these cases were proven to be genuine then we should revisit them and think about mechanisms like the above in this paragraph.

As can be seen, anecdotal reports and studies suggest the possibility of behavioral changes that mirror, in some cases, that of the donor. But the concept of cellular memory is currently speculative and lacks empirical evidence. We could have controlled studies on animal models to see whether behavioral or physiological traits associated with the donor are transferred to the recipient. We could also analyze gene expression, epigenetic modification, RNA expression, DNA methylation, and protein levels within transplanted tissues or organs from donors to recipients. We could then male comparisons between tissues and organs from donors and recipients to ascertain any kind of differences or similarity which could be indicative of memory transfer. These are but a few empirical tests I can think of that we can begin to carry out to test this if it’s more than coincidence or post hoc rationalization.

Lastly, in August of 2023 I formulated a theory of dualism I call cognitive interface dualism which argues that action potentials are the interface that Descartes was looking for. (I had an A&P professor state that out of the whole textbook he taught out of that muscle movement was some of the only conscious activity that could be done. Then that dawned on me and I formulated my dualist framework.) Dualism posits that mind and body are two separate, substances with mind being irreducible to body/brain. So even if there is a personality change, that doesn’t entail that the mind has changed. In cognitive interface dualism, interactions between the mind and body occur through action potentials (APs). Personality changes could occur through the interface of the interactions, but changes in physical organs like the brain do alter the fundamental nature of the immaterial mind. (Of course damage to the brain can influence the mind since the brain is a necessary pre-condition for human mindedness, but that’s different.) Even if a person’s personality undergoes changes after a transplant, their underlying sense of self, consciousness, and subjective experiences remain intact. It doesn’t necessarily imply a direct alteration of mind,

The other explanations I discussed above are also on different levels of explanation than dualism. Dualism is about ontological explanation whereas the other explanations operate at the physiological and molecular levels. Cellular mechanisms could influence certain aspects of behavior or experience, but it doesn’t undermine the existence of a separate, irreducible mental realm. Dualism and biology can also be complimentary, where biology would address any possible mechanisms like cellular memory, RNA/DNA/epigenetic expression while dualism addresses questions of consciousness, the nature of the mind and subjective experience. Even if cellular memory would be shown to be true this wouldn’t undermine my theory, since the core aspects of one’s consciousness, self, and subjective experiences remain intact. So these would offer complimentary perspectives.

In sum, while this is an interesting area to look at, I am a skeptic. I won’t completely discount it being true, but I have proposed some empirical tests to see if it does hold. And if it does, it doesn’t have any implications for dualist theories, including my cognitive interface dualism.