Can organ transplants really change a person's personality?

"Remarkable Changes: The Intriguing Phenomenon of Personality Alterations Post Heart Transplantation"

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 who experience personality changes. These changes can occur after transplantation of any organ.

Around two hundred heart transplants are performed in the UK each year

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.

The cells of a transplanted organ not only perform the functions expected of them -- beating heart cells, filtering kidney cells, metabolizing liver cells -- but 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.

The heart seems most commonly associated with personality changes. This chamber releases peptide hormones such as "atrial natriuretic peptide" and "brain natriuretic peptide," which help regulate fluid balance in the body through their actions 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 basic hormone and peptide production and may 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 essentially 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 the function of an organ 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 flow into the recipient's nervous system, causing physiological responses that can influence the recipient's personality according to the donor's memories.

We know 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.