Changes in personality following a heart transplant have been noted pretty much ever since transplants began. In one case, a person who hated classical music developed a passion for the genre after receiving a musician’s heart. The recipient later died holding a violin case.

In another case, a 45-year-old man remarked how, since receiving the heart of a 17-year-old boy, he loves to put on headphones and listen to loud music — something he had never done before the transplant.

What might explain this? One suggestion could be that this is a placebo effect where the overwhelming joy of receiving a new lease on life gives the person a sunnier disposition. However, there is some evidence to suggest that these personality changes aren’t all psychological. Biology may play a role, too.

The heart transplant seems to be most commonly associated with personality changes. The chambers release peptide hormones which help regulate the balance of fluid in the body by affecting the kidneys. They also play a role in electrolyte balance and inhibiting the activity of the part of our nervous system responsible for the fight-or-flight response. The cells in charge of this are in the hypothalamus — a part of the brain that plays a role in everything from homeostasis (balancing biological systems) to mood.

So, the donor organ, which may have a different base level of hormones and peptide production from the original organ, could change the recipient’s mood and personality through the substances it releases.

We know that cells from the donor are found circulating in the recipient’s body, and donor DNA is seen in the recipient’s body two years after the transplant. This again poses the question of where the DNA goes and what actions it may have.

Whichever mechanism, or combination of mechanisms, is responsible, this area of research warrants further investigation so that recipients can understand the physical and psychological changes that could occur following surgery.

Possible Preaching Angle:

This phenomenon is still unproven medically, but what is certain is that before salvation each of us had a desperately sick heart (Jer. 17:9). But by the process of regeneration, God implanted a new heart (Ezek. 36:26, Ezek. 11:19; Psa. 51:10-12; 2 Cor 5:17). This gradually and radically changes a believer’s personality to reflect the Christlike qualities of a new nature (Eph. 4:22-24). With a new heart, a Christian will begin to show unconditional love, kindness, and forgiveness. They become less focused on themselves and exhibit simple acts of servanthood toward others.