Is Alzheimer's Disease Contagious?

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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How Alzheimer's occurs is still largely unclear. One thing is certain: deposits form in the brain. But now there is much to suggest that the pathological deposits in the brain can be transferred to other people.

“Is Alzheimer's disease contagious?” The man who throws this question into the room is Prof. Armin Giese. He presented them at the opening press conference of Neurowoche 2014, which is currently taking place in Munich. It is the largest interdisciplinary congress of German-speaking clinical neuromedicine.

Alzheimer's as a communicable disease - the idea is terrifying! First. "That does not mean that you are not allowed to give your grandpa with dementia any more kisses," said conference president Prof. Wolfgang Oertel, correcting the situation. A simple transmission from person to person, such as with tuberculosis, AIDS or even flu, seems to be ruled out.

Matches with BSE

However, with Alzheimer's disease, so-called amyloid beta plaques, which are made up of incorrectly folded protein molecules, form in the brain. The structures are dubiously reminiscent of prions - those likewise misfolded proteins that appear in the brain in mad cow disease BSE and Creuzfeldt-Jakob disease and ultimately cause them to decay. And these two brain diseases are actually contagious, for example through the consumption of contaminated meat.

Alois Alzheimer, the discoverer of the disease of the same name, found the changes in the brain of his deceased dementia patient Auguste D. "These protein derivatives could not only be an accompanying phenomenon of Alzheimer's dementia, but the driving force behind the disease mechanism," says Giese.

Domino effect in the head

The discussion about this is not yet over. But there is increasing evidence that the tangled protein zombies, which cannot be broken down by the body, behave dynamically: “They develop a toxic domino effect,” explains the researcher. As soon as they come together with normally folded protein building blocks, they also cause a faulty restructuring of these. “It goes through the brain like a wave,” says the scientist.

This chain reaction could already be observed in cell cultures. And macaques that were injected with pathologically altered proteins into the brain also developed the pathological plaques. But that takes time: 12 to 14 years can pass before the fatal domino effect finally shows.

Contagion through blood products?

However, it is possible that the disease can also be transmitted in other ways than by injecting it into the brain - for example through blood. Because at least BSE prions cavort in the blood, albeit in small numbers. "Getting infected with Alzheimer's disease through a blood donation is actually an option, albeit a hypothetical one," says Giese.

One method to counteract this would be that people who have already received a blood donation are no longer allowed to donate themselves to be on the safe side. Similar to everyone who was in England at BSE weddings and perhaps ate a contaminated steak there. This would interrupt a possible chain of infection. "That would be an elegant solution - also for other known and unknown diseases," says Giese. However, there is one catch: You would have to do without many blood donors. And in an emergency, a person might have to bleed to death because there is no canned food available for them.

Chain reaction stopped

More important than the discussion about possible routes of transmission, however, are the options that arise from a more precise knowledge of the disease mechanism: namely the chance for new therapeutic approaches. So drugs that interrupt the protein chain reaction in the head. This would stop the fatal spread of plaques - in Alzheimer's disease but also in other diseases such as the classic prion diseases BSE and Creutzfeld-Jakob. Giese says: "At least with the latter we have the first promising results."

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