New heart, new you? Can organ transplants change us

In one case, a person who hated classical music developed a passion for the genre after winning the musician's heart. The recipient later died with the violin case still in his hands.

New heart, new you? Can organ transplants change us

There are two main explanations for personality changes after organ transplantation. One is the psychological impact of the emotional roller coaster of the experience, and the other is the biological impact of hormones and perhaps the cellular memory of the donor organ. More research is needed to clearly understand how transplantation affects personality, but this knowledge can help future recipients prepare for possible changes.

Personality changes after heart transplantation have been observed virtually since the early days of transplantation. In one case, a person who hated classical music developed a passion for the genre after winning the musician's heart. The recipient later died with the violin case still in his hands. In another case, a 45-year-old man liked to wear headphones and listen to loud music since he received the heart of a 17-year-old boy, something he never did before the transplant. said. Recent research suggests that heart transplant recipients may not be the only ones experiencing personality changes. These changes can occur after transplantation of any organ.

What could explain it?

One suggestion may be that this is a placebo effect, where the overwhelming joy of new life gives the person a cheerful disposition. Other transplant recipients experience guilt, depression, and other psychological problems, which are also considered personality changes. However, there is evidence that these personality changes are not simply psychological. Biology may also play a role. Cells in the transplanted organ not only perform their expected functions, such as beating heart cells, filtering kidney cells, and metabolizing liver cells, but they also play roles elsewhere in the body.

Many organs and their cells release hormones or signaling molecules that act locally and elsewhere in the body. Mind seems to be most commonly associated with changes in personality. This chamber releases peptide hormones such as ``atrial natriuretic peptide'' and ``brain natriuretic peptide,'' which help regulate fluid balance in the body through their effects on the kidneys. It also plays a role in electrolyte balance and inhibits activity in the part of the nervous system responsible for the fight-or-flight response. The cells involved in this are located in the hypothalamus. The hypothalamus is the part of the brain responsible for everything from homeostasis (balancing biological systems) to mood. The donor organ may differ from the source organ in its production of basic hormones and peptides, which can alter the recipient's mood and personality through the substances it releases. Levels of natriuretic peptides have been shown to increase after transplantation and do not return to normal. Some of the increase may be a response to the trauma of the surgery, but that doesn't explain everything.

Memories stored outside the brain

The body stores memories in the brain. We access them when we think, but they can also be triggered by sight or smell. However, memory is fundamentally a neurochemical process in which nerves transmit impulses to each other and exchange special chemicals (neurotransmitters) at their interfaces.

During transplant surgery, many of the nerves that control organ function are severed and cannot be reconnected, but this does not mean that the nerves within the organ are not still functional. In fact, there is evidence that partial recovery is possible within a year after surgery. These neurochemical effects and interactions can affect the recipient's nervous system, cause physiological responses, and influence the recipient's personality according to the donor's memories. It has been found that cells from the donor circulate within the recipient's body and that the donor's DNA is visible in the recipient's body two years after the transplant. This again raises the question of where DNA ends up and what effects it can have. Among other things, it stimulates the immune response. These immune responses may be sufficient to cause personality changes, as long-term, low-level inflammation is known to alter personality traits such as extraversion and conscientiousness. No matter what mechanism or combination of mechanisms is responsible, further research is needed in this area of ​​research to help recipients understand the physical and psychological changes that may occur after surgery.

(The author works at Lancaster University)