The idea that Alzheimer’s disease could spread via blood transfusions, has been causing a stir, and a new study has proved that this could be the truth. 

According to New Scientist, a study found that an Alzheimer’s protein can pass between mice sharing a blood supply. When a healthy mouse is conjoined with a mouse that has Alzheimer’s plaques, it will start to develop plaques of beta-amyloid protein in its own brain. When the plaqus form, their brain tissue starts to die. 

The results confirm that Alzheimer’s spreads via beta-amyloid in blood. Weihong Song, from the University of British Columbia in Canada, who led the work, explained, “The protein can get into the brain from a connected mouse and cause neurodegeneration.”

The team carried out the study on mice with a gene that makes the human version of beta-amyloid, because the animals don’t normally develop Alzheimer’s. This gene meant the mice developed brain plaques and neurodegeneration. 

Later, the team surgically attached mice with the Alzheimer’s like condition to healthy mice without the beta-amyloid gene, so that they shared a blood system.

As a result,the healthy mice began accumulating beta-amyloid in their brains. Within four moths, the mice also had altered patters of activity in brain regions that are key for learning and memory. This is the first time such a finding has been proved. 

“They somewhat convincingly show that it is possible to induce plaques in mice just by connecting the circulation,” said Gustaf Edgren, at the Karolinska Institute in Stockholm, Sweden. “It strengthens the case that beta-amyloid is infectious somehow, it may actually be a prion or act like a prion.”

The findings disagree with a study published earlier this year by Edgren and his colleagues, which tracked 2.1 million recipients of blood tranfusions across Sweden and Denmark. They found that those who received blood from people with Alzheimer’s didn’t seem to be at any greater risk of developing the disease. 

Edgren believes that their is a strong chance that the study didn’t run long enough to catch evidence that Alzheimer’s proteins might be transmissible. He said, “It could take a long time for the disease to develop, or there could not be enough data. A lot of researchers fear that it’s an infectious protein. 

Despite the results, stitching mice together is not a situation that applies to people. Mathias Jucker at the German Centre for Neurodegenerative Diseases in Tübingen doesn’t believe that the study show it is a transmissable disease. He also suggests that the team has not yet looked at the behaviour of the mice to see if they show signs of the cognitive decline characteristic of Alzheimer’s. 

Many will be aware of the difficulties involved in treating Alzheimer’s, a large part of which is the challenge of designing drugs that are able to cross the brain’sprotective barrier. Although the findings may lead to new medical approaches, it might be easier to target the protein in the bloodstream, which could have knock on effects for the brain, concluded Song.