Blood Transfusion Study Asks: Is Alzheimer’s… Transmissible?

By | November 15th, 2023

Scientists found that people who receive blood from someone who experienced multiple brain bleeds also have a higher risk of developing these bleeds. The consensus so far: No cause for panic.

Before donating blood, healthcare technicians will screen for viruses like Hepatitis B and C to prevent the disease from being transmitted to a recipient. But viruses aren’t the only infectious agents in the blood that can make someone sick: Scientists are exploring whether proteins in the blood could also transmit beta-amyloid proteins, and potentially, Alzheimer’s disease. Here’s the question of the moment: Could cerebral amyloid angiopathy, a condition caused by Alzheimer’s biomarker amyloid buildup on blood vessels — which makes blood vessels more likely to rupture — transmit these proteins to others?

A study published in the journal JAMA drew on medical records of more than one million patients living in Denmark and Sweden, suggests that these amyloid plaques may be transmissible via blood transfusion. The researchers found that receiving a blood transfusion from a donor who had experienced multiple brain bleeds would make them three times more likely than individuals who received a donation from people without one to develop brain bleeds within the next six to 12 years.

“We speculate that there are factors in the blood that may speed up existing processes for CAA, but we do not have conclusive evidence for this,” the study’s lead author, Dr. Jingcheng Zhao, a neurologist at the Karolinska Institutet, told Being Patient. “So far, studies have not been able to show a link with dementia.”

No need to panic about blood transfusions

While the study results are provocative, more research is needed to figure out what is actually going on.

“We do not think we should change any policy based on our results, and more research is required,” Zhao added.

The researchers could not confirm whether or not the donors with brain bleeds had CAA and will require future studies to confirm whether amyloid is transmissible via blood and if it increases the chances of brain bleeds or Alzheimer’s. 

Many other conditions besides CAA may make someone more prone to brain bleeds. Several researchers took to AlzForum to comment on the findings of these results and universally found the findings intriguing, warranting a closer look.

“The results of this impressive and provocative study raise important questions that will stimulate necessary research on the mechanisms underlying vascular aging,” Larry Walker, professor at Emory University, wrote. However, he isn’t sure that beta-amyloid is responsible for brain bleeds in this case because CAA can take a lot of time to develop. 

“Perhaps rather than beta-amyloid seeds, the blood of subjects with multiple ICHs [brain bleeds] includes other agents that compromise the vasculature of recipients,” Walker wrote.

Dr. Henrik Zetterberg, a clinician and professor at the University of Gothenburg wrote that many researchers have argued that proteins like beta-amyloid have “prion-like characteristics”. This means that one misfolded beta-amyloid protein could cause other healthy beta-amyloid proteins to misfold and become toxic. 

“Their transmissible capacity in humans has been debated a lot, with little solid evidence except for prion disease,” Zetterberg noted. 

Were the vampires right all along?

If receiving a blood transfusion with proteins like beta-amyloid ages the brain and its blood vessels, could blood from healthy individuals do the opposite?  

Several researchers have explored this idea using a surgical technique that joins the blood circulation of a young mouse with that of an old mouse. The chemical signals and proteins in the young mice helped the older mice stay alive a few months longer. Tech billionaire Bryan Johnson is already running with the idea, receiving blood transfusions from his 17-year-old son in an effort to stave off aging altogether.

However, researchers haven’t been able to replicate these findings in humans yet. More research will be needed to determine whether factors in the blood can affect the brain and its risk of developing Alzheimer’s or other forms of dementia.

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