Since the time transplantation surgeries began, there has been a steady increase in the number of patients waiting for and receiving the surgery. According to DLA Donor Designation Report, 33,611 transplants were performed in 2016 and there are 116,000 people waiting for a transplant as of August 2017. Transplants involving the liver and bone marrow are known to change the recipient’s blood type to that of the donor’s over time. But, researchers have been studying a new phenomenon among heart transplant patients who seem to have experienced changes in tastes into those of the donors’ after the surgery. Here’s more about it.

There are at least 70 reported cases in which transplant recipients reported personality changes that reflect the donors’ characteristics, more so in those who receive a heart transplant.

According to a study published in Quality of Life Research journal, among the 47 heart transplant patients interviewed over a period of two years, 79 percent did not feel any change in their personality, 15 percent experienced a change because of the life-threatening event, and six percent confirmed a drastic change. Another study was conducted at the School of Nursing at the University of Hawaii in Honolulu, which focused on 10 heart transplant patients. The researchers found that there are at least two to three changes per patient after the surgery reflecting the tastes of donors in food, music, art, and preferences in sex, entertainment, and career.

In some cases, the changes are simply in tastes and preferences, while in others it is the trauma, memories, or feelings the donors experienced before they died. In one case, a woman began to crave beer and chicken nuggets, favorite foods of the donor.

There have been several cases of harmless personality changes. David Waters, who received the heart of an 18-year-old Kaden Delaney, started craving Burger Rings, a daily favorite snack of the donor. In another case, Claire Sylvia, who received the heart of an 18-year-old male who died in a motorcycle accident, began craving beer and chicken nuggets. She also kept having recurring dreams about a “Tim L.” She searched the obituaries only to find that Tim was her donor and loved eating the foods she began craving. She also wrote about her experiences in her book A Change of Heart.

On the negative side, after heart transplant surgery, an eight-year-old girl kept having nightmares about the man who murdered her donor. Interestingly, the details of her dreams were so precise that the police were able to track down the murderer who eluded them until then and convict him. Another example is that of an American transplant patient, Sonny Graham, who in 1995 received the heart of Terry Cottle who committed suicide by shooting himself in the head. Later, Graham and Cottle’s widow Cheryl fell in love and married. But 12 after that, Graham died after shooting himself in the throat.

Despite decades of research, the forming and storage of memories is still not completely understood. Currently accepted theory is that the brain’s synapses play a major role in memory formation.

Memory is the ability of our mind to encode, store, and retrieve any information we need. It could be something we voluntarily do and it could also be something the mind does unconsciously. From what scientists understand now, different areas of the brain are involved in creating and managing different types of memory. The hippocampus, for example, is believed to take care of spatial and declarative learning, and the amygdala is believed to take care of emotional memory. There is another theory known as “body memory” which proposes the body’s organs, not just the brain, are capable of storing memories. It is considered pseudoscience by many. There is a variation of this theory called “cellular memory” which claims to explain the changes in transplant patients.

According to cellular memory theory, the memories are also stored outside the brain and nervous system in the body’s cells.

Scientists at Tufts University conducted studies in which trained worms were chopped into pieces and reduced to 1/279th of their original size. These pieces regrew into more individual worms in a few weeks’ time and showed signs of the training the original worm received.

Another major contribution to this theory were the experiments conducted in the 1950s and 1960s by James McConnell, an American biologist and animal psychologist at the University of Michigan, well known for his research on learning and memory transfer in planarians. During his experiments, McConnell trained a group of flatworms to move around a maze by stressing them using electric shocks to avoid mistakes. These flatworms were then chopped into small pieces and fed to untrained flatworms. These flatworms, when put in the maze, were able to complete it faster than those that weren’t fed the bodies of the former group. However, the stress from electric shock produces hormones which stay in the body. So, the behavior was attributed to hormone transfer rather than memory transfer.

Though the cellular memory theory seems to explain what the transplant recipients are experiencing, there is also skepticism surrounding it with many calling it pseudoscience since there is no known way in which memory can be stored in cells that are not the type resident in the brain.

[sources: MedicalDaily, ScientificAmerican, Wikipedia]