A team of UK researchers has said that a protein that causes Alzheimer disease can be passed to patients during surgery, which meant that there could be an acquired form of the disease, popular science reports.
Scientists have always maintained the hypothesis that Alzheimer disease results from a combination of environmental, genetic and lifestyle factors.
The study was published in the journal Nature.
Prions, or "proteinaceous infectious particles," are proteins that exist in the body but can sometimes cause disease when they become misfolded. Prions can form sporadically or can be transmitted, including through food, causing diseases such as Mad Cow Disease and Creutzfeldt-Jakob disease (CJD) that eventually lead to death.
Under the study, the researchers studied the brains of eight people who died of Creutzfeldt-Jakob disease between the ages of 36 to 51, caused by proteins known as prions. As children, all the eight patients had undergone a medical procedure that was found to transmit prions.
Reuters reports that the patients had contracted the disease via accidental exposure to prions when they were given a contaminated growth hormone to treat growth problems.
However, the researchers were surprised to find that six of patients' brains contained the protein amyloid beta, believed to be a driver of Alzheimer's disease.
Four of the patients had "quite substantial Alzheimer-like pathology," says John Collinge, one of the authors of the study said in a press conference. "In that age group you don't really see this sort of pathology; it's only really seen in elderly individuals unless you have a genetic predisposition to it, and none of these patients did."
The researchers noted that medical procedures like surgery or blood transfusions could play a role in transmitting prions.
Some researchers argue the amyloid protein's precursor, a-beta amyloid, sticks to metal surfaces. Therefore, it was possible that the human growth hormone given to patients, "in addition to being contaminated with CJD, probably also was contaminated with a-beta seeds," Collinge said.
Since 1985, human hormone injections have been replaced with synthetic ones.
Collinge said that research would be needed to ensure that procedures like blood transfusions don't increase a person's chance of developing Alzheimer's.
